|David George 1||16/10/2019 17:24:49|
946 forum posts
Hi I had a spindle and chuck given a few months ago and had a bit of spare time and made a useful bit of kit. I have tried drilling milling and grinding with it. It is a little bit slow for grinding at only 4000 rpm but it does work on all three operations.
4761 forum posts
Interesting. A safety conscious model engineer who actually encloses the belt.
There seems to be a lot of weight (the motor) at a distance from the tool mount. Will it hold firm under vibration?
|David George 1||16/10/2019 19:20:31|
946 forum posts
Hi it's solid as a rock no vibration even with a grinding wheel that needs truing up. It has a flat belt with a 50mm pulley driving a 25mm pulley and I just like making tooling. The motor is offset to give me more room on the lathe.
|John Hinkley||16/10/2019 20:05:12|
765 forum posts
One of my first tool builds was of very similar design - I didn't even consider covering the belt drive, however! The spindle was a home-brewed ER25 affair running in cheap ball races. The toothed belt is tensioned by the ball race jockey wheel mounted in a slot for adjustment and the driving pulley and idler (bottom left in the picture) are interchangeable to give high and low speed ranges. It's (under) powered by a sewing machine motor but it revs to 10,000 rpm - it says on the box! Vibration is a bit of a problem and I wouldn't trust it to do any accurate grinding but if fitted with a proper spindle it might pass muster. Still, like I said, it was one of my first projects. I've learnt a lot in the five years since then.
Edited (twice) for sloppy typing.
Edited By John Hinkley on 16/10/2019 20:06:15
Edited By John Hinkley on 16/10/2019 20:08:31
|1243 forum posts|
John, at 10,000 revs perhaps the toothed belt drive system is contributing to the vibration issue.
|Ian P||16/10/2019 21:27:06|
2217 forum posts
Since this is a low powered tool (motor power is the limiting factor) I was going to suggest using flat pulleys and using the back of the existing belt as a flat belt. Possibly though the teeth on the outer face might still impart some vibration effects that would effect grinding.
However rather than reverse a toothed belt, better would be a reversed polyvee because the full power transmission capabilities of the multi 'V's not really be required for this tool.
|John Hinkley||16/10/2019 23:16:24|
765 forum posts
Emgee and Ian P,
Rest assured, I don't think it achieves anything like 10k rpm! Certainly not when I have used it. In fact it spends 99% of its time languishing on a shelf. I have better and more equipment to do those jobs, acquired in the intervening years. I was quite pleased with the two-speed arrangement, though.
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