Roller end caps from pvc or nylon Help!

Hi all,

Hope someone can help.

I am trying to find someone who can make me some roller end caps from pvc or nylon rod.

The diameter of the roller is 80mm. The wall thickness is 2mm. All I need is the rod machined to fit in the roller (like a cap) and a grove machined for a belt. Also needs to have a centre hole drilled of 8mm and bigger diameter hole part way through for a bearing. Hope that all makes sence!:confused:

I have not been able to find anywhere where I can get these off the shelf and all the machine shops I have tryed want to charge me a fortune!

If anyone thinks they can make these at a reasonable cost, I would be very keen to hear from you. :tup:

Have you got a drawing of them? If so post it here or email it to me ... it sounds like something I could make and I wont charge a fortune. Will you be providing the material?

I think I can visualise what you want, and should be able to do it, but really need a diagram.

Hi again. Thanks for the replys. I have done a couple of drawings of what need. Technical drawing is not one of my strong points, so I hope they make sence! Attachment 4561Attachment 4562

Hi Again. The last pictures I posted were wrong!! This is what I am trying to make. Thanks for the help.Attachment 4563Attachment 4564

Looks fairly easy to do, however an idea of tolerances are needed.

Is the part to be a pressfit into the roller, or a slight clearance fit to allow it to be glued/bonded in?
Is the recess in the rollers consistent?
i.e. are they a consistent size, and true.
If they're not, then it may be better to machine the shoulder, press/bond them in, then machine the through hole/bearing recess/belt groove to ensure things run true.
I'm guessing the bearing will be a pressfit?

Also, how many?

It's not a hard part to make, however there's lot of potential for things to not be quite right without the above information.

Hi. Thanks for the reply. The caps coud do with being a nice tight fit, as not planning on using glue. There will be a axel through the roller with a nut each end compressing the caps. This should be fine and I can send you a section of the roller. All the roller sections are of the same diameter.

The bearing does need to be a press fit. Not sure how much smaller the cut out would need to be but I can send you a bearing.

I only need 2 with the groove and 4 without the groove for the first one. I can supply the Nylon or Pvc rod.

I got some dimentions wrong again! So here is another drawing.Attachment 4592


Cheers

Steve

Hi Guys,

Just a couple of thoughts, if you are going to press fit the bearings it maybe a better option to fit them by hand but also secure them with a small grub screw from the side, just to lock them off a little so they can’t spin in the pocket.

I’m not sure how well those materials would stand up against the forces of press fitting, I've not checked your wall thickness either but I would hate to see all that machining only for the caps/material to crack.

It would be best to have the bearings to hand as well, they may say 30mm outside race but I bet their not spot on and would read different on two different callipers. A 30mm pocket with the grub screw method should save some headache, would also allow for easy swapping of the bearings in the future should you need to.

.Me

It's easily doable, but my lathe just went up in smoke!

For the bearing tolerance, of the top of my head, you'll need about 0.1 undersize in plastic for it, but plastic can be very much trial and error.
As Lee has said, a grub screw may be a wise addition, but I don't think cracking will be an issue given the amount of material, and standard bearings are usually very accurate!

Quote:

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Originally Posted by Lee Roberts

It would be best to have the bearings to hand as well, they may say 30mm outside race but I bet their not spot on and would read different on two different callipers.

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Bearings will never differ enough to measure with a caliper. I'm pretty sure the tolerance for that size is something in the tenths of micrometers region, so even with a micrometer you'd struggle.
Being able to change the bearing is a point, but iff the bearing is broken anyway there's surely nothing wrong with applying a large force to the inner ring to remove it.

Quote:

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Originally Posted by m_c

It's easily doable, but my lathe just went up in smoke!

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Seriously?! What happened?

I agree they're easily doable, I've got a lot to do as it is though and going back to university in <1week.