Drill/Mill Spindle brake (RF30)

**BillTodd** · 31-08-2009

Here's the varispeed idea I'm playing with ATM

Basically it's mounting a Piaggio Scooter CVT on top off the existing pulleys (believe it or not they will fit inside the belt cover).

I'm not sure exactly what range the CVT will give (calculating the ratios it's not as simple as measuring the min/max diameters) but it should be at least a 3:1 range.

**BillTodd** · 12-09-2009

Well the CVT sort of works:

the back of fenner final drive belt just catches the post causing a horrible buzzing. I'll need to source a slightly longer CVT belt, so that the intermediate pulley arm can swivel out slightly to allow the belt to clear the post

[ame="http://www.youtube.com/watch?v=s5iAb3IL1Hc"]YouTube - RF30 CVT1[/ame]

**BillTodd** · 14-09-2009

Knocked up a new shaft for the intermediate pulley .

**BillTodd** · 19-09-2009

Finished! New belt arrived today - no more buzzing noise.

Changing the front belt I can get speeds from 175 to 1860 in four over lapping ranges.

Pulley Vmin - Vmax
1 == 548 - 1860
2 === 393 - 1409
3 ==== 290 - 977
4 ===== 175 - 633

**John S** · 19-09-2009

So basically if you only ran 1 and 4 you would have the whole range ?

What about doing just a two speed pulley using a 6 rib Poly vee belt drive and that way you could get the smaller pulley on the intermediate shaft a tad smaller without loosing wrap round as Poly vees' don't suffer from this like V belts and you could probably get to less than 100 rpm.

Mind you if you are on CNC then it's a different ball game to the manual owner who needs low revs for large cutters and boring.

**BillTodd** · 19-09-2009

Originally Posted by John S

So basically if you only ran 1 and 4 you would have the whole range ?

What about doing just a two speed pulley using a 6 rib Poly vee belt drive and that way you could get the smaller pulley on the intermediate shaft a tad smaller without loosing wrap round as Poly vees' don't suffer from this like V belts and you could probably get to less than 100 rpm.

Yes, that would do it. The front pulley on these machines fits on a large taper so I'd have to make the poly V pulley...

I started thinking seriously about this conversion after I discovered that the original motor step-pulley was the wrong type ('A' section not 'B') I wanted to replace the belts with Fenner's (since they're supposed to be better) and did not want to run them on the wrong pulley. 'B' section step pulley aren't available of the shelf, so I was facing either making one or trying this; I'm glad I chose the later 'cos this works nicely :)

**BillTodd** · 02-11-2009

Just thought I'd share this with you...

My nephew Lee has a bad habit of asking me to make him things out of stupid sized bits of metal; a couple of weeks ago he asked me to make him a 35mm diameter steel sleeve with a 25mm bore and then supplied a length of 50mm bar - I couldn't find any 40mm bar locally, so had to spend hours turning the bloody thing down.

Saturday, he dropped off a 'technical' drawing - anyone who has seen the The film "The Hudsucker Proxy" would have recognised the drawing straight away i.e. two roughly concentric circles with 120 written in the middle and 12 by the edge with a side note saying 100mm long.

With it came a 4" long by 6" diameter block of steel - I'm suppose to make it into a tube