Loosing steps

[Normann]

I have just finnished my first cnc router and everything works fine (almost). Last night I was makeing a puzzle for my kid. I was routing in 6mm ply an suddenly I noticed that the X-axis was about 5mm off (minus).

I have read a lot of posts on the zone about loosing steps, but I have not found an answer to why this happends.

I notice if I turn up the velocity the motors are making sound but stops. Likewise if I turn down the accelleration (very low) the motors accellerate and suddenly stops, but they are making sound.

Can anyone tell me what is the proper figures for my setup?
Some data:
Hardware: http://www.kelinginc.net/ThreeXCNCPackage2.html
Leadscrew: 1.75mm
Microstep: 1/4
Amps on controller: 3A
Units: mm

Best regards
Terje

[Juka]

Hello!
You should change step and dir pulse to 5, I think that would help you!
Accelleration will be fine (50mm/sec), step/mm is correctly 457,14

[Khalid]

Please if somebody tell me if the speed(IPM) can be increased by changing the step and dir values in Mach3. what effects can we get by changing these values setting from 0-5. please explain

[ger21]

Originally Posted by Khalid Please if somebody tell me if the speed(IPM) can be increased by changing the step and dir values in Mach3. what effects can we get by changing these values setting from 0-5. please explain

No, the speed won't change. Those numbers specify the duration of the step and direction pulses. Some drives need higher numbers to work correctly.

If you lower the accel and are still losing steps, you'll need to lower the velocity as well. Most likely you're exceeding the limits of your machine. There are a couple things you can do to increase top speed.

Increase the voltage to the steppers. If your drives can handle it, increasing the voltage will give you a proportional speed increase.

Change to higher lead screws or gear them so the motors turn slower. Steppers have more torque at lower rpm's, so changing screws can increase your speed up to double in some cases.

It's possible that you're experiancing resonance. If so, this thread may give you some help.

http://www.cnczone.com/forums/showth...639#post256639

[Normann]

I did what Juka wrote. I changed the step and dir pulse to 5.
I did a testcut of 138 circles (see attached file). The code contained 26000 lines and the cut was finished after 1,5 h. Success
I used a v-bit at 1.5 mm depth, so the cut did not stress the motors. Maybe I will loose steps when I begin to carve deeper?

I must ask the same as Khalid: What did I do?

Regards
Terje

[Normann]

Ger21
I read the post about resonance and damping. That was some interesting reading. I fond my problem in post #45. The video shows exactly the same problem I am facing.
I ran down to my workshop and made a flywheel out of wood and a role of tape. (just to test the concept).
I tested without flywheel, and when I reached a velocity of 690mm/min the motor stalled. I mounted the flywheel and started to increase the velocity. When I reached 1800 mm/min I did not want to go any further because my flywheel wasn’t balanced well enough. (the whole gantry was shaking) I think I have to make a real damper so I can speed up my router.

Terje

[Khalid]

My Dear Ger21
Thank U For Ur Kind Information