I have my desktop machine finally running, using the roadrunner as a sample to set things up, I seem to be losing steps, the design never comes out quite the same each time, I am using ordinary 3/8 x16 threaded rod for lead screws, would proper acme thread be an inprovement and if so what lead or tpi should I be looking at? I am running half step with 125oz 2amp motors.
Thanks for any help offered.
Terry

Hi Terry,

standard V threads will work, they are not the most accurate but they should repeat.

The type of thread used will not cause you to loose steps, but the backlash may be a problem.

Have you checked the backlash?

If you slow down the velocity and increased the acceleration time do you still have the same problem?

Graham.

Thanks for the reply Graham, I did play with the velocity etc. and it seems to help, can you give me a general setting that most are using?
Terry

Hi Terry,

thats not easy to do as everybody's setup is different.

Try setting the velocity at 500, acceleration at 100 for a start.

Then run the roadrunner and see how it looks and sounds,  at these settings you should hear the motors ramp up and down quite a bit.

Keep increasing the velocity by about 50 at a time until it starts to stall, then back it off by 50.

Then try dropping the acceleration 5 at a time until you get stalling, then up it again.

I am afraid its all suck it and see with motor tuning.

Graham.

Hey Terry,
    There is no such thing. Everyones set up is different. Above all, you want repeatability. You could start by upping your speed until it starts to skip steps and then back off about 10%. Depending on your setup, tool load, etc. you may be able to go faster or slower. I wish there was a set in stone number for everyone but then again, that would be boring.

I hope this helps,
Brett

I see Graham has beat me to the punch. Hey Graham.

Thanks guys for the replies, I will try your suggestions.
Terry