drilling stainless

[leadpig]

i got asked to remove a broken 6mm stud the other day some type of stainless, jesus it was hard
i managed to drill enough out to use a reverse bit but even after heating etc it would not budge and eventually the stud disintegrated
as a temporary fix i decided to drill out re thread and helicoil it, it was melting the sodding drill bits, ie a bright flash and the bits were disintegrating
admittedly they were cheapish of fleabay but advertised as titanium.
my question is, i have bought a 99 piece set of cobolts of uk drills as i needed more bits anyway are these suitable or do i need titanium carbide for stainless
tia dave

 

[Erie Fred]

Many stainless steel alloys "Work Harden" and I'll bet you did just that.

 

[Hood]

You don't need any special drills for stainless, you do need decent quality ones however and also you need to drill at a slowish spindle speed with a fair bit of pressure. If your spindle speed is too fast and the cutting pressure not enough you will rub rather than cut and the stainless will work harden in an instant. Once that has happened then often the only way to get it drilled is with carbide.

 

[leadpig]

cheers that makes perfect sense now, i was using a cordless drill lol, and remember telling my helper not to press so hard
it was also way easier to drill at the beginning

 

[brightspark]

You don't need any special drills for stainless, you do need decent quality ones however and also you need to drill at a slowish spindle speed with a fair bit of pressure. If your spindle speed is too fast and the cutting pressure not enough you will rub rather than cut and the stainless will work harden in an instant. Once that has happened then often the only way to get it drilled is with carbide.

and dont forget the cutting compound not just crappy oil

 

[julianthegypsy]

I'd add, don't centrepunch the hole, because that will workharden it instantly and don't peck or you'll do the same thing. Bang it straight in and keep going till it's done.

 

[leadpig]

I'd add, don't centrepunch the hole, because that will workharden it instantly and don't peck or you'll do the same thing. Bang it straight in and keep going till it's done.

bugger

 

[Hood]

..... i was using a cordless drill lol...

A pilar drill or mill is the best option but if using a hand drill a cordless is probably the best option as they are usually slower speed than a mains drill.

 

[Hood]

and dont forget the cutting compound not just crappy oil

90% of the time I don't bother using a cutting oil and I do a lot of stainless but it will certainly not do any harm using it.

 

[brightspark]

90% of the time I don't bother using a cutting oil and I do a lot of stainless but it will certainly not do any harm using it.

reduces friction and makes your drills last longer but if your not realy bothered about them i use the original brown rocol not there red chlorine free rubbish

 

[Dcal]

DeWalt extreme bits work well in a cordless and I find they need less push to get results.
Very easy to break mind you.

 

[leadpig]

A pilar drill or mill is the best option but if using a hand drill a cordless is probably the best option as they are usually slower speed than a mains drill.

ta, keep meaning to get a pillar drill, but i was onsight and got asked if i could help, they needed it and 2 week lead time on the replacement holder

 

[Hood]

reduces friction and makes your drills last longer but if your not realy bothered about them

It can do but if you keep the proper feed pressure I find it often cuts better without. That being said with the wrong pressure it can go downhill fast and a cutting compound or oil can help prevent that.

 

[Hood]

ta, keep meaning to get a pillar drill, but i was onsight and got asked if i could help, they needed it and 2 week lead time on the replacement holder

Yes, a lot of my stainless work is outwith the workshop on boats so battery gun is what I use.

 

[leadpig]

A pilar drill or mill is the best option but if using a hand drill a cordless is probably the best option as they are usually slower speed than a mains drill.

any recommendations on a half decent pillar drill, that wont break the bank
was saving for a mag drill and making a stand, but cant see me using it much at the minute

 

[Hood]

Earlier I said if the stainless has work hardened then often the only solution is carbide but I should really have added that carbide drills need a rigid setup, both in the workpiece holding and the drilling machine so it is not advisable to try carbide unless you have a milling machine. Carbide is very brittle and the slightest movement will snap it.

 

[Hood]

any recommendations on a half decent pillar drill, that wont break the bank
was saving for a mag drill and making a stand, but cant see me using it much at the minute

Not really, my preference is for a gear head drill and that is the reason I bought an old Arboga, doesn't look much but they are superb. Having said that other people know they are good and second hand prices are often high.
Realistically any oldish pillar will do, a Meddings or similar and will likely be a lot better than the new Chinese ones but even a Chinese one will be better than a hand drill.

 

[ukracer]

bugger

I have heard that before. But it does not always work.

 

[julianthegypsy]

bugger

Lesson for next time so not wasted!
Guess where I learned that!

 

[ukracer]

A pilar drill or mill is the best option but if using a hand drill a cordless is probably the best option as they are usually slower speed than a mains drill.

It's amazing the way a pillar drill will cut as opposed to a hand drill even if the put all your weight on it.