Drill Press Speed Adjustment

Noel · 22 Mar 2004

When using a circle cutter on the drill press I need to reduce speed to about 250 rpm for holes (or discs) bigger than 3" or so. Only problem the lowest speed I have is 500 rpm and at this speed the counter weight on the cutter reacts like a mini earthquake...
Any ideas? Speed controller, add a couple of new belt wheels to the spindles? Would a variable speed controller do any harm to the induction motor?

Rgds

Noel

DaveL · 22 Mar 2004

To vary the speed of an induction motor you need a controller that changes the frequency of the supply. They do make then but they are not cheap

I think you would be better looking for some different pulleys.
Could you add a counter balance to reduce the imbalance :?:

Bean · 22 Mar 2004

I did this with an old single speed Bench Drill, its now five speed and runs on twintub washing machine belts. I had to make a complete new belt guard for it though.
I did this with the old drill (circa 1960) as it is made entirely of cast iron and absorbs more vibration than the newer fabricated drills.

pulley blocks for V Belts are available through engineers suppliers in most towns and are supplied both singulary and in pairs, you will need to know the bore diameter's and size of keyway's if fitted.
The ratios and hence the speeds can be worked out simply.

I hope this helps

Bean

Noel · 22 Mar 2004

Bean & Dave,

Many thanks for your posts. Think the Speed Controller is a no no. Counter balance? Cracker lateral thinking. Plenty of room on the bar if I get the weight right. See here:

Though I suppose an additional/replacement pulley wheel would be very handy in the future.

Rgds

Noel

Alf · 23 Mar 2004

Hah, chuck in in a brace and stop mucking about.

:wink:

Cheers, Alf

Noel · 23 Mar 2004

Isn't the journey much more interesting than the destination.....?
I would throw it in a brace but 30 mins per hole? Life is waaaay too short.
But it is the best circle cutter I've ever used, thanks to your mate Robin.

Rgds

Noel

PS Any chance of seeing your music sheet stand story again? Rather enjoyed that.