Messages

831

General Mach Discussion / Re: High speed spindle recommendations

« on: August 24, 2010, 02:46:37 PM »

Hood,

Are those gears you found ground? Otherwise don't think it would be a good idea to spin them at the speeds you like...

Daniel

832

General Mach Discussion / Re: High speed spindle recommendations

« on: August 24, 2010, 08:21:57 AM »

Oh... sorry for that. It's strange. Must be something wrong with that particular belt you used or the pulleys. May be they were not meshing correctly... may be didn't have same tooth profile. Otherwise, I think, the speed was not that high to cause what you described. Could be a bad alignment of the pulleys...?

Daniel

833

General Mach Discussion / Re: High speed spindle recommendations

« on: August 24, 2010, 02:11:06 AM »

Good results

Daniel

834

General Mach Discussion / Re: High speed spindle recommendations

« on: August 21, 2010, 01:41:48 PM »

Thanks Hood

Daniel

835

General Mach Discussion / Re: High speed spindle recommendations

« on: August 21, 2010, 09:09:42 AM »

I agree on the Poly V-belt (or a grooved belt like you say) Already mentioned it being used on industrial lathes. Not sure about the pricing though - was getting mine for ridiculously low prices - something like $5 for a 17" XL belt. Much cheaper than the polyurethane reinforced V-belts I've been buying - about $20 for about the same size belt. But then it may be just my supplier

Daniel

836

General Mach Discussion / Re: High speed spindle recommendations

« on: August 21, 2010, 08:39:02 AM »

"Wee Gearbox"... hmm... sounds good, but what is it anyway

Daniel

837

General Mach Discussion / Re: High speed spindle recommendations

« on: August 21, 2010, 06:56:06 AM »

Hood,

Yes, extra cooling sure wouldn't hurt in any case. Especially if it's so easy to do

An O-ring is stretchable by nature and I don't know of any 'scientific' recommendations for its tension. And here is its advantage, I think, you don't need any tensioning mechanism. I designed my drives so that the O-ring is a bit stretched - about 5mm shorter than required (if memory serves me well) worked fine for me. But it would depend on the overall length of the belt. Mine were made from long stock O-ring, cut to size and melt joined the ends.

Steve,

Correction: V-belts work better at high speeds. Much better in most cases! Timing belts produce noise (and heat) as the speed increases - this is a fact! As the speed increases you have to consider for precise aligning of the timing belt. As the speed increases the teeth wear becomes more of an issue. For high speed application not requiring positive belt grip don't use timing belts. There are big industrial lathes with spindle speeds to 18,000RPM capable of rigid tapping which use poly V belts - NOT timing belts.

Daniel

838

General Mach Discussion / Re: High speed spindle recommendations

« on: August 20, 2010, 09:48:01 AM »

Hood,

Oh... so speed is not really an issue I would say. You could get by with the timing belt and the cooling. Another thing is that if you wanted a quieter and smoother operation, then an O-ring would be beneficial. Unless you've already made your decision about drilling cooling holes in whatever case or you have other reasons for it than the heat generated by the belt, I am pretty confident that an O-ring configuration wouldn't need them.

Daniel

839

General Mach Discussion / Re: High speed spindle recommendations

« on: August 20, 2010, 08:49:20 AM »

Hood,

It's going to be an interesting project with the cooling channels

I would still replace the timing belt with a V-belt or O-ring. Timing belts are just not designed for such high speeds. What matters for a belt is not the RPM, but rather the linear speed it runs at. A 20mm diameter timing pulley carrying a belt and revolving at 3000RPM would probably have no issues, but a 100mm pulley rotating at the same speed would mean a much higher linear speed of the belt and wouldn't be OK.

I have a grinder which I built few years ago and it uses O-Rings for driving the shafts. Have never had an issue with them, and they transfer quite a moment compared to the spindle speeded you built. The pulleys have a round profile to match the O-ring. Was pretty easy to make them. I ground a HSS tool bit to the appropriate radius.

Dan

840

LazyTurn / Re: Slow spindle on my lathe

« on: August 19, 2010, 01:16:24 PM »

What is the line count of your servo's encoder? It would probably be a quadrature encoder so multiply whatever the line count is by 4 and that should be the steps per revolution.

Dan