Belt drive question

Hi,
I want to drive a milling machine spindle from a motor, and think a belt drive is the best way to go.
Question is, how do I work out what belt to use?
The motor runs at 10,000 rpm and a 1:3 ratio sounds good. 600 W, one problem might be that the shaft centers are 3" apart.
Any suggestions? Thanks,
-- Peter Fairbrother
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With only 3" between shaft centres, I think you will be struggling to get any belt typeto work as your pulleys would need to be quite small. At 10K rpm aswell, you might have additional issues. I would have thought gears would have been a better solution here. Mike
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I think that the only easy way to go would be with toothed 'timing' belts, but gears would be a more professional method, but require more engineering to get the centres and meshing correct. I assume you will be working with small cutters as3300 rpm is quite fast. If you wish to get things going slower, a layshaft could be used to give a further 3:1 reduction ie to 1100 rpm, I made one like this some years ago to give two sets of 3 speeds by incorporating a pair of step pulleys. Peter
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According to Gates DFpro, it's doable with toothed belts/pulleys.
Link below shows the possible combinations.
http://farm4.static.flickr.com/3111/2759234739_3f02e721d4_o.gif
moray
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moray wrote:

Thanks.
I may go with a poly-vee belt instead, but that's useful to know.
-- Peter Fairbrother
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DFpro didn't find any workable solutions using their range of v-belts/pulleys. It did come up with 2 'problem' drives, but I never actually looked to see why they didn't work.
moray
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If the shaft centres are 3" apart and the radii of the two pulleys are r1 and r2 then you need r1 + r2 = 3 (give or take a bit for clearance)
If you want a speed reduction of 3 then the circumference of one pulley has to be 3 times the other so r1 = 3 x r2
So we have 3r2 + r2 = 3 or 4r2 = 3 or r2 = 3/4"
and r1 = 3 - r2 = 2 1/4.
So a 1.5" diameter pulley driving a 4.5" diameter gives you your speed ratio and a 3" separation of centres.
Sounds perfectly do-able with poly-V drive, though you'll have to settle for slightly smaller pulleys to allow for a bit of clearance? You also need some movemenrt somewhere to allow setting up of belt tension if you go that route.
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"Norman Billingham" <norman.at.tumulus.org.uk> wrote in message

I used a poly-V belt to drive a countershaft from the motor on my lathe, I manufactured both driver and driven pulley using the JohnS "tap in the tool post" method to cut the grooves. The difference in the thread angle and the belt "v" angle has proven to be a non issue in real life use.
The other nice thing here is you can choose any odd ball diameters of pulley to suit your need and they are easy to make.
Steve
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Steve wrote: [...]

I'd ask about that, but it seems obvious enough. Only problem, where can I get a 0,092"/ 2.34 mm pitch tap? What tap did you use?
The difference in

Good to know.
I rather fancy a belt drive which will slip if something goes >clonk!<, rather than a timing-type notched belt.
Seems a 12" 6- or 8- rib PJ section belt would do the job, but where do I get one? Maybe my google-fu is weak today, but I'm having no luck :(
-- Peter Fairbrother
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Use an 11 tpi Whitworth form pipe tap of Coventry die insert.
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I used a single point tool ground to 40 degrees included angle and 0.105" depth of cut then space along using the top slide 0.092" per groove So start at zero next cut .092" next cut 0.184" next cut 0.276 etc. It may be better to set the top slide at 20 degrees and cut down one flank to 0.110" deep and space along using the saddle and a 0.092" stop. Depends on your lathe and chatter etc. Regards Alan
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wrote:

Too difficult - honest - cut it once as above really easy and works well
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wrote:

That'll depend, to some extent on the possession of a 5/8"BSW tap or die box insert.
Mark Rand RTFM
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On Thu, 14 Aug 2008 01:15:17 -0700 (PDT), John S

I've done them with a single point tool (DRO makes it much easier) and finished with an 11 tpi hand chaser. The pitch difference taken off by the chaser is minimal.
Tim
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wrote:

I've done them with a single point tool too as my machine wouldn't be solid enough to use a 11 tpi tap. I use a HSS tool ground to 40 degrees with the tip ground down to 0.022" width and use it to cut each groove to a depth of 0.081" plunge, or 0.086" with the topslide offset by 20 degrees. The pitch of the grooves is 0.092". The result is the bottom of the groove is 0.022" wide and the top of the groove is 0.081" wide, and the crest of the tips 0.011" wide. The edges of the crests can be rounded with a super smooth file. The above figures are based on the the spec for the belt where the bottom of the groove has a radius of 0.4mm and the crest a radius 0.2mm. I could have rounded the tool tip but decided the flat bottom was OK for my pulleys. This has worked OK for stainless and mild steel, and the belts and pulleys appear to work OK and don't look like they are wearing, however only time and use will tell.
Mike
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Could a link belt, e.g. powertwist, be useful? Can be made in any lange, +/- one link. Dirk
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PG1D/PA-1112 wrote:

Thanks for thew suggestion (and thanks to everyone else too!), but I think a poly-V belt is the best way to go. Good grip, good strength, very flexible, low mass and therefore high speed, plus it will slip if there is a crunch.
The pulleys are not hard to make - by the way, I found a scavenged washing machine motor with a hardened J size pulley, it's the wrong diameter but I think I can use it to make a tool to clean up the rib profile.
That leaves finding a source for the belt, which isn't going well - any ideas?
Thanks to all again,
-- Peter Fairbrother
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Peter
Try Tony at lathes.co.uk, he advertises Poly V belts.
He did a bespoke round belt for my Naerok pillar drill recently - very efficiently and at a good price.
Cheers
Peter
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BSL-Brammer
But I suspect your requirement will to prove to be for a shorter belt than is readily available.
--
Charles Lamont

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I buy here, quick and a huge choice http://www.keilriemenexpress.de / Dirk
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