Z axis problem losing steps solved (I hope)

[zeeway]

I have been going a little crazy trying to make my machine behave in the z axis moves. It seemed to lose steps all the time, especially when trying to v-carve something. In carving a name sign, if I didn't re-zero the z axis after every letter, by the end of the carving the router bit would clear by 3/8 inch and think it was at z zero.

I went through all the mechanicals: changing couplings, better feed, screw and AB-nut, and it improved a little - but not enough.

Oh yes, my machine is plywood/MDF, kinda like a JGRO with 380 oz in stepper motors, Gecko 540, and Mach3.

The last changes made, I think (I am saying this with my fingers crossed) seem to have done the trick. I don't know if all of them are necessary, but at this point, I am not going to risk angering the CNC gods by changing anything. Here are the changes:

1. I took the router power cord out of the cable chain to get it away from the motor leads. I recently read about electrical noise issues caused by AC lines being too near signal lines. I also moved my surge suppressor/plug-in strip away from my control box.

2. I changed the Mach3 engine speed to 35000 Hz.

3. I increased the debounce interval and index interval to 300. My understanding is that this helps screen real signals from noise.

4. I switched to Sherline half-pulse mode. I have no idea what this does, but I read the suggestion somewhere here, and thought I would try it. Perhaps it gives longer signal pulses...but then why is it called a half-pulse mode?

Okay with all of that, the router is behaving very well. If it is still losing any steps, it is very few. Yes, I would feel more confident, if I had run a hundred trials, but I am happy for now.

Oh yes, there is one more change I am going to make. I have ordered some insulated 14 gauge wire which I will use as my router power cord, to try to reduce noise even further. If I get real brave I may try to put the router power cord back into the cable chain after that switch.

Maybe this info will be helpful to some other soul lost in the horror of losing steps.

[jsheerin]

I went through all this as well - it's a pain. If the sherline pulse mode fixed the problem, then the real problem is likely either with your parallel port or your G540. I eventually found my parallel port would not source enough current to correctly drive the G540. I have some posts in the Geckodrive forum with pictures of scope traces showing this. Before I figured this, what I would have happen would be perfect operation except when one or more of my axes moved very, very slowly while the other axes were also moving. The slow moving axis would lose steps and / or move erratically in little jerks. The fix was a pci card with dual parallel ports and a custom cable I made to utilize some of the pins from each port (not all the pins would source the required current, but most would).

There was also an issue with bad chips on the G540 for a while that caused issues like this. If you got yours more recently, that's all been fixed as far as I know. There is info about that in the Gecko forum as well.

[zeeway]

Thanks for the info. I just read your thread on the gecko forum. Hmmm...maybe I need to spring for a separate PCI parallel port card to make sure.

[zeeway]

Well, I was still losing steps - just a few on the Z axis, but enough to force me to re-zero the Z axis frequently to make sure everything would come out the proper depth.

So decided I would try a separate PCI card with a parallel port. The first attempt to install it was not successful. I reread the instruction several dozen times, and I thought I had done everything correctly, but the install process could not find the driver on the CD.

In the meanwhile, I tried to order a SmoothStepper - sent a email to get on the wait list to warp9td.com. Sent a second e-mail. Sent a third email asking for an acknowledgment....no response over 6 days...strange.

So I today I downloaded the PCI card driver from the vendor web site onto the hard drive, and referenced the location during the installation. The install was successful.Through the device manager on the computer, I made this new card LTP1. In testing, the router comes back to the same zero point after running a long v-carve file - even with the router on - even with the router power cord adjacent to the signal cables in the cable carrier. so with fingers crossed (as I often do), I believe my router is ready to go finally.

Looks like I don't need a SmoothStepper - which is good, since it looks like I can't buy one anyway...

[zeeway]

In the interest of fair and balanced reporting...Warp9 finally responded yesterday - said they had been focused on fixing some contract issue.