Re: [Emc-users] Gear Tooth Profile
On Wed, 2009-05-13 at 18:17 +0200, Peter blodow wrote: Hello Kirk, I wonder how much fuss you guys are making about gear cutting. ... snip I managed to buy module 0.5 to 2 sets of 8 cutters each, in beautiful wooden boxes, almost unused, from a machine factory which had to move out of the town, for 50 Euros. Just keep looking! Large factories don't use this method of gear making because it takes longer than hobbing. Take to the guys at their coffee break. Look into ebay, not only in ebay.com for the US, but for instance at ebay.de or ebay.at. Don't be afraid of eastern European dealers, they need to make money just as we all and are as honest as we all are. :-)) There seems to be a lot of material the communist era has left which is now being socialized by private hands. Best regards Peter Blodow PS: Don't get me wrong: I studied physics and have been working in a research company for 34 years, so I know when to use complicated theory, but from my own private work I know when not... Thanks for the eBay hints. I wonder if eBay will some day have the clout to create a universal world-wide shipping system, no goofy tariffs, customs and other social swarf? So far, the gear cutters I have found have been expensive and limited. Using a rack cutter is one option, but then you need to know the ins and outs of the gear profiles to make the setup, and would require a rotary axis, which I am only lusting over at this point. I plan on making a few gears of very different forms each year, so investing in expensive and limited tooling, doesn't seem to make sense. A new rack cutter from MSCDirect cost about the same as a pair of gears from Mcmaster, if they happen to have the size I need. For the particular gear set I need now, I can make them from sheet material and they can be fairly large, so I can use a small end mill to cut the gear, but again this requires me to know the details of the gear tooth form. Finally, I enjoy learning about gear details, playing with math, plus some of what I have learned will be handy in other areas. If I had my production hat on, I would certainly be taking a different approach. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- Crystal Reports - New Free Runtime and 30 Day Trial Check out the new simplified licensing option that enables unlimited royalty-free distribution of the report engine for externally facing server and web deployment. http://p.sf.net/sfu/businessobjects ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
On Wed, May 13, 2009 at 6:13 AM, Kirk Wallace kwall...@wallacecompany.com wrote: On Tue, 2009-05-12 at 22:03 -0500, Stuart Stevenson wrote: Kirk, I have software (FAPT) that will generate the tooth profile using the information out of the machinery's handbook charts. I would be happy to input the data and send you the profile in G-code. Stuart Thank you Stuart. I am able to generate the tooth profiles, or rather points on the profile with QCAD by drawing the rack and doing the involute copy/move. This gives me an idea of what's going on. As I learn more, I am able to simplify the process. I have a particular 4:1 gear set I need for my turret encoder on the Shizuoka, which I have enough profile points on. I'll connect the dots with lines, then use dxf2gcode to get the .ngc file. see the g code I posted (in [Emc-users] [OT] Fun with Math thread) for 4 axis all it needs is a fly cutter ground to your rack form (near enough does not have to be uber accurate) and it will generate the form. Run it cutting air to get a feel for what it does. I wrote it for use on a vertical so the sideways movement is on Z It calculates the Z from the circumference of the PCD which is the rolling circle of the gear. Currently the depth of cut is hand set but should be calculated Addendum+Dedendum then PCD could be calculated from either Module or DP. Start point is turn blank to OD mount touch off to OD . Number of passes per slot was an arbitary number increase for a better curve. The 20 degree was also an arbitary number it should be calculated to make sure the complete curve is generated ie at the first pass it should just be cutting air. The code was thrown together Monday night in about an hour after watching this thread and the other. It wont take too much to add the few missing starting points and later to amend to 5 axis and helical involute generation (I know this as its hacked from code I use already for form tool gear milling) Dave Caroline (archivist) -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
At 01:23 AM 5/13/2009, you wrote: On Wed, 2009-05-13 at 07:24 +1000, Frank Tkalcevic wrote: On Tue, 2009-05-12 at 15:30 -0400, Douglas Pollard wrote: I don't know where to tell you to look but the metric gear info is out there somewhere for little or no money. I thought you where wrong here because I was getting nearly goose eggs, but I tried Googling metric gear rack profile and got this: http://www.sdp-si.com/d785/html1/D785T000.html On the sdp-si web site you can download 2d and 3d models of all the gears and pulleys they sell. Does anyone know if the models are accurate enough to generate gcode from? Sorry I don't have a .dwg compatible CAD program, so I can't view these gear files. From the links I have received, it's turning out that it's not that difficult to generate the gear profile ounce you have the pitch diameter and pitch determined, so the drawings might not be all that handy. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA Kurt, Can you read in .dxf's? If you want, you could send me the gear drawings of the gears you're interested in, and I can save them in AutoCad 2003 as dxf's and send them back to you. Mark -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
Sorry I don't have a .dwg compatible CAD program, so I can't view these gear files. From the links I have received, it's turning out that it's not that difficult to generate the gear profile ounce you have the pitch diameter and pitch determined, so the drawings might not be all that handy. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA Kurt, Can you read in .dxf's? If you want, you could send me the gear drawings of the gears you're interested in, and I can save them in AutoCad 2003 as dxf's and send them back to you. Mark SDP/SI exports 3D cad models in step, iges and dxf formats, if that helps. -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] gear tooth profile
try this site. Just type in the gear size and it will make you a cad drawing. http://www.rushgears.com/Tech_Tools/PartSearch3/partSearch.php -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
On Wed, 2009-05-13 at 09:07 +0100, Dave Caroline wrote: ... snip see the g code I posted (in [Emc-users] [OT] Fun with Math thread) for 4 axis all it needs is a fly cutter ground to your rack form (near ... snip It wont take too much to add the few missing starting points and later to amend to 5 axis and helical involute generation (I know this as its hacked from code I use already for form tool gear milling) Dave Caroline (archivist) Thanks Dave. I meant to reply to your g-code post, but I wanted to study it first. I still need to do that. I suppose I could load it in a sim configuration and save myself a lot of brain work. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
On Wed, 2009-05-13 at 05:29 -0400, Mark Wendt (Contractor) wrote: ... snip Kurt, Can you read in .dxf's? If you want, you could send me the gear drawings of the gears you're interested in, and I can save them in AutoCad 2003 as dxf's and send them back to you. Mark Thanks Mark. I will be generating the gear profiles from QCAD or a spreadsheet, so I don't need the conversion. I hope you don't mind me keeping you in mind for other .dwg files though. I think Frank wanted to know if a gear vendor's .dwg files were good for making gears. I responded with, I don't know, because I can't view them. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] gear tooth profile
On Wednesday 13 May 2009, Alpha wrote: try this site. Just type in the gear size and it will make you a cad drawing. http://www.rushgears.com/Tech_Tools/PartSearch3/partSearch.php Unforch, the site doesn't like FF newer than 2.00.20, and reports that no viewer is available for my OS of choice. Too bad, it does look like a neat site, one where one could order a custom made gearset and probably get it quicker than designing our own. There is a certain wide grin that is worth quite a lot to us when we are able to do it ourselves, but when the gearset we want can be had from Boston Gear for a fifty plus shipping? Use the BG gears get it done faster... -- Cheers, Gene There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order. -Ed Howdershelt (Author) Never invest your money in anything that eats or needs repainting. -- Billy Rose -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
At 11:11 AM 5/13/2009, you wrote: On Wed, 2009-05-13 at 05:29 -0400, Mark Wendt (Contractor) wrote: ... snip Kurt, Can you read in .dxf's? If you want, you could send me the gear drawings of the gears you're interested in, and I can save them in AutoCad 2003 as dxf's and send them back to you. Mark Thanks Mark. I will be generating the gear profiles from QCAD or a spreadsheet, so I don't need the conversion. I hope you don't mind me keeping you in mind for other .dwg files though. I think Frank wanted to know if a gear vendor's .dwg files were good for making gears. I responded with, I don't know, because I can't view them. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA Kirk, No problem, any time. Mark -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
Hello Kirk, I wonder how much fuss you guys are making about gear cutting. Small machine (table mill): Last year I bought a small, but high precision table mill with most of the gears missing, so I had to make them myself. They are module 0.8. I bought a set of 8 cutters in ebay from an ukrainian dealer for less than 15 Euros, set up my small division head, equipped with a stepper and off we went! I made a set of some 60 gears up to 200 teeth within a week, only after work. One tooth takes about 45 seconds. (Note: I never before made gear wheels!) 1.) Determine the number of teeth desired, add 2 and multiply by the module. That gives you the blank diameter in mm. 2.) Get a suiting blank (I got mine from the guy at the band saw cutting hydraulic piston rods, fine molybdenum steel for a tip). 3.) Turn blank to size, finish faces and bore. 4.) Mount blank on the mill's dividing head, center axes, adjust cutter to just scratch surface (touch off, is that right?) 5.) Move slide out of the way and adjust cutting depth (from the excel sheet) 6.) Lubricate, start mill and PC and watch. Large machine: I made a lot of other gears for my lathe, module 2, with the larger knee mill, but same setup except for mechanical feed in X. All the gears turned out to be of perfect shape, except for a few mischiefs I caused by my own fault. Those I turned down to make the next smaller blank. After about 2 or 3 gear wheels grind the cutter slightly. When making different size gears be sure to change the cutter according to the table. There is no need for much math, you need not even to use pi, even EMC isn't really necessary. The only figuring is to divide the number of teeth into the number of steps for one rotation of the dividing head. In my case: 40 (number of crank turns per rev.) 60 / 11 = 5.454545...: ratio of the gear belt drive on the dividing head 400: number of steps per rev. of the stepper motor 40 * 60 / 11 * 400 = 87272.727272... steps per one rev. of the divider For a 44 teeth gear: 87272.72727 / 44 = 1983.5 steps per tooth I give the stepper those 1983 pulses with a very simple demo software from the manufacturer of my stepper board (http://www.emisgmbh.de/fsoftware.htm;), to avoid errors alternatingly 1984, make the mill go through a cut once, crank back, start the stepper again etc. Module 2 gears I cut in two turns, smaller ones in one. After the last cut I add another just to listen if there has been any division error (you would hear one or two steps lost on the way because the cutter bites a few hundredths quite audibly). You'll know immediately if you had produced garbage or not. Keep in mind that you are cutting spaces, not teeth. I made a whole drawer full of these module 2 gears for the lathe. Hardening is not necessary for use in a lathe or mill, since there is little power transmitted, comparing the size, and short term use only. If a gear wears out, just make another one, or make two from the beginning. Telling from your picture, I would guess that the large red gear in front had module 3, the smaller in the background maybe 2, the small ones in the gear transmission on the left 1.75. Hard to tell without a measure in the picture (hint!). Determine your module from the formula in the excel sheet: Count the teeth, add two and divide this into the outer diameter. The figure two accounts for the fact that you can't very well measure the theoretical diameter where the gears really mesh. I managed to buy module 0.5 to 2 sets of 8 cutters each, in beautiful wooden boxes, almost unused, from a machine factory which had to move out of the town, for 50 Euros. Just keep looking! Large factories don't use this method of gear making because it takes longer than hobbing. Take to the guys at their coffee break. Look into ebay, not only in ebay.com for the US, but for instance at ebay.de or ebay.at. Don't be afraid of eastern European dealers, they need to make money just as we all and are as honest as we all are. :-)) There seems to be a lot of material the communist era has left which is now being socialized by private hands. Best regards Peter Blodow PS: Don't get me wrong: I studied physics and have been working in a research company for 34 years, so I know when to use complicated theory, but from my own private work I know when not... gear teeth.xls Description: Binary data -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
On Sat, 2009-05-09 at 11:45 -0700, Kirk Wallace wrote: I would like to make gears, but I need to know the tooth shape in order to make a form tool or cut an outline. This is what I came up with, if there are any mistakes or bad assumptions, please let me know. I referenced: http://en.wikipedia.org/wiki/Gear http://en.wikipedia.org/wiki/Involute_gear http://en.wikipedia.org/wiki/Involute http://en.wikipedia.org/wiki/Rack_and_pinion My example gear is a 2m(module) pitch - 20mm. A sample is on this page: http://www.qtcgears.com/RFQ/default.asp?Page=../KHK/newgears/KHK044.html (Short URL) http://alturl.com/whp2 Pitch is the tooth length, but expressed in pitch circle diameter, so a ... snip Dooh, I've had my Dad's Machinery's Handbook for almost twenty years and it hadn't occurred to me until now to see if there is any gear information it. It seems to cover everything I've been trying to hash out the last few days, including the ANSI 20 degree rack form. The gearing section is about four hundred pages, fortunately, about ten or fifteen cover what I need. One problem is my 1971 edition doesn't cover metric gears, so if anyone has any leads to the metric standards, I'd appreciate hearing from you. I suppose I could just buy a current edition. I found another interesting link here: http://science.howstuffworks.com/gear8.htm -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
Kirk Wallace wrote: On Sat, 2009-05-09 at 11:45 -0700, Kirk Wallace wrote: I would like to make gears, but I need to know the tooth shape in order to make a form tool or cut an outline. This is what I came up with, if there are any mistakes or bad assumptions, please let me know. I referenced: http://en.wikipedia.org/wiki/Gear http://en.wikipedia.org/wiki/Involute_gear http://en.wikipedia.org/wiki/Involute http://en.wikipedia.org/wiki/Rack_and_pinion My example gear is a 2m(module) pitch - 20mm. A sample is on this page: http://www.qtcgears.com/RFQ/default.asp?Page=../KHK/newgears/KHK044.html (Short URL) http://alturl.com/whp2 Pitch is the tooth length, but expressed in pitch circle diameter, so a ... snip Dooh, I've had my Dad's Machinery's Handbook for almost twenty years and it hadn't occurred to me until now to see if there is any gear information it. It seems to cover everything I've been trying to hash out the last few days, including the ANSI 20 degree rack form. The gearing section is about four hundred pages, fortunately, about ten or fifteen cover what I need. One problem is my 1971 edition doesn't cover metric gears, so if anyone has any leads to the metric standards, I'd appreciate hearing from you. I suppose I could just buy a current edition. I found another interesting link here: http://science.howstuffworks.com/gear8.htm My 1974, 19th Edition, Machinerys handbook, has British metric standards but they may be different. Their threads are. Seems everyone wanted to go metric, but they just wanted their own metric standards. -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
On Tue, 2009-05-12 at 14:21 -0400, Douglas Pollard wrote: Kirk Wallace wrote: On Sat, 2009-05-09 at 11:45 -0700, Kirk Wallace wrote: I would like to make gears, but I need to know the tooth shape in order ...snip My 1974, 19th Edition, Machinerys handbook, has British metric standards but they may be different. Their threads are. Seems everyone wanted to go metric, but they just wanted their own metric standards. I cruised Amazon.com, they have the 28th Edition for $66. It would probably the best CNC dollars I could spend. They appear to offer a limited number of any pages in the book as a preview, so I get a good start there. It's funny that eBay 28th Edition prices are much higher. I think a gear designer would be a great cloud computing application. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
Kirk Wallace wrote: On Tue, 2009-05-12 at 14:21 -0400, Douglas Pollard wrote: Kirk Wallace wrote: On Sat, 2009-05-09 at 11:45 -0700, Kirk Wallace wrote: I would like to make gears, but I need to know the tooth shape in order ...snip My 1974, 19th Edition, Machinerys handbook, has British metric standards but they may be different. Their threads are. Seems everyone wanted to go metric, but they just wanted their own metric standards. I cruised Amazon.com, they have the 28th Edition for $66. It would probably the best CNC dollars I could spend. They appear to offer a limited number of any pages in the book as a preview, so I get a good start there. It's funny that eBay 28th Edition prices are much higher. I think a gear designer would be a great cloud computing application. Most likely the info you want is in the 28th edition. Fully 90 % of the info you will need in the coming years is in the edition you have. I don't know where to tell you to look but the metric gear info is out there somewhere for little or no money. As to the Machinerys hand book my father had ,I think, the 6th edition , my older brother had the 11th About 1939. and my first one was the 13th edition about 1958 they all had mostly the same info though there were additions and deletions as new things came along and old ones became obsolete. My brothers son now is the proud owner of all three editions he is also a machinist. What ever you do keep the old book. I call my nephew from time to time and ask him to look up something in the old books. Doug -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
On Tue, 2009-05-12 at 15:30 -0400, Douglas Pollard wrote: I don't know where to tell you to look but the metric gear info is out there somewhere for little or no money. I thought you where wrong here because I was getting nearly goose eggs, but I tried Googling metric gear rack profile and got this: http://www.sdp-si.com/d785/html1/D785T000.html Looks good so far,but now I have more to read. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
Kirk, Are you wanting to develop the CAM algorithms for gear generation or are you just wanting the G-code for a specific gear profile? Stuart On Tue, May 12, 2009 at 3:10 PM, Kirk Wallace kwall...@wallacecompany.com wrote: On Tue, 2009-05-12 at 15:30 -0400, Douglas Pollard wrote: I don't know where to tell you to look but the metric gear info is out there somewhere for little or no money. I thought you where wrong here because I was getting nearly goose eggs, but I tried Googling metric gear rack profile and got this: http://www.sdp-si.com/d785/html1/D785T000.html Looks good so far,but now I have more to read. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- you can lead a person to knowledge but you cannot make him think -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
On Tue, 2009-05-12 at 15:30 -0400, Douglas Pollard wrote: I don't know where to tell you to look but the metric gear info is out there somewhere for little or no money. I thought you where wrong here because I was getting nearly goose eggs, but I tried Googling metric gear rack profile and got this: http://www.sdp-si.com/d785/html1/D785T000.html On the sdp-si web site you can download 2d and 3d models of all the gears and pulleys they sell. Does anyone know if the models are accurate enough to generate gcode from? -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
On Tue, 2009-05-12 at 17:24 -400, Frank Tkalcevic wrote: On Tue, 2009-05-12 at 15:30 -0400, Douglas Pollard wrote: I don't know where to tell you to look but the metric gear info is out there somewhere for little or no money. I thought you where wrong here because I was getting nearly goose eggs, but I tried Googling metric gear rack profile and got this: http://www.sdp-si.com/d785/html1/D785T000.html On the sdp-si web site you can download 2d and 3d models of all the gears and pulleys they sell. Does anyone know if the models are accurate enough to generate gcode from? I don't know about all the gear types, but I know the timing belt pulleys are accurate enough to machine from. HTH Greg www.distinctperspectives.com -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
Gentle persons: Kirk and others may find the following references to be useful: 1) The Involute Curve, Drafting a Gear in CAD and Applications, by Nick Carter. http://www.cartertools.com/involute.html 2) Direct Gear Design for Spur and Helical Involute Gears, by Alexander L. Kapelevich and Roderick E. Kleiss. http://www.akgears.com/pdf/direct.pdf Regarding calculating tables of values of Kirk's representation of an involute of a circle, or any other parametric equations, don't forget that OpenOffice Calc is a fully functional spreadsheet application that has all the necessary mathematical machinery including trig functions like sine, cosine, and arctangent. OpenOffice is available for and runs in Linux, Winders, etc. Like Microsoft Excel, it can generate various forms of plots, although I personally don't like either for generating publication-ready graphs. It should be easy to code up Calc and/or Excel programs to automate the calculations discussed in the above papers. As for displaying mathematical functions easily, one can take advantage of the OpenOffice Math interface, but since I'm an old-fart (it's official, even the Social Security Administration says so), I use LaTeX, which has been around since the days when all we had were mainframe computers (and had to walk barefoot through the snow to hand over our punched card decks to the operator at the counter). Now that MathML is fairly mature, there is a lot of interest in MathML-based tools. See, for example, the following MIT pages on displaying mathematics: http://web.mit.edu/acs/faq/webmath/contents.html and http://web.mit.edu/ist/topics/webpublishing/mathml/ Finally, regarding the Machinery's Handbook, just find the cheapest price for any recent edition. I bought my 26th Edition (2002) copy on eBay in 2005 for about $35. With the exception of a torn fly leaf, it was in pristine condition. Sometimes eBay is cheapest, sometimes abebooks.com, sometimes amazon.com. Like everything else, you have to be patient. Regards, Kent -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
Kirk, I have software (FAPT) that will generate the tooth profile using the information out of the machinery's handbook charts. I would be happy to input the data and send you the profile in G-code. Stuart On Tue, May 12, 2009 at 9:22 PM, Kent A. Reed knbr...@erols.com wrote: Gentle persons: Kirk and others may find the following references to be useful: 1) The Involute Curve, Drafting a Gear in CAD and Applications, by Nick Carter. http://www.cartertools.com/involute.html 2) Direct Gear Design for Spur and Helical Involute Gears, by Alexander L. Kapelevich and Roderick E. Kleiss. http://www.akgears.com/pdf/direct.pdf Regarding calculating tables of values of Kirk's representation of an involute of a circle, or any other parametric equations, don't forget that OpenOffice Calc is a fully functional spreadsheet application that has all the necessary mathematical machinery including trig functions like sine, cosine, and arctangent. OpenOffice is available for and runs in Linux, Winders, etc. Like Microsoft Excel, it can generate various forms of plots, although I personally don't like either for generating publication-ready graphs. It should be easy to code up Calc and/or Excel programs to automate the calculations discussed in the above papers. As for displaying mathematical functions easily, one can take advantage of the OpenOffice Math interface, but since I'm an old-fart (it's official, even the Social Security Administration says so), I use LaTeX, which has been around since the days when all we had were mainframe computers (and had to walk barefoot through the snow to hand over our punched card decks to the operator at the counter). Now that MathML is fairly mature, there is a lot of interest in MathML-based tools. See, for example, the following MIT pages on displaying mathematics: http://web.mit.edu/acs/faq/webmath/contents.html and http://web.mit.edu/ist/topics/webpublishing/mathml/ Finally, regarding the Machinery's Handbook, just find the cheapest price for any recent edition. I bought my 26th Edition (2002) copy on eBay in 2005 for about $35. With the exception of a torn fly leaf, it was in pristine condition. Sometimes eBay is cheapest, sometimes abebooks.com, sometimes amazon.com. Like everything else, you have to be patient. Regards, Kent -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- you can lead a person to knowledge but you cannot make him think -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
On Tue, 2009-05-12 at 22:03 -0500, Stuart Stevenson wrote: Kirk, I have software (FAPT) that will generate the tooth profile using the information out of the machinery's handbook charts. I would be happy to input the data and send you the profile in G-code. Stuart Thank you Stuart. I am able to generate the tooth profiles, or rather points on the profile with QCAD by drawing the rack and doing the involute copy/move. This gives me an idea of what's going on. As I learn more, I am able to simplify the process. I have a particular 4:1 gear set I need for my turret encoder on the Shizuoka, which I have enough profile points on. I'll connect the dots with lines, then use dxf2gcode to get the .ngc file. I do have some other projects that need gears. For instance, they don't show up in this photo: http://www.wallacecompany.com/old_lathe/head-1a.jpg but there are a bunch of teeth missing from the small spindle gear and the back gear set on this lathe. I am considering, making new parts from scratch. I think I'll learn enough from the encoder project to be able to get these gears done. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
On Wed, 2009-05-13 at 07:24 +1000, Frank Tkalcevic wrote: On Tue, 2009-05-12 at 15:30 -0400, Douglas Pollard wrote: I don't know where to tell you to look but the metric gear info is out there somewhere for little or no money. I thought you where wrong here because I was getting nearly goose eggs, but I tried Googling metric gear rack profile and got this: http://www.sdp-si.com/d785/html1/D785T000.html On the sdp-si web site you can download 2d and 3d models of all the gears and pulleys they sell. Does anyone know if the models are accurate enough to generate gcode from? Sorry I don't have a .dwg compatible CAD program, so I can't view these gear files. From the links I have received, it's turning out that it's not that difficult to generate the gear profile ounce you have the pitch diameter and pitch determined, so the drawings might not be all that handy. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
On Tue, 2009-05-12 at 22:22 -0400, Kent A. Reed wrote: Gentle persons: Kirk and others may find the following references to be useful: 1) The Involute Curve, Drafting a Gear in CAD and Applications, by Nick Carter. http://www.cartertools.com/involute.html 2) Direct Gear Design for Spur and Helical Involute Gears, by Alexander L. Kapelevich and Roderick E. Kleiss. http://www.akgears.com/pdf/direct.pdf Thanks Kent. These are good links. Regarding calculating tables of values of Kirk's representation of an involute of a circle, or any other parametric equations, don't forget that OpenOffice Calc is a fully functional spreadsheet application that has all the necessary mathematical machinery including trig functions like sine, cosine, and arctangent. OpenOffice is available for and runs in Linux, Winders, etc. Like Microsoft Excel, it can generate various forms of plots, although I personally don't like either for generating publication-ready graphs. It should be easy to code up Calc and/or Excel programs to automate the calculations discussed in the above papers. It didn't occur to me to use OpenOffice. Sometimes I can't see the forest for the trees. As for displaying mathematical functions easily, one can take advantage of the OpenOffice Math interface, but since I'm an old-fart (it's official, even the Social Security Administration says so), I use LaTeX, which has been around since the days when all we had were mainframe computers (and had to walk barefoot through the snow to hand over our punched card decks to the operator at the counter). Now that MathML is fairly mature, there is a lot of interest in MathML-based tools. See, for example, the following MIT pages on displaying mathematics: http://web.mit.edu/acs/faq/webmath/contents.html and http://web.mit.edu/ist/topics/webpublishing/mathml/ I'll have to check these links out when I get time. Also, it's interesting what you get when one searches latex on Google. Finally, regarding the Machinery's Handbook, just find the cheapest price for any recent edition. I bought my 26th Edition (2002) copy on eBay in 2005 for about $35. With the exception of a torn fly leaf, it was in pristine condition. Sometimes eBay is cheapest, sometimes abebooks.com, sometimes amazon.com. Like everything else, you have to be patient. Regards, Kent It took me a while to realize that the British metric section in my nineteenth edition is still applicable, or close enough. I agree there are great deals to be had on eBay, but it seems to be getting harder, or maybe, more fun. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
On Sat, 2009-05-09 at 22:13 +0100, Dave Caroline wrote: ... snip If you make a generic cgode involute program I would be interested seeing it. Dave Caroline It's not g-code, but is what I have so far: http://www.wallacecompany.com/machine_shop/gears/involute_equation-1a.png (Short URL) http://alturl.com/oqwv -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
I would like to make a rack that matches an involute gear. I guess we could just put in a radius of a 'very large' number, rather than infinity. The square root radical would evaluate to the square root of 2, but I don't know what I would use as the value of alpha. Suggestions? IHS ... Jack On Mon, May 11, 2009 at 2:42 AM, Kirk Wallace kwall...@wallacecompany.comwrote: On Sat, 2009-05-09 at 22:13 +0100, Dave Caroline wrote: ... snip If you make a generic cgode involute program I would be interested seeing it. Dave Caroline It's not g-code, but is what I have so far: http://www.wallacecompany.com/machine_shop/gears/involute_equation-1a.png (Short URL) http://alturl.com/oqwv -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
just get(calculate or read a table) the circular pitch of the gear and cut an acme form of that pitch on the rack the angle is as quoted for the gear you are using, either 14.5 deg or 20 Dave Caroline On Mon, May 11, 2009 at 12:05 PM, Jack Coats j...@coats.org wrote: I would like to make a rack that matches an involute gear. I guess we could just put in a radius of a 'very large' number, rather than infinity. The square root radical would evaluate to the square root of 2, but I don't know what I would use as the value of alpha. Suggestions? IHS ... Jack On Mon, May 11, 2009 at 2:42 AM, Kirk Wallace kwall...@wallacecompany.comwrote: On Sat, 2009-05-09 at 22:13 +0100, Dave Caroline wrote: ... snip If you make a generic cgode involute program I would be interested seeing it. Dave Caroline It's not g-code, but is what I have so far: http://www.wallacecompany.com/machine_shop/gears/involute_equation-1a.png (Short URL) http://alturl.com/oqwv -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
On Mon, 2009-05-11 at 06:05 -0500, Jack Coats wrote: I would like to make a rack that matches an involute gear. I guess we could just put in a radius of a 'very large' number, rather than infinity. The square root radical would evaluate to the square root of 2, but I don't know what I would use as the value of alpha. Suggestions? IHS ... Jack I believe the involute of a circle with infinite diameter, which makes the circumference a line, is a perpendicular line. The involute describes the path the pinion tooth takes in relation to the rack tooth as the pinion tooth rotates away from the rack. The involute says nothing about the tooth shape, the rack shape defines this, and can be any shape you want. My assumption is that common rack shapes are trapezoidal, symmetrical about the pitch center line because the relative angular velocity between resulting gears turns out to be constant or smooth. The common trapezoidal rack shapes have 20 degree and 14.5 degree side angles relative to a perpendicular to the pitch center plane. If you have a gear with unknown specifications, you could measure the tooth form, then use the gear's involute path to derive the rack shape. The problem here is, you need the pitch diameter of your gear to get the involute. Because of tooth base and tip clearance issues, the pitch can't be easily measured. You could roll the gear on a flat sheet of clay to make a rack, then study the shape to guess at what the ideal shape might be. There should be a a way to do this mathematically, but I haven't given this much thought. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
On Sat, May 09, 2009 at 11:22:20PM +0100, Dave Caroline wrote: I have a single tooth rack form carbide cutter...I feel this should be relatively simple to code as a generic x module x teeth 4 axis. Involute teeth should be able to be cut with that, if you run many passes, moving it between passes, in Z relative to a vertical gear, as it is stepwise rotated. (We're cutting the horizontal tooth, here.) In a higher productivity version of that, in Model Engineering Workshop magazine issue 72, page 54, the author used a 4 tooth _non_helical_ acme hob to take successive passes at -,0,+ elevation with the gear rotated proportionately, to produce a piecewise-linear approximation to the correct form. IIRC, he did about 4 passes, then ran two such gears together, to finish the job. (Just as you recommend) It transmitted power to his satisfaction. I'd love to hear such gears running. Perhaps that mimicss how the involute form was discovered? Brick-sized wooden cogs, in gearwheels several meters across, were used in water and windmills. With the corners cut off, they ran, but wore down, due to sliding rather than rolling friction. Once they'd worn to shape, the rolling instead of sliding friction preserved their shape, and the rattling stopped. The pain with hobbing (even in prospect) must surely be the building of a hobbing machine. That isn't necessary any more, though. A stepper motor suffices to rotate the gashed gear blank in synchronism with the hob. (i.e 1 tooth for every hob rotation) In MEW issue 75, a simple programmable divider was used to vary the gear ratio between hob and blank, to determine the number of teeth. (I still haven't tried it myself, for lack of a need for gears.) Tilting of the hob and gear blank (to the hob's helix angle), as described earlier in this thread, will produce a spur gear. That's maybe easiest, because feed is along the gear's axis. But spur gears tend to run noisily, compared to helical gears, so it would be attractive to be able to make them. If the hob axis remains perpendicular to the gear axis, then we are in a position to begin cutting a helical gear, I figure. The feed needs to be at the helix angle, or there'll be no teeth left when we finish. Also, my mental image says we need to adjust the phase of the gear relative to the hob, as we feed across the tooth width. That is because the middle of a helical tooth leads one side by half a tooth pitch, and so must be cut by the hob earlier in its rotation. A simple programmable divider can't do that, but a processor in its place can. Hand grinding the rack form on flycutters will be easy enough and you can run the gear pairs in after making. The cycle time to make is going to be a bit slow though hobbing will always win there and hobbing cutters are pretty cheap for certain sizes we just need to convince EMC about geared spindles to match a real machine. Yes, two rotary axes, driven with a fixed ratio (= desired number of gear teeth), and a fixed phase relationship to the hob's index pulse for spur gears, or proportional to helix angle and current feed travel for helical, should spit out a good involute gear quite quickly. And if one has a lathe, then there's not much need to buy a hob. Even the hardening and annealing would be interesting. Some recommend annealing by sliding a hot plug of copper or aluminium into the hob, so the tips are the hardest, not softest, part. But my mobo has just run its first latency test, and isn't in a box yet. It'll be some time before I could dream of making gears. (Yes, my little mill has a swivelling table, so can feed at the helix angle, relative to the horizontal spindle. I just don't know whether it's worth converting to CNC.) Erik -- Never worry about theory as long as the machinery does what it's supposed to do. -- Robert A. Heinlein -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
There was some information on the South Bend lathe list where a fellow claimed that a perfect generated tooth for can be cut by useing a tap running on the perifery of a gear blank and feeding across the face. The blank is left to freewheel and be pulled around by the tap. He claims it makes a perfect tooth??? This method certainly works for making wormwheels - I have used it a number of times and the worm only needs to be a length of screwed rod the same size as the tap. My little rotary table on the mill uses 10mm threaded rod running against a brass wormwheel cut with a tap. The only difficulty is in getting the right number of teeth in the wheel as it is almost impossible to calculate properly. The wheel on my rotary took three attempts to get the right number of teeth but, since it only takes a matter of a couple of minutes to cut the teeth, that is no big deal. I put the tap in the lathe chuck and I screwed a stub 'axle' vertically into a bar held in the toolpost. The blank ran free on this axle but I had a nut on a little threaded bit at the top end to stop the blank from lifting while it was being cut. This, of course, produces a concave thread but, on a wormwheel, that can be an advantage as it gives more contact with the worm. If you wanted to use this method for cutting wheels, it would work but you would have to tip the blank over to the helix angle of the thread to get straight teeth and move the blank vertically as well to get teeth which are even across the wheel. Of course, you may be able to consider making helical gears but you would need both right and left hand taps for this. -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
[Emc-users] Gear Tooth Profile
I would like to make gears, but I need to know the tooth shape in order to make a form tool or cut an outline. This is what I came up with, if there are any mistakes or bad assumptions, please let me know. I referenced: http://en.wikipedia.org/wiki/Gear http://en.wikipedia.org/wiki/Involute_gear http://en.wikipedia.org/wiki/Involute http://en.wikipedia.org/wiki/Rack_and_pinion My example gear is a 2m(module) pitch - 20mm. A sample is on this page: http://www.qtcgears.com/RFQ/default.asp?Page=../KHK/newgears/KHK044.html (Short URL) http://alturl.com/whp2 Pitch is the tooth length, but expressed in pitch circle diameter, so a 10 tooth gear with a 20mm pitch circle = 20mm/10t = 2, but this is not the linear tooth length. I believe the basis for involute gears is the trapezoidal rack, so I need the linear tooth length, which should be 2 module x pi. A common pressure angle is 20 degrees. I assumed the rack base and top are horizontally midway between the rack center line and the 20 degree peaks, such that the X length of the rise, flats and falls are equal. Here is my rack and pitch circle: http://www.wallacecompany.com/machine_shop/gears/rack_and_pitch_circle.png (Short URL) http://alturl.com/7t8a The first pinion tooth form guess is the complementary shape of the rack tooth, but as the rack moves the pinion rotates and lifts, so the pinion tooth shape needs to change to take the trapezoidal shape that matches the rotation and lift. If I move the rack one quarter of a tooth the pinion will rotate a proportionate angle. 1/4t = 1.5708mm C = pi x D = pi x 20mm = 62.832mm = 360 degrees 360deg x 1.5708mm/62.832mm = 9 degrees per 1/4t If I move the rack shape 1/4t to the right, then rotate it 9 deg clockwise back to the home position, the mesh point will be somewhere on the new shape. http://www.wallacecompany.com/machine_shop/gears/rack_and_quarter_tooth.png (Short URL) http://alturl.com/gd75 If I continue the process, I'll have more mesh points. http://www.wallacecompany.com/machine_shop/gears/rack_and_pinion_shape.png (Short URL) http://alturl.com/54oj I can then trim the lines, mirror the shape on the tooth center line, guess at a tip and base clearance shape. http://www.wallacecompany.com/machine_shop/gears/gear.png (Short URL) http://alturl.com/cqcw The problem is, have I made any mistakes? Is there a better, easier way? -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
Kirk Wallace wrote: I would like to make gears, but I need to know the tooth shape in order to make a form tool or cut an outline. This is what I came up with, if there are any mistakes or bad assumptions, please let me know. I'm no gear expert, but I have a few comments. The only gears I've made are worm gears, and I hobbed them so the tooth shape was generated automatically. I referenced: http://en.wikipedia.org/wiki/Gear http://en.wikipedia.org/wiki/Involute_gear http://en.wikipedia.org/wiki/Involute http://en.wikipedia.org/wiki/Rack_and_pinion My example gear is a 2m(module) pitch - 20mm. A sample is on this page: http://www.qtcgears.com/RFQ/default.asp?Page=../KHK/newgears/KHK044.html (Short URL) http://alturl.com/whp2 Pitch is the tooth length, but expressed in pitch circle diameter, so a 10 tooth gear with a 20mm pitch circle = 20mm/10t = 2, but this is not the linear tooth length. I believe the basis for involute gears is the trapezoidal rack, so I need the linear tooth length, which should be 2 module x pi. A common pressure angle is 20 degrees. I assumed the rack base and top are horizontally midway between the rack center line and the 20 degree peaks, such that the X length of the rise, flats and falls are equal. Here is my rack and pitch circle: I think that assumption might not be valid. I believe the height above the pitch line, and the depth below the pitch line have names - addendum and dedendum IIRC, and they are not necessarily equal to each other. In particular, for a pinion with a small tooth count like yours, the dedendum is made less to avoid undercutting the teeth - the undercut shows up in your last image. That would result in weak teeth if the gear was heavily stressed. http://www.wallacecompany.com/machine_shop/gears/rack_and_pitch_circle.png (Short URL) http://alturl.com/7t8a The first pinion tooth form guess is the complementary shape of the rack tooth, but as the rack moves the pinion rotates and lifts, so the pinion tooth shape needs to change to take the trapezoidal shape that matches the rotation and lift. If I move the rack one quarter of a tooth the pinion will rotate a proportionate angle. 1/4t = 1.5708mm C = pi x D = pi x 20mm = 62.832mm = 360 degrees 360deg x 1.5708mm/62.832mm = 9 degrees per 1/4t If I move the rack shape 1/4t to the right, then rotate it 9 deg clockwise back to the home position, the mesh point will be somewhere on the new shape. http://www.wallacecompany.com/machine_shop/gears/rack_and_quarter_tooth.png (Short URL) http://alturl.com/gd75 If I continue the process, I'll have more mesh points. http://www.wallacecompany.com/machine_shop/gears/rack_and_pinion_shape.png (Short URL) http://alturl.com/54oj I can then trim the lines, mirror the shape on the tooth center line, guess at a tip and base clearance shape. http://www.wallacecompany.com/machine_shop/gears/gear.png (Short URL) http://alturl.com/cqcw The problem is, have I made any mistakes? Is there a better, easier way? I think your derivation of the shape is correct. There is probably a mathematically purer way (one that doesn't involve small increments of motion that you then blend into the form). But I like your way better. Note that what you did on paper is what happens in metal when you hob a gear. Imagine that your rack is actually one side of an acme threaded rod. Since the screw threads are helical, not just rings around the rod, the rack teeth are inclined where they meet the gear. So you have to lift one end of the rod out of the paper, until the helix angle is canceled out. Then you cut flutes on the rod, and spin both rod and gear blank, so you get the effect of the gear rolling along the rack. Finally, you slowly feed the rod across the face of the gear. The other approach is to buy a gear cutter with the proper form. Note that unlike a hob (which can be used to cut gears with any number of teeth), a gear cutter is designed for a specific range of teeth. I think there is usually a set of 8 to cut everything from 12 tooth pinions thru many tooth gears up to a rack (basically a gear with an infinite number of teeth). Regards, John Kasunich -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
On Sat, 2009-05-09 at 15:07 -0400, John Kasunich wrote: Kirk Wallace wrote: ... snip I assumed the rack base and top are horizontally midway between the rack center line and the 20 degree peaks, such that the X length of the rise, flats and falls are equal. Here is my rack and pitch circle: I think that assumption might not be valid. I believe the height above the pitch line, and the depth below the pitch line have names - addendum and dedendum IIRC, and they are not necessarily equal to each other. In particular, for a pinion with a small tooth count like yours, the dedendum is made less to avoid undercutting the teeth - the undercut shows up in your last image. That would result in weak teeth if the gear was heavily stressed. A thought I had on this, is that for different gears of the same pitch to work together they need to have the same base rack form. Since a gear and it's mate can be derived from the top or bottom of the base rack form, the base form should be symmetrical. A non-symmetrical base form could be used, but I think the gear pair will only work with its original mate. Actually, the more I think, the rack base and top lines don't even count, because the mesh zone is well within these limits. I could do the derivation again with a sawtooth instead of a trapezoidal form. I suspect the way to adjust the addendum/dedendum is with pressure angle, but this is just a hunch at this point. I think I have enough to make what I need, so I'm not sure how far I'll get on this issue. Some engineers have made a life on these matters, I've only got spare time. http://www.wallacecompany.com/machine_shop/gears/rack_and_pitch_circle.png (Short URL) http://alturl.com/7t8a The first pinion tooth form guess is the complementary shape of the rack ... snip The problem is, have I made any mistakes? Is there a better, easier way? I think your derivation of the shape is correct. There is probably a mathematically purer way (one that doesn't involve small increments of motion that you then blend into the form). But I like your way better. Wikipedia covers the involute equations, but I suspect the mesh points are not on obvious function points. Note that what you did on paper is what happens in metal when you hob a gear. Imagine that your rack is actually one side of an acme threaded ... snip My one real CNC employer had an old gear hob machine. The problem was it was easy to stand and watch it, right through your break. Another problem was that when the guy that runs it retires, the machine gets scrapped. The other approach is to buy a gear cutter with the proper form. Note that unlike a hob (which can be used to cut gears with any number of teeth), a gear cutter is designed for a specific range of teeth. I think there is usually a set of 8 to cut everything from 12 tooth pinions thru many tooth gears up to a rack (basically a gear with an infinite number of teeth). Gear cutting tools are too expensive for me since I usually need one or a few of each. Having a way to make any gear without special tooling would be a big plus. One reason I am looking at a 2m - 10mm gear is that I can use a .063 end mill to cut a thin version. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
Hobbing is easy if you can measure the gear in some way easily, I use the OD as my size reference and infeed re run to size, the nice thing about a hobbing machine (well the one here anyway) is you can go back to the start and still be in gear and run again. As for the use of an endmill to create the form we had a user in IRC who posted a picture of his day job doing just that but on a very large scale, I use a slitting saw to do escape wheels for clocks so is an interesting exercise in roughing out then following the form. A form tool is easiest for plain gears but then you are limited to tooth number ranges as JMK mentioned. If you make a generic cgode involute program I would be interested seeing it. Dave Caroline -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
On Sat, 2009-05-09 at 22:13 +0100, Dave Caroline wrote: Hobbing is easy if you can measure the gear in some way easily, I use the OD as my size reference and infeed re run to size, the nice thing about a hobbing machine (well the one here anyway) is you can go back to the start and still be in gear and run again. As for the use of an endmill to create the form we had a user in IRC who posted a picture of his day job doing just that but on a very large scale, I use a slitting saw to do escape wheels for clocks so is an interesting exercise in roughing out then following the form. A form tool is easiest for plain gears but then you are limited to tooth number ranges as JMK mentioned. If you make a generic cgode involute program I would be interested seeing it. Dave Caroline Here is the involute I believe applies to my gear. http://www.wallacecompany.com/machine_shop/gears/involute.png The dots to the right on the horizontal line are spaced 9 degrees of pitch circle apart. So when the pinion rotates 9 degrees it moves one dot on the rack. The left side shows the same horizontal dots but rotated around the pinion center the corresponding degrees. The yellow lines are the distance of the corresponding 9 degree moves. The red line is the involute of the pitch circle. It's just an XY move and a rotate for each point. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
On Sat, 2009-05-09 at 17:10 -0400, Douglas Pollard wrote: Kirk Wallace wrote: On Sat, 2009-05-09 at 15:07 -0400, John Kasunich wrote: ... snip It has been my understanding that the number eight cutter will cut a gear with 12 and 13 teeth. If you get below 12 teeth there has to be undercutting for the teeth to run right without chafing against each other. The problem is you can't cut the base of the tooth where the required path narrows the base, which is a problem if your setup requires you to keep the cutter's center radial plane in line with the gear axis. I would think that a 10 tooth gear would need to be generated with a hob or a gear shaper. There was some information on the South Bend lathe list where a fellow claimed that a perfect generated tooth for can be cut by useing a tap running on the perifery of a gear blank and feeding across the face. The blank is left to freewheel and be pulled around by the tap. He claims it makes a perfect tooth??? Doug Well the tap has a trapezoidal shape, just like a hob cutter. After a couple of turns of the gear, the tap and gear might self synchronize, like a knurling tool does. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Gear Tooth Profile
I have a single tooth rack form carbide cutter...I feel this should be relatively simple to code as a generic x module x teeth 4 axis. Hand grinding the rack form on flycutters will be easy enough and you can run the gear pairs in after making. The cycle time to make is going to be a bit slow though hobbing will always win there and hobbing cutters are pretty cheap for certain sizes we just need to convince EMC about geared spindles to match a real machine. Dave Caroline -- The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
