Re: [Emc-users] Rifling machine
First off I don't want to start a shouting war of Tastes Great vrs Less Filling. As a (former) firearms manufacturer I researched barrel manufacturing methods in depth after being ask to reproduce a replacement barrel for a long since out of production item. The Hook and pull (sine method) was developed back in the black powder days when steel was soft and bores were large. Keep in mind that one reason a single groove is cut has to do with chips in the bore. The cutter often takes less than .0002 per pass. Early machines could easily be hand powered, albeit a long monotonous process. Because of the time factor Enfield actual made some barrels with only 2 grooves. As bores got smaller 6.5mm became about the smallest bore that could be produced reliably with current materials. During WWI material science improved. The cutter is often held straight in larger bores and all twist timing is done externally. Button rifling on the other hand relies on the angle of the flutes of the button to control twist rate. Button rifling is like a swaging operation because no cutting takes place. Broach rifling is like button rifling in that the twist is controlled by how the broach was ground, but the grooves are cut, not pressure formed. If this were attempted with LCNC I think it is an application which begs for absolute encoder support. Any loss of position while in process would likely destroy both work piece and the cutter and cutter carrier unless machine was dis-assembled to allow removal of work and cutter assy together so tool could be backed out by hand. The beauty of the original design is that short of taking a chuck key or wrench to the machine it is nearly impossible to get out of sync. Greg Bentzinger -- Slashdot TV. Video for Nerds. Stuff that matters. http://tv.slashdot.org/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Rifling machine
Mount the cutter bar on a rotary for controlled rotation, then a A plain g1A(rotation degrees)x(barrellength) would be what I would do. I have done some very coarse helix cuts that way The taper wedge putting on the cut is interesting, that can be the same/similar just adjusting the out stroke as it runs Dave Caroline On 05/09/2014, Gene Heskett ghesk...@wdtv.com wrote: On Thursday 04 September 2014 22:04:46 Len Shelton did opine And Gene did reply: We have a customer who is wanting to make a motor controlled rifling machine. I spent a good bit of time researching it for him today and I was surprised that it seems that no one is doing it with motors (or at least I couldn't find anyone). I understand the need for the linear relationship of the cutter to the position of the indexer in such a machine. But I wanted to hear your guys thoughts on doing this with motors, which will inherently have some degree of granular positioning. Here is the best machine design I could find that really demonstrates the issue: https://www.youtube.com/watch?v=L_yemjfgkE0 Len I don't see a thing there that cannot be done with steppers, nema 23's driving the big pulley thru timing belts, with the rotation being a variation of the G33.1 function. But I'd not use the pulley crank at all, but just a bigger stepper and ball screw because then you would not need the math to translate the rotary motion into the linear position to drive the G33.1 inputs. The biggest problem would be in adjusting the number of grooves in software, but I don't believe that its a problem hal or gcode cannot solve by running a start point cycle back and forth with a mod function in the gcode math. Interesting problem, but one that I believe lcnc can do with creative coding. But is cut rifling enough more accurate than the other two methods, both of which are at least 100x faster, to make it worthwhile to do it that way? Thats the $64K question. IMO yes. :-) I wish I knew I had 10 years left, I'd be getting started on just such a machine. Just for SG. And bug hole sized 10 shot groups of coarse. Cheers, Gene Heskett -- There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order. -Ed Howdershelt (Author) Genes Web page http://geneslinuxbox.net:6309/gene US V Castleman, SCOTUS, Mar 2014 is grounds for Impeaching SCOTUS -- Slashdot TV. Video for Nerds. Stuff that matters. http://tv.slashdot.org/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Slashdot TV. Video for Nerds. Stuff that matters. http://tv.slashdot.org/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Rifling machine
On 9/5/2014 12:13 AM, Dave Caroline wrote: Mount the cutter bar on a rotary for controlled rotation, then a A plain g1A(rotation degrees)x(barrellength) would be what I would do. I have done some very coarse helix cuts that way The taper wedge putting on the cut is interesting, that can be the same/similar just adjusting the out stroke as it runs Longer stroke after each round of passes to bung the wedge in farther. Another method uses a threaded plug to push the wedge in to raise the cutter. That could be automated too by using a second rotary indexer with a hole into which the end of the plug fits. After each trip around all the grooves, run the tool farther out to engage the plug and turn it. Lock the indexer so it will remain aligned for the next adjustment. Either way simpler and on the fly adjustable VS the complicated ratcheting system that has to be rigged to only advance after the barrel is turned a full revolution. It might be possible to mount two or three or more cutters at once, combining the features (mainly speed) of button and broach with the fine accuracy of cut rifling. With three cutters a six groove barrel could be cut in only two passes between advancements of the cutters. For the group's next trick, automate the deburring and lapping process while at least duplicating if not surpassing the accuracy of hand lapping. ;-) --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com -- Slashdot TV. Video for Nerds. Stuff that matters. http://tv.slashdot.org/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Rifling machine
On 5 September 2014 03:04, Len Shelton l...@probotix.com wrote: Here is the best machine design I could find that really demonstrates the issue: https://www.youtube.com/watch?v=L_yemjfgkE0 Well ,if that worked then a CNC version would. My concern would be with the torsional stiffness of the pull-rod. I think that the rifling lead might always have to be largely set by the cutter itself. To make cutter up-feed easier I think I would look at designs with a stationary cutter and a moving barrel. I am seeing two collet chucks with adjustable spacing on a rail that oscillates up and down a fixed cutter bar. This would allow the cutter bar to be anchored at both ends to double the torsional stiffness (at the expense of increased part-changeover time). You would need very flex-resistant cabling for the barrel-rotation motors in this scenario, unless drive to the barrel chucks was via a ball-spline for example. Hydraulic cutter feed might be worth investigating. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Slashdot TV. Video for Nerds. Stuff that matters. http://tv.slashdot.org/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Rifling machine
On Fri, Sep 5, 2014 at 4:19 AM, andy pugh bodge...@gmail.com wrote: Well ,if that worked then a CNC version would. My concern would be with the torsional stiffness of the pull-rod. I think that the rifling lead might always have to be largely set by the cutter itself. Having zero experience with this process may hamper my thoughts but here goes anyway. I agree with Andy about the torsional stiffness. I don't believe there is any way to overcome that limitation. I don't think suspending the second end will add enough stiffness to allow controlling the lead in any meaningful way. I do think suspending the second end would have benefits. Torsionally float the second end and measure the torsional rotation. Use the measurement to control the rotation of the pulling end. This would allow the truest cutter lead rotation and cutter orientation through the barrel. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto thanks Stuart -- Slashdot TV. Video for Nerds. Stuff that matters. http://tv.slashdot.org/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Rifling machine
On Friday 05 September 2014 03:34:41 Gregg Eshelman did opine And Gene did reply: On 9/5/2014 12:13 AM, Dave Caroline wrote: Mount the cutter bar on a rotary for controlled rotation, then a A plain g1A(rotation degrees)x(barrellength) would be what I would do. I have done some very coarse helix cuts that way The taper wedge putting on the cut is interesting, that can be the same/similar just adjusting the out stroke as it runs Longer stroke after each round of passes to bung the wedge in farther. Another method uses a threaded plug to push the wedge in to raise the cutter. That could be automated too by using a second rotary indexer with a hole into which the end of the plug fits. After each trip around all the grooves, run the tool farther out to engage the plug and turn it. Lock the indexer so it will remain aligned for the next adjustment. Either way simpler and on the fly adjustable VS the complicated ratcheting system that has to be rigged to only advance after the barrel is turned a full revolution. It might be possible to mount two or three or more cutters at once, combining the features (mainly speed) of button and broach with the fine accuracy of cut rifling. With three cutters a six groove barrel could be cut in only two passes between advancements of the cutters. That would stretch the ability to make a uniform cut. So it is not something that I would attempt. As for putting an High Density rear shoe on the back of the cutter carrier, I would fear for its ling term life since it would be running in the cutters debris, ripping it up quickly. Here in WV we have an annual labor day bash out at Jacksons (Stonewall) Mill, and one of the exhibitors is a black power rifle maker of considerable years who has brought his rifling rig to the show on several occasions. Hand powered, driving the cutter with a set of handles similar to an old push mower, the rifling bit is turned by a spiral groove chiseled into a log about 6 in diameter, groove worn dead smooth by decades of use. He meticulously cleans the cutter and applies a drop or 2 of some sort of cutting oil to it before every pull, and its designed to catch its own shavings so the barrel stays fairly clean. His wedge is IIRC driven by a screw that gets tightened 1/4 turn at a time. The rifles he brings to the show are all Kentucky style flintlocks. But they are all tagged only as to caliber date he completed them. I saw him turn down an offer of $5,000 for one of them several years ago. As Ky style flintlocks go they are, every one of them, truly both a labor of love and a work of art. Worth every bit of that $5000 offer. I asked about his stock wood and he said he has driven as much as 20,000 miles over a 3 or 4 year period before buying the right plank. The target he says that rifle shot laying on the table under each are equally impressive. No flyers, often under an inch at 50 yards for 10 shots. For the group's next trick, automate the deburring and lapping process while at least duplicating if not surpassing the accuracy of hand lapping. ;-) If the cutter is sharp kept clean, de-burring is the first shot. It really should not need anything more. Cheers, Gene Heskett -- There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order. -Ed Howdershelt (Author) Genes Web page http://geneslinuxbox.net:6309/gene US V Castleman, SCOTUS, Mar 2014 is grounds for Impeaching SCOTUS -- Slashdot TV. Video for Nerds. Stuff that matters. http://tv.slashdot.org/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Rifling machine
Remember, the maker of muzzleloaders typically had a big bore to work with and may not have been too worried about torsion. His steel/iron was also dead soft but good for lead bullets. Ouch! varies as the forth power... θ = 32 L T / (G π D^4) Dunlap shows a drawing for the take up of the rifling cutter. I like the idea of rotating the barrel but some of the sine bar rifling machines used during WWII are still being used. Clearly craftsman using either broaching or cutters produce good barrels. Apparently the hammer forged barrels are still the best but the $ 1E+6 price tag limits ownership. ;-) But it is like one shooter said,I shoot one round and I know where I hit. It is only subsequent rounds that confuse the issue. Dave On Fri, 2014-09-05 at 09:28 -0400, Gene Heskett wrote: On Friday 05 September 2014 03:34:41 Gregg Eshelman did opine And Gene did reply: On 9/5/2014 12:13 AM, Dave Caroline wrote: Mount the cutter bar on a rotary for controlled rotation, then a A plain g1A(rotation degrees)x(barrellength) would be what I would do. I have done some very coarse helix cuts that way The taper wedge putting on the cut is interesting, that can be the same/similar just adjusting the out stroke as it runs Longer stroke after each round of passes to bung the wedge in farther. Another method uses a threaded plug to push the wedge in to raise the cutter. That could be automated too by using a second rotary indexer with a hole into which the end of the plug fits. After each trip around all the grooves, run the tool farther out to engage the plug and turn it. Lock the indexer so it will remain aligned for the next adjustment. Either way simpler and on the fly adjustable VS the complicated ratcheting system that has to be rigged to only advance after the barrel is turned a full revolution. It might be possible to mount two or three or more cutters at once, combining the features (mainly speed) of button and broach with the fine accuracy of cut rifling. With three cutters a six groove barrel could be cut in only two passes between advancements of the cutters. That would stretch the ability to make a uniform cut. So it is not something that I would attempt. As for putting an High Density rear shoe on the back of the cutter carrier, I would fear for its ling term life since it would be running in the cutters debris, ripping it up quickly. Here in WV we have an annual labor day bash out at Jacksons (Stonewall) Mill, and one of the exhibitors is a black power rifle maker of considerable years who has brought his rifling rig to the show on several occasions. Hand powered, driving the cutter with a set of handles similar to an old push mower, the rifling bit is turned by a spiral groove chiseled into a log about 6 in diameter, groove worn dead smooth by decades of use. He meticulously cleans the cutter and applies a drop or 2 of some sort of cutting oil to it before every pull, and its designed to catch its own shavings so the barrel stays fairly clean. His wedge is IIRC driven by a screw that gets tightened 1/4 turn at a time. The rifles he brings to the show are all Kentucky style flintlocks. But they are all tagged only as to caliber date he completed them. I saw him turn down an offer of $5,000 for one of them several years ago. As Ky style flintlocks go they are, every one of them, truly both a labor of love and a work of art. Worth every bit of that $5000 offer. I asked about his stock wood and he said he has driven as much as 20,000 miles over a 3 or 4 year period before buying the right plank. The target he says that rifle shot laying on the table under each are equally impressive. No flyers, often under an inch at 50 yards for 10 shots. For the group's next trick, automate the deburring and lapping process while at least duplicating if not surpassing the accuracy of hand lapping. ;-) If the cutter is sharp kept clean, de-burring is the first shot. It really should not need anything more. Cheers, Gene Heskett -- Slashdot TV. Video for Nerds. Stuff that matters. http://tv.slashdot.org/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
[Emc-users] Rifling machine
We have a customer who is wanting to make a motor controlled rifling machine. I spent a good bit of time researching it for him today and I was surprised that it seems that no one is doing it with motors (or at least I couldn't find anyone). I understand the need for the linear relationship of the cutter to the position of the indexer in such a machine. But I wanted to hear your guys thoughts on doing this with motors, which will inherently have some degree of granular positioning. Here is the best machine design I could find that really demonstrates the issue: https://www.youtube.com/watch?v=L_yemjfgkE0 Len -- Slashdot TV. Video for Nerds. Stuff that matters. http://tv.slashdot.org/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Rifling machine
I've thought that LinuxCNC might make a good basis for a universal barrel rifling machine, either using a small off-the-shelf carbide insert, or using custom carbide cutters. There's a shop close to me that will make custom carbide cutters. The very well done animated video from your link demonstrated some clever old school mechanisms (sine bar, rack and pinion, pawl, etc. Almost all of that could be replaced by LinuxCNC with some stepper motors or servo motors and encoders. The manual rifling method requires a custom cutter to be made that is hammered/pulled through the bore. That's how rifle barrels were rifled in the old days. The angle on the end of the cutter determined the rifling rate (rate of twist), and it was a bit of an art with some trial and error. A barrel smith might want one turn in nine inches and might get one turn in 10.3 inches. Using LinuxCNC to essentially thread the inside of the bore should ensure a precise and repeatable rate of twist. If you follow through with this project, I'd love to see what you create and the results you get. Boring and rifling barrels is a specialized trade. There aren't many companies that do it. The equipment is quite specific to the task. Most firearms manufacturers buy rifled barrel blanks and do the finish work - threading the muzzle, cutting the chamber, fluting, etc. It's about time for CNC to make it much easier to cut barrel rifling. On 09/04/2014 10:04 PM, Len Shelton wrote: We have a customer who is wanting to make a motor controlled rifling machine. I spent a good bit of time researching it for him today and I was surprised that it seems that no one is doing it with motors (or at least I couldn't find anyone). I understand the need for the linear relationship of the cutter to the position of the indexer in such a machine. But I wanted to hear your guys thoughts on doing this with motors, which will inherently have some degree of granular positioning. Here is the best machine design I could find that really demonstrates the issue: https://www.youtube.com/watch?v=L_yemjfgkE0 Len -- Slashdot TV. Video for Nerds. Stuff that matters. http://tv.slashdot.org/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Slashdot TV. Video for Nerds. Stuff that matters. http://tv.slashdot.org/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Rifling machine
On Thursday 04 September 2014 22:04:46 Len Shelton did opine And Gene did reply: We have a customer who is wanting to make a motor controlled rifling machine. I spent a good bit of time researching it for him today and I was surprised that it seems that no one is doing it with motors (or at least I couldn't find anyone). I understand the need for the linear relationship of the cutter to the position of the indexer in such a machine. But I wanted to hear your guys thoughts on doing this with motors, which will inherently have some degree of granular positioning. Here is the best machine design I could find that really demonstrates the issue: https://www.youtube.com/watch?v=L_yemjfgkE0 Len I don't see a thing there that cannot be done with steppers, nema 23's driving the big pulley thru timing belts, with the rotation being a variation of the G33.1 function. But I'd not use the pulley crank at all, but just a bigger stepper and ball screw because then you would not need the math to translate the rotary motion into the linear position to drive the G33.1 inputs. The biggest problem would be in adjusting the number of grooves in software, but I don't believe that its a problem hal or gcode cannot solve by running a start point cycle back and forth with a mod function in the gcode math. Interesting problem, but one that I believe lcnc can do with creative coding. But is cut rifling enough more accurate than the other two methods, both of which are at least 100x faster, to make it worthwhile to do it that way? Thats the $64K question. IMO yes. :-) I wish I knew I had 10 years left, I'd be getting started on just such a machine. Just for SG. And bug hole sized 10 shot groups of coarse. Cheers, Gene Heskett -- There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order. -Ed Howdershelt (Author) Genes Web page http://geneslinuxbox.net:6309/gene US V Castleman, SCOTUS, Mar 2014 is grounds for Impeaching SCOTUS -- Slashdot TV. Video for Nerds. Stuff that matters. http://tv.slashdot.org/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Rifling machine
On 9/4/2014 8:04 PM, Len Shelton wrote: We have a customer who is wanting to make a motor controlled rifling machine. I spent a good bit of time researching it for him today and I was surprised that it seems that no one is doing it with motors (or at least I couldn't find anyone). I understand the need for the linear relationship of the cutter to the position of the indexer in such a machine. But I wanted to hear your guys thoughts on doing this with motors, which will inherently have some degree of granular positioning. Here is the best machine design I could find that really demonstrates the issue: https://www.youtube.com/watch?v=L_yemjfgkE0 Amazing what was done with purely mechanical methods before being replaced with CNC. Neat to see how rifling cutting a grove at a time was automated before single pass 'button' cutting was invented. I'd have the cutting slide just run straight and put the barrel in a computer controlled rotator to both index and control the twist of the rifling. That would make it a fairly simple task to cut any twist including gain twist which always has to be cut, can't be hammer forged on a mandrel. The cutting bit advance control could also be operated by a stepper. Those two changes, put under computer control, would drastically simplify the construction of the rest of the machine. Instead of the crank to run the cutter back and forth you could use a motor driving a ballscrew. With a rotary encoder on that and the barrel indexer/rotator you'd have complete CNC rifling with infinitely adjustable twist and length of stroke. Something else I'd try is backing the bottom of the cutter bar with a half round of UHMW. That would make it slide easy in the barrel and wouldn't make any lengthwise scratches. As for the motor turning the barrel, to get fine, step-free positioning there are a few ways to do it. Got $ to spend? Try a direct drive with a hollow shaft servo motor. Not so much $? A double-enveloping, high ratio worm gear set driven by a fast motor, with the encoder mounted to directly read the barrel position. Well, that might not be so inexpensive but compared to a hollow shaft servo with a hole large enough to pass a rifle barrel... Then there's ye olde cogged pulleys and toothed belts. Use two belts off both ends of a double shaft stepper just for added strength of doubling up on belts and balancing pressure on the motor bearings. Whatever is used to rotate the barrel it must have enough torque at very slow speeds to keep the cutting pressure from moving it from the movement the control commands. No problem with the worm drive since those can't be back-driven unless specially designed for it. Like so many things, how precise do you want it? How much money do you have or how good are you at scrounging for bargains on precision equipment? Is this for competition grade tack driving guns or for mass produced everyday shooters? --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com -- Slashdot TV. Video for Nerds. Stuff that matters. http://tv.slashdot.org/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Rifling machine
On 9/4/2014 9:42 PM, Bruce Layne wrote: The manual rifling method requires a custom cutter to be made that is hammered/pulled through the bore. That's how rifle barrels were rifled in the old days. Here's a good site on rifling methods. http://firearmshistory.blogspot.com/2010/05/rifling-manufacturing-hammer-forged.html --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com -- Slashdot TV. Video for Nerds. Stuff that matters. http://tv.slashdot.org/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
