[borne2fly]

I've heard a few complaints about steppers skipping steps ..... is there anything like a step sensor you can place on the motor to confirm that it actually responds to the applied steps? The end goal would be to issue a warning if the motor fails to turn the specified amount, then the user can decide whether to continue or reset everything.

I'm looking into getting a small CNC machine, and was wondering if there's any advantage to EMC (not sure which machines can utilize this, it seems like so many are captives of some proprietary software). Can Tormach run EMC? Are there any negatives to running EMC?

[Don Clement]

[QUOTE=borne2fly;743724]I've heard a few complaints about steppers skipping steps ...QUOTE]

Yeah I heard that also...but in three years of running a Tormach have never experienced missing steps. Don’t believe everything you hear.

[Tormachmaster]

I have had mine for 3 years now and have not found it off at all. I had a tool pull out of the holder an extra inch that did make it skip but only after it was bent for good--3/4 boring bar.

[borne2fly]

Good to hear it's not a common problem. I was worried after reading a few posts here.

Still, with any open loop system it's nice to know if the thing issues a warning of any sort if an intermediate step gets skipped. An example is a PWM driver overtemp function ..... it doesn't always close the loop by shutting down the system, sometimes it issues a flag and the user then decides what to do.
Does the Tormach offer a 3-axis dig position readout? It would sure help to confirm the function of the steppers.

[Tormachmaster]

It would be very easy to add one but I have put indicators several times and it held exact every time where are you located?

[zephyr9900]

is there anything like a step sensor you can place on the motor to confirm that it actually responds to the applied steps?

I've only seen that once. On a machine I worked at at my last job, we put encoders on the step motors with resolution that matched the microsteps we were using (800/revolution). It was a benchtop laboratory device to take core samples from electrophoresis gels for research, and we needed to verify the position before actually taking the sample. So we would move it in X and Y, poll the encoders to verify that the moves were done correctly, and then move Z and take the sample. But that was positioning only--the encoder pulses went into accumulators which were read after the fact. I think that it would be a very difficult thing to do in realtime motion since each step would need to be verified before taking the next one, and at that point just going to servos would probably be easier.

Randy

[borne2fly]

That sounds like what I'd want to do. As you say, making it function as a closed loop system might be difficult. Verifying each step would probably introduce an unacceptable slow-down, but verifying every, say, tenth step might not be so bad. In any case, I'd only be using it to check positioning, not to make a servo system out of it.

I'd like to see one of these machines in action. Is anyone here in the San Jose Bay Area?

[zephyr9900]

[offer to demo my machine withdrawn as it is now out of service unexpectedly, and won't be up and running again until after we moveto a new place]

Randy

[borne2fly]

Randy ...... I sent you a PM

[mvcalypso]

You might consider visiting TechShop in Menlo Park - I understand they have a Tormach now.
http://www.techshop.ws/

Dave

I'd like to see one of these machines in action. Is anyone here in the San Jose Bay Area?