Why Does It Always Have To Be Like This?

[pw8757]

The title is not a cry of woe because of unrequited love, but more a cry for help over something you would think might be relatively simple.

Drill Bits

I'm getting to the stage that I think it's me. I have nice, clean drill bits for drilling metal on my vehicle. I don't buy cheap ones, but generally go up the range. However, I find that they are absolutely perfect until I use them for..............drilling metal! At that stage they perform as if they want to be in one of those photos circulated by @youhadonejob on Twitter.

Today, as part of cleaning up my rear axle to replace it in the Disco, I came across two sheared bolts that had decided to give up the ghost when I was removing it.

I got out my (brand-new) drill bits and set to, intending to drill them out.

The job has taken (in all) about six hours and I am now the proud owner of two drill bit sets comprising the very smallest and the largest, with the remainder reduced to being either broken or burnt out.

The bearing on my trusty Makita drill sounds rough and as the afternoon wore on I found myself resorting to more and more bizarre methods of getting rid of the pesky sheared off bits of metal. The only good news is that I have achieved the objective and I can replace the bolts when I refit the axle.

However, the issue remains. Somewhere in the world, somebody must make decent drill bits, which they then resolve not to sell to Halfords, B&Q, Machine Mart or at motor shows.

Can anyone tell me where I can get drill bits which are good at doing what they are meant to do?

[miketomcat]

It's more likely that your using to higher speed and no cutting paste. My dad always said the harder it is the slower you go. So drill Ali reasonably fast say 900rpm steel around 500rpm and stainless about 350rpm all figures are very rough as I generally go with what feels right.

Mike

[pw8757]

The expression "High Speed Steel" being a misnomer then?

(starts to feel a little stupid)

[CwazyWabbit]

Also the larger the bit size the slower the speed or you will burn the wings of the drill.

[studmuffin]

All good advice.

Every so often Aldi or Lidl sell an electric drill bit sharpener which from memory handles up to M10 bits.

If you cannot sharpen free hand on a grinding wheel these are pretty good, and give you a much extended drill life.

Cheers

Barry

[miketomcat]

The expression "High Speed Steel" being a misnomer then?

(starts to feel a little stupid)

Don't feel silly I've had to explain this to skilled guys in the boat industry. If you have never been told you don't know.

Mike

[pw8757]

Thanks guys!

(.......and I'm sixty this month - who says you're never too old to learn......)

So to sum up - slow, gentle, lubricated?

[miketomcat]

So to sum up - slow, gentle, lubricated?

Ooo er misses....

[CwazyWabbit]

You don't have to be gentle, but slow and lubed yes

[discomikey]

drilling slower drills faster with a general hand drill like my makita 18v Li ion type thingy i wouldnt really consider drilling a hole in speed 2, always drop it to speed 1. our pillar drill isnt slow enough for anything above 8mm if you ask me too! i avoid cutting pastes or lubricants, but rarely have a problem with drill bits blunting off, but the best thing you can learn if you "share" drill bits with a moron (sorry dad) is how to sharpen them properly!

i tend to always tickle a brand new drill bit before first use too. but thats just me.

[simonr]

Most domestic hand drills are way too fast, even on their lowest speed for anything above about 6mm. I have a DeWalt battery drill which goes down to 300rpm - but even that is too fast really for much above 12mm.

I have a plaster mixing drill (cost all of £20 from Screwfix) which goes down to 30rpm - which is OK up to about 30mm (I have some large 'Blacksmiths drills' that fit in a 13mm chuck - before you ask).

What it's fantastic for is hole saws which people always run way too fast. With it I can cut holes up to about 250mm with the hole saw only getting warm. Mostly I use it for tube notching with a 1 3/4" hole saw - and it's paid for itself in longer lasting hole saws.

Don't be afraid to push really hard - the more the better with a hand drill.

Si

[Tanuki]

If you're drilling fast - or slow - you need to be able to apply serious amounts of pressure - watch what production-line drills/mills do even when going fast into cast-iron.

Without adequate pressure the bit just spins uselessly against the workpiece without ever biting - and converts RPM into heat not cutting-effort - so you end upp with a heat-detempered cutting tool which is then just so much scrap.

If drilling generic non-heat-treated non-alloy steel you should expect to produce good lengths of spiral swarf. If you don't you're not applying enough pressure, you have a blunt tool, or both. Cast-iron,heat-treated and alloy steels will 'chitter' on the tool and produce smaller fragments.