Pillar drill questions

[Paddy346]

Hi lads iv a single phase pillar drill . And I'm wondering how I would go about slowing down the speed for bigger drill bits

 

[Agroshield]

For all practical purposes, you cannot vary the speed of a single phase motor. So you will need to gear it down using the pulleys. This may involve a larger driven pulley (cannot go too small on the drive pulley or the belt will slip) or making a countershaft so there is a two-stage reduction.

 

[Hopefuldave]

Not much you can do without some effort - a single phase motor can't be run from VFD or similar to slow it, so you're looking at mechanical means - I've seen a third pulley set on an outrigger to give another stage of speed reduction, assuming you don't already have the
third pulley/2 belts.

Dave H. (the other one)

 

[Paddy346]

Ya I have two pulley in the middle between the drive and the spindle pulley if I replace them with larger pulleys would that do

 

[frank horton]

paddy
some times there's enough slop in the belts to alter twhere they sit on the middle pulley.....
the belt will be out of alignment but as long as it's the odd job it doesn't matter much.....
I do this on the odd occasion...
(to get the slowest speed poss u need the smallest pulley on the motor and the largest on the quill shaft.....
then u need to adjust the size of the pulley's to get the speed that u req.....but this is just a guide.....
for example....
if u have a 2inch pulley on the motor and 4inch pulley on the quill ..the quill shaft speed will be 1/2 the motor speed...)

 

[Paddy346]

I'll try that cheers . I dunno why they don't make the belt driven drills with slower speeds mine is a good drill and never slips but the so are just too fast

 

[Hopefuldave]

I'll try that cheers . I dunno why they don't make the belt driven drills with slower speeds mine is a good drill and never slips but the so are just too fast

I think they imagine you'll be drilling that brown stuff that splits, not metal...

Dave H. (the other one)

 

[brightspark]

the size of the chuck gives it away. if its a half inch chuck on it the lowest speed on the drill is sufficient unless your putting in blacksmiths drills that will pull the guts out of your machine

 

[Paddy346]

It's a Mt 3 chuck iv a full st of bits upto 30mm

 

[Agroshield]

It's a Mt 3 chuck. I've a full set of bits up to 30mm

Can you post a picture or find one elsewhere on the 'net. I think we are all imagining it is a £30 B&Q special that you want to use in excess of its design and clearly it is not. Thanks.

 

[Paddy346]

Ya I'll send a picture today . It's an optimum b 26 pro. It's a decent enough drill

 

[Paddy346]

Are single phase gear head drills any good .

 

[Agroshield]

OK, thanks. Pictures and specs. here: https://www.techsoft.co.uk/WorkshopEquipment/Drills/OptimumFloorDrills

Spanish manual here: https://www.aslak.es/pub/media/fichas_tecnicas/3003171.pdf

Belt arrangement for all 12 speeds shown on page 29.

Having seen the above, does the lowest speed agree with the 200rpm given in the manual? If not, is it possible the motor has been changed from a circa. 1400rpm one to a 2800rpm one?

 

[Turbo]

It looks like your slowest speed is 200 rpm which is just under the recommended drilling speed for a 1" bit in mild steel. If you want to go slower you could try adding an extra idler pulley wheel. It's a lot of work, I tried it on a Meddings with mixed success.

The simplest way would be to fit a 3 phase motor & use an inverter to run it slowly.

The best option & what I finished up doing would be to buy an old pillar drill fitted with a back gear, mine goes down to 80 rpm.

 

[Munkul]

I can't see that drill having the power or the rigidity to drill much bigger than 13mm anyways! Just because it has a 3MT doesn't mean it can comfortably run a 1" twist drill bit. I'm guessing that table will flex something awful.