10mm holes in 8mm mild steel

[Alpha-Dave]

found this video of a guy demonstrating it.

Isn’t the problem that he’s drilling into the support structure of the vice? Second time around he has removed enough of the jaw to let the drill pass through.

 

[Fergie 307]

If you have ever tried drilling a hole that size in thin sheet with a normal drill bit, you tend to get a very irregular hole, often much worse than in the first example in the video. The cloth trick gives you neat round holes every time. No idea why it works, seems completely counter intuitive, but it does. I was shown this years ago by my dad.

 

[Threadedpipe]

not read all the replies before but after drilling literally thousands of holes in steel over the years use a dot punch then either use a 4mm then 8 and finally 10mm drill bits or 5mm then 10mm if 3 bits is too much work
drill bits on steel don't waste your time on cheap drills I would use dormer and only dormer tried the cheap ones they are not worth it don't see big brand and think must be good i.e. Bosch drills in my eyes have a special place to be stored - the rubbish bin if you get resistance don't keep pushing let the drill do the work

 

[Limey Lurker]

I, too, have drilled many, many holes, in every common metal. I can't imagine an occasion where I'd have used a pilot hole to drill a 10mm hole in 8mm mild steel. I served an apprenticeship as a toolmaker.

 

[Fergie 307]

I think to be fair it's about speed, if you have a good pillar drill that will go down to a suitably slow speed, then I agree a pilot hole is quite unnecessary. The video I posted is a good example, clearly a fairly heavy duty machine with auto feed, and running at something like 100rpm, although he is using a pilot hole, probably owing to the fact that the material is pretty thin. But I think most people on here are probably using kit designed primarily for woodworking, so may have 500 or so rpm as their slowest speed, in which case a pilot hole is a good idea. You could of course use a cordless to give a slower speed, but might not have the torque for the job.

 

[pe2dave]

not read all the replies before but after drilling literally thousands of holes in steel over the years

I do wonder if that's the difference? For every hole in steel, I drill 100 in wood. I'm on my second box of
?cheap? drills (apart from replacing tiny ones I break through my fault) and they work fine.
Were I to drill lots, in steel, I guess I'd invest in better drill bits.

 

[AES]

I do wonder if that's the difference? For every hole in steel, I drill 100 in wood. I'm on my second box of
?cheap? drills (apart from replacing tiny ones I break through my fault) and they work fine.
Were I to drill lots, in steel, I guess I'd invest in better drill bits.

I do sympathise with you mate. My own experience is that it's just not true that all cheapo no name twist drills are rubbish. Some definitely are, some definitely are a LONG way from being rubbish - in fact just as good as the big names - sometimes!

And that's why I sympathise, because when buying no name cheapos, unless there are obvious visible defects (say in the grinding) there's just no way to tell without buying and trying. Some even "look" just as good/better than the big names!

Over the years when buying drill sets (I mainly buy one offs for special sizes or replacements now), I reckon I've ended up with sets with about 50% complete rubbish and about 50% acceptable to good. A couple of cheapo sets had several good and several rubbish drills in the same set.

If there is a way to sort the wheat from the chaff, I don't know it.

 

[pe2dave]

If there is a way to sort the wheat from the chaff, I don't know it.

<grin/> Drill lots and lots and lots of holes in steel?
(Sorry, couldn't resist).

There must be a median way with drills for 'ordinary' use.
My ?? 40 yo set has no name, Marked HSS DIN 338, description in 3 languages. 1-10mm by 0.5mm.
Still in use - I bet there are some in there I've not used!

 

[Fergie 307]

I agree that you can't beat really good quality ones, especially in very small sizes where cheap ones are often not properly formed, however for day to day use I have been very surprised by the quality of the sets from Aldi, the ones they do in a folding plastic case. Both wood and metal bits have been very good, and seem to be very accurately ground. I have drilled loads of holes with the metal working ones in both steel and aluminium, and haven't had to sharpen one yet.

 

[hairy]

I' didn't know the dead bit on the point of a drill is called the web.
Does the size of this vary much, so a smaller web allows a bigger step in drill sizes as you go up to the required size?

 

[AES]

I' didn't know the dead bit on the point of a drill is called the web.
Does the size of this vary much, so a smaller web allows a bigger step in drill sizes as you go up to the required size?

I'm not sure if there's a proper "formula" or not (there probably is), but YES, the size of the web is smaller on a "small" drill than it is on a "big" drill. Obvious really! It's in the grinding angles. Purely from "idly looking" I'd say web size is directly proportional to drill dia - about 10 or 15% at a guess. But I'm sure someone better informed than me will be along in a minute to confirm - or to ridicule!

 

[AES]

I agree that you can't beat really good quality ones, especially in very small sizes where cheap ones are often not properly formed, however for day to day use I have been very surprised by the quality of the sets from Aldi, the ones they do in a folding plastic case. Both wood and metal bits have been very good, and seem to be very accurately ground. I have drilled loads of holes with the metal working ones in both steel and aluminium, and haven't had to sharpen one yet.

And other "non-professional" suppliers too, such as my local DIY Emporium - but only sometimes! Again, I'm back to "have a look, if it looks OK, try it" - and it's pot luck if they're any good or not. But Yes, for me, the 2 Aldi sets I've tried are at least "OK".

 

[hawkeyefxr]

As have been said basically, safety. The bit about clothes is especially important nit just about grabbing the work piece but loose clothing. Swarf can grab ahold of cloths and pull you in.You will not stop that drill!

 

[hairy]

I was more wondering if different brands, or drills aimed at different materials, would have bigger or smaller webs? So a posher drill has a smaller web for any given size?

 

[AES]

Again no doubt somebody will correct me if necessary, but AFAIK hairy, "general" twist drills (e.g. not for glass drilling, masonry drilling, or wood drilling to think of 3 examples off the cuff) are indeed just that - general purpose/general materials drills. As said, that's only my own take, no doubt someone knows better.

And BTW, "standard length", "standard material", "standard dia/steps" twist drills are often called "jobbers twist drills". I presume/guess the name is a clue

 

[Fergie 307]

I was more wondering if different brands, or drills aimed at different materials, would have bigger or smaller webs? So a posher drill has a smaller web for any given size?

Never really thought about this issue but it seems to me that this will be determined entirely by the angle and back relief used to grind the tip. The issue I have found with the cheap micro drills you can buy is that if you look at the tip they are often a right mess. If you get a dormer drill in say 0.5mm and look at it under magnification it is as perfectly formed as one say 10mm. I would love to know how they grind ones that small. But you pay for it, the last time I bought some they were about £5 each. I use these small sizes in watchmaking. I also have a set of Mikuni carburettor jet drills, again tiny but perfectly formed, and also an eye watering price when I bought them many years ago. If you buy some really cheap and nasty jobber type bits you can sometimes find that the tips aren't even on centre, which makes them essentially useless. Overall I would say if you buy something like a dormer then you know it's going to be good. If you buy cheap then you take pot luck, some will surprise you and be very good, some will be dreadful. But the difference in price is so great you can certainly see why people are tempted by the cheap ones.

 

[TRITON]

"I want to drill some holes in a bit of metal".

Now we're 3 pages in to a bun fight

 

[AES]

"I want to drill some holes in a bit of metal".

Now we're 3 pages in to a bun fight

I can't see any sign of a bun fight. What have I missed, please do tell.

 

[TRITON]

I can't see any sign of a bun fight. What have I missed, please do tell.

You've missed nothing, just seemed that way with the thread going on so long. I must be too used to how long threads go

 

[jonn]

Never really thought about this issue but it seems to me that this will be determined entirely by the angle and back relief used to grind the tip. The issue I have found with the cheap micro drills you can buy is that if you look at the tip they are often a right mess. If you get a dormer drill in say 0.5mm and look at it under magnification it is as perfectly formed as one say 10mm. I would love to know how they grind ones that small. But you pay for it, the last time I bought some they were about £5 each. I use these small sizes in watchmaking. I also have a set of Mikuni carburettor jet drills, again tiny but perfectly formed, and also an eye watering price when I bought them many years ago. If you buy some really cheap and nasty jobber type bits you can sometimes find that the tips aren't even on centre, which makes them essentially useless. Overall I would say if you buy something like a dormer then you know it's going to be good. If you buy cheap then you take pot luck, some will surprise you and be very good, some will be dreadful. But the difference in price is so great you can certainly see why people are tempted by the cheap ones.

If you want to find the quality of drill bits, get a Tormek DBS-22. With poor drill bits they just disappear while grinding, whereas with quality bits you get superb usability in both wood and metal. Also found some 12 to 25 mm Chinese bits with reduced shank which cut very well, also in steel.