Using Holesaws

[JimM]

I need to cut a disc approx 75mm diameter out of some 6mm plate - fortunately I have a 76mm holesaw in my cheapy market stall set which should do the job - only have to do the one so no problem if it's knackered at the end.

When using these is it just a case of keeping the drill speed low (think my pillar drill goes down to about 100rpm) and using plenty of cutting fluid (have to be tapping fluid or 3in1 as that's all I have)

Cheers

Jim

 

[madkayaker]

low speed and plenty of lube. Drill the pilot hole first keeps it straighter

 

[Pete.]

Heat is what kills them. Use fluid or oil and keep the speed down. Keep pecking up and down to clear the swarf from the teeth. I once had to drill two 6" holes with a starrett cutter in the web of a huge RSJ that was 32mm thick, working overhead off an ally tower with a 2-handle wolff drill. I managed two holes in an 8 hr shift and could hardly move my shoulders to drive home.

 

[madkayaker]

great fun. i use holesaw's daily but only into thin tin tat.

 

[Paul.]

Clamp it down on a block of hardwood to stop it chattering, the wood will also support the pilot drill, plenty of cutting oil, Rocol RTD or similar is the stuff to use, 3 in one is a lubricant, not good for cutting

 

[hotrodder]

Just to add to what's already been said, drilling a clearence hole (or 3) for swarf ejection helps a lot.

 

[rtbcomp]

Keep quite a bit of pressure on the drill too, that will encourage it to cut rather than just rub the surface.

 

[shenion]

I reversed the pilot drill on mine. That helps it from widening the pilot hole.

 

[Paul.]

Ive taken the pilot drill out of mine and replaced it with a piece of 1/4" bar, for that very reason

 

[madkayaker]

I plan to do that with a piece of 6mm bar. Anyone got a couple of two inch bits spare?

 

[simon718]

take it m6 threaded wouldnt do the job mk, are you thinking of just round bar? might be able to lay my hands on some m6 if it would do you

 

[madkayaker]

m6 might bend and snag but starter for ten. Was thinking round bar.

 

[Paul.]

I think most arbors are 1/4 " rather than 6mm, Mine have a piece of stubbs silver steel in them, it doesn't bend too easy, If your serious about holesawing
steel or stainless, cobalt saws are the ones to use.

 

[madkayaker]

there the ones i use. I'll measure the hole when i get chance.

 

[Hitch]

I hate them bosch holesaws. To much play in the quick release arbor, and the bodys distort easily. Sandvick or Starett are the way if you want good ones. I find screwfix own brand are good quality at a reasonable price.

Plenty of pressure, slow as posible, and the taping fluid you have.

 

[madkayaker]

use the screw fix ones as well. And the wholesaler use Starrett

 

[hareng]

As said before drill at least one other hole to help swarf plus 1/4" round to replace 1/4" drill bit.
Some hole saws are not round or screw on the p..s. The larger Starret arbour with twin lug, theres plenty of lateral movement, in addition runout of drill chuck and or arbour in it.

To be honest i dont think the ****** cheapies will last long enough to go through that thickness, so more holes round the o/d will help a lot.

Use decent holesaws all the time without drilling with centre drill, but bored out to size after. Usually cuts in around 3mm then breaks out in a recess on other side, this clears the swarf with me. http://pic20.picturetrail.com/VOL15/728921/1252422/14584660.jpg

 

[JimM]

Thanks for the replies guys

Just finished the disc, took a while to get through but got there in the end. Biggest problem was that the saw would catch in the hole and as I raised the quill it pulled the MT2 arbour out of the quill. Tried a different chuck and although this one stayed in the quill the chuck kept separating from the arbour. Spent most of the time pressing everything back together again

The cheapy saw proved to be the least troublesome part of the whole opearation.

One thing I didn't consider is that although the hole is 76mm the disc removed is only 71mm, should still be OK to do the job but this is where my inexperience shows as I'm sure you guys would have thought of this in advance.

Cheers

Jim

 

[Hitch]

If you want a way to cut accurate circles like that, a trepanner is handy bit of kit. Quite easy to make for yourself aswell. Use broken taps as the cutters

 

[Paul.]

Didnt realise it was the disk and not the hole size that was important, an 80mm would cut about 77mm inside