Drilling stainless steel?

[TheJay]

Super sharp HSS better than anything else. And if you break a bit it's not the end of the world. Start using £5 drill bits and it gets upsetting.

Which ones do you get/where from?

 

[Kram]

I use one of these sets, mine was the 1-10mm set and was about £20. They dont appear to have that set anymore. Hard to say if the extra 6 large drills are worth paying double for, I'd rarely use them.

25 Piece Cobalt M35 HSS Drill Bits Set 1-13mm Bit High Quality DIN 338 Motamec | eBay UK

High quality manufactured HSS M35 5% Cobalt drill bits, suitable for drilling mild steel, stainless steel, alloys, wood, plastics etc. Cobalt (HSCO) drill bits are much harder than HSS as it includes 5% Cobalt blended into the base material and therefore can be more brittle.

www.ebay.co.uk

Very good bits and last ages longer than a normal set.

For rougher work I use a cheap Lidl set, not much good but no problem if they get damaged. Drilling round tube has a risk the bit will catch and snap as it exits for example.

Also dont use your best drills for enlarging holes. A 2 flute twist drill will tend to chip and wear very fast when enlarging so do that with cheap drills.

 

[barracuda816]

I bought a fair few guhring bits recently and wasn't impressed. Im not sure if they have sold out or what. I like to stick to Dorma now, but I'll be honest their range confuses me, too many types HHS tiN coated or not, or carbon content differences maybe. They are not cheap but be careful they last. I never bought cheap after buying some Chinese rolled cheese bit that got me so angry, they were all bent and dull as dish water.

 

[Ross365]

Also dont use your best drills for enlarging holes. A 2 flute twist drill will tend to chip and wear very fast when enlarging so do that with cheap drills.

So, you are saying that for larger holes, start with a pilot drill (3mm ?) but then don't go through incremental step sizes - go straight to final diameter ?

I ran out of cutting compound the other day; I found a recipe for a homebrew approach; 70ml water, 30ml engine oil and ~10g of soap (a bar cut in pieces and then dissolved in hot water) it makes a kind of paste - it worked amazing well, maybe not Rocol but got me out of a hole.... or do I mean got me into several holes

 

[brightspark]

I usually enlarge an initial pilot hole - remember that surface cutting speed is zero at the centre of the hole-to-be.

the flat center of the drill is called the chissel and when it turns it just scrapes thats why you use a small pilot drill

 

[Brad93]

Which ones do you get/where from?

90% of my drills are Dormer A002.

I don't rate the extra cost of the Cobalt A777 over the standard jobber drills.

Guhring also very good.

Having some good results with Titex too.

If you want cheap drills it's hard to go wrong with Cleveland or Sherwood

 

[Kram]

So, you are saying that for larger holes, start with a pilot drill (3mm ?) but then don't go through incremental step sizes - go straight to final diameter ?

Pilot drilling is ok but the size should be rougthly the same or 1.5x the chisel of the larger drill. You shouldnt make a habbit of step drilling 2mm larger each time unless your using a proper step drill in sheet metal.
If the final size was 20mm, you dont drill, 3, 6, 8, 10, 12, 16,20. Drill 3mm, 10mm, 20mm. 10mm will be about 1.5x the web of a 20mm bit.

Bigger holes can be step drilled in that a 24may need a 10mm pilot, which itself may want a 3mm pilot. It is mentioned here and worth reading

https://www.presto-tools.co.uk/file.php?filename=PrestoCounsellor2016.pdf

While a 3 flute or core drill may be ideal, realistically they are extremely expensive and so in most cases it is better to sacrifice a cheap drill knowing it could need sharpening after half a hole.

I am not a fan of Dormer drills, even their plain HSS A002's, I have found them to be brittle. Another brand where recent stuff is crap, my dads old set was great and I still use them.

 

[Trevorleach]

Tbh I just use std dormer bits, bit of grease on the drill bit end, slowish speed and a good amount of pressure, but I do this on most holes i drill regardless of material.

 

[Brad93]

Pilot hole size usually wants to be the web thickness as a minimum

 

[Onoff]

+1 on DeWalt Extreme. Very impressed. I use with whatever cutting compound I have. Expensive for a full set up to 13mm mind.

 

[Munkul]

+1 for Dormer.

I’ve never had great results with cobalt drills, even nice Presto ones. They just seem to chip the edges off when hand drilling. I’d rather spend a little more and get solid carbide for the mill, also.

Dormer A002 just work. They’re not badly priced if you shop around, and they resharpen over and over.

I also like Milwaukee shockwave drills, they’re very sharp to start with and stay sharp for a long time, great for stainless. Just hard to buy in bulk for a good price.

Anything I pilot, I use a 3mm drill first off. Then go straight to finished diameter. And always use lube

 

[Brad93]

+1 for Dormer.

I’ve never had great results with cobalt drills, even nice Presto ones. They just seem to chip the edges off when hand drilling. I’d rather spend a little more and get solid carbide for the mill, also.

Dormer A002 just work. They’re not badly priced if you shop around, and they resharpen over and over.

I also like Milwaukee shockwave drills, they’re very sharp to start with and stay sharp for a long time, great for stainless. Just hard to buy in bulk for a good price.

Anything I pilot, I use a 3mm drill first off. Then go straight to finished diameter. And always use lube

Used the milwaukees the other day, very impressed