RE: [CAD_CAM_EDM_DRO] Ultimate backlash free reduction

Graham,

Curvelinear profile timing belts with large pulleys
might work. Gates GT2 have esentially zero backlash
when properly tensioned. They register to about .004",
so absolute accuracy would be about 0.096 degrees
with a 5 " pulley.

If you need the accuracy as good as the backlash spec
(0.007 degrees) I see an extreme 50,000 PPR as the least
expensive way. You can interpolate further than 4X with
encoders as well, but things get a little dicey.

Les

Leslie M.Watts
L M Watts Furniture
Tiger Georgia

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-----Original Message-----
From: Graham Stabler [mailto:eexgs@...]
Sent: Wednesday, August 18, 2004 7:51 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] Ultimate backlash free reduction



What is the best way of acheiving approximately 5:1 gear ratio with
as little backlash as humanly possible?

The application is the increase of optical rotary encoder resolution
so there are no large forces involved. You can also assume the
encoder has ball bearings or is at least coupled to a shaft with
them. The encoders are already 2500CPR/10000PPR so we are talking a
requirement of 0.007 degrees of backlash.

If this is going to cost the earth then knowing the best possible
method without it costing the earth would be a help.

Thanks

Graham





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