Hi folks,

I have a cnc router with a Intel Atom (1.6Ghz) single core with 1gb of RAM as the control PC and running Mach3,

It behaves peculiarly - when running small programs like say which have a time span of less than an hour - the router works perfectly, however when there are programs which run for like 2 hrs or more the last move "g0x0y0Z25" wehere Z 25 is the safe height of the program triggerrs a high acceleration  move which results in lost steps on the Z and Y axis as I have noted.

This also happens in another point during use of "run from here" option here say the safe height is set to 25 and the machine tries to get it done so fast that the Z motor just looses its position,

For me it is as if the mach is not able to provide the pulses the way it is set to (on motor tuning) and is pulsing way fast for the steppers to cope up.

Any ideas on why this behaviour - the mechanicals seem to be perfect from my point of view -

I use PP to run my router.

R/ Irfan

Reduce your acceleration in motor tuning, it would seem you have it set beyond the capabilities of your stepper, ie they are losing steps because they can not physically accelerate at the rates you have specified.
Hood

Hood, well have done that already - the thing is that the machine works well when I run programs which last less than an hour, and all works as it is supposed too, only when I run huge programs with file sizes upto 6lakh lines, is when I face the problem.

Ok could  be axis heating and tightening and thus causing higher friction. Could also be your stepper drives overheating. One last thing I can think of is the large toolpath is causing issues with your computer, you could try turning that off on the Diagnostics page, its right above the Reset button.
Hood

Hood thanks I will try that - ( turning off the toolpath display on the diagnostic page)

on the other hand there is no issues with the axis or the drives, this is confirmed buy the fact that - immediately if we run a new smaller program then we do not face this issue.

The axis performs really well and we use offset machine for carving on hard wood.

R/ Irfan