joeaverage, the pulse rate would be unrealistic for a pp. Its a 2500 line encoder and spins 4k rpm.

Rich, I thought screenset too and had already tried the oem turn screen with no luck. I'm also using an unmodified 1076 file. In fact, i pulled a copy out of the other lathe just to rule out that it had been corrupt or something. I did try g32 over the weekend and it still feeds at the incorrect rate.

Hi fast89,
that's about 660kHz. What controller are you using? I know the ESS says its good to 4MHz so 660kHz should be fine with differential signalling.
Anyway are you trying to thread at 4000rpm? General turning I can imagine 4000rpm but threading?

Craig

Not Def not 4k. Just trying to thread at 800rpm. I don't use any external motion controllers. Tried smooth stepper years ago and didn't care for it so I just stick with parallel ports.

Have you contacted Mach Motion about what this and if so what did they say?

RICH

No I have not contacted them yet.  I have two other lathes with the same breakout board though and both thread great. I'm just baffled because it reads the rpm perfectly all the way to 4k. But seems like it is using gearing when threading.

Recommend you do contact them.

During threading the rpm is monitored ( based on the index / true rpm read by Mach and the Z axis feed is changed depending on the monitoring ).
So how can the internal threading cycle  change the feed rate of an axis when it is controlled / influenced by something else other than the based on the index.

RICH

Also the feed rate of the axis from initial start to some specific point is done so the axis arrives at a specific place all the time.
If the internal threading ( meaning the internal scripting of the Mach software controller and no one has access to it) is also looking at what the axis capabilities are, and if adequate, it controls  the  feed rate to get to that start point.

Lots of stuff going on ............

RICH

Ok,
Back from vacation and finally working on this again. It's hard to go on vacation and not think about your broken machine that has a pile of work lined up. Anyhow, attached is my xml file  and screenset if someone could check it. I still need to call Machmotion this week about the breakout board. Just for the sake of it, i tried another pc today and it did the same thing.

If i uncheck spindle sync in ports and pins, it threads air fine at the proper feed rate. If i check spindle sync it puts the right feed into the dro but when it makes the move to start position, it drops the feedrate to near zero. When it begins the z feed, it changes the feed to .001" not matter what i put in the g76 p.

Can you post your G-code program showing this problem?

Chris D