RE: [CAD_CAM_EDM_DRO] Got Gates Timing Belt Information

Thanks for doing the legwork, Les!

I've been meaning to do some homework on the GT belts also, to use them on
my mill. They are deceptively small for a given load, aren't they? I'm
using Dan Mauch's 420 oz-in (peak) motors, so the 3mm pitch at 9mm wide
would seem to be adequate. I'll have to use a lower tension, though.

Good luck,

Carlos Guillermo
VERVE Engineering & Design

-----Original Message-----
From: Les Watts [mailto:leswatts@...]
Sent: Monday, February 19, 2001 4:32 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] Got Gates Timing Belt Information


Ok I got the design information. Gates ran it on the software to double
check. I will be using GT 3mm pitch 15mm wide at 40 lbs tension. I can
expect positional accuracy well under .010" but slightly reduced belt life.
This is good enough
to keep the encoder on the motor as it is the equivalent of
less than .0003" cyclic error or backlash on a 5 turn per inch
ballscrew. This belt would be pretty close for any servo/stepper
transmission of similar type and is much better than HTD or trapezoidal-
some several times in position accuracy they say.

The 80 lb load on the motor bearing is beyond it's fatigue limit
of 27 lbs but that just means it won't last forever. Dynamic load rating on
that bearing is 5000 lbf so it will last a while!

According to the ap engineer 2 and 3 mm pitch are known
as GT. 5, 8, and 14 are known as GT-2 and are HTD
compatible. So a GT sprocket is only for GT belts and will not
fit any other. I mentioned that the 2, 3, and 5 were called
GT-2 on a Stock Drive Products price list and he said this was in error. And
that was just a copied Gates document.

Confusing , huh?

I wanted to be sure because those spockets are as much as
$50 each in 2" size. I have a few to buy.

OK now to call in the order and then back to the shop!

Leslie Watts
L M Watts Furniture
Tiger, Georgia USA
http://www.rabun.net/~leswatts/wattsfurniturewp.html


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