In short, for the past 7 years I've been running an CNC dedicated old Windows XP computer with mach 3 with no anti-virus, no anti malware, no internet connections. I have always had intermittent problems with loosing steps. I have changed driver boards, I've increased the size of my motors to more then double original, I've rewired it a couple times, changed the LPT cable, but would still loose steps at random times.
My last few projects have been between 300,000 and 400,000 lines of code (8-10 hours of cut time), so fairly large files. After ruining about $200 in wood and unknown number of hours from these lost steps, I decided to try upgrading to a USB breakout board and individual motor drivers. It didn't change, on my current project the first attempt lost steps around line 90,000 (about 2-1/2 hours in), the second attempt lost some at 20,000 (only 30 mins into program), a third attempt lost some around line 177,000 (about 5 hours of cut time), the forth attempt ran the whole program (8-3/4 hours) without any program issues.
Now I'm trying to repeat this project with no luck, again it started randomly loosing steps. Because I now have a USB board, I tried hooking up my laptop (running windows 7, Celeron Dual-Core 1.90 GHz 4.00 GB RAM on a 32 bit operating system) to see if it was the old computer is having some type of glitch that was interrupting the steps even thou the USB board was suppose to eliminate that. The laptop jogs everything perfectly, full speed, nice and smooth, but when I tried to run this program, it jogged from home to its starting point flawlessly, but then it started cutting. It was pulsating the stepper motors. Very noticeable on a slight z axis incline, the Y axis motor speeds up, then slows down, then speed up then slows down. These "pulses" and the uneven speeds of all the axis is taking the program almost twice as long to run. So I thought maybe my laptop just wasn't quite big enough, fast enough or plain not capable of running the CNC.
So, I grabbed my one office computers (windows 10) and temporarily hooked that one up, turned off everything that didn't need to be running and it does the same exact thing as my laptop. This computer is an Intel Core i7-2600 @ 3.40GHz with 8GB of RAM with a 64 bit processor, custom built, usually runs 3 screens and ANY multiple programs at the same time including AutoCad and 3D software while being on the internet. Way bigger and faster then I should ever need to run this CNC, but it won't run it efficiently. I've checked and double checked all my setting, I've tried changing as many settings that I know of to try to solve this problem with no luck.
ANY suggestion are welcome!!!