Ok,

After fighting problems on my Y and Z gantry's I decided to break down and get a set of the Vextra's from MPJA. I drilled and tapped them for 1/4-20 and the install was quick and easy. Once done, X is un beleiveable - 900+ ipm. Y runs (belt mod) easily the same, and 100% realiable. Z on the other hand, is a whole other animal. Before the change, I ran stock steppers with 3/8 - 12 acme screw, and got about 20 ipm but no mater what there were occasional lost steps. After much tweaking of the rails, and screw alignment, and anything else I could think of. It finally drove me to think the new stepper would solve all my issues. After Installing the new stepper, I can get it to run a little faster, like 25 or so, but more annoying is that it dosn't always run the right direction or changes direction while it's traversing.

So my question, If my gantry/screw is binding would I see this behaviour or should I be looking at somthing else? This is not a problem I have had, so it is perplexing to say the least...

-Glen

 

Instead of actually swapping the chips to test, could you just swap the channel and change the pin assignment in Mach3?

 

I can try that, I am using a diffrent board and have a spare channel, so I can give that a go, But I thought I remembered somone having simular problems, but couldn't find them, although it may have been on cnc zone... Would having +/- crossed on one phase do this? Not sure thats whats up but this is the only motor I didn't think to double check how things were wired. I'm just trynig to avoid pulling this thing apart yet another time...

 

Ok, I've checked the wireing, it's ok, and hooked it up to the 4th channel and get the same result. Would binding cause this behiviour??

-Glen

 

I've never tried it, but I've read swapping the two wire of a phase just reverses the direction of the motor.

 

I had similar problems with my Z axis.

I ended up removing the gantry and installing stainless steel rods with oilite bearings, 3/8 Acme thread drive, and a good quality coupler.

I still can't push much over 25 with a Vextra 166 but it is consistent and does not miss any steps now so I am happy with it.

You want to exhaust all of your options before going this route. Make sure you do not have any loose connections from the board to the stepper and that your wire diameter is sufficient to carry the load.

 

The wire, not that would make since, I'll bet I have a pinched or broken strand. Time to find a new peice. It also may be that the stock wire is not heavy enough for the current we are using without causing a voltage drop. So the new peice will be heaver as well...

I'll let you know how It works out.

-Glen

 

Ok, Runng throught a dry run psudo-cut now to make sure we get back to zero in the end, But I'm 100% positive that I had a bad wire. I triple checked connections, and it mde no diffrence, but I but in a new legnth of wire and we are now looking like this thing is going to be 100% solid right where I want it. I still can't get over the 900+ rapids on x & y...

-Glen

 

Glad to see you're up and running again. Don't be too concerned about obtaining high speed rapids. I was able at one time to run 1200ipm but have since toned it down to 500ipm just because it is really too fast if you have lite ply or other materials that you want to cut.

You can get slippage in the roller at high speed and it just won't make that much difference in the long run. Plus, you have to remember to set a reasonable feed rate in your cut files once your machine is capable of obtaining faster rates as the different bits and dremel speeds and material will all dictate it.