Drilling ss

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I want to drill some holes in a 2mm thick(approx) ss plate which is in situ.

Any advice abouth the best way to do this?
 

fireball

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Start with a smallish bit,
Put some masking tape on the surface - stops the bit from slipping
You can do it with a cordless drill - on slow speed
Once through with the pilot drill, step up the size of the bit - this can step up quite quickly depending on your final hole size.
Don't be tempted to speed up the bit too much - it just heats up the bit and blunts it ...
 

jjj

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I would check the rake and clearance of the drill bit and if all is in order I would use a drill press at a low speed with constant pressure and plenty of cutting fluid.
 

tcm

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agree with others, and use a fabulously expensive drill bit - drilling ss is not easy.

Once finshed, you should aim to polish up the drilled hole and area around it, cos with your carbon steel drill bit you have left carbon deposits on the surface, and hence loads of amateur drilled holes in ss (and some pro drilled holes too) go a bit rusty. Use a new grinder bit such as for a dremel to smoothe the hole, and a countersink one to clean up the entry and exit. I spose that it needs repassivating too but i don't know the product names - pbo did summink about it recently i think...
 

fireball

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I forgot to mention - as the bit is in situ, don't forget to clean up around the area very well - or protect it to start with ... having had to spend some time cleaning rust spots out of the cockpit (cut up some mild steel as a template for a plate - didn't clean out properly /forums/images/graemlins/frown.gif ) ... mind u - if you use that Cilit Bang stuff, spray on and leave for 30 minutes - clean off with a non-stick scourer ... bobs your uncle!
 

Crazyjane

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When drilling stainless steel the following points will ensure a successful job with minimum pain:
1) Use a new HSS drill bit or a bit that is properly sharpened. Stub drills are excellent as their shorter length minimises the risk of breaking the bit.
2) Use plenty of lubricant while drilling. Thread cutting compound is excellent for drilling on site.
3) Use plenty of pressure on the drilling machine. It is essential to keep the drill cutting as any sliding will rapidly lead to work hardening of the surface of the stainless and will burn and blunt the drill bit.
4) For the same reason as above use a slow speed while drilling
5) If using a pilot drill first ensure that there is a relatively large difference in diameter between the pilot and finished drill diameters, otherwise it is very easy to burn the corners off the finishing drill.
6) If possible use a backing pad, of say plywood, when drilling in thin sheet material. If this is not possible be careful when the drill is breaking through
7) Be careful it is easy to have an accident when drilling sheet material.
 

mikebees

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IMHO all the above very good advice.
I used cobalt drills reasonably priced from Screwfix and easily drilled through 5mm stainless.
 

William_H

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I use lots of old engine oil. The advantage being that idf the drill or the job are getting too hot there is plenty of smoke to tell you. If you get smoke. let it cool down then try with more pressure. If you use a hand held drill use all the pressure you can then stop for a rest but don't continue unless you can give lots of pressure.
As they say u8se a new drill bit. however me being of short arms and deep pockets (a religious thing) I find I can sharpen drill bits quite successfully using an oil stone with the bit in a vice. look very closely at the bit or a new one to see the angle of the cutting edge and so maintain it. you can use a grinding wheel but there is a risk of taking too much off and losing the angles. Obviously a bigger bit is easier to sharpen. regards olewill
 

reeac

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"My" expert says don't use a lubricant as that means that you will just have to apply more pressure to compensate. He also said - and this is a nice simple tip - make sure that swarf is being produced all the time that you're drilling, showing that the drill is cutting rather than just slipping over the surface.
 
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