scudderfish
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| posted on 30/10/13 at 03:46 PM |
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Drilling stainless steel
I ned to drill (& tap) a large hole in a 70mm stainless steel elbow to fit an air temp sensor
However I can't make a dent in it! I thought I'd start small (4mm) and then use a stepped drill to open it up, but when I had it under
the drill press all that happened was the drill bit started to bend.
What sort of bit should I be using? Is there a particular technique?
Regards,
Dave
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Slimy38
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| posted on 30/10/13 at 03:52 PM |
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Was it bending because it was simply sliding round the curve? I wouldn't expect that sort of tube to be very thick or particularly strong, it
would just be a problem to keep the drill bit straight.
Perhaps a centre punch to make a dent so the drill bit didn't stray? And check your bit to make sure it's actually sharp?
[Edited on 30/10/13 by Slimy38]
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nick205
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| posted on 30/10/13 at 04:13 PM |
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As above, use a centre punch to make a start mark for the drill bit. Might also be a good idea to use a centre drill to produce a pilot hole for the
larger drill bit.
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ReMan
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| posted on 30/10/13 at 04:23 PM |
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Def center dot it and make sure you use a new / high quality sharp bit
Should go easily enough then
www.plusnine.co.uk
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40inches
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| posted on 30/10/13 at 04:28 PM |
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The slowest drill bit speed, lots of lubricant and steady pressure. If it starts to squeal, stop, you've blunted the drill bit and are hardening
the stainless.
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theprisioner
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| posted on 30/10/13 at 04:35 PM |
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Cobalt 5% drills are recommended and slow drilling speeds.
http://sylvabuild.blogspot.com/
http://austin7special.blogspot.co.uk/
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mark chandler
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| posted on 30/10/13 at 04:48 PM |
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Cannot see you tapping a thread and it being any good without you having a bung welded in.
I,d be inclined to put it into the side of the top hat, loads of meat to hold things there.
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scudderfish
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| posted on 30/10/13 at 04:59 PM |
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quote:
Originally posted by mark chandler
Cannot see you tapping a thread and it being any good without you having a bung welded in.
I,d be inclined to put it into the side of the top hat, loads of meat to hold things there.
There is already a nicely tapped hole in the hat, but I'd need to cut a sensor sized slot in the bonnet so that it could close over it. Ideally
I want to hide the sensor underneath the pipe. I'm probably going to have to fit a bung, but I still need to make a (bigger) hole for that.
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FuryRebuild
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| posted on 30/10/13 at 05:31 PM |
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two things - when I was making sumps in stainless I bought specific stainless bits (cobalt I think), and also just the right lube. No amount of
punching and standard drills will make a dent - they'll just skid right off. If you don't use a proper cutting oil (that doesn't
break down under the tremendous pressure at the cutting head) then things will blunt quickly. My local nuts and bolts and stuff shop sold the cutting
oil in an aerosol for about £10. WD40 won't cut it (ahem).
Then, you need to buy a stainless tap. I couldn't get anywhere with a good conventional tap, and I found there are specific stainless taps. Cost
me about £5 from ebay.
When all you have is a hammer, everything around you is a nail.
www.furyrebuild.co.uk
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PSpirine
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| posted on 30/10/13 at 06:15 PM |
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Doesn't stainless work-harden when you drill it too quickly/get it hot?
I remember we found this out after one guy went through 3 drill bits trying to bore a hole on a lathe in a piece of stainless bar.
Good quality bit, lube, slow and steady!
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macc man
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| posted on 30/10/13 at 06:48 PM |
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I would be inclined to sub this out to a machine shop. A guy near me does lots of small jobs for little money.
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scudderfish
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| posted on 30/10/13 at 07:51 PM |
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Thanks all for the advice. I've gone off on a tangent instead. On the back of the hat (you can just see it) is another threaded hole which is
larger than the 3/8" NPT of my sensor. However digging through the garage I found a brass adapter which fitted. I needed to put a small notch
in the bonnet to clear the wiring, but I can now get the bonnet closed  However I've got this thread bookmarked for the next time I'm
thinking about drilling such a hole.
Regards,
Dave
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gremlin1234
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| posted on 30/10/13 at 08:36 PM |
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quote:
I found a brass adapter which fitted. I needed to put a small notch in the bonnet to clear the wiring, but I can now get the bonnet closed
you will need 10mm+ between the engine and the bonnet, - they really do move
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britishtrident
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| posted on 31/10/13 at 11:07 AM |
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Why not put the sensor in the aluminum alloy airbox?
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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scudderfish
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| posted on 31/10/13 at 11:23 AM |
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quote:
Originally posted by britishtrident
Why not put the sensor in the aluminum alloy airbox?
That's what I've ended up doing.
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