Problems after upgrades

[stargategfx]

Just installed a new set of rail gears on the x-drive on one of our PRT Alphas.
These were direct replacments for the previous gears.
Also updated to Shopbot 3.514, and updated the control box firmware after having missed several updates.
Now having major headaches cutting circles with both imported files and the CC command, they are coming out slightly ovalled and not really smooth.
We've cleaned and lubed everything, checked for square, level and plumb.
This is one of the very last PRT's to be shipped and was upgraded to Alpha shortly after purchase, and doesn't have the hi-def motors.
Any suggestions?

[rhfurniture]

Strictly my experience (I've just replaced my gantry racks):
1. The new rack gears take a little while to "run in" - settle down and loose their sharpness.
2. I needed to fine tune the applicable unit value. Drop 2 holes along the axis, measure the exact distance, do the sums, and change the UV to get it exactly right. Cut rack to the same spec from different suppliers can be slightly different when set up on the machine.
Don't know about 3.514.
HTH - R.

[stargategfx]

Thanks Ralph, interesting about the gears needing to seat themselves.
I've got the 'bot doing repeat "air cutting" the full length of the table.
I'll keep that up for a few hours and see what kind of results we get afterwards.

[stargategfx]

Ralph, what exactly is the formula for determining unit values?
Over a 24" span, I was off by about 1/16"

[rhfurniture]

Something like:
Current Unit Value x Typed Distance / Measured Distance
(I think I tried it both ways up and chose the answer that sent it in the right direction - but I am not the best of mathematicians)
Mine was something like 0.2mm out in a meter, and the result was a (metric)UV of 90.2133 rather than shopbot default of 90.2296 (note these strictly for my 20th pinion PRT). It is as spot on as I can measure now. Yours sounds a bit more out than that, so it might be something else. Did the firmware go in OK? I had a dreadful time getting mine in last time (so bad I've forgotten about it now).

[stargategfx]

Ralph, thanks again for the reply but now I'm really stumped...
We milled a series of .25" holes with a .125" bit on the X axis on a piece of scrap at 48", 60", 80" etc. apart.
The distance between the holes were for all intents and purposes correct, however each and every milled hole was ovalled and slightly skewed to the right.
The symptoms look like a pinion on one of the X rails is out by one tooth, but we checked and everything is setup as it should be.
Any ideas???

[stargategfx]

Okay, problem solved.
One of the pinion lock screws had backed out and wasn't visible because of the grease on the pinion.
When I did a shake test on the X drive everything seemed tight, that is until I disconnected each X motor one at a time.
Thanks again Ralph!