Taig mill at 250 IPM!

[Jeff-Birt]

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://cnczone.com/Documents/Taig_250IPM.3gp .

[joeybagadonuts]

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

[Hirudin]

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?

[Jeff-Birt]

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.

[noisillator]

Originally Posted by Jeff-Birt 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.

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.

[Jeff-Birt]

but from what I can tell, anything greater than 50 IPM just isn't very important to most folks.

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.

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.

[ger21]

Based on Joeys comment, then that means you're spinning the stepper reliably at 5000rpm?

[hoss2006]

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. 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.

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

[Jeff-Birt]

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.

[hoss2006]

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

[MrWild]

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.

[jalessi]

Hoss2006,

Dinoflagellate's eat detritus for dinner, some may even believe it is a delicacy.

Have a most awesome Fourth of July.

Jeff...