2.x las: Connecting pulley with 6mm bore to M6 threaded rod

Bearings/Motors/Belts/Gears/Etc.

2.x las: Connecting pulley with 6mm bore to M6 threaded rod

Postby Ischcuch » Thu Jun 06, 2013 9:01 pm

My pulleys arrived today and I noted they have about 0.2 mm play on the M6 threaded rod used for the z lift table. Will this be a problem due to eccentricity caused by the single grub screw connecting it to the rod?

I could shim it with 0.1 shim or are there any other ideas?

TIA
Ischcuch
 
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Re: 2.x las: Connecting pulley with 6mm bore to M6 threaded

Postby BenJackson » Thu Jun 06, 2013 10:34 pm

The laser table is by no means a precision axis. What you describe is not going to matter for focusing purposes. Notice that the tabs that hold the table have captive but loose nuts with even more play.
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Re: 2.x las: Connecting pulley with 6mm bore to M6 threaded

Postby Ischcuch » Fri Jun 07, 2013 9:53 pm

Thanks Benjackson,

My captive nuts are "hand made" and maybe they don't have enough play. viewtopic.php?f=16&t=2056#p19530

I was more concerned about the belt tension if the pulleys are "out of phase" due to being eccentric on the four shafts.

I built the z lift assembly today and have found that the system does not run smooth. The force required (when moving the belt by hand) for one rotation varies through the rotation. it runs easy for most of the rotation and then sticks a bit.

I shimmed the pulleys on the shafts and it improved but 1 pulley is still visibly wobbling and i can feel it tightening up at one point through the rotation.

The problem goes away when I slack the belt off. I'm not sure what tension is required but it will definitely not slip a tooth. I will test it with the stepper motor and will tension the belt to the highest tension that the motor can handle.
Ischcuch
 
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Re: 2.x las: Connecting pulley with 6mm bore to M6 threaded

Postby Ischcuch » Wed Jun 26, 2013 10:25 pm

It looks like I have solved my problem. :D

The idler wheel was not on the same plane as the 4 drive pulleys. It was a bit higher. When i dropped it in line with the drive pulleys the system runs smoothly. I think the resistance in the system was caused by friction on the drive pulley being out of plane.
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