As part of my 24v re-motoring exercise I¡¯m making new pulleys from aluminium. I¡¯m not finding it easy to machine the groove for the belt and would appreciate any tips (apart from ¡®buy them online¡¯ and ¡®do it on a bigger lathe¡¯ - I just have the U3).
I use ¡®O¡¯ rings for belts, they have a 5mm cross-section diameter. The finished inner diameter at the bottom of the groove will be 38mm. The pulley body is 9mm thick to allow for the flange portions either side of the groove.
For a cutter I first tried a 6mm drill bit cut off at 45 degrees and then milled clean. Blimey a drill bit is hard to saw with a hacksaw. Two blades later¡ the endmill had no problem however. ?The finished ¡®cutter¡¯ didn¡¯t cut very well though.
Next I ground a cutter (my first!) from a 6mm blank. Semi-circular, with a 6 degree angle, and some top relief (as recommended for aluminium I believe). This was moderately successful but it is doing more of a scrape than a cut. It is literally ¡®stop start¡¯. It did however produce some beautiful swarf, almost like snowflakes, or frost.
It is making pulleys - but painfully slowly. I have more material to remove and it is not working well at the moment.
I think I should be taking out excess material in smaller chunks first then finishing with the shaped tool, but a plan to do this is puzzling me given the finished shape. It¡¯s taken a long time to get this far from a large chunk of aluminium and I don¡¯t want to ruin anything!
So far I¡¯m going in at one position. I did wonder if alternating cuts between two slightly altered positions (kind of left and right) would be beneficial - the cutter would (or might) only be using 50% of the cutting edge.
I¡¯m making three pulleys in all - one for the motor and one each for the lathe and mill.
As usual I have very little idea what I¡¯m doing so am looking to tap into folks wealth of knowledge and experience. Any tips gratefully received. Thanks!
(Sorry for the overlong post - the quick version would be ¡®How would you make a pulley groove?¡¯ :-)
