Motor torque…..do I need more?

[Richards]

The specs on that driver show a maximum of 200,000 pulses per second. Most stepper motors move 1.8-degrees per full step, or 200 steps per revolution. Most of us don't use 200 steps per revolution. To let the Centroidcnc software work at its optimum, if I've read Keith's posts correctly, he recommends that we set steps per revolution to 3,200 or 16X as many pulses to spin the shaft one revolution. That means that at 200,000 pulses per second, the motor might be able to spin 62.5 times per second. Now, add in the 10:1 gearbox. It reduces the speed to 6.25 times per second. In another thread, the figure 2.69 revs per inch was used. Using that figure, the maximum speed for that motor with that driver running at 3,200 steps per revolution through a 10:1 gearbox will be 2.32 inches per second or about 140 inches per minute.

To go faster than than, something must be changed. If you remove the gearbox, you lose torque. If you reduce steps per revolution, you increase chatter on arcs and circles. Keep in mind that the physical components you choose to use create an envelope of possibilities. You can only take from the envelope things that you put in it. Personally, I can't see how that motor will help solve the problem. I think that either the gearbox has to be changed to 5:1 or less or the steps per revolution setting has to be lowered to 1,600, or 800 or 400. At 800 steps per revolution and a 10:1 gearbox, the axis might run as fast as about 550 inches per minute. At 400 steps per revolution and a 10:1 gearbox, the axis might run as fast as about 1,100 inches per minute. On a light-weight machine, at those speeds, I would be worried about flex and binding. Adding a piece of angle-iron to the backside of each aluminum rail might stop the flexing, but it would also add weight which requires more torque to move.

Building a CNC machine requires tradeoffs. I don't expect my little TAIG mill to run like a HAAS, but given enough time, it gets the job done.

[RoxanaPS]

https://www.omc-stepperonline.com/ts-se ... cl57t-s30a

Thank you. I am going to order this motor. I have discovered that my Y axis can still run very fast even with the planetary gears installed.

It's worth a shot dude. And I know you don't want to hear this, but I'm still betting hard on there is something binding. I assume with a rack system when the machine is powered off, you can by hand push the axis. Not sure, I've never had a rack system, but I wouldn't see what not.

I would 100% be checking this. I would 100% be adding grease to the linear rail bearing blocks/carriages. I would 100% be lubricating the rack as well.

You have to see at this point that your issue no matter what you do is the same, there is something wrong with the linear motion of that axis.

In that video you posted the machine would move almost to the middle of the machine and it would bind there. If that is always the point of the problem, I'd be looking, measuring, etc.

It moves perfectly smoothly by hand when the machine is off. No binding at all.

[RoxanaPS]

Extruded aluminum frame? Wonder if it's flexing in the middle of the span with torque applied? You wouldn't be able to tell pushing it by hand, necessarily.

Maybe chuck a pencil in the spindle and tape a sheet of paper on the table, set Z to just touch the tip of the pencil, run full speed and see if it draws a straight line or if there's a "hump" when it stalls?

I will try that.

[Jerminator96]

Extruded aluminum frame? Wonder if it's flexing in the middle of the span with torque applied? You wouldn't be able to tell pushing it by hand, necessarily.

Maybe chuck a pencil in the spindle and tape a sheet of paper on the table, set Z to just touch the tip of the pencil, run full speed and see if it draws a straight line or if there's a "hump" when it stalls?

I will try that.

If you need a hand with anything, let me know. I think I saw you're in the Raleigh area. I live just off Tryon Rd.

[RoxanaPS]

Extruded aluminum frame? Wonder if it's flexing in the middle of the span with torque applied? You wouldn't be able to tell pushing it by hand, necessarily.

Maybe chuck a pencil in the spindle and tape a sheet of paper on the table, set Z to just touch the tip of the pencil, run full speed and see if it draws a straight line or if there's a "hump" when it stalls?

I will try that.

If you need a hand with anything, let me know. I think I saw you're in the Raleigh area. I live just off Tryon Rd.

Hey, really? Yeah, I live in Garner. I appreciate that. I am happy to pay you for your time if you think you can help me out.

[RoxanaPS]

Ok my new motor arrived and has been installed. My max travel speed went from 200 to 350. I haven’t tried messing with any of the steps settings on the drivers are in the software to see if I can increase that but quite frankly 300 is fine for me. I just wanted to be able to go to 300 that’s what it was important to me. So far it looks like I’ve achieved that fortunately.

[CNCMaryland]

That's great news!