Hi,
it sounds like you steppers are just operating at their maximum. Can you post some pics of your machine? I'm wondering if its so heavy
that in effect the steppers are to small. The speed and particularly the acceleration look very low, should be easy going for them.

There is still the possibility that the PC is intermittently stopping. It only needs to stop or pause for a few milli seconds and when it starts
again the motor has already slowed to the extent that it can't accelerate back to speed and therefore stalls with a squeal. Not quite
sure how to go about either proving or disproving that yet.

There was at one time a document floating around the forum that had a whole list (30-40 items) of things that you could set/disable/remove
from you PC to have it operate well under parallel port. Your PC is not a laptop is it? Parallel ports were always a bit picky about the PC.

One possibility is to get away from the parallel port altogether and use an external motion controller. They are very much more tolerant
of different PCs. It would of course require you buy another board. Good ones, don't go near the Chinese crap, start at $120. The ESS suchas
I have is $180. Does your budget allow for that sort of investment?

Craig

Hi Craig
I built the PC specifically for the CNC its a dell desk top Ive removed just about as much as I dare but you could be right the machine is a beast it has a heavy router mount so once again cant rule it out but I did try and stop it myself it pushed me no problem the steppers are 100mm it is a professionally built machine bed is 600 X 900 in fact heres the advert of the actual machine http://www.mycncuk.com/threads/10773-3-axis-Rhonmac-R1824-%28460mm-x-610mm-x-75mm%29-bench-top-router-for-sale 
I'm afraid the budget at the moment is not good but I would like to try and solve it without throwing money at it at least not yet.

Hi,
your machine looks pretty good and I would have guessed the steppers are adequate for the job.

Can you post your <profile>.xml, maybe we can spot a weakness or fault. You'll need to rename it to something like daxprofile.xml
and attach it to  a post with the Addition Options feature.

Craig

Been looking into the PC put in a new (old) graphics card changed the lpt to epp no stalls on jog yet will run a full test tomorrow fingers crossed. dont understand the xml stuff sorry for being a noob

Hi,
the xml file is the profile that you provide Mach necessary to set it up. If you look in the lower right hand corner you will see the profile Mach is using.
In the Mach3 folder find the file <profile>.xml and rename it to daxprofile.xml

Post to this thread on the forum and hit <Additional Options> to the left of the text window and you will be able to browse to the Mach3 folder
and attach your renamed xml file.

Craig

  Its working after a complete computer rebuild new graphics card I have ran it for 2 days with not once did it make that awful sound in fact it ran for 3 hours constant today it didnt put a foot wrong so thank you everyone for the information and help, now how do I make money with it 

Hi Dax,
good news. Parallel ports can be very cranky...it was much of the impetus for people to make external motion
controllers.

Craig