drilling stainless steel

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owen

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i need to drill out some stainless bolts. i have already drilled out 2 but blunted 3 bits in the process. i was drilling v slowly. any suggestions for bit types-- i was using the "best " b and q titanium type
 
1 - you are using crap quality drills

2 - are you going really slowly with lots of pressure, and lots of cooling oil?

drilling stainless is reasonably easy until you "work harden" the steel, by trying to drill with a red hot blunt drill bit.
 
He did .... 2

Getting enough coolant through is very important - as Talbot says - get it hot and it'll work harden .. then your stuffed.
 
Talbot does not like B&Q and I can see his point. But he does not say what bits he does like or where you get them. This is supposed to be a forum for swapping info so lets's swop?
 
I prefer to use quality branded drills. Suggest you buy a diamond sharpener and trim the drill tip as soon as any slowing takes place. To restart after work hardening, you will need a sharp drill and high pressure. It is risky to use a smaller drill, but it will increase pressure over a smaller area, and the next size of drill will have less work to do. This will minimise work hardening.

Philip

ps I have twice been beaten by stainless that could not be drilled. One was stainless banding, and the other was a part pinched from a scrap copier. Annealing made no difference. Rather supprising, as the former was soft and bendy.
 
You've had some good advise. Only thing I'd add is. Bench drill is much better and whatever you do, dont do it anywhere near the boat, else it will be covered in rusty filings the next day and nearly imposible to remove.
 
[ QUOTE ]
Try something like <span style="color:red">SDS</span> drill bits... good quality.... and then drill VERY slowly.... LOADS of pressure and LOADS of lubricant... like butter when you get it right!

[/ QUOTE ]Since when did the drill holder have anything to do with drilling SS ?
 
Had to do this with a stanchion base a couple of years ago, a trip to the local engineers supply company resulted in a selection of bits designed specifically for stainless. [Different angle of cut to normal HSS drill bits]. Made all the difference and knife through butter type performance. Still have the bits and still working well after several more uses. Well worth the money.
 
In support of Talbot: /forums/images/graemlins/laugh.gif

B&Q drill bits are utter, utter crap. (Whether titanium (i.e. gold coloured) or not).

Oh, sorry, no - they work OK in softwood.

Ideally go to an engineering supplier for "jobbing" drill bits, or even a decent builder's merchant if you don't want anything over about 6mm.

Go cobalt, or special stainless steel bits if you wish, but a decent HSS bit will knock spots off B&Q's "titanium", and will probably be cheaper. My nearest 'bit' to hand is branded "TITEX PLUS" if this helps!

I use engine oil as a lubricant when working SS. As others have said, heat builds up very quickly and will blunt the blade and harden the SS at the same time.

0.02p

Andy
 
Definitely cobalt drill bits and definitely lots of oil - cutting oil. Agree with boatbuilder about pilot drills and working up. Got mine from Machine Mart and they're good. Mind you, it depends on the gauge of the bolt. Unless it's fairly thick, it's the devil's own job to keep the drill bit point 'on the job'. I was using a drill press on 4mm screws in an aluminium window frame and the bit kept slipping off the bolt end, favouring the softer aluminium, I guess.
 
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