Smooth Idler Pulleys

Questions, Suggestions, Tips, Etc

Smooth Idler Pulleys

Postby bdring » Tue Jun 28, 2011 11:32 pm

I got some smooth delrin idler pulleys today. These use the same bearing as the v wheels, but use 2 bearings instead of one. Dual bearings take any rocking out of the assembly. The brackets need to change to a single 5mm hole rather than the counter sunk hole that is used now. Since the bearing is in the idler, it will rotate with the minimum amount of runout.

I will be replacing the existing pulleys (3) when I can coordinate the plastics parts.

smooth_idler.jpg
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Re: Smooth Idler Pulleys

Postby BenJackson » Wed Jun 29, 2011 2:04 am

I assume these have a larger diameter and will make the belt path somewhat triangular. Make sure you adjust the height of the pulleys so that the belt connection to the carriage is still flat.
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Re: Smooth Idler Pulleys

Postby bdring » Wed Jun 29, 2011 2:11 am

The diameter is very close, but I already dealt with that. A nice side affect is that a single idler block can be used for both X and Y since the hole is only 5mm. Two hole that size can fit on a single block.
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New Bracket

Postby bdring » Fri Jul 01, 2011 3:27 pm

This is the proposed design for the new idler bracket. It works for both the gantry and the Y axis. The gantry uses the lower center hole and the Y uses the 2 upper holes. The overall part is a little narrower to allow you to stretch the usable area. The bracket mounting holes have been separated enough to allow you to use the cheaper t nuts.

A bolt is run through the bracket, through a spacer, through the bearings and then gets a nylon locking nut. The bearings have a precision washer in between to prevent binding. The idler wheel has a step to set the depth. The step goes towards the bracket so if the wheel ever rode off the bearings if would be less exciting. I suggest a dab of superglue on the bearing near the step to prevent that from ever happening. With two bearings pressed in it doubles the pullout anyway.

comments before I cut the test pieces???

Untitled Project 57.jpg
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Re: New bracket

Postby Tomi » Fri Jul 01, 2011 6:24 pm

Am I right, that the one showed on the image (the one on the top on my image - I painted it black) could be replaced?

Foto.JPG


Could it be, that this way it couldn't be fixed on the new makerslide? The "triangle" of the makerslide would be in the way. Of course the new bracket could be tweaked by drilling a kerf on it, but this would weaken it's strenght. On the other part, drilling a part (the triangle part) of the makerslide would be very hard, i think...

Wouldn't it be possible to make a bracket which is mounted from the top (especially for the future)?
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Re: Smooth Idler Pulleys

Postby J45on » Fri Jul 01, 2011 6:30 pm

When I replace my x and y-axis with makerslide when it becomes available I plan just to mill or carefully file off the rail where it is not needed
so I could reuse my existing brackets
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Re: Smooth Idler Pulleys

Postby bdring » Fri Jul 01, 2011 6:39 pm

I like the black...BTW

A grooved version was already planned for the MakerSlide upgrade kit. It would get a small square groove. I think it would be plenty strong. I'll think about using that new MakerSlide slot on top. The MakerSlide top groove is temping to use, but might be difficult in a simple one sided machined part.
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Re: Smooth Idler Pulleys

Postby BenJackson » Fri Jul 01, 2011 7:42 pm

Tomi, your bracket is even farther over than mine and mine comes very close to the laser path. Yours looks like it is dead centered on the laser path. There's a pic in my buildlog where I show with a red laser where my beam passes.

Bart, for that same reason I think you will lose a tad of X travel because the squared-off bracket will have to be placed farther inward to avoid the beam. I can definitely see the value in being able to ship N identical parts instead of a few of each, though.

BTW the front left travel is limited by hitting the SHCS holding that bracket. It could pass a button head.
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Re: Smooth Idler Pulleys

Postby bdring » Fri Jul 01, 2011 7:47 pm

I think a few people have been confused by the multiple brackets too. It is easy for the extreme travel junkies to 'customize" the gantry bracket anyway.
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Re: Smooth Idler Pulleys

Postby BenJackson » Fri Jul 01, 2011 8:00 pm

bdring wrote:It is easy for the extreme travel junkies to 'customize" the gantry bracket anyway.

Woah woah woah... There are people who aren't travel junkies?!
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