Adjusting the horizontal mill

[Steve355Participant @steve355]

Posted by Dave Halford on 14/04/2023 12:22:03:

Steve,

You have three separate problems in reality.

1 you are starting to go around the circle again

2 spindle speed

3 table feed speed

2 can be fixed with the 12" countershaft pulley solution from page 2 that you suggested and from Jasons post gives you 80, 250, 750 spindle speeds that you seem to have rejected for some reason. 90 is fine for slitting saws on my Centec 2A. Keep the smaller pulley and belt in the drawer for when you want to use end mills ( assuming you can find /make a B&S taper cutter holder.)

3 is based on feed speeds for a 12 tooth cutter. Buy cutters that have a tooth count matching the machine.

Hi Dave

It is true that I’m going around in circles again to some extent

The reason for rejecting the pulley based solution was that it didn’t work quite as Jason anticipated. A 12” pulley would give around 250 rpm at the countershaft 119, 244, 325 at the spindle, given the ratios of the existing pulley. I actually need around 150 at the countershaft, which would give 71, 146, 195 at the spindle.

This means I need a motor that runs at about 450rpm, to get 150 at the countershaft- which is too low for VFDs without losing significant power, in theory anyway.

Now, I could go for a motor which runs at 750 rpm AND a bigger countershaft input pulley. That might be the way to do it, and by changing countershaft pulley, I’d have access to higher speeds if I need them.

Steve

[Dave HalfordParticipant @davehalford22513]

Try the pulley first — 71 is too slow if 119 is too fast, I don't think 119 too far off to worry about.

[Steve355Participant @steve355]

Any reason not to go for a 12 pole, 3 phase, 1 hp, 450 rpm motor that popped up on eBay?

12 pole motor

it’s cheaper than the 12” pulley and would provide the “correct” speeds.

Steve

[AJAXParticipant @ajax]

Posted by Steve355 on 18/04/2023 21:22:24:

Any reason not to go for a 12 pole, 3 phase, 1 hp, 450 rpm motor that popped up on eBay?

12 pole motor

it’s cheaper than the 12” pulley and would provide the “correct” speeds.

Steve

That advert is strange. Many photos, but none of the data plate. Maybe it is 440V only.

[Steve355Participant @steve355]

Posted by AJAX on 19/04/2023 19:18:35:

Posted by Steve355 on 18/04/2023 21:22:24:

Any reason not to go for a 12 pole, 3 phase, 1 hp, 450 rpm motor that popped up on eBay?

12 pole motor

it’s cheaper than the 12” pulley and would provide the “correct” speeds.

Steve

That advert is strange. Many photos, but none of the data plate. Maybe it is 440V only.

it is a little strange but the guy selling it seemed sensible. It is a 3 phase motor which isn’t totally ideal but I have a converter I use for my surface grinder so it’s feasible. At £55 it’s a cheap solution which only needs wiring and mounting, so I’ve ordered it and we’ll see how it goes. Hopefully I’ll have a usable horizontal mill next weekend.

[Author]

Posts