Large capacity drill bits

[nightjonboy]

Can anyone recommend a decent 55mm cutter for 10mm 304 stainless? I currently have one of those cheap n’ nasty TCT hole saw types from eBay - it cuts ok but with a fair amount of chatter - the problem is the cutting depth. Once it gets past 3mm it just locks up the motor of my (piece of proverbial ) Clarke CDP5RB drill press. First 3mm in less than a minute, another 2mm takes 10 mins, then turn over and go again ‍ The hole saw does have a slight internal taper which i think is causing the cutout piece to bind against the cutter itself. I’m using molyslip.

I’ve looked at Annular/Rotabroach cutters but they’re so expensive. PLUS the drill press I have doesn’t have a replaceable arbor - it’s linked to the spindle in an all in one job. Current Chuck is 13mm max and I haven’t found a large Annular cutter that’s less than 19mm shank. I don’t want to shell out for a more industrial drill press just yet, so I’m thinking that if/when I buy a mini lathe I might attempt to machine a new spindle that I can attach different arbors to. That’s the long term plan, but in the meantime... does anyone have any suggestions? Any suggestions greatly appreciated.

 

[Munkul]

You need rigidity, some good downward force, and therefore drilling power for stainless, and at that size, your little drill press isn't up to the task... you could put the very best HMT cutter on your drill and it won't do any better.

You have another option though... a Starrett holesaw... they take less driving and less force... they won't like 10mm thick stainless, but they WILL do it, just take your time, and clean the swarf out of the cut often once you're deeper than a few mm. Lots of cutting lube, as usual.

I suspect part of the reason why your motor is locking, is the flex in the drill quill and the flex in the table. It will add up and pinch the sides past a certain point.

 

[hotponyshoes]

No offence but I think you are going to struggle with that drill for that job whichever bit you use.
Your best bet is probably another TCT saw but a decent one.
I can't remember what brand i use but they don't have any sort of taper and chomp on through in one cut with no problems.

Molyslip can sometimes cause the chips to get stuck in the cutting line once you get below the depth of the teeth which is probably what's happening here. Have you compared the 3mm easy cutting depth to the height of the teeth on the cutter you have now? If that might be causing an issue maybe fill a plant sprayer with soluble cutting oil mix and flood the thing out with it continuously. It will make a mess mind!

 

[Agroshield]

Buy a good HSS hole saw. Starrett or Abracs or Lennox. Read the manufacturer's literature to see if they offer a grade or tooth profile specifically suited for stainless.

Almost certainly, you are turning it too fast. This (https://littlemachineshop.com/reference/cuttingspeeds.php) says 115 sfm for stainless. For a 55mm dia. saw, that is 200 rpm.

Do not recut the chips. Plunge in hard. Count to three. Withdraw, Brush off chips with a toothbrush. Repeat.

Other option is proper flooding with soluble oil and maybe a wet vac to remove the chips (turn the drill press on its side and gravity will help you).

 

[123hotchef]

If you have work hardened the stainless start again on a new piece if you can!
or heat it up until glowing and let it cool

 

[cheb]

You can minimise the table flexing by supporting it with a scissor jack or similar.

 

[h-dom]

How precise does it need to be? I had to do the same 45mm and had a cheap HSS holesaw and on my drill press it was doing the same, 3/4mm in no time then ages for the rest. Using molyslip too.
In a moment of anger after stalling the drill press again I stuck it on my cordless drill and it cut straight through. No idea why.

 

[mtt.tr]

Are you lifting the cutter out the workpiece holes saws have no method of chip extraction so will clog the gullets


I get around is drill a few holes say 6mm inside but on the hole saw line then the chips can drop through and clear the holesaw gullet

 

[Maker]

I get around is drill a few holes say 6mm inside but on the hole saw line then the chips can drop through and clear the holesaw gullet

I was just scrolling down to say this, makes it so much faster.

 

[Agroshield]

I get around is drill a few holes say 6mm inside but on the hole saw line then the chips can drop through and clear the holesaw gullet

With this, you have to weigh up the possibility of the 6mm holes themselves work hardening the material where you want to use the holesaw. It is a difficult call.

 

[nightjonboy]

You need rigidity, some good downward force, and therefore drilling power for stainless, and at that size, your little drill press isn't up to the task... you could put the very best HMT cutter on your drill and it won't do any better.

You have another option though... a Starrett holesaw... they take less driving and less force... they won't like 10mm thick stainless, but they WILL do it, just take your time, and clean the swarf out of the cut often once you're deeper than a few mm. Lots of cutting lube, as usual.

I suspect part of the reason why your motor is locking, is the flex in the drill quill and the flex in the table. It will add up and pinch the sides past a certain point.

Thanks mate. It is a weedy little machine and I am searching for one of those old British-made presses but can’t afford it right now, so I’ll just have to make do.
I forgot to mention Starrett, I do have a 50 and 55mm cutter of theirs and it works a little better than the cheapo ones.
Thanks for the tips!

 

[nightjonboy]

No offence but I think you are going to struggle with that drill for that job whichever bit you use.
Your best bet is probably another TCT saw but a decent one.
I can't remember what brand i use but they don't have any sort of taper and chomp on through in one cut with no problems.

Molyslip can sometimes cause the chips to get stuck in the cutting line once you get below the depth of the teeth which is probably what's happening here. Have you compared the 3mm easy cutting depth to the height of the teeth on the cutter you have now? If that might be causing an issue maybe fill a plant sprayer with soluble cutting oil mix and flood the thing out with it continuously. It will make a mess mind!

Thank you sir! You know what, I haven’t even tried a liquid cutting compound yet. Does anyone use motor oil or does that not work?
The molyslip turns to liquid anyway seeing as the part gets so hot ‍
I’m happy to make a mess if it gets me a faster cut

 

[nightjonboy]

Buy a good HSS hole saw. Starrett or Abracs or Lennox. Read the manufacturer's literature to see if they offer a grade or tooth profile specifically suited for stainless.

Almost certainly, you are turning it too fast. This (https://littlemachineshop.com/reference/cuttingspeeds.php) says 115 sfm for stainless. For a 55mm dia. saw, that is 200 rpm.

Do not recut the chips. Plunge in hard. Count to three. Withdraw, Brush off chips with a toothbrush. Repeat.

Other option is proper flooding with soluble oil and maybe a wet vac to remove the chips (turn the drill press on its side and gravity will help you).

Cheers for the reply! 200rpm the slowest speed this thing can do is 620rpm so I’m going potentially 3x faster than recommended?
I’ll make a short vid of it later so you can all have a laugh.
Already doing all of the above - except wet vac or turning it horizontally. Will definitely give that a go!!

 

[nightjonboy]

If you have work hardened the stainless start again on a new piece if you can!
or heat it up until glowing and let it cool

Good shout, thanks will give this a try

 

[nightjonboy]

How precise does it need to be? I had to do the same 45mm and had a cheap HSS holesaw and on my drill press it was doing the same, 3/4mm in no time then ages for the rest. Using molyslip too.
In a moment of anger after stalling the drill press again I stuck it on my cordless drill and it cut straight through. No idea why.

Yea that’s a good shout. Maybe I’ll get it started with the press on both sides so I’ve got a good Z axis and then run it home with a hand drill. Will try and let you know the results.

 

[nightjonboy]

Are you lifting the cutter out the workpiece holes saws have no method of chip extraction so will clog the gullets


I get around is drill a few holes say 6mm inside but on the hole saw line then the chips can drop through and clear the holesaw gullet

Great idea!!! Will do that today for sure. Any pics of your hole saw after you’ve modded it??? Thanks!!

 

[nightjonboy]

With this, you have to weigh up the possibility of the 6mm holes themselves work hardening the material where you want to use the holesaw. It is a difficult call.

Forgive my ignorance but I don’t understand. Can you please explain?

 

[Wallace]

Great idea!!! Will do that today for sure. Any pics of your hole saw after you’ve modded it??? Thanks!!

The holes are drilled in the material you are cutting within the cutting circle line of the holesaw.

Forgive my ignorance but I don’t understand. Can you please explain?

Stainless steel work hardens if it gets hot and kills the cutting edge (then you get more heat generated) so you could end up with a series of hardened holes to drill through.

 

[nightjonboy]

The holes are drilled in the material you are cutting within the cutting circle line of the holesaw.


Stainless steel work hardens if it gets hot and kills the cutting edge (then you get more heat generated) so you could end up with a series of hardened holes to drill through.

Got it!

 

[nightjonboy]

Got it!

I was thinking you meant to drill holes in the side of the actual hole saw - which might actually work too, if I can find a bit strong enough to get through tool steel.