Our Father would be so proud. (Eli Whitney) Some of you younger guys, (less than 65) might find reading his book on the theory of tolerancing parts very useful. I agree that the application of CAD drawing has put a lot of the actual design stuff in the box, out of sight, like tolerancing. Just like before, you always have to manually stack the tolerances of all interconnecting parts just to make sure. Eli has some thoughts on that also. My pet rant is getting a so called drawing from someone with all the line weights exactly the same. When did ANSI change the drafting standards to allow a part edge to be the same weight as an extension line? On Sun, 2009-06-14 at 14:53 +0000, [email protected] wrote: > Send Emc-users mailing list submissions to > [email protected] > > To subscribe or unsubscribe via the World Wide Web, visit > https://lists.sourceforge.net/lists/listinfo/emc-users > or, via email, send a message with subject or body 'help' to > [email protected] > > You can reach the person managing the list at > [email protected] > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Emc-users digest..." > > > Today's Topics: > > 1. Re: Roles in the manufacturing chain (was Metriks) (Matt Shaver) > 2. Re: Roles in the manufacturing chain (was Metriks) > (Stuart Stevenson) > 3. Re: DIY encoder chipset (Dirk) > 4. Re: .ngc file RFReview (Kirk Wallace) > 5. Re: DIY encoder chipset (Frank Tkalcevic) > 6. Re: DIY encoder chipset (Sven Wesley) > 7. Re: Roles in the manufacturing chain (was Metriks) > (Douglas Pollard) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Sat, 13 Jun 2009 18:36:18 -0400 > From: Matt Shaver <[email protected]> > Subject: Re: [Emc-users] Roles in the manufacturing chain (was > Metriks) > To: "Enhanced Machine Controller (EMC)" > <[email protected]> > Message-ID: <1244932578.5951.16.ca...@m2a-vm> > Content-Type: text/plain > > On Sat, 2009-06-13 at 11:27 +0100, Andy Pugh wrote: > > Most of the dimensions for the general geometry were +/- 0.2mm except > > for the flexural element, which was 0.2mm +/- 0.05mm dimensioned from > > a face with a stacked-up positional tolerance of about 0.4mm. > > The machinist set up his CNC mill to the centre value of each > > tolerance starting from a part edge and pressed "go". When the program > > finished the flexural element was not even there. > > > > Who was at fault? I argued that the wider tolerances elsewhere in the > > geometry were specifically so that they could get the flexure right, > > they said "You always work to mid-tolerance, and the drawing should > > assume that" > > The machinist. I used to do job shop work in my shop. The feature that > you described should be inspect-able, and the from dimension you quote > it should have measured (by whatever method is appropriate) > between .15mm and .25mm. Since it was not there, we can assume that it > would measure 0.00mm and is therefore out of tolerance. > > I have heard this "middle of the tolerance" argument many times and it > is as wrong today as it ever has been. And I was on the side > (machinists) that tried to use it to our advantage! > > If the stack-up of multiple tolerances actually prevent the part from > being made such that each individual tolerance limit can be observed, > then the drawing should go back to drafting with that explanation. If > you actually make the part, then it must pass inspection, even if some > features must be created near their tolerance limits to allow other > features to exist within their own tolerance limits. The "middle" of the > tolerance band is no more valid or important than any other point within > the tolerance limits. > > Wow, who would have thought I was this opinionated? :) > > Thanks, > Matt > > > > > > ------------------------------ > > Message: 2 > Date: Sat, 13 Jun 2009 20:50:22 -0500 > From: Stuart Stevenson <[email protected]> > Subject: Re: [Emc-users] Roles in the manufacturing chain (was > Metriks) > To: [email protected], "Enhanced Machine Controller (EMC)" > <[email protected]> > Message-ID: > <[email protected]> > Content-Type: text/plain; charset=UTF-8 > > Gentlemen, > As loooonnnngggg as opinions are being proffered. > When we encounter a print that the 'nominals' will not make the > part as drawn we wonder just 'who the hell drew this?'. A license from > a crackerjack box does not make a draftsman. With the advent of CAD > this discovery is waning. A solid model is a wonderful thing. > The only time you should have to 'fudge' the numbers is when you > are making parts from forgings or casting. Tolerance stackage, > warpage, die slippage and a host of other 'ages' can cause the > features to shift. Most of the time a forging or casting will have a > sweet spot. Find the sweet spot prior to making the first cut and you > are home free. > Our aerospace customers want the parts as close to nominal as > possible. They would like all parts to be 'dead on' so the parts weigh > the expected amount. No more/ no less. They allow tolerances because > perfection is not attainable but they wish for you to get closer with > each succeeding part. > thanks for reading my rant > Stuart > > On Sat, Jun 13, 2009 at 5:36 PM, Matt Shaver<[email protected]> wrote: > > On Sat, 2009-06-13 at 11:27 +0100, Andy Pugh wrote: > >> Most of the dimensions for the general geometry were +/- 0.2mm except > >> for the flexural element, which was 0.2mm +/- 0.05mm dimensioned from > >> a face with a stacked-up positional tolerance of about 0.4mm. > >> The machinist set up his CNC mill to the centre value of each > >> tolerance starting from a part edge and pressed "go". When the program > >> finished the flexural element was not even there. > >> > >> Who was at fault? I argued that the wider tolerances elsewhere in the > >> geometry were specifically so that they could get the flexure right, > >> they said "You always work to mid-tolerance, and the drawing should > >> assume that" > > > > The machinist. I used to do job shop work in my shop. The feature that > > you described should be inspect-able, and the from dimension you quote > > it should have measured (by whatever method is appropriate) > > between .15mm and .25mm. Since it was not there, we can assume that it > > would measure 0.00mm and is therefore out of tolerance. > > > > I have heard this "middle of the tolerance" argument many times and it > > is as wrong today as it ever has been. And I was on the side > > (machinists) that tried to use it to our advantage! > > > > If the stack-up of multiple tolerances actually prevent the part from > > being made such that each individual tolerance limit can be observed, > > then the drawing should go back to drafting with that explanation. If > > you actually make the part, then it must pass inspection, even if some > > features must be created near their tolerance limits to allow other > > features to exist within their own tolerance limits. The "middle" of the > > tolerance band is no more valid or important than any other point within > > the tolerance limits. > > > > Wow, who would have thought I was this opinionated? :) > > > > Thanks, > > Matt > > > > > > > > ------------------------------------------------------------------------------ > > 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 > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > > > -- > you can lead a person to knowledge > but you cannot make him think > > > > ------------------------------ > > Message: 3 > Date: Sun, 14 Jun 2009 06:58:02 +0200 > From: Dirk <[email protected]> > Subject: Re: [Emc-users] DIY encoder chipset > To: "Enhanced Machine Controller \(EMC\)" > <[email protected]> > Message-ID: <[email protected]> > Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes > > > On Jun 13, 2009, at 11:36 PM, Frank Tkalcevic wrote: > > >> I was Googleing for encoders when I found a bunch of radio > >> amateur web pages where people have made DIY encoders with > >> the following chip: > >> http://www.austriamicrosystems.com/eng/Products/Magnetic-Encod > > ers/Rotary-Encoders/AS5040 > >> > >> Anyone tried it? It looks really nice even though it may be > >> too few pulses for some of you guys. > >> I have 400 ppr on my router, gear ratio 3:1 on 5 mm/rev > >> ballscrews, so it's still more precise than the machine can handle. > > > > > > This has been mentioned once before. The magnet is hard to source. > > You can > > You can get the magnets here: > https://www.hkcm.de/ > > Now I only need a supplier for one or two of those encoders. I thought > the austria microsystems itself sold them by piece, but now they only > list prices for 1000 pieces. > > Dirk > > > > > ------------------------------ > > Message: 4 > Date: Sat, 13 Jun 2009 22:31:00 -0700 > From: Kirk Wallace <[email protected]> > Subject: Re: [Emc-users] .ngc file RFReview > To: "Enhanced Machine Controller (EMC)" > <[email protected]> > Message-ID: <1244957460.5734.170.ca...@kw-ws> > Content-Type: text/plain > > On Fri, 2009-06-12 at 22:22 -0700, Kirk Wallace wrote: > > In case anyone is interested, I have an .ngc file that I'll probably run > > tomorrow, but if anyone finds anything that might improve it, I would > > appreciate hearing from you. Thanks. > > > > http://wallacecompany.com/machine_shop/EMC2/ngc/encoder-100ppr-4c.ngc > > > > I tried making the part tonight and ran into a problem. I did a dry run > in air which stopped at slot 19 of 25. I rebooted, re-ran the part and > it ran fine. I touched off on the material, ran the part, but again it > stopped on slot 19. I tried one more time with no luck. It ran fine in > the office on a sim config. When the machine stops the stop button in > AXIS is active and AXIS is in manual mode with the spindle and mist > running, but I can press spindle stop and mist to turn them off and jog > fine, so it seems it's in normal manual mode. Could bad memory or other > PC hardware do this? I'll try to swap out the PC and try again. EMC2 is > 2.3.1 running on 6.04. > > Also, I jogged out of the slot, cleared the compensation with g40 and > did a g28, which ran the tool into the vise (no length comp was used). > It may have tried this on the last run, but I hit e-stop before it could > get too far. > -- > Kirk Wallace > http://www.wallacecompany.com/machine_shop/ > http://www.wallacecompany.com/E45/index.html > California, USA > > > > > ------------------------------ > > Message: 5 > Date: Sun, 14 Jun 2009 17:15:17 +1000 > From: "Frank Tkalcevic" <[email protected]> > Subject: Re: [Emc-users] DIY encoder chipset > To: "'Enhanced Machine Controller \(EMC\)'" > <[email protected]> > Message-ID: <437d002c3f3a427c8555d5e2bf9ef...@mainpc> > Content-Type: text/plain; charset="us-ascii" > > > You can get the magnets here: > > https://www.hkcm.de/ > > > > Now I only need a supplier for one or two of those encoders. > > I thought the austria microsystems itself sold them by piece, > > but now they only list prices for 1000 pieces. > > > I got a couple from www.futureelectronics.com > > > > > ------------------------------ > > Message: 6 > Date: Sun, 14 Jun 2009 09:37:03 +0200 > From: Sven Wesley <[email protected]> > Subject: Re: [Emc-users] DIY encoder chipset > To: "Enhanced Machine Controller (EMC)" > <[email protected]> > Message-ID: > <[email protected]> > Content-Type: text/plain; charset=ISO-8859-1 > > 2009/6/13 Gary Fiber <[email protected]> > > > More than likely for radio frequency tuning. Using an encoder to > > control the tuning of a Direct Digital Synthesizer. Tuning up and > > down in frequency in as small as 1 Hertz increments. > > For my High Sierra HS1800/Pro adjustable antenna, I utilize SWR > > readings to adjust it. > > I also have an automatic device that controls the radio tuning > > sequence and then runs the motor of the antenna until the SWR > > measurement is where I set it to be originally. > > > > Step motors however would be very useful for satellite communications. > > > > Gary Fiber K8IZ > > > > Maybe so, but the DIY'ers I read about use them for _antenna_ tuning - ro > rotate the big thing outside that is. > (The radio hobbyists I know love gardens, not as much for the apple trees as > to fit a bigger antenna...) > > > ------------------------------ > > Message: 7 > Date: Sun, 14 Jun 2009 10:31:41 -0400 > From: Douglas Pollard <[email protected]> > Subject: Re: [Emc-users] Roles in the manufacturing chain (was > Metriks) > To: "Enhanced Machine Controller (EMC)" > <[email protected]> > Message-ID: <[email protected]> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > Stuart Stevenson wrote: > > Gentlemen, > > As loooonnnngggg as opinions are being proffered. > > When we encounter a print that the 'nominals' will not make the > > part as drawn we wonder just 'who the hell drew this?'. A license from > > a crackerjack box does not make a draftsman. With the advent of CAD > > this discovery is waning. A solid model is a wonderful thing. > > The only time you should have to 'fudge' the numbers is when you > > are making parts from forgings or casting. Tolerance stackage, > > warpage, die slippage and a host of other 'ages' can cause the > > features to shift. Most of the time a forging or casting will have a > > sweet spot. Find the sweet spot prior to making the first cut and you > > are home free. > > Our aerospace customers want the parts as close to nominal as > > possible. They would like all parts to be 'dead on' so the parts weigh > > the expected amount. No more/ no less. They allow tolerances because > > perfection is not attainable but they wish for you to get closer with > > each succeeding part. > > thanks for reading my rant > > Stuart > > > > On Sat, Jun 13, 2009 at 5:36 PM, Matt Shaver<[email protected]> wrote: > > > >> On Sat, 2009-06-13 at 11:27 +0100, Andy Pugh wrote: > >> > >>> Most of the dimensions for the general geometry were +/- 0.2mm except > >>> for the flexural element, which was 0.2mm +/- 0.05mm dimensioned from > >>> a face with a stacked-up positional tolerance of about 0.4mm. > >>> The machinist set up his CNC mill to the centre value of each > >>> tolerance starting from a part edge and pressed "go". When the program > >>> finished the flexural element was not even there. > >>> > >>> Who was at fault? I argued that the wider tolerances elsewhere in the > >>> geometry were specifically so that they could get the flexure right, > >>> they said "You always work to mid-tolerance, and the drawing should > >>> assume that" > >>> > >> The machinist. I used to do job shop work in my shop. The feature that > >> you described should be inspect-able, and the from dimension you quote > >> it should have measured (by whatever method is appropriate) > >> between .15mm and .25mm. Since it was not there, we can assume that it > >> would measure 0.00mm and is therefore out of tolerance. > >> > >> I have heard this "middle of the tolerance" argument many times and it > >> is as wrong today as it ever has been. And I was on the side > >> (machinists) that tried to use it to our advantage! > >> > >> If the stack-up of multiple tolerances actually prevent the part from > >> being made such that each individual tolerance limit can be observed, > >> then the drawing should go back to drafting with that explanation. If > >> you actually make the part, then it must pass inspection, even if some > >> features must be created near their tolerance limits to allow other > >> features to exist within their own tolerance limits. The "middle" of the > >> tolerance band is no more valid or important than any other point within > >> the tolerance limits. > >> > >> Wow, who would have thought I was this opinionated? :) > >> > >> Thanks, > >> Matt > >> > >> > >> > >> ------------------------------------------------------------------------------ > >> 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 > >> [email protected] > >> https://lists.sourceforge.net/lists/listinfo/emc-users > >> > >> > >> > > > > > > > > > A couple things I think I can add is what you are saying is in a > way pretty much a continuation of what we have always done. The other > thing is there are two over all tolerances involved. One is a tolerance > involving quality. It s a kind of tolerance where an aircraft builder > may say, we would like the part to come to us at a specific cost of plus > or minus some amount. The maker of the part says, "I can hold any > tolerance any one else can hold at some specific price. If Joe part > maker works to nominal and then says, "I will aim at nominal but I have > no idea where it will fall within the tolerance", then he is defectively > not working to nominal. > His competion may try harder to work to nominal and if the buyer > prefers him over the first contractor then the effective tolerance as > actually tighter and the price of the part goes up. > Hopefully we are all serving our own interests and at the same time > cooperating to serve both parties interest. > I don't think a designer should ever design with a tolerance and > hope for nominal. That seems to me unprofessional and unenforceable. A > drawing should say what it means and nothing more. > Of course this is whole thing is an age old unsettled argument. > > Doug > > > > ------------------------------ > > ------------------------------------------------------------------------------ > 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 > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > > > End of Emc-users Digest, Vol 38, Issue 50 > *****************************************
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