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View Full Version : Cheap Source for Timing Belts and Pulleys?



samualt
09-07-2004, 05:47 AM
Anyone know of a good cheap source for timing belts and pulleys? McMaster-Carr (http://www.mcmaster.com/) is a little pricey. I have two ball screws and one rack-n-pinion to step-down. So, closed ended belts and timing pulleys are the order of the day.

Somebody throw me a bone here!..................TIA, Sam
:drowning:

Bubba
09-07-2004, 06:38 AM
samualt,
I got my last order of belts and pulleys from Stock Drive and Parts:
https://sdp-si.com/index.asp

I found the prices quite reasonable and service was good. YMMV, but it is another source.

Usual disclaimer.

Bubba

cncadmin
09-07-2004, 08:59 AM
I have gotten mine at Mcmaster Carr, don't know if their the cheapest, but they have them.

BigDaddyG
09-07-2004, 09:19 AM
I have to second Bubba! I have been getting my belts, pulleys and shaft connectors from them for some time now and am very happy with them and the service. Good Luck.
Regards,
Glen

FLUTE HEAD
09-07-2004, 12:07 PM
Maybe off an old engine at the scrap or salvage yard. May be to heavy.

samualt
09-07-2004, 09:36 PM
I would like to ask the "Pulley People" a question:

Are regular pulleys with set screws OK to use on smooth shafts with no keyway or flat sides etc.....? All 3 of my motors have a smooth round shaft, as well as my Z-axis shaft, and my X-axis pinion shaft. Not sure about my Y-axis shaft cause it's in the mail. :)

Also, XL belts are only about 1/4" to 3/8" wide. That doesn't seem very sturdy. Would L belts at 1/2" wide be overkill?

Thanks for any reply..............Sam

Bubba
09-08-2004, 07:15 AM
samualt,
It is MY opinion that set screws are in-adequate in the long run by them selves. On my present setup, I have cross-drilled the shaft and used 1/4-20 socket head bolts to hold the pulleys in place.
I am presently up-grading to ball screws and will have key ways cut in all the pulleys and shafts. I don't want them to move:)

As for the belts, I have been using 3/8 XL belts on my mill/drill and they seem to be satisfactory. I have been using them for over a year now with no apparent loosing of the belts or other problems. I am going to use them again on the ball screw conversion with the only difference being better shielding to keep swarf and coolant off the belts and pulleys, especially the Y axis.

Bubba

samualt
09-09-2004, 03:21 AM
Bubba:
My last question is this, do you think aluminum alloy pulleys are OK? Or, do they have to be Steel? The aluminum pulleys are cheaper, lighter, and won't rust. But I'm wondering if they don't wear down because aluminum is so soft.

Bubba
09-09-2004, 07:01 AM
samualt,
I'll let you know in a year or two as I am using aluminum this time around (they look pretty:) ). I don't think there will be a problem as they appear to be of the heat treat varity and machined quite well. I had to bore them out to make them fit.

If properly setup, I don't think there will be much wear on the surfaces and with tight fits on the shafts, there should be no play. This is also a function of guards on the setup. This will keep the swarf out of the action and not allow the wear problem in the first place. Also, I would be more worried about the swarf "cutting" the belt than wear on the pulley.

Bubba

samualt
09-09-2004, 09:06 PM
Bubba:
I just bought $120 worth of pulleys from Stock Drive Products/Sterling Instruments (https://sdp-si.com/eStore/). All aluminum for 3/8" XL belts. I got away with only minimal step-down on the Z and Y axis, but my X axis (rack-n-pinion) needed a 25:1 so that pretty much doubled my price.
They were slightly cheaper for retail and had the best selection and easiest to use online catalog.
I think if I did start drilling into the pulleys and shafts I'd just use spring pins (roll pins) to keep them in place. But the thought of drilling a 1/8" hole into a irreplaceable hardened-steel ball screw shaft makes me cringe! But I may do it.
Thanks for all the advice!

Bubba
09-10-2004, 07:41 AM
I'll let you know (hopefully today) as my 1/8" carbide endmills came in and I am procrastinating on doing that now. I cut the ends of my ballscrew down to 12mm for the bearings and pulleys and there is still a slight "skin" of RC 56 that I have to get through for the keyway. Thus the reason for the carbide end mill. I will use a starter hole 1/16 deep again drilled with carbide, and then cut the keyway.

Wish me luck:)

Bubba