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dvo
09-07-2011, 08:27 PM
Any one know how to make a rib pulley using basic tools or is this beyond basic. I have a lathe and a mill.

lakeside53
09-07-2011, 08:36 PM
Are you talking about a Poly-vee pulley? Which profile? If so, it is "basic" lathe work, but requires you to grind a tool to the correct profile, and have a way (travel indicator) to space the ribs.

SGW
09-07-2011, 08:42 PM
The last I knew, the specs for the Poly-V belt/pulley profile were available on the Gates Rubber website. I think Gates calls it Micro-V, but it's all the same thing. From memory, not always reliable:

The included angle of the V is 40 degrees. Spacing of the Vs is in 32nds of an inch (e.g. 7/32" between Vs, or whatever, depending on the belt model.)

dvo
09-07-2011, 08:53 PM
It's the one for a treadmill. I just need to make a bigger one for the treadmill motor to bump up the fpm of the belt.

I'll take a look at gates and see what I can find.

Thanks

darryl
09-08-2011, 12:40 AM
I don't know about the specs, but for the actual cutting, I think you'd approach it kind of like threading- the tool is advanced via the compound, which is set at the appropriate angle. Each groove is cut using one side of the cutting tool, and the opposite side just skims its side of the V. Spacing of the grooves is done by advancing the carriage, and depth of the grooves is done by advancing the compound. The crosslide is locked in place. Unlike threading, you don't withdraw the crosslide and dial it back in to zero again.

For threading you set the compound to 29.5 degrees to end up with a 30 degree flank- for a 40 degree flank you'd set to 39.5 degrees.

macona
09-08-2011, 01:00 AM
Several companies make inserts just for poly-v belts.

Also the angle of the pulley grooves varies depending on pulley size. I think machinery's handbook has the info on the angle variance.

WestCoastPat
09-08-2011, 01:22 AM
Just cut it flat. You don't need the ribs. You could recess the flat with 2 outer shoulders only.

Most likely you have a ribbed pulley on the other shaft, but even if you didn't a flat to flat pulley system works. Your alignment has to be correct for it to track true, which it should anyway.

Evan
09-08-2011, 01:43 AM
Poly V pulleys are easy to make. Aluminum is perfect for the job. The angle of the vees isn't critical as long as they are properly spaced and the same. It will give much better traction than a flat pulley even when oily.

http://ixian.ca/pics9/sheave5.jpg

lakeside53
09-08-2011, 01:55 AM
I don't know about the specs, but for the actual cutting, I think you'd approach it kind of like threading- the tool is advanced via the compound, which is set at the appropriate angle. Each groove is cut using one side of the cutting tool, and the opposite side just skims its side of the V. Spacing of the grooves is done by advancing the carriage, and depth of the grooves is done by advancing the compound. The crosslide is locked in place. Unlike threading, you don't withdraw the crosslide and dial it back in to zero again.

For threading you set the compound to 29.5 degrees to end up with a 30 degree flank- for a 40 degree flank you'd set to 39.5 degrees.


I've made numorous Poly-vee pullys in aluminum, and found it remarkably easy just to plunge cut with the cross feed and a very sharp HSS tool ground to the required profile. Mine were all "J" section. You can control the rate of cut easily as it's all in one revolution. Yes, with a light lathe you can cut slightly off angle with the compound, then a final cleanup with the crossfeed.

The spec is a little exactling if you want to get it "perfect", but it really doesn't matter a lot if you do. The top radius is easy to achieve by rounding off with a fine file and cratex. The are a few suppliers of full-form inserts, but unless you have the base tool, and a quanity to make, it isn't worth it.


15 thou tip, 40 degree, postive rake. I used an ancient optical comparator to get it "right".

http://i238.photobucket.com/albums/ff150/lakeside53/x72%20Belt%20grinder/DSCN1615Medium.jpg


Tool after a couple of test cut in pvc - it's much sharper and polished than it looks!
http://i238.photobucket.com/albums/ff150/lakeside53/x72%20Belt%20grinder/DSCN1619Medium.jpg



Test cut and spec

http://i238.photobucket.com/albums/ff150/lakeside53/x72%20Belt%20grinder/DSCN1631Medium.jpg



Ready for broaching!

http://i238.photobucket.com/albums/ff150/lakeside53/x72%20Belt%20grinder/DSCN1642Medium.jpg

WestCoastPat
09-08-2011, 01:59 AM
Anyone here make a AL sheave pulley that takes a SK tapered bushing? Pics on how you did it?

EVguru
09-08-2011, 04:50 AM
Once you exceed about 3:1 ratio between the two pulleys you don't really need grooves on the larger, it will still be the small one that slips first.

WestCoastPat
09-08-2011, 10:42 AM
Agree- I run as much from 7"-18" flat driver pulley, to a 2.5" grooved an no slippage with a decent load on a 16hp. None. You just don't the need ribs.

I need to turn 1" AL sheave pulleys, that use the SK/Browning bushings at various diameters for experiments. I'm thinking just chucking up a factory pulley- indicate the angle then turn the AL with the compound.

John Stevenson
09-08-2011, 10:49 AM
Anyone here make a AL sheave pulley that takes a SK tapered bushing? Pics on how you did it?
Ironically enough just done one, not a sheave pulley but a fan hub, took some pics but it was done before I saw this post so I'll post later tonight, just on a break at the moment and will start a new post, link to the new post will be edited here and I'll call it Tapered Bushing

[EDIT] New post here:-

http://bbs.homeshopmachinist.net/showthread.php?p=697287#post697287

John Stevenson
09-08-2011, 10:53 AM
Poly vee J series cutting tool.

http://www.stevenson-engineers.co.uk/files/poly%20vee%20tool.jpg

11 tpi chaser die [ pipe thread ] not quite the correct angle but I have been doing these for years, some of which run 8 hours a day at 9,000 rpm.

Quick, cheap simple, choose all three of three.

.

WestCoastPat
09-08-2011, 11:12 AM
Awesome! .....!

dvo
09-08-2011, 07:34 PM
I was intrigue by the pipe die cutter thing so I tried it with the die from one of those hand pipe threader 1" size. Worked great except only the first 3 groove fitted, the rest got progressively worse (J series 8rib). I hope by 11tpi you meant 11.5tpi? cause that was what I used. Anyway grounded a bit to roughly 40 degree and plunge with the cross slide to finished depth and move down .092 for the next groove. Chatter a bit but worked. Mission accomplished :)
Thanks everyone.

John Stevenson
09-08-2011, 07:55 PM
No, 11 tpi not 11.5

11 tpi has a pitch of 0.0909" a J series belt has a pitch of 0.092" so very close.

11.5 tpi is 0.0867" hence your error.

boslab
09-09-2011, 12:43 AM
nice job, at least i know how to do it now!, Ta John.
an unrelated story of an aprentice training centre and a poly rib belt pully, said apprentice misread /misunderstood the drawing which was in fairness a cigar packet, made a pully and single pointed the groove using the screwcutting box on the lathe, the grooves were replaced with one groove!, it took a while for everyone to realise that was why the belt immidiatly popped off! lol