RE: Belt drive

Hi Ron - I am working on a similar project with G1004 mill.

The belt system I am using is the Gates Powergrip GT which seems to have the
best combo of low backlash and capacity I could locate. I am using the 3 mm
pitch with a 74 tooth leadscrew sprocket and am experimenting with both a 20
and 28 groove motor sprocket. At the moment I have the x axis moving on the
original lead screws with a 125 oz-in stepper driven by a JR Kerr Picservo
system. Max speed is about 30 IPM ( I would like higher )and the low speed
seems to have plenty of force for when the machine is actually cutting. More
comments below.

If you are interested I milled the x-axis bracket out of an aluminum block
Boeing surplus! ) and could send you a drawing.


-----Original Message-----
From: ginger@...
[mailto:ginger@...]On Behalf Of Ron Ginger
Sent: Wednesday, December 15, 1999 6:54 AM
To: CAD_CAM_EDM_DRO@onelist.com
Subject: [CAD_CAM_EDM_DRO] Belt drive


From: Ron Ginger <ginger@...>

I have ordered one of the new Grizzly mini-mills and plan to make a CNC
machine out of it. I am viewing the mill as a 'part machined kit of
castings' I expect to throw away just about everything except the
castings, scrape them to a good fit and build up from there.

I intend to use belt drive between the stepper motor and the leadscrews.
Are there any tips on setting the correct pulley ratio?

Anyone have a program that calculates belt length given pulley diameters
and center distance?

[ The Gates design manual has this info. 303-744-1911 ] Also available
online.

Where is the best place to order belts and pulleys?
[I had to order from a distributor - Mine is Applied Motion Technologies ]

What is best to tension the belt- slotted screws for mounting or an
idler pulley?
[ I believe an idler will add backlash ]

Ive got some nema34 steppers of 250oz/in rating. Are these likely to do
this small mill?
[ Should be good esp. if you go with ballscrews. ]

thanks for the tips,

ron

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