Hollydog, I read your posts on engraving at an angle. Tell me was your original 2 boards usb or parallel?
Bazza.

So some more info. I have tried sherline mode, I have tried running drives at 250mm per min with acc of 1. Still the same. I have repeated it over and over and the amount of lost steps are near enough to be exactly the same. So I tried swapping z and y drives by pin selection. Exactly the same. This counts out my mill. I tried adjusting the voltage to the first buffer chip on the parallel port input. I tried it at 5v. 4.5v. 4v. 3.5v and 3 volts. By doing this I would be varying the required input high signal. If the problem was that the computer was not always sending a good enough signal the amount of lost steps would change as the hysteresis of the Schmidt buffer chip changed. However the discrepancy was exactly the same.So I have to figure its in Mach3. Or still in the computer. Any ideas?
Bazza

Do you have a desktop you can try instead of the laptop?
Hood

Unfortunately not. I do have a motherboard and a couple of ods and ends that I might try and cobble together.
Bazza

I still haven't been able to try with a desktop. I ran the road runner program 5 times. The end result was a discrepancy in the x and y movements. Each run ended up with the exact same discrepancy about 0.3mm ,+- the variables of my home switches (about 0.002mm). I am thinking that the next step for me is to get a smooth stepper and run from usb. With my motor test, there is a perfectly straight line, except for an odd bump of 1/8 inch. However on the far right hand side, just visible before the far edge of the box there is an occasional large spike. Maybe 1/2 inch above and below the line. The test comes back as a pass but maybe I am on to something here. Does the smooth stepper require the same sort of computer control from mach, or is it more like a standard setup where the computers processor just sends out standard usb serial info for the smooth stepper to decode.
Bazza

Mach does the trajectory planning and tells the SS what to do, its kind of similar when using the PP except Mach tells the driver what to do.
With the SS your computer doesnt have to worry about using the driver so its less stress on the computer and also as the SS does the pulsing so a computer that has issues with pulses is no problem with the SS.
 There are still a few niggles with the SS but for the most part it works well and most are getting worked on so hopefully it will be out of Beta soon.
Hood

Hello Bazza,
               Yes you are thinking the same as we the only way to run mach3 is with usb and the smooth stepper also the C25 board, when trying with a labtop and smoothstepper system it really sounded right on and correct. So have ordered both items, looking at the info there is some very clever filters etc. in the circuitry. Although there is probley thousands of machine working satisfactory on parrel mine will not so again waiting for the postman.

I know lots of folks run the SS with great success, but it was a problem for me.  Every time one of my motor starters pulled in, the SS would drop out.  Too much electrical noise I guess.

You have a voltage problem. Start adjusting the voltage on your driver board and you will see Your step loss Increase or decrease. You will have to find a happy middle point.