@Ryan_Carlyle back in the old days, T5 belt was all steel core (+polyurethane), I don’t think I’ve ever had a problem with it even after thousands of hours of printing (on printed pulleys). Steel core GT might be different, though.
Oh yeah, buy belts from an authorized Gates distributor (like SDP/SI) and you’ll automatically get GT3. The part number doesn’t include the series because Gates only ever sells the newest version. GT3 is the same tooth shape as GT2 and use the same pulleys, but have nylon fabric facing on the teeth for added durability and tooth stiffness in shear. No-name Chinese belts are GT2 knock-offs… it’s the GT2 tooth shape but often with lower quality tension yarn and elastomer blend. No way to know without destructive testing.
Actual “GT” belts haven’t been sold for years. They were superseded by the GT2 tooth shape before China started copying everything. GT came out in the 1980s!
HTD (which predates GT) is still sold but it has too much backlash for 3d printers.
Personal opinion is at those speeds you are fighting the carriage momentum and mechanical design more than the steppers. The cantelever bed is a concern just because of the arm length amplifying the motion.
Next area to tackle would be effector mass, but with your design I am sure you have already tried to address that as much as is reasonable, but might be worth more review.
Lastly I would look at frame mass to try and dampen the resonance at the corners. If you Accel or Deccel too hard at those corner that force has to go somewhere. Mass is a easy place to impart that force into to. That and something like NinjaFlex risers between the frame and the components (rails, carriages, etc).
It was my understanding that gt3 is gt2 but with 3mm pitch, thicker backing and larger teeth.
@Stephanie_A it’s a common point of confusion. 2GT is 2mm pitch, 3GT is 3mm pitch, on through 5GT, 8GT, and 14GT. Whereas GT, GT2 and GT3 are version numbers of the Gates PowerGrip GT series of belt designs. People screw this up constantly.
Here’s the history I’ve pieced together during book research. These curvilinear belt types have been under continual development since around 1970 when a division of Uniroyal developed the POWERGRIP HTD belt. HTD is a power transmission belt with a lot of backlash and is still in use today. Uniroyal then developed POWERGRIP GT around 1980, as a precision motion AND power transmission belt… it’s stronger than HTD and has a tighter tooth mesh for less backlash. Gates bought that division from Uniroyal in the mid-1980s. Sometime after that, Gates realized GT had some meshing issues due to tolerance stackups and the like, and released a modified tooth profile (GT2) with smoother meshing. That’s now off-patent and knock-offs abound. GT3 is the newer design – it’s a materials upgrade on GT2 (and thus new patent) but with the same tooth shape. GT3 belts are used with GT2 pulleys.
Nobody sells actual GT(#1) anymore as far as I can tell. It’s all GT2 from knock-offs and GT3 from authorized Gates distributors. But they’re all called “GT” because Gates phases out old versions and thus doesn’t really need to use the series number.
Interestingly, Gates also has a patent on carbon fiber timing belts (which could be amazing for us) but they only sell them in 8mm and 14mm pitch (as Gates Poly Chain GT).
So these are the belts I bought that I thought were gt3: http://sdp-si.com/products/timing-belts/gt3.php
I guess they’re gt2-3mm
I don’t see sdp-si selling gt3 belts.
@Stephanie_A SDP/SI is in the process of selling out their stock of GT2 and switching over to GT3 for new stock. You can get either when you order from them right now, they don’t differentiate. Have to look at the part number when it arrives and see what you got. (They started the transition a while ago, I would think they’re mostly on to GT3 by now, but who knows.)