Drilling Stainless !

[Snoozer]

Ok need some advice from any engineer types please.

Got a project that requires me to fabricate from stainless and need to drill 2 x 11mm holes for attaching a work piece.

I was thinking pilot around 3mm then finish with the 11mm but want a drill bit that will both do the job and do it repeatably.

Looking on the web gives drill bits with a HSS ground bit with a Tungsten Carbide Tip but they seem far to cheap with the 11mm @ £5.88

Anyone got recommendations of a very good brand i can purchase ?

[fuzzypigeon]

Plenty of cutting fluid! Very easy to burn drills out.....be patient. Use the best drills you can afford...as for material hss will do it but if you are too rough you will burn them out....drill speed is important on stainless...

[Seadog1408]

Forget hss, go for cobalt drill bits and cutting fluid.

[bear-uk]

I failed miserably trying to drill two 2mm holes in some box section. The Titanium tipped Dorma drill bits would not touch it. Cable ties did the job eventually    

[johnnytheboy]

Irwin tct drill bits, we tested loads of tct drill bits and most shattered quickly, the Irwin ones outlasted all of them! We were drilling boron Steel with them 

[Dougy]

If you can, make sure you have something to drill through to, clamped to the piece your drilling.  it reduces braking the bits. Cobalt are a tad better than hss  if my memory serves me well. 

 

Blooming predictive text. 

Edited April 14, 2018 by Dougy
Has not hss

[Mice!]

33 minutes ago, Seadog1408 said:

Forget hss, go for cobalt drill bits and cutting fluid.

This, also are you drilling by hand or pillar drill? If your doing a lot and have a pillar drill you might be better getting a slot drill to suit.

[bornfree]

I always found HSS bits OK for stainless. I use RTD cutting fluid and a slow speed.  High speed and heat are your enemy.

 

[wisdom]

I drilled 316 stainless successfully after learning the hard way (burning drill bits out).

I drilled slowly and used rocol cutting fluid in a plastacine well and it was perfect. pilot drill first then up in stages

[The Heron]

The most important thing here is that the drills are sharp in my experience new HSS drills bought from shops need sharpening before use.

[Remimax]

cobalt drills with a pilot hole  first and plenty of cutting fluid,if you have a pillar drill even better .

i find slow speed & plenty of pressure doesn't give the stainless time to heat up and harden which then takes the edge off yer bit if that makes any sense.

 

Edited April 14, 2018 by Remimax

[Snoozer]

Thanks Guys.

Will be using a pillar drill with cutting fluid.

[Andy H]

At work all we use to drill any grade of stainless are Cobalt drill's  Hss are just not up to production work just do not go to fast and use a lube if is starts to squeel you are getting it tohot and blunting the drill.

Edited April 14, 2018 by Andy H
more info

[Winston72]

Blacksmiths bit in a pillar drill job done

[Mice!]

just measured a BS 5 centre drill and its 11.09mm would that do the job for you? I always find centre drills cut great short and sturdy? 

[Snoozer]

5 minutes ago, Mice! said:

just measured a BS 5 centre drill and its 11.09mm would that do the job for you? I always find centre drills cut great short and sturdy? 

I have a tolerance around 11mm so 11.09 is as near as dam it lol

If i got one would i need a pilot ?

[Mice!]

No mate they are a pilot, but i often drill thin stuff with them.

If you want one to try pm me your address I'll stick one in the post 

[Snoozer]

That's a great idea Mice, Thank you muchly

[figgy]

For 11mm hole use a 6mm or 1/4” pilot hole. 3mm is too small requiring lots of down pressure for the 11mm drill to cut. 

I find tct carbide hole cutters work well in thin stainless of a few mm thick. As that’s when Colbalt drills get chipped breaking through. 

As said slow and plenty of cutting fluid. 

Have a search I’m sure there was a thread on this not that long ago. About hole cutters and drills. 

Edited April 15, 2018 by figgy

[washerboy]

You shouldn’t need a pilot hole, as said sharp drill slow speed and plenty of cutting fluid not just water . 

[amateur]

Mark the hole out first with a centre punch to avoid the drill skidding.

The idea (above) of starting off with a centre drill is a good one, and one that I use too

Drill at slow speed with a pillar drill and sharp HSS bits, going up in diameter in stages and a fair pressure with  lots of lubricant to avoid overheating.

[seph234]

Another for Cobalts here. Thats the only drill i carry in the van now. and what has already been said, slow and steady with plenty of cooling.

[Jonty]

Plus one on the cobalt bits, I struggled with HSS with a stainless project and was advised to use cobalt, it was a revelation.

[washerboy]

I drilled 114 pre toughen stainless using a normal hss drill and cutting compound , take it steady 

[Snoozer]

Thanks for all the info Guys