I just finished my upgrade to 3GT3 9mm belts and 270oz steppers (thanks tbdcnc!). I tensioned my belts to 3.8lbs @ 1inch, set my vref voltage to 1.31v for 2.8amps to X and Y. I calibrated my $100 and $101 steps per mm and it’s accurate. Is there anything else I should do to get the most out of the upgrade? Max ipm speed or something like that? Next upgrade is a cnc4newbies z axis, but until then, anything I should do? Thanks!
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You’ll find you can probably crank your IPMs by a little bit from where it was with the stock 6 mm 2GT3 belts. Everyone’s machine is a smidge different, so you’ll just have to experiment.
…and yes, tbdcnc is awesome. 
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You could play with acceleration rates, note that hard acceleration values and rapid back’n’forth motion is hard on belts. Less an issue if your main cut profile are large outlines, more an issue with intricate 3D surface carving.
I’ve seen some people suggest increasing the current past 2.8 to overdrive the steppers slightly. Has anyone done this or recommend it?
Not recommended.
While I haven’t seen such mentioned here on the forum - the only real enemy to the stepper motors are heat and heat = wasted energy. If you keep them below max operating temperature you can go as high as your driver is capable of.
Most quality steppers are rated at 80degC (176degF) case temperature as max service temp. The core/coils will be hotter as this is where the heat is generated.
The drivers used in the Xcontroller are 4A max so they’ll take it just fine.
If you can place your palm on the motor case and keep it there for 3s or so, the temp is around 60degC (140degF) and you are well within the comfort of the stepper.
So, if the case temperature dont exceed 176degF then you are per the specs safe, but providing some head room is wise in terms of longevity. My recommendation is to not take them past 60degC/140degF.
That’s great info. I have an infrared thermometer I keep near my machine so I’ll keep an eye on my steppers just to see for my own curiosity. I know steppers running belts generally run a little cooler than steppers in a screw drive setup. My screw drive machines get hot, regularly.
Back on topic, if that’s the case then I guess I’m good to go. I’ll run some test cuts tonight to see how all the axis are running. Is 3.8lbs about right for belt tension with 9mm belts? I had some trouble finding some solid info.
Welcome back @Pyrex 
I can’t give you a number but I always tension my belts as hard as I can stretch them by hand. Seems to work for me.
Long live the wet finger approach!
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lol, touché!