Which ones do you get/where from?
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Kram
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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.
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.
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
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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
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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
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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
Kram
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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
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
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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.
Munkul
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+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
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
