After some decent drill bits

[acealfa]

I'm in the process of drilling some bolts out but going through drill bits like butter.

Can anyone recommend a place for good quality ones?

The last ones I brought were expensive but still really bad.

Cheers

[E-bmw]

To be honest, the best are Cobalt, and like anything else, pay for what you know.

These should be pretty good.

http://www.ebay.co.uk/itm/Draper-19-piece-Cobalt-C...

One other thing.

Not trying to be all sucky eggy, but ANY lateral load on them WILL snap them.

Also fast isn't necessarily good.

You need to be drilling at a speed where the tip is cutting properly.

Depending on the material this may look like a "spring" of metal or a series of "chippings" depending on the material you are drilling.

SLOWER is better generally.

Also cutting compound helps keep the bit clear/sharp and should be re-applied when it melts & evaporates off.

Edited by E-bmw on Sunday 7th February 14:42

[acealfa]

Thanks for the advice. I think that may be where I'm going wrong.

I'm looking to drill a 10mm hole, is it best to start small with a 3mm and build up, say to a 6mm then 8mm and 10mm or just go straight in with a 10mm?

[Big Al.]

Use pilots wherever you can, and increase to your 10mm, just remember the harder the material you are drilling the slower the speed, fast speeds for small drills low speeds for large drills.
Keep an even pressure and don't try to rush it, you could also use a bit of lubricant, i.e Rocol cutting compound (for steel) or even some light oil, not WD 40 though.

[buzzer]

I buy all my drills from this Ebay seller... I bought some TCT bits recently... They will drill VERY hard material!

http://www.ebay.co.uk/itm/TCT-DRILL-BITS-TUNGSTEN-...


I needed to drill some stainless recently... 50 holes. I managed three with a new cobalt drill and gace up. I bought a TCT one and did the remainder with one drill. Thats the difference!

Edited by buzzer on Monday 8th February 08:58

[kambites]

In my experience even cheap HSS (and wood for that matter) drill bits will last quite a long time if you use them properly (ie keep them cool, spin them slowly and apply no transverse loads); more expensive ones give you the ability to abuse them without ruining them which in practice lets you cut much faster.

WD40 is better than nothing, but hardly ideal as a cutting oil.

Edited by kambites on Monday 8th February 19:34

[acealfa]

Thanks all for the advice. I purchased some WD40 lithium grease and had great success slow drilling. My instinct has always been to drill fast but now I know better.

[Escy]

All drill bits eventually go blunt with use, I sharpen mine on a bench grinder.

[blueST]

Escy said:

All drill bits eventually go blunt with use, I sharpen mine on a bench grinder.

Well worth learning, I did recently and they often cut better than new.

[kambites]

Depends how much you use drill bits and whether you actually have a bench grinder, I suppose. A bench grinder may not be an expensive tool but it's several orders of magnitude more expensive than a drill-bit; plus some people don't have a convenient place to mount one.

[E-bmw]

Even a quick "touch-up" with an oil-stone can breathe fresh life back into a drill bit that has lost its edge.

Obviously it won't re-sharpen a cream-crackered one.

[buzzer]

I have always struggled to sharpen drills... the smaler they are, the harder it seems to be.

Just lately, I have found that a 20mm grinding wheel in my Dremel is ideal! great for just touching up the edges....

[Escy]

kambites said:

Depends how much you use drill bits and whether you actually have a bench grinder, I suppose. A bench grinder may not be an expensive tool but it's several orders of magnitude more expensive than a drill-bit; plus some people don't have a convenient place to mount one.

I use an angle grinder