Re: [Emc-users] Cable drive for a gas torch pattern follower?
--- On Sat, 3/30/13, cogoman cogo...@optimum.net wrote: Acceleration due to gravity = 16 feet/second/second One thing I do remember from junior high science class is gravity acceleration is 32 feet/second/second on Earth. 'Course I looked it up just now to be sure. ;-) So, yeah, no servo drive available to us mere mortals is going to be able to out-accelerate gravity. -- Own the Future-Intel(R) Level Up Game Demo Contest 2013 Rise to greatness in Intel's independent game demo contest. Compete for recognition, cash, and the chance to get your game on Steam. $5K grand prize plus 10 genre and skill prizes. Submit your demo by 6/6/13. http://altfarm.mediaplex.com/ad/ck/12124-176961-30367-2 ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
On 31 March 2013 07:31, Gregg Eshelman g_ala...@yahoo.com wrote: So, yeah, no servo drive available to us mere mortals is going to be able to out-accelerate gravity. This doesn't add up. Any Z-axis capable of lifting the head can out-accelerate gravity. All that is required is for the force exerted by the actuator to be greater than the weight of the parts being moved. (I do mean weight here, the mass of the parts x little-g) There is a little more to it than that, as the motor inertia becomes much more relevant under acceleration than under constant-speed (or stopped) conditions. Taking the example of the 1kW motor here: http://literature.rockwellautomation.com/idc/groups/literature/documents/pp/mp-pp001_-en-p.pdf It has a peak output torque of 7.9Nm and an inertia of .78 kg-m2 (kg-m2 = Nms2) So, the motor itself can accelerate at a rate of 100,000 radians/sec2 = 16000revs/s2 If we have a 500mm length of 20mm x 5mm ballscrew rigidly coupled then that adds a further 0.41Nms2 to the system http://www.gg-powertransmission.com/ball-screw-drives/ball-screws/ So now the system can accelerate at 1revs/s2 = 52m/s2 = 5g. That doesn't tell us very much, other than that this system can't accelerate any payload whatsoever at more than 5g. However, at 2.5g we have 4Nm of torque left over. That's 5kN on a 5mm pitch screw, enough to accelerate a 200kg payload at our stipulated 2.5g. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Own the Future-Intel(R) Level Up Game Demo Contest 2013 Rise to greatness in Intel's independent game demo contest. Compete for recognition, cash, and the chance to get your game on Steam. $5K grand prize plus 10 genre and skill prizes. Submit your demo by 6/6/13. http://altfarm.mediaplex.com/ad/ck/12124-176961-30367-2 ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
On 03/26/2013 01:21 AM, Gregg Eshelman wrote: I am not sure you will see good acceleration. In fact, it is always going to be less than 1g. This is because for any faster acceleration the strings go slack as the weighs don't fall fast enough. No need to go anywhere near that fast because an oxy-acetylene torch or plasma cutter can't cut that fast. This rig is most often used for cutting steel 3/4 thick or thicker. Since counter weights are often used on Z axes on servo machines, I once decided to calculate how much of a limit the acceleration due to gravity would be. The metric calculations are left for you folks across the pond. Acceleration due to gravity = 16 feet/second/second After 1 second the velocity can be 16 feet per second times 60 = 960 feet per minute (I love spreadsheets!) times 12 = 11520 inches per minute divide that by two, so half of that force can be applied to your cable = 5760 inches per minute HERE'S WHERE I AM MAKING ASSUMPTIONS THAT MAY BE OFF BY A LITTLE. If I recall properly 1500 inches per minute is a FAST servo system. 1500/5760 = .26 ( assuming linear acceleration it should only take .26 seconds to reach 1500 IPM) 1500/60 = 25 inches per second at 25 inches per second that servo system would travel 6.5 inches at full speed while the gravity system would be accelerating to 1500 IPM. Of course the servo system wouldn't be able to accelerate instantaneously, so the counter weight would only slow a 1500 IPM servo system down a little bit. I thought gravity would be much more of a limit too. -- Own the Future-Intel(R) Level Up Game Demo Contest 2013 Rise to greatness in Intel's independent game demo contest. Compete for recognition, cash, and the chance to get your game on Steam. $5K grand prize plus 10 genre and skill prizes. Submit your demo by 6/6/13. http://altfarm.mediaplex.com/ad/ck/12124-176961-30367-2 ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
On Sat, 2013-03-30 at 17:34 -0400, Gene Heskett wrote: On Saturday 30 March 2013 17:32:05 cogoman did opine: On 03/26/2013 01:21 AM, Gregg Eshelman wrote: I am not sure you will see good acceleration. In fact, it is always going to be less than 1g. This is because for any faster acceleration the strings go slack as the weighs don't fall fast enough. No need to go anywhere near that fast because an oxy-acetylene torch or plasma cutter can't cut that fast. This rig is most often used for cutting steel 3/4 thick or thicker. Since counter weights are often used on Z axes on servo machines, I once decided to calculate how much of a limit the acceleration due to gravity would be. The metric calculations are left for you folks across the pond. Acceleration due to gravity = 16 feet/second/second Uhh, when I went to school back in rural IA, in 2 feet of snow, uphill 2 miles both ways, gravity's acceleration was 32 feet per second per second. Did I go to the wrong school? After 1 second the velocity can be 16 feet per second times 60 = 960 feet per minute (I love spreadsheets!) times 12 = 11520 inches per minute divide that by two, so half of that force can be applied to your cable = 5760 inches per minute HERE'S WHERE I AM MAKING ASSUMPTIONS THAT MAY BE OFF BY A LITTLE. If I recall properly 1500 inches per minute is a FAST servo system. 1500/5760 = .26 ( assuming linear acceleration it should only take .26 seconds to reach 1500 IPM) 1500/60 = 25 inches per second at 25 inches per second that servo system would travel 6.5 inches at full speed while the gravity system would be accelerating to 1500 IPM. Of course the servo system wouldn't be able to accelerate instantaneously, so the counter weight would only slow a 1500 IPM servo system down a little bit. I thought gravity would be much more of a limit too. -- Own the Future-Intel(R) Level Up Game Demo Contest 2013 Rise to greatness in Intel's independent game demo contest. Compete for recognition, cash, and the chance to get your game on Steam. $5K grand prize plus 10 genre and skill prizes. Submit your demo by 6/6/13. http://altfarm.mediaplex.com/ad/ck/12124-176961-30367-2 ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene Gene, But in physics there are often special cases. ;-) My father would, in good weather, ride his 3 speed bike downhill to work and downhill going home. Now, of course this take a bit of explanation: We lived at 1230 ASL. Work was at 920 ASL and when he finished work he rode the elevator to the top of the dam at 1310 ASL and rode home. That (the road) disappeared with the construction of the 3rd powerhouse at Coulee so this special case no longer exists. :-) Dave -- Own the Future-Intel(R) Level Up Game Demo Contest 2013 Rise to greatness in Intel's independent game demo contest. Compete for recognition, cash, and the chance to get your game on Steam. $5K grand prize plus 10 genre and skill prizes. Submit your demo by 6/6/13. http://altfarm.mediaplex.com/ad/ck/12124-176961-30367-2 ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
On Saturday 30 March 2013 22:30:04 dave did opine:
On Sat, 2013-03-30 at 17:34 -0400, Gene Heskett wrote:
On Saturday 30 March 2013 17:32:05 cogoman did opine:
On 03/26/2013 01:21 AM, Gregg Eshelman wrote:
I am not sure you will see good acceleration. In fact, it is
always
going to be less than 1g. This is because for any faster
acceleration
the strings go slack as the weighs don't fall fast enough.
No need to go anywhere near that fast because an oxy-acetylene
torch or plasma cutter can't cut that fast. This rig is most
often used for cutting steel 3/4 thick or thicker.
Since counter weights are often used on Z axes on servo machines,
I
once decided to calculate how much of a limit the acceleration due
to gravity would be. The metric calculations are left for you
folks across the pond.
Acceleration due to gravity = 16 feet/second/second
Uhh, when I went to school back in rural IA, in 2 feet of snow, uphill
2 miles both ways, gravity's acceleration was 32 feet per second per
second. Did I go to the wrong school?
After 1 second the velocity can be 16 feet per second
times 60 = 960 feet per minute (I love spreadsheets!)
times 12 = 11520 inches per minute
divide that by two, so half of that force can be applied to your
cable = 5760 inches per minute
HERE'S WHERE I AM MAKING ASSUMPTIONS THAT MAY BE OFF BY A LITTLE.
If I recall properly 1500 inches per minute is a FAST servo system.
1500/5760 = .26 ( assuming linear acceleration it should only take
.26 seconds to reach 1500 IPM)
1500/60 = 25 inches per second
at 25 inches per second that servo system would travel 6.5 inches at
full speed while the gravity system would be accelerating to 1500
IPM. Of course the servo system wouldn't be able to accelerate
instantaneously, so the counter weight would only slow a 1500 IPM
servo system down a little bit.
I thought gravity would be much more of a limit too.
-- Own the Future-Intel(R) Level Up Game Demo Contest 2013
Rise to greatness in Intel's independent game demo contest. Compete
for recognition, cash, and the chance to get your game on Steam.
$5K grand prize plus 10 genre and skill prizes. Submit your demo by
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Cheers, Gene
Gene,
But in physics there are often special cases. ;-)
My father would, in good weather, ride his 3 speed bike downhill to work
and downhill going home.
Now, of course this take a bit of explanation: We lived at 1230 ASL.
Work was at 920 ASL and when he finished work he rode the elevator to
the top of the dam at 1310 ASL and rode home. That (the road)
disappeared with the construction of the 3rd powerhouse at Coulee so
this special case no longer exists. :-)
Dave
Good thing my coffee cup is empty. :-) I just knew somebody would have to
call me on that.
Actually, I rode a horse if the weather was above 10F, below she stayed in
grandpa's own, much better sealed barn, nice warm for the old mare, but
the only barn (not near as tight as grandpa's) I could put her in for the
day while I was in school was still 3/4 mile short, so I had to walk the
rest of the way. Even in -15F weather, then I had to walk all the way,
most of 2 miles. Snow days was a concept that hadn't made it to the little
one room IA schoolhouses in 1940-41.
And I am still trying to figure out which of the 3 xy pairs is which on
that center.c util. I /think/ if have it converted into an o50 sub in
GCode, and its working for the first invocation, but not the 2nd, and its
preclearing all its internal vars before loading the o50 call's [var] [var]
[var] [var] [var] [var] in the o50 sub. So I am fairly sure its working
with clean data to about 8 or 9 digits right of the decimal point.
If you can cross check my work, and confirm which pair of xy's is which,
I'll be glad to post what I have after about 8 hours of frustrating typing
testing in sim mode.
Thanks Dave.
Cheers, Gene
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Re: [Emc-users] Cable drive for a gas torch pattern follower?
--- On Mon, 3/25/13, jeremy youngs jcyoung...@gmail.com wrote: From: jeremy youngs jcyoung...@gmail.com http://www.ebay.com/itm/3Axis-Nema-23-Stepper-Motor-425oz-in-CNC-Mill-Controller-SD-2H044MA-driver-/130835449799?pt=LH_DefaultDomain_0hash=item1e766687c7 Those might be a bit much for the torch arm, 3 newton meters. That's the torque rating used on many Bridgeport type mills. I can move the torch around with one finger. Those motors might be just the thing for an h-bot drive X-Y gantry, depending on how heavy the cross beam is. -- Own the Future-Intelreg; Level Up Game Demo Contest 2013 Rise to greatness in Intel's independent game demo contest. Compete for recognition, cash, and the chance to get your game on Steam. $5K grand prize plus 10 genre and skill prizes. Submit your demo by 6/6/13. http://p.sf.net/sfu/intel_levelupd2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
--- On Mon, 3/25/13, jeremy youngs jcyoung...@gmail.com wrote: http://www.ebay.com/itm/3Axis-Nema-23-Stepper-Motor-425oz-in-CNC-Mill-Controller-SD-2H044MA-driver-/130835449799?pt=LH_DefaultDomain_0hash=item1e766687c7 i like the idea of using a capstan with offsetting weight , if you use 2 motors for x,y then use the same weight in tension the motors will see nothing but frictional resistance . If your capstan is sufficently large you should see very good accel and top feed rates , i think you could do this for less than 500 easily I explained the idea to Ned and he wants to add that to the torch. He also wants to build an X-Y table for his plasma cutter capable of holding 4x8 foot sheets. Would have to make it around 8.5x9 foot so the head could cover the whole sheet. Not a problem building the table, he has plenty of precision ground shaft and linear bearings at his shop that have been laying about, looking for something to be done with them. Think that same kit on ebay would be strong enough for the X-Y table? I figure a cable drive at both sides of the gantry with a synchronizing shaft at one end, could use two of the motors for that axis and just always command them the same. -- Own the Future-Intelreg; Level Up Game Demo Contest 2013 Rise to greatness in Intel's independent game demo contest. Compete for recognition, cash, and the chance to get your game on Steam. $5K grand prize plus 10 genre and skill prizes. Submit your demo by 6/6/13. http://p.sf.net/sfu/intel_levelupd2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
On 26 March 2013 23:49, Gregg Eshelman g_ala...@yahoo.com wrote: Not a problem building the table, he has plenty of precision ground shaft and linear bearings at his shop that have been laying about, looking for something to be done with them. I like the HBot layout. (I reckon it would be another good use for bicycle chain. http://youtu.be/ei4lPk_aM9Y -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Own the Future-Intelreg; Level Up Game Demo Contest 2013 Rise to greatness in Intel's independent game demo contest. Compete for recognition, cash, and the chance to get your game on Steam. $5K grand prize plus 10 genre and skill prizes. Submit your demo by 6/6/13. http://p.sf.net/sfu/intel_levelupd2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
--- On Tue, 3/26/13, andy pugh bodge...@gmail.com wrote: On 26 March 2013 23:49, Gregg Eshelman g_ala...@yahoo.com wrote: Not a problem building the table, he has plenty of precision ground shaft and linear bearings at his shop that have been laying about, looking for something to be done with them. I like the HBot layout. (I reckon it would be another good use for bicycle chain. http://youtu.be/ei4lPk_aM9Y Interesting setup. Certainly solves the issues of running long wires to the gantry and having to do something to keep them from wadding up and getting caught in the works. Chain can be less expensive that multi wire cable. I was thinking this arrangement must be quite a bit like an etch-a-sketch but that uses two crossed rods which are held at their ends by tensioned steel cable, no support tracks at the rod ends. For a plasma cutter where height control is pretty much irrelevant, that could work assuming the cables could be held tight enough. -- Own the Future-Intelreg; Level Up Game Demo Contest 2013 Rise to greatness in Intel's independent game demo contest. Compete for recognition, cash, and the chance to get your game on Steam. $5K grand prize plus 10 genre and skill prizes. Submit your demo by 6/6/13. http://p.sf.net/sfu/intel_levelupd2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
On 25 March 2013 05:45, Dave e...@dc9.tzo.com wrote: They abandoned that design in favor of a more conventional CNC design. I think you would be smart in doing the same. I wonder if they abandoned it because they didn't have LinuxCNC kins? Having said that, it does seem that by the time you have engineered the cable drums you could have engineered a gantry. The cable might be more resilient to filth and nastiness. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_mar ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
I don't know if you have seen the Torchmate version or not before but here are some similar picts and discussion. http://www.cnczone.com/forums/cnc_plasma_waterjet_machines/31685-cnc_retrofit_heath_torchmate_upright_magnetic_follower_shape_cutter.html The Torchmate I remember was only big enough to fit over an upright 55 gallon drum that it used as a stand and slag catcher. So the max part size that could be cut might be 20 in diameter or so, very small by current standards but big enough for a lot of brackets. However, it would make for an interesting technical application and if it worked with sufficient accuracy, it could make for a very cheap, small CNC cutter. The Kins could be similar to a Scara robot. Using screws to move the joints would be a very interesting application of LinuxCNC kins and could be a lot simpler mechanically than using cables, drums, but with limited motion and speed which might be fine for the work envelope of the machine...The screws could be mounted above the filth to minimize maintenance issues. Perhaps there is a more clever way to drive this via cables?? Dave On 3/25/2013 4:55 AM, andy pugh wrote: On 25 March 2013 05:45, Davee...@dc9.tzo.com wrote: They abandoned that design in favor of a more conventional CNC design. I think you would be smart in doing the same. I wonder if they abandoned it because they didn't have LinuxCNC kins? Having said that, it does seem that by the time you have engineered the cable drums you could have engineered a gantry. The cable might be more resilient to filth and nastiness. -- Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_mar ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
I just noticed that Torchmate is now part of Lincoln Electric (a big welder manufacturer in the US). Dave On 3/25/2013 4:55 AM, andy pugh wrote: On 25 March 2013 05:45, Davee...@dc9.tzo.com wrote: They abandoned that design in favor of a more conventional CNC design. I think you would be smart in doing the same. I wonder if they abandoned it because they didn't have LinuxCNC kins? Having said that, it does seem that by the time you have engineered the cable drums you could have engineered a gantry. The cable might be more resilient to filth and nastiness. -- Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_mar ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
This would probably work in a bipod conficuration, with just a pair of springs on the hinges to extend the arm. Like this device: http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Koppi's_Toy With gravity replaced by springs. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_mar ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
Yes is the short answer. From some of the other answers you can get details. The only real question comes in can you use canned kenimatics or are custom ones required. Even modifying canned ones isn't to hard and this group can always be available for consistance. On Mar 24, 2013 2:11 AM, Gregg Eshelman g_ala...@yahoo.com wrote: Looking into the possibility of fitting CNC to an old oxy-acetylene pattern following torch. (It can also mount a plasma cutter.) The torch mounts on the end of an articulated arm with two joints. On top of the arm is a variable speed motor with a 1/4 diameter, knurled, magnetic shaft. That runs around the edge of any bit of steel plate in just about any shape bolted to the pattern holder arm. The problems with that, the pattern has to be steel and has to be 1/8 smaller all around than the piece cut out will be, and you have to have a pattern to be able to do anything with the tool. I've been thinking that a system with three or four servo motors and cables connected to the torch mount could move it around as well as a 2-axis gantry. Can LinuxCNC run such a setup? -- Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_mar ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Own the Future-Intelreg; Level Up Game Demo Contest 2013 Rise to greatness in Intel's independent game demo contest. Compete for recognition, cash, and the chance to get your game on Steam. $5K grand prize plus 10 genre and skill prizes. Submit your demo by 6/6/13. http://p.sf.net/sfu/intel_levelupd2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
On Mon, Mar 25, 2013 at 12:34 PM, andy pugh bodge...@gmail.com wrote: This would probably work in a bipod conficuration, with just a pair of springs on the hinges to extend the arm. Like this device: http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Koppi's_Toy With gravity replaced by springs. or cable attached weight so as to have constant tension , my thought is how to maintain spool diameter on the steppers? as cable winds up then the diameter increases unless a capstan of some sort is utilized, i do like the simplicity that this could bring though -- jeremy youngs -- Own the Future-Intelreg; Level Up Game Demo Contest 2013 Rise to greatness in Intel's independent game demo contest. Compete for recognition, cash, and the chance to get your game on Steam. $5K grand prize plus 10 genre and skill prizes. Submit your demo by 6/6/13. http://p.sf.net/sfu/intel_levelupd2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
--- On Mon, 3/25/13, Dave e...@dc9.tzo.com wrote: From: Dave e...@dc9.tzo.com Subject: Re: [Emc-users] Cable drive for a gas torch pattern follower? To: emc-users@lists.sourceforge.net Date: Monday, March 25, 2013, 10:40 AM I don't know if you have seen the Torchmate version or not before but here are some similar picts and discussion. http://www.cnczone.com/forums/cnc_plasma_waterjet_machines/31685-cnc_retrofit_heath_torchmate_upright_magnetic_follower_shape_cutter.html Interesting info there. Finally remembered what this has been used on quite a bit. Look up wall plotter. The math has already been done many times. Most use only two cables or chains and motors, relying on gravity to keep the pen in tension. They have issues with imprecision and slack in the upper corners. Without a tension system they have to be slow so the pen doesn't wobble all over the place. To translate this to a horizontal system would require some way to keep tension to the end of the arm. How I'd connect the cables to the arm is to put a washer on the end of each cable with a hole just large enough to fit over the magnetic drive shaft. That would ensure all the cables are pulling on exactly the same point and easy to slip off for reversion to pattern follower use. -- Own the Future-Intelreg; Level Up Game Demo Contest 2013 Rise to greatness in Intel's independent game demo contest. Compete for recognition, cash, and the chance to get your game on Steam. $5K grand prize plus 10 genre and skill prizes. Submit your demo by 6/6/13. http://p.sf.net/sfu/intel_levelupd2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
On 25 March 2013 22:25, jeremy youngs jcyoung...@gmail.com wrote: or cable attached weight so as to have constant tension , my thought is how to maintain spool diameter on the steppers? as cable winds up then the diameter increases unless a capstan of some sort is utilized, There is a nicely engineered solution here: http://www.youtube.com/watch?v=RCa8uDFzbsw -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Own the Future-Intelreg; Level Up Game Demo Contest 2013 Rise to greatness in Intel's independent game demo contest. Compete for recognition, cash, and the chance to get your game on Steam. $5K grand prize plus 10 genre and skill prizes. Submit your demo by 6/6/13. http://p.sf.net/sfu/intel_levelupd2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
--- On Mon, 3/25/13, jeremy youngs jcyoung...@gmail.com wrote: or cable attached weight so as to have constant tension , my thought is how to maintain spool diameter on the steppers? as cable winds up then the diameter increases unless a capstan of some sort is utilized, Lots of ways to do that. Wrap a few turns in one layer around a drum then past that use a spring loaded roller or weight or zigzag arrangement of pulleys up and down. Whatever it takes to avoid having to adjust for changing amount of pull per degree of rotation. -- Own the Future-Intelreg; Level Up Game Demo Contest 2013 Rise to greatness in Intel's independent game demo contest. Compete for recognition, cash, and the chance to get your game on Steam. $5K grand prize plus 10 genre and skill prizes. Submit your demo by 6/6/13. http://p.sf.net/sfu/intel_levelupd2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
I guess the real question is then are you going to do it? if so will you post your results ? i would like to see them i think this could be a very inexpensive solution using small steppere and 1/8 in cable a few scraps lying around and presto a simple plasma cutter :) -- jeremy youngs -- Own the Future-Intelreg; Level Up Game Demo Contest 2013 Rise to greatness in Intel's independent game demo contest. Compete for recognition, cash, and the chance to get your game on Steam. $5K grand prize plus 10 genre and skill prizes. Submit your demo by 6/6/13. http://p.sf.net/sfu/intel_levelupd2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
--- On Mon, 3/25/13, jeremy youngs jcyoung...@gmail.com wrote: I guess the real question is then are you going to do it? if so will you post your results ? i would like to see them i think this could be a very inexpensive solution using small steppere and 1/8 in cable a few scraps lying around and presto a simple plasma cutter :) Need to figure out the hardware required and cost. Yeah, old obsolete pattern follower torches - suddenly becoming sought after for CNC plasma cutter conversion. ;-) Now I'm thinking it needs a semi-active tension system using a computer controlled 3rd motor but with a spring so it doesn't have to be super precise in following the two 'rigidly' (in tension) connected to the end of the arm. I wonder how this would handle a water jet, would have to strengthen/accurize the arm pivots. -- Own the Future-Intelreg; Level Up Game Demo Contest 2013 Rise to greatness in Intel's independent game demo contest. Compete for recognition, cash, and the chance to get your game on Steam. $5K grand prize plus 10 genre and skill prizes. Submit your demo by 6/6/13. http://p.sf.net/sfu/intel_levelupd2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
On 26 March 2013 00:48, Gregg Eshelman g_ala...@yahoo.com wrote: Now I'm thinking it needs a semi-active tension system using a computer controlled 3rd motor but with a spring so it doesn't have to be super precise You could just run a DC or brushless motor at a constant current on the third drum, and simply not worry about its position. But if you are going to have the third motor, and its controller, than making it an active part of the system is only software, so free. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Own the Future-Intelreg; Level Up Game Demo Contest 2013 Rise to greatness in Intel's independent game demo contest. Compete for recognition, cash, and the chance to get your game on Steam. $5K grand prize plus 10 genre and skill prizes. Submit your demo by 6/6/13. http://p.sf.net/sfu/intel_levelupd2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
http://www.ebay.com/itm/3Axis-Nema-23-Stepper-Motor-425oz-in-CNC-Mill-Controller-SD-2H044MA-driver-/130835449799?pt=LH_DefaultDomain_0hash=item1e766687c7 i like the idea of using a capstan with offsetting weight , if you use 2 motors for x,y then use the same weight in tension the motors will see nothing but frictional resistance . If your capstan is sufficently large you should see very good accel and top feed rates , i think you could do this for less than 500 easily -- jeremy youngs -- Own the Future-Intelreg; Level Up Game Demo Contest 2013 Rise to greatness in Intel's independent game demo contest. Compete for recognition, cash, and the chance to get your game on Steam. $5K grand prize plus 10 genre and skill prizes. Submit your demo by 6/6/13. http://p.sf.net/sfu/intel_levelupd2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
How about just using some air cylinders to pull your counter balance cables. - Original Message - On 26 March 2013 00:48, Gregg Eshelman g_ala...@yahoo.com wrote: Now I'm thinking it needs a semi-active tension system using a computer controlled 3rd motor but with a spring so it doesn't have to be super precise You could just run a DC or brushless motor at a constant current on the third drum, and simply not worry about its position. But if you are going to have the third motor, and its controller, than making it an active part of the system is only software, so free. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Own the Future-Intelreg; Level Up Game Demo Contest 2013 Rise to greatness in Intel's independent game demo contest. Compete for recognition, cash, and the chance to get your game on Steam. $5K grand prize plus 10 genre and skill prizes. Submit your demo by 6/6/13. http://p.sf.net/sfu/intel_levelupd2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Todd Zuercher mailto:zuerc...@embarqmail.com -- Own the Future-Intelreg; Level Up Game Demo Contest 2013 Rise to greatness in Intel's independent game demo contest. Compete for recognition, cash, and the chance to get your game on Steam. $5K grand prize plus 10 genre and skill prizes. Submit your demo by 6/6/13. http://p.sf.net/sfu/intel_levelupd2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
On 26 March 2013 00:59, jeremy youngs jcyoung...@gmail.com wrote: i like the idea of using a capstan with offsetting weight , if you use 2 motors for x,y then use the same weight in tension the motors will see nothing but frictional resistance . If your capstan is sufficently large you should see very good accel and top feed rates , I am not sure you will see good acceleration. In fact, it is always going to be less than 1g. This is because for any faster acceleration the strings go slack as the weighs don't fall fast enough. I think bicycle chain might be the thing to use for the string. I think that a grooved drum, sat on a spline and free to slide vertically could be guided by a wheel engaged in the groove. As an alternative to the spline, it could be driven by a toothed-belt pulley several times wider than the belt. Or (thinking out loud) a square drive-shaft in the middle of the drum and some ball-bearings to drive it. (4 of the ever-popular V-groove style) -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Own the Future-Intelreg; Level Up Game Demo Contest 2013 Rise to greatness in Intel's independent game demo contest. Compete for recognition, cash, and the chance to get your game on Steam. $5K grand prize plus 10 genre and skill prizes. Submit your demo by 6/6/13. http://p.sf.net/sfu/intel_levelupd2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
On 26 March 2013 01:07, Todd Zuercher zuerc...@embarqmail.com wrote: How about just using some air cylinders to pull your counter balance cables. That would work, and with a set of pulleys (like a 4:1 block-and-tackle) the travel could be only a fraction of the total string length. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Own the Future-Intelreg; Level Up Game Demo Contest 2013 Rise to greatness in Intel's independent game demo contest. Compete for recognition, cash, and the chance to get your game on Steam. $5K grand prize plus 10 genre and skill prizes. Submit your demo by 6/6/13. http://p.sf.net/sfu/intel_levelupd2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
Andy said I am not sure you will see good acceleration. In fact, it is always going to be less than 1g. This is because for any faster acceleration the strings go slack as the weighs don't fall fast enough. jeremy bounces head of keyboard realizes his stupidity and pays homa ge :) whats that homer simpson says ?? doh thanx for the correction andy -- jeremy youngs -- Own the Future-Intelreg; Level Up Game Demo Contest 2013 Rise to greatness in Intel's independent game demo contest. Compete for recognition, cash, and the chance to get your game on Steam. $5K grand prize plus 10 genre and skill prizes. Submit your demo by 6/6/13. http://p.sf.net/sfu/intel_levelupd2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
--- On Mon, 3/25/13, andy pugh bodge...@gmail.com wrote: I am not sure you will see good acceleration. In fact, it is always going to be less than 1g. This is because for any faster acceleration the strings go slack as the weighs don't fall fast enough. No need to go anywhere near that fast because an oxy-acetylene torch or plasma cutter can't cut that fast. This rig is most often used for cutting steel 3/4 thick or thicker. -- Own the Future-Intelreg; Level Up Game Demo Contest 2013 Rise to greatness in Intel's independent game demo contest. Compete for recognition, cash, and the chance to get your game on Steam. $5K grand prize plus 10 genre and skill prizes. Submit your demo by 6/6/13. http://p.sf.net/sfu/intel_levelupd2d ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
2013/3/24 Gregg Eshelman g_ala...@yahoo.com: Looking into the possibility of fitting CNC to an old oxy-acetylene pattern following torch. (It can also mount a plasma cutter.) The torch mounts on the end of an articulated arm with two joints. Can LinuxCNC run such a setup? The description really looks to me like a scara-type robotic arm. LinuxCNC already is supplied with appropriate kinematics module. -- Viesturs If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_mar ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
On 24 March 2013 08:11, Gregg Eshelman g_ala...@yahoo.com wrote: I've been thinking that a system with three or four servo motors and cables connected to the torch mount could move it around as well as a 2-axis gantry. Can LinuxCNC run such a setup? At first I thought you were talking about motorising the existing arms, but reading more carefully, I think you are talking about pulling the arm around with cables and drums? When I thought you were talking about motorising the arm I was going to suggest pulling the arm around with cables and drums instead :-) Alex Joni has done this on a small scale. http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Alex_Joni's_Toy -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_mar ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
--- On Sun, 3/24/13, Viesturs Lācis viesturs.la...@gmail.com wrote: From: Viesturs Lācis viesturs.la...@gmail.com 2013/3/24 Gregg Eshelman g_ala...@yahoo.com: Looking into the possibility of fitting CNC to an old oxy-acetylene pattern following torch. (It can also mount a plasma cutter.) The torch mounts on the end of an articulated arm with two joints. Can LinuxCNC run such a setup? The description really looks to me like a scara-type robotic arm. LinuxCNC already is supplied with appropriate kinematics module. But it's not a robot arm. The two joints in the torch support arm are simple hinges, no provision to mount a motor and from what I've seen they're not super accurate. 'Course neither is a gas axe. ;-) It's not used for precision work, the shop it's at uses it for cutting out one to a few pieces for rebuilding pellet mills. Either the pattern holder or the heavy slabs of steel have to be moved after each piece is cut. Being able to control it to cut and step over for 2 or more pieces would make it faster to use, so would not needing to first make the patterns and get the correct amount of undersize. To put motors directly on the arm joints would require first doing something to ensure they're more accurate. I haven't checked how much play the joints have, but I bet it's enough that there'd be significant slop at the end of the arm if there was a motor attempting to precisely move it. What got me thinking about using cables are those flying cameras used at outdoor sporting events. There are setups large enough to move a camera all over huge racetracks. A cable system for an old pattern follower torch would be quite a bit less ambitious. I figure the best location to attach the cables would be at the top, centered on where the magnetic drive spindle is, which is centered directly over the torch. The shop has welders (and a weldor to use them) plus plenty of steel on hand to add supports for the motors. -- Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_mar ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
--- On Sun, 3/24/13, andy pugh bodge...@gmail.com wrote: At first I thought you were talking about motorising the existing arms, but reading more carefully, I think you are talking about pulling the arm around with cables and drums? When I thought you were talking about motorising the arm I was going to suggest pulling the arm around with cables and drums instead :-) Alex Joni has done this on a small scale. http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Alex_Joni's_Toy Pretty much exactly like that, but on a tool that's about 4x4 feet. Would have to build the motor supports so at least two sides of the table aren't blocked. Could possibly build it heavy enough to cantilever out from the same side that the arm is on, can't have the work hanging out that side anyway. The guy who owns the shop is pushing 80 but is interested in adding some CNC capability, especially if it's easy to use on pieces that're often one-off parts - if it can be faster than doing it by hand. I've seen the stuff he's cut with this pattern follower, plenty of circles and sort of C shaped parts, some pieces that have a two different sizes of circular ends with tangent edges and a hole in each end. I figure the time savings would mostly come from not having to make a physical pattern every time some new shape/size has to be cut. Another common problem with this old tool is when the drive magnet gets stuck in an inside corner or pops loose from the pattern so the torch goes wandering off across the slab of steel. CNC control would fix that. -- Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_mar ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Cable drive for a gas torch pattern follower?
I think that Torchmate used to make those years ago prior to their intro into CNC cutting. I considered buying the kit long ago but considered it too limiting. They abandoned that design in favor of a more conventional CNC design. I think you would be smart in doing the same. Dave On 3/24/2013 3:11 AM, Gregg Eshelman wrote: Looking into the possibility of fitting CNC to an old oxy-acetylene pattern following torch. (It can also mount a plasma cutter.) The torch mounts on the end of an articulated arm with two joints. On top of the arm is a variable speed motor with a 1/4 diameter, knurled, magnetic shaft. That runs around the edge of any bit of steel plate in just about any shape bolted to the pattern holder arm. The problems with that, the pattern has to be steel and has to be 1/8 smaller all around than the piece cut out will be, and you have to have a pattern to be able to do anything with the tool. I've been thinking that a system with three or four servo motors and cables connected to the torch mount could move it around as well as a 2-axis gantry. Can LinuxCNC run such a setup? -- Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_mar ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_mar ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
