Belt working tension of 6.25 lbs? Why nothing in the assembly instructions?

So the other day the press on ring on the stepper cog popped resulting in the belt being cut. So in looking at the GT2, I noticed in the spec it states the working tension is 6.25 lb. this should be the tension on the belts on the Xcarve? I would assume so since the teeth spacing, angle of the teeth and the radius are most likely measured under load. This could explain why my machine started cutting closer to machine tolerances stated by Inventables after I increased the belt tension up to 5 lbs.

Specs from Inventables web site.

2mm pitch
6.35 mm width
Color is black.
Material is Neoprene (for quiet operation)
Reinforcing Cords are Fiberglass (belting can be easily cut with regular scissors)
124 lb / 56kg Breaking Strength
6.25 lb / 2.8kg Working Tension

i doubt mine is anywhere near that and its working fine

We only have few guys with broken belts. Caused by rubbing against the stepper pulleys. Check your pulleys to make belt traveling on center of the pulleys. I use and I can tell abuse my machine months now, have no broken belt.
I hope it gives you a little idea.

The belt breaking was my fault one of the set screws as loose and caused the pulley to move.

My post and question still is. What is the tension in lbs for the belts? How come a number is not given to get new Xcarve owners something to start with? I mean really “guitar string tight” give me a break. A Bass guitar? An electric guitar? Hell what string and what note then?

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Although I agree with you in principle that it would be nice to have the specification… How is the average person supposed to measure the tension? I could potentially see rigging up some sort of hanging scale to see what 6 lbs feels like, but that won’t help me set the position of the tension screw. If you have a simple repeatable method of setting the tension to a specific value, I’m sure Inventables would like to know about it to help future builders. Heck, it might even qualify for one of the tip/challenge prizes.

If it helps, I did a video showing how I tension my belts, you can see it at X-Carve Maintenance/Troubleshooting Videos - Add Your Own!.

My belts are tensioned to where it takes about 3.5 pounds to pull the belt up at mid-span, and it seems to work just right for me. I had them up to 6 pounds at one point, and broke 3 belts within a couple weeks.