PDA

View Full Version : Custom indexer unit values



3imoh
03-04-2008, 10:02 PM
Howdy all-

I finally got around to finishing the belt-box reducer for a custom indexing fixture I am building. I am running an alpha 7.2:1 through 2 4:1 belt reduction drives. I am having an issue getting the proper unit value for this. I believe the proper unit value for this should be 320...I got this by doing the following per the manual:
(7.2*4*4) * 1000 ) / 360 = 320

When I input this into the SW, I only get around 3/4 of a revolution when I tell the B axis to move 360 degrees. I can get it closer by setting the unit value to around 400 or so, but I would prefer to get the right value instead of figuring this out empirically...

I am at a total loss. I have checked and rechecked the pulley sizes, and everything checks out...I am running 72 tooth large pulleys and 18 tooth small ones.

Any thoughts on what I am missing here?

thanks,
howie

Brady Watson
03-05-2008, 01:57 PM
It depends...Did you buy the 7.2:1 from ShopBot or from somewhere else? What are the resolution settings on the Alpha driver set to? There is a 500/1000 switch & an X1/X10 dip switch. Make sure they are set to 1000 & X1. I believe the default indexer setting is X1/500. I am not sure off the top of my head if the multiplier value in VU has to be changed or not.

-B

3imoh
03-05-2008, 08:31 PM
The folks at SB noodled over it a while and Ted finally figured it out...the dip switch needed to be set to 500, with a multiplier of 4.

The unit value they came up with does not make sense to me but when I type in 360 degrees I get a full rotation so I am happy...

-Howie