Reply with QuoteJeff-Birt,
Are you sure it is running at 300 ipm?
I don't think that is possible, the stepper would need to be turning 6000 rpm.
JoeyB
Taig mill at 250 IPM!
As you guys probably know I keep preaching the mantra that bigger stepper motors do not always equal better stepper motors. I use and recommend 166 oz-in motors for Taigs and some folks always insist that you have to use 270 to 387 oz-in motors or a Taig just won't work properly.
I was doing some feed-rate testing tonight and though I would see how fast I could get my Taig going. I am using the 166 oz-in motors I sell, with a G540 and a MeanWell 48V power supply, and a SmoothStepper. Generally I have the motors tuned to a max velocity of 40 IPM as nothing I do requires any faster rapids than that.
I first tried 100 IPM and the mill worked fine. I upped the X axis to 150 IPM, then 200 IPM, then 250 IPM, finally at 300 IPM it quit! 250 IPM is kind of scary as there is a lot of vibration from the lead screw.
The moral of the story is that choosing components that are well matched will always work better than just slapping on the largest motor you can. I made a short crappy video with my cell phone, I'll shoot a better one at a later date: http://soigeneris.com/Documents/Taig_250IPM.3gp .
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Jeff Birt
Jeff-Birt,
Are you sure it is running at 300 ipm?
I don't think that is possible, the stepper would need to be turning 6000 rpm.
JoeyB
A doughnut a day keeps the doctor away.
I think he's saying that he tried 300, but it didn't work. 250 was the fastest it would go.
250 seems extremely fast to me too, but what do I know?
It 'will' do 250 IPM but the imbalance of the lead-screw causes a lot of vibration. 100 IPM seems very comfortable. These speeds would not be possible with a larger (270 oz-in) motor as the inductance is too much higher to get the stepper moving that fast (given that you hold all other things constant; driver, power supply, etc.)
So I will loudly proclaim that "bigger motors != better motors". You MUST size the motor to fit your machine.
Jeff Birt
I'm still new to all this, but from what I can tell, anything greater than 50 IPM just isn't very important to most folks. What I'm interested in, more than achieving ultimate rapids, is the ability to hog out metal at lower speeds without losing steps. That would include cutting various thicknesses of steel plate in circles and arcs, and vigorous Z-axis movements through the metal as well. Unfortunately, there's no standardized test for comparing different motors this way. The hardness of the metal, type of cutter, motor RPM etc. all come into play. Empirical (statistical) data from multiple users seems the only way to really get a handle on this for a newcomer like myself.Originally Posted by Jeff-Birt
That has been my point all along. Just because my mill will do 100 IPM does not mean that I will run it there; just like my truck will do 100 MPH but I don't drive it at that speed.but from what I can tell, anything greater than 50 IPM just isn't very important to most folks.
The motors/drive/power supply need to be matched to the machine. All I'm proving with the crazy speed is showing that the 'small' motors are a better choice for a Taig. Acceleration takes torque, so being able to accelerate to crazy speeds shows that the combination I am proposing has more than adequate torque and speed for the true operation range of the machine. A larger motor simply won't perform as well.
Jeff Birt
Based on Joeys comment, then that means you're spinning the stepper reliably at 5000rpm?
Gerry
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All you are proving is that SMOOTHSTEPPER is wicked awesome.
If the point is that people don't need faster than 50 ipm and you can get that with just the motors at 25kHz,
why in the world would you spend an extra $155 for something that you never use?
An extra parallel port card is cheaper.
People tell you that they get better performance with slightly larger motors (jalessi) but they are dismissed
because they spent $30 more for speed they don't need in your opinion.
Sounds a bit more logical than $155.
Hoss
Gosh, you've... really got some nice toys here. - Roy Batty -- [URL]http://www.g0704.com[/URL]
All the smoothstepper does is generate pulses. If the PC could generate pulses as fast then the LPT would work just as well. You can continue to doubt but I've shown I'm correct with both the theory and by empirical evidence.
Jeff Birt
If a car engine could generate it's own nitrous oxide then you wouldn't have to add a bottle either.
It doesn't happen in the real world.
Ignore whatever jalessi or anyone else tells you that they do in the real world
and believe what you want to believe in your world.
Hopefully the newbies can sift thru the detritus.
Have a good holiday, Hoss
Gosh, you've... really got some nice toys here. - Roy Batty -- [URL]http://www.g0704.com[/URL]
Real world empirical evidence would be rapid speeds, material hog, and at the end come back to home 0,0 showing no lost steps. If it can't machine or accelerate without losing steps, what good is speed? If it does do all of the above, then you've made a great point.
Hoss2006,
Dinoflagellate's eat detritus for dinner, some may even believe it is a delicacy.
Have a most awesome Fourth of July.
Jeff...
Patience and perseverance have a magical effect before which difficulties disappear and obstacles vanish.
Makes me wonder if the vibration described was in fact the stepper motor losing steps.
The smaller motor can do the job, but there's no proof the bigger can't, nor that there aren't some things the bigger motor does better.
Personally, I like my mill to be able to move over 100 IPM, but then it has quite a bit more travels than the Taig.
Cheers,
BW
Folks the whole point is that the motors, drive, power supply etc needs to fit the machine. On the TAIG larger motors than the range I'm talking about offer no additional benefits. They only cost more and use more power and would most likely harm performance.
The noise was most definitely the lead screw. It is not supported on both ends so it can whip around. At 100 IPM I did several repeated sweeps across X and indicated at zero and was dead on. The 250 IPM speed is way out on the edge and I am certain that it will loose steps at that speed.
For larger mills larger motors and faster speeds may be what is called for. That is exactly the point I have been trying to make. Some folks are under the impression that on a TAIG you need to put a 270~370 oz-in motor for the machine to work properly. That is clearly not the case. Then the argument was "well it will be too slow", so I decide to see how fast it will go and when I prove emperically that it is is certainly 'fast enough' the response is 'well that is just the SmoothStepper".
I hooked a a LPT cable and set Mach to a 60 kHz kernel as that is as fast as my shop PC will go. I could run 90 IPM just as well on the LPT as I could the SmoothStepper.
I took some new video of the mill doing 90 IPM with the SS and LPT and a better one of the @%) IPM. I'll get them on you tube tonight and add links here.
Here is a better video of 250 IPM: "http://www.youtube.com/watch?v=tYn9lCgZPEw"]YouTube - 250 IPM SS
Here is 90 IPM on the SS: "http://www.youtube.com/watch?v=RzrBcXCNDhU"]YouTube - 90 IPM SS
Here is 90 IPM on the LPT: "http://www.youtube.com/watch?v=Fo-9qYWopCE"]YouTube - 90 IPM LPT Machine
Last edited by Jeff-Birt; 07-03-2009 at 05:46 PM.
Jeff Birt
If even you are certain it will lose steps at this speed, then please don't claim it will "do" that speed. For a speed to have any use, it had better not lose steps otherwise what is the point? No operation, including rapids between feed moves is any good if it loses steps.
Just because one motor "will" do something, it also does not disprove the fact that another motor can do the same thing.
I feel like I'm in an episode of 'Who's on first?" I am not claiming that 250 IPM is advisable or reliable or anything of the sort. As I stated in the very first post, I wanted to see how fast it would go. I have to admit being a bit amused at all the flack I'm getting by simply trying to present some factual information about motor sizing. If you are happy with your motor choice than I am happy for you.
If anyone is interested in learning the facts about motor sizing get yourself a copy of this book: http://www.copperhillmedia.com/ServoSizingBook.html.
Jeff Birt
All I can say is I have ~280 oz·in motors (Keling KL23H276-30-8B) and there have been a few times my machine has inexplicably lost steps. I have to guess that less powerful motors would lose steps more often.
My motors wired in bipolar parallel have a lower inductance than the inductance listed on the spec sheet for those 166 oz·in motors (but I don't know how those motors are suppose to be wired). My rotor inertia is 480 g·cm² compared to the 166 oz·in motors that are 271 g·cm².
The max speed I can get my Taig to move (reliably, and with my ways and nuts properly adjusted) is around 75 IPM. I limit the machine to around 60 though as I figure that's fast enough.
I think I'm going to pick up a SmoothStepper. If it doesn't give me anything else it'll let me use USB which I prefer over parallel anyways.
Last edited by Hirudin; 07-03-2009 at 08:08 PM.
What driver are you using?
Lost steps can be from a variety of reasons:All I can say is I have ~280 oz·in motors (Keling KL23H276-30-8B) and there have been a few times my machine has inexplicably lost steps. I have to guess that less powerful motors would lose steps more often.
1) A running process can interfere with Machs generation of the pulse stream.
2) Noise in the system from spindle motor, wiring issues etc
3) Running a machining operation that is right on the edge.
4) Using backlash comp in Mach.
5) Improper motor tuning.
6) Power supply not keeping up / driver issues.
I would probably suspect noise or PC issues as I think you probably have a good handle on feeds/speeds. With the Taig I recommend using a line filter mounted up by the spindle motor to eliminate it as a problem. Motors are noisy and it will cause problems. I just added some good line filter to my site that work well on the Taig spindle.
Jeff Birt
Sorry, I have a bad habit of editing my posts 20 times, one of those times I had put the driver, but I must have edited that part out.
I'm using Gecko G203v drivers with a Keling 48 volt 12.5 (IIRC) amp PSU.
Yeah, it could have been a few of those things, most likely 3 (which I took to mean: "right on the edge of being too much for the motors to handle). When I was more of a beginner I would try to push the machine too hard. But, the last part I made (which was also used the most operations of any part I've made) didn't have any issues.
I have my suspicions about noise in my wiring too. If I keep using the AC spindle I'll have to look into getting a filter.
