Hi, I have been upgrading over time to a 72 x 31 bed, and now have upgraded to the newest xcontroller and makerslide. It all is making a nice difference in jobs cutting well. But one thing I would like to upgrade still is belts if possible, is there a stronger belt less prone to breaking? I have the ones it shipped with. Using the new xcontroller I am trying to cut at faster speeds and I think the belts are the weak link. Does a belt upgrade if possible require a pulley upgrade? thx
This has been talked about before. Do a search on them and check out Phil’s tips thread.
I have a 2000mm y axis that I upgraded to 3mm pitch pulleys and belts, and they are better, but I am still breaking them. (I just ordered up my third one today)
The scenario is I crash the rail somehow, the belt gets a little stretched and or squished at that spot. Later when I adjust / tighten the belt it snaps. 
I have not had one just “snap”, it is always damaged due to operator error first. 
Now that I have upgraded the rails, wheels, motors and drivers the Y axis belt is the weakest link. My X axis is screw driven c-beam and I have also noticed a quality difference in the threaded rod vs belt axis resolution and accuracy.
I want to replace the belt with threaded rod but 8mm threaded rod can only go up to 1000mm.
So I have to go with something like a 16mm ball screw. Doable but more expensive, about $175 each.
There is also the option of Rack and pinion for the longer rails, but I have not really looked into it as it seems to be a even more expensive than a ball screew.
The easiest and most straight-forward belt upgrade is 9mm wide 2mm pitch GT2
Discussion of this and parts lists at: Shapeoko CNC Router, Rigid, Accurate, Reliable, and Affordable and Shapeoko CNC Router, Rigid, Accurate, Reliable, and Affordable — just need new pulleys, belt anchors, and belts.
Buying good-quality belts may help as well.
The 3mm pitch belts have greater backlash and give up a bit of positional accuracy, but seem to work out for some folks.
5mm wide. It is a little wider than the stock bet but still fits on the stock idler pulleys There is a 9mm version but I have only found it in small loops for the Z axis.
Sounds good. Where did you get the belt, pulleys and idlers?
does anyone have a link for a belt like this but longer? I have expanded mine to 1800 mm on the y axis.
inventables support said they have these belts and pulleys, but is the belt not same specs? it’s 9mm wide but looks less thick
how many teeth on the pulleys?
the bore is 1/4 for the nema 23 motors?
total of two pulleys and four idlers ?
What’s your $120 and $121. It’s sounds like you are stopping and starting very aggressively.