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[2Bits]

Hopefully I put this in the right forum.

I have a generic sim I bought from a guy out east and now I can't get ahold of him. I'm trying to cut some cast acrylic with some bits where I need around 100 ipm. But in motor tuning, I can't get the thing to go above 90. (Using Mach 3). It makes a hard bump and locks up. I've been playing with different settings and can't come up with a solution.

All I know about the system is the following:
24"x12"x 3" cutting area
- 282 oz/in steppers on all axis direct driving the lead screw
- 12 Precision linear ball bearings (4 per axis)
- Hardened shafts
- Anti-backlash wear compensating lead nuts
- Two years warranty (Parts and labor)
- 3 axis chopper microstepping controller


Does this info provide any help on why I can't achieve 100 ipm?
Appreciate any help on this .

Mark

[ger21]

Assuming you can set a higher speed in motor tuning, but the machine can't actually do it?? Sounds like the steppers are just running out of power. Do you know what pitch the screws are? and what voltage you're running the steppers at?

[2Bits]

I know that the screws are 10 tpi. Any specs other than what I have are unknown to me. I would have never bought this system knowing what I know now (still need to know a whole lot more).

I have no idea what the controller is made up of or from. It's a sealed box at present and I just plug the wires into the steppers.

I'm kinda disappointed if in fact I'm limited by the controller. Yes, I can go to motor tuning and ramp the velocity all the way up to 90 and vary the acceleration, but if I go above 90 and hit the movement key, there's a loud chirp like the motor got confused what to do. I actually can do short taps on key, but forget it if I try to hold it down, not gonna work.

Is it possible that the controller is limiting the ability of what I can do with this? The steppers seem to be of average size.

[pminmo]

Originally Posted by 2Bits I know that the screws are 10 tpi. Any specs other than what I have are unknown to me. I would have never bought this system knowing what I know now (still need to know a whole lot more). I have no idea what the controller is made up of or from. It's a sealed box at present and I just plug the wires into the steppers. I'm kinda disappointed if in fact I'm limited by the controller. Yes, I can go to motor tuning and ramp the velocity all the way up to 90 and vary the acceleration, but if I go above 90 and hit the movement key, there's a loud chirp like the motor got confused what to do. I actually can do short taps on key, but forget it if I try to hold it down, not gonna work. Is it possible that the controller is limiting the ability of what I can do with this? The steppers seem to be of average size.

If you have an adjustment knob on a motor, with no power on the machine slowly turn it to see how many revolutions it takes to move 1 inch. a 10 tpi screws single start screw will take 10 turns, a 10 tpi 2 start will take 5, etc...

Steppers loose power as the go up in rpm's. If you have a single start screw, then you probably can't get enough power at the rpm's needed for 100 ipm.

Pictures might help us evaluate your issues. For more detailed info:

http://pminmo.com/mechancial-power

[ger21]

My Z axis has a 10tpi screw and I can only reliably get 50ipm out of it. My X and Y axis have 1/2-8 2 start acme (4 turns/inch) and get get over 175ipm. All have the same motors, 253oz-in. Xylotex drive @ 24volts.

You're motors are staling bcause they don't have enough power to move as fast as you want. If it stalls immediately, then the acceleration it too fast. Try it at 4 or 5. That should let you get higher speeds.

[2Bits]

Tried the acceleration at 1, made no difference from 90 above. Even at 70 - 90 I don't get a good clean smooth operation. So it looks like 60 is my magic number and I may have to look at upgrading to a bigger better machine in the near future.

What a hobby to get hooked on!

[pminmo]

You maybe able to change motors or drivers to get what you need if the mecahnical size of the machine is acceptable.

[ger21]

Originally Posted by 2Bits Tried the acceleration at 1, made no difference from 90 above.

With accel at 1, and feedrate 90, it still won't move? Or, it won't get to 90? If it's running on 24V (probably), it's unlikely you'll get 90ipm.

Two best fixes are change screws, and get a Gecko G540 and higher voltage power supply.

[2Bits]

It will move some maybe a .5" then stall with a 'cool' sound. That's holding the key down. If I tap it, then it's ok for short bursts, so basically it can't do it. I'm getting fair results on a .0313 bit at 50 ipm, but it should really be double that (cutting cast acrylic).

That old adage always holds true, 'you get what you pay for'. I didn't have the extra grand or more for a higher end system than I have. I'm not sure this system is worth upgrading. I'm better off building or getting a 'all metal' system for some strength etc. This one is made from hpde plastic, while it's not bad, forget about milling aluminum which I want to do.

[pminmo]

Sounds like the motors are resonating.
This actually may be able to be worked out, is there a p/n on the motors?

[2Bits]

That I did find sometime back.
Pn: 57BYGH405

Attached is the pdf doc of specs I found on it.

[pminmo]

It's a six wire motor 280 ozin motor, so possibly a couple of options depending on the controller. Any chance of you taking a picture of the controller internals and posting it.