Guys I hope some of you can help!!!  I noticed this afternoon that my machine was really slowing down and shuttering on the 3d contours.  I don't know if it the acetal nut on the acme shaft heating up as it runs causing drag the motor down.  All axis seem to be waiting on the z axis.  I thought it was my program but I reverted back to settings that I had ran earlier this morning and the seem problem still seemed to exist.  Could be a voltage problem?  I am at a loss.  I am going to run the program in the morning on a fresh start up to see what happens.  The problem seemed to get gradually worse as the machine ran.  I am running a keling 425 oz inch four axis kit with the 36 volt power supply.  Three to one gear reduction on all axis.  1/2 acme screw with acetal nut on the z, dual drive y axis slaved together running on rack and pinion, and the same set up in x as y with one motor.  Don't seem to be loosing any steps and work is coming out slick as a ribbon but the shuttering really is slowing the program down.  Hopefully someone has the answer because it is driving me nuts.  I even noticed this same shutter in my roughing programs as well.  As I said I didn't have any of this when I started running my machine this morning.  I am attaching some pics!!!

You could try to change acceleration on the motor tuning tab,


Jeff

Could it be that you are operating in exact stop mode ? if so try changing it to constant velocity (Config  :General Config ; Motion Mode).
Check your GCode to see if it contains a G61 if so replace it with G64 and test the results to see if there is any improvement.

Tweakie.

Thanks for the info.  I will go check it out this morning.  I did have one other issue as well and this one sounds really stupid.  I am running Alibre Cam(Visual Mill 6.0) and when I right a simple drill program it won't run.  It goes through all of the rapid moves and goes to all of the hole positions but never physically drills the material.  I thought that maybe mach wouldn't do a peck drill so I changed it to a regular drill and still hand no luck.  Finally I just circle profiled the holes to get it done but I definitely need to figure this one out as well.

You could make a drill cycle in one of the wizards, and then compare it to the one you wrote, to see what you missed. I think the Mach 3 manual has some examples also.

Okay I will give it a look.  I checked all of my settings this morning, constant velocity and exact stop.  I was running in constant velocity.  I loaded the program that was giving me fits yesterday and wa la transition was smooth and there was no shuttering.  Only thing that changed was I rebooted.  Program time was cut in half on the simulation.  The only thing that I can think of is yesterday when I was having problems drilling holes and gave the spindle an on command and was going to manually drill the holes.  The spindle came on but then turned itself back off.  Not sure what the deal is there either.  Basically I am using commands that I use at work to turn the spindle on for edge finding and location.  I am sure that it is just me and something stupid that I am doing.  I will keep working and trying to figure some of this out.  I am going to do some voltage checks today to see if that could be causing some problems.  Thanks for all of the input and if anyone can think of anything else I would appreciate it.