The 5v is coming from the computer's USB port via a USB "power cord". The 5v there is metering as 5.02v and I checked it with my scope and it's nice and clean.
Unfortunately the rest of my computers are all laptops without parallel ports, so I can't switch out very easily. I've been thinking about getting a Smoothstepper, though, so that would remove a lot of these variables.
I'll run all the scope tests you outlined tonight and report back. Thanks for taking the time to offer suggestions.
Jason
If that makes "total sense" then your question should already be answered, no need to go chasing voltages. The simple fact is that if the backlash comp doesn't use the accell profiles, and tries to accelerate the screw (it's still mass, and it's still subject to causing issues with motor missing steps) too fast, you'll lose steps. If you can't get backlash comp to work over 15 IPM, but you can get reliable although backlash prone operation at higher speeds with it turned off, that is the limiting factor, not a parallel port voltage issue.
What I meant when I said it makes total sense is that the BLC doesn't use the accel profile. Not that it explains the issue I am having. I still don't think my table is binding, but if more experienced people than I think it's worth checking, then I will check it.
The reason I don't think it's that is that the stepper doesn't just miss steps, it seizes. Even if the BLC caused it to miss several steps under full acceleration, when the acceleration of 2 kicked in the axis should start to move. It doesn't, as the video shows. Since Mach3 has no way of telling if the stepper has missed steps it should (under this theory) miss the steps required to do the BLC and then work fine for normal axis movement, but it doesn't.
I tend to agree with you. I don't think it's voltage or noise or anything electrical, and I also don't think it's physical. I think it's a software issue. That said, I believe it's useful to check "just to be sure" too cause I just don't know.
As for my question being answered; it's still not. If I can't use BLC above 15 IPM I'd like to know why. If it's a limitation of my controller, or steppers, or mill, or anything else I'll consider upgrading.
For whatever it's worth I seem to recall the smooth stepper having issues with BLC as well. I'd check before dropping the coin.
Personally I prefer to physically eliminate all the lash I can, and go with no comp. I have double ball nuts on all 3 axis, with no measurable lash. BLC has always seemed a little hacky to me, and I've read a number of reports of people having issues with it. Is this an option for you?
I just ran a 2'' circle contour at 10 continuous repetitions, at 70ipm. Once with blc off, and once with it on. Both runs were virtually identical, no problems whatsoever.
my settings are as follows:
Blc y .0266
blc x .003
backlash speed 80%
shuttle accel. .005 seconds
If you can't beat 15ipm, then trust me, you definitely have something out of sorts(or possibly need some better parts). I was under the impression that your setup was already working well at higher speeds, and only a couple of days ago, it had begun acting up. Did you not have the backlash set, prior to when you noticed you had issues?
Thanks for running that test. It's good info to have. Are you running a stepper based system?
I have had backlash set since I got the mill but I had only been doing runs of 12 IPM or less. I have only recently tried to go higher to speed up operations at a smaller DOC on the advice of another forum member in another thread.
Yes, I'm running steppers. Currently using Keling drivers(kl-6050), and an Astec 48v/25a supply. By the way I just ran the same test successfully at 100ipm.
Not really any need to check anything more in the binding area if you have access to and can turn the screws by hand if they turn freely with no power to the steppers you should be ok there. I saw in a post (and I forgot it was there:withstupi) the backlash speed. Have you tried to mess with it? Also I see you have a switching power supply. I hate those things. Most people have not one issue with them but I can never trust something that needs so much current to one of those types. Just a feeling I get from being an electronics tech for 25+ years. I use the unregulated type. I have the 6050s too and haven't had any problems with them. Also my mill never skips a step - if it skips it stalls and doesnt recover until it switches direction if that helps any. I like it that way cuz then I know my part is f@$k!d and I can stop it right there.
Rick
Just to follow up on this thread: I asked for some help in the Mach 3 forums and someone told me to try quite a few different settings. Last night I spent a bunch of time adjusting every setting I could find. The one that finally did the trick was the shuttle setting. I am not sure what I originally had it set to. The default, probably. Then the other day I changed it to .005 based on Hoss' video. The setting that fixed my problem was .05.
After setting that value I can now jog and cut at 35 IPM no problem, and I tested at 50 IPM and that worked fine too.
Thanks for all the help everyone. I appreciate you taking your time to answer my questions and make suggestions!
Thanks,
Jason