Re: [CAD_CAM_EDM_DRO] Timing Belts and Pulleys

If they have been hobbed, or done on a gear gear generator of any type, they will (should) have used the pilot bore as the mandrel datum.
If the cutter doesn't "crown" the tooth crests, then the outside could be "out". The root dia. and general profile should always be true to the pilot.
Dave Pope.

----- Original Message -----
From: Steve Blackmore
To: CAD_CAM_EDM_DRO@yahoogroups.com
Sent: 20 November, 2006 9:30 AM
Subject: Re: [CAD_CAM_EDM_DRO] Timing Belts and Pulleys


On Sun, 19 Nov 2006 18:42:32 -0600, you wrote:

>Steve Blackmore wrote:

>>I just chuck them in the "Griptru" or 4 Jaw, clock the bore central then
>>bore them out.
>>

>If the original bore is off-center, then you have made an eccentric
>pulley. Not a good idea where
>positioning accuracy is important. On a number of pulleys, the runout
>of the bore was
>CLEARLY visible! So, I either use an indicator on the major OD or
>something that will
>guarantee centering the teeth. Also, on flanged pulleys you can't
>assume the flanges
>are concentric to the teeth.

I'd stop buying off that manufacturer Jon, and buy concentric pulleys.

Steve Blackmore
--





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