Plastic belt drive pulleys?
 

I have been eying these pulleys as a way to reduce the motor plate costs.

https://sdp-si.com/eStore/PartDetail...63&GroupID=218

$8.66

I think our design would support this setup

Here is the same pulley in Aluminium

https://sdp-si.com/eStore/PartDetail...40&GroupID=217

$21.31

The thought is to use a version that has a metal hub and some form of hard plastic gear.


Needs a deeper dive - but may be something to look into.

You can get that in aluminum for $14.63 from B&B Manufacturing. $12.88 if you buy 25 at a time.
http://catalog.bbman.com/db/service?...ct=40XL037-6A6

I'm not worry about the polycarbonate, should have enough strength to do the job, Also it will have good wear & tear characteristic.
More concern with the bonding strength of the aluminum insert to the pulley. Especially with the driver pulley.

Would static electricity collect more dust on metal/plastic?

I agree with Ken and Gerald. An 880 oz*in motor (Oriental Motor PK299-F4.5 wired parallel) on a 4:1 belt drive can produce 220 lb*in of holding torque. That's a lot of torque for the metal to plastic junction to handle and as Gerald stated, plastic will not dissipate static charges. If that static causes "gook" to collect on the pulleys, you'll have a mess before long.

Lower price is a benefit as is lighter weight. Nobody wants to spend more than they have to, but it might be a good idea to run a substantial test with plastic pulleys using high torque motors in a dusty environment.

I agree it would need testing . But figured it was worth looking in to.

I think it is definitely worth looking into. Static is one of the things to consider...I did not say it would be bad with plastic. Shipping costs will be lower.

I agree its worth looking into. The plastic to aluminum insert should be on the testing list.

I know its been over a year since you guys talked much about these plastic pulleys but I have received 4 from spdi-si for myself to try but didn't like the thin aluminum bore sleeve (~0.080" thick) It was going to cost almost as much for restocking fees as they originally cost so I kept them as back-ups. The pulleys are 72 tooth XL 1/2" bore. I can send one to someone if they want to test it and report back to the MM community. Any takers?

Tom

I have 4 of them as well.
I still think these are a good option as they fit directly onto a 1/2 inch ground shaft.
A few quick 6mm tapped holes and it is in place.
If it breaks put another on on, mind you no one has actually reported one breaking.

or here in Australia
Buy the far more expensive aluminium pulley, pay postage on top of that.
Find an engineer to bore the pulley.
Ring engineer on the day they say it is ready.
Discuss with engineer the job so they remember which job it was.
Engineer promises to call me back with an update.
No update is forthcoming or even forthgoing !!
Give engineer another 8 days to do job.
Ring engineer after another 8 days suggesting they were going to call back 8 days ago.
Success - the job is done (just this morning by chance).
But... it was tricky, had to machine up soft jaws... far more complicated than first anticipated ??
Payment time $99 AUD for two (2) holes.
Quality of job, pretty darn rough for a pro and visibly out of round.

A cheaper plastic pulley that sides straight on to a shaft, devoid of massive machining costs and fits beautifully is nothing short of a miracle here in Australia.
Rant over :)

Ross

Ross, my concern is two fold, 1) accidental stripping of the set screw, and 2) if you use screw lock and have to remove the grub with heat - that would lead to disaster for the plastic. Are you actually using them and how are they faring?

I am in the process of selling my machine and was doing touch ups all over prior to delivery.
So the pulleys are aluminium as per original. This was all done only a few days ago so my wallet is still hurting.:)

The original shafts are 12mm on my design so I would have had to buy new pinions or have them rebored to 12.5 mm to try the plastic pulleys.
I did consider doing just one drive as a test but as the machine was being sold it was prudent to keep everything the same for the new owner.

You could tap two holes and mount it on the shaft and see you can strip the grub screws.
There is no need to apply any shaft lock fluid (heat to remove) if you grind two flats on the shaft and can tighten them down with out stripping.
If it strips you have three interesting ornaments, if not you have 4 working pulleys.

Ross

This is true. By the way, do you still have copies of your belt drive plate dxf's? If I remember correctly I found that your design was to my liking and like I've said in another thread, I don't want to reinvent a wheel.

Here they are Tom

http://www.mechmate.com/forums/showt...&postcount=870

These ones use a flange bearing instead of the Acetal cups.

Ross

Thanks Ross. I read your build thread awhile back, you said you're pursuing another machine situation, is that correct?