Drill Bits

[Guest oddsocks]

I find when i've drilled a couple of holes in the chassis that the drill bit is blunt or seems to take forever, What drill bits do you use when drilling into the chassis?

I've got steel bits-just in case you thought i was using wood bits!!

 

Thinking about buying a drill bit sharpener but cant seem to find one that fits 3.2mm bits.

J

[Redspec]

For s/s you really need to be using Cobalt drills, these will last much longer and go through s/s like a knife through butter.

 

A little cutting compound will also help the life of the drill bit

 

Like this stuff http://www.cromwell.co.uk/TRX7033500A

 

Steve

[Redspec]

Just realised you are building a Zero so you don't have a s/s chassis, Just the same Cobalt drills are great.

 

Steve

[harvs]

Hi

 

I've started using titainium coated bits which I found to last a little longer and are cheaper than cobalt (but not as good).

 

I've also found that if I put a lot of pressure on and use a low speed that the bits tend to last a bit longer too.

[fry61]

If you can; buy HSS drills by Dormer; 25+ years of selling these & they were one of the best. Superstores drills may be called High Speed Steel but they won't cut like Dormers. N.B. -- HSS does not mean run at max. revs. around 200-500rpm is fine dependant on diameter & as above moderate pressure to ensure drill is cutting all the time,or else you'll be workhardening the job, cutting fluid by Rocol if poss. DOn't know of a good drill sharpener for below 4mm; I sharpen these by eye; roughly O.K. gets a bit more work out of them.

[Shaft]

I fully agree with comment above regarding HSS drill bits. I'm on the same Dormer HSS 1/8th bit that i started with. (been sharpened though! )

Also fully agree with the comment about RPM, to fast and you'll just 'burn' the cutting edge away and not enough pressure will do the same.

Basically, a drill is a 'Cutting' tool, so make sure it's cutting, not just spinning around in the hole. Work hardening isn't a real biggy on mild steel, but venture onto St/St and it's a nightmare if it starts to happen on you.

 

Also try and avoid "Slamming" the drill point into the opposite side of the chassis rail being drilled as you break through.

 

Titanium Nitride coated drills are very good, yes............ but the 1st time you sharpen it you'll lose the coating, so it sort of defeats the object for the DIY user who isn't going to just throw it away when it's blunt.

 

Sharpen your drills by hand on a bench grinder, it's a piece of p##s to do, with practice........... so practice.

 

HTH,

 

Nick.

[speedtripledan]

I use black and decker piranha bullet bits Focus sell them i got a set 1mm to 10mm for approx £20 i have drilled over 100holes with the 3mm in stainless making a hop screen for my brewing equipment and it is still going all of them cut through my stainless 2b chassis like its mild steel which it isn't..

 

flea bay item no.130345119550

[Guest robinj66]

This is a reasonably priced , decent set of cobalt drill bits. I've got a set and they're excellent

 

Cobalt Drill Bits

[Guest The Modfather]

Gonna get me a set of them then. Fed up with crap bits. I always found drilling slowly and with moderate pressure is best. Titanium bits are just as bad as HSS bits, but dearer. I bought a set of drill bits that had titanium and "normal" bits, and actually found the normal bits to drill much better.

Never tried the cobalts, but will defo get them for that price.

[speedtripledan]

This is a reasonably priced , decent set of cobalt drill bits. I've got a set and they're excellent

 

Cobalt Drill Bits

Just ordered a set of these to compare with piranha bullets i have. If they are better then they will be bl*+dy good!

[fry61]

Cobalt is indeed able to retain its sharpness for longer; but they are much more brittle & when used in hand-held drills are more likely to break,they will not put up with being "flexed" when drilling or at break-through.

[Knock-on]

Had a few cobaltt 3.2 and about 6 SS 3.2 to do my SS 2b.

 

Got mine from Wurth and they were great. Couldn't be bothered to sharpen (will get round to it) but the price they were, it was easier to just change.

 

Think my 3.2's cost me about a tenner in total and still have spares.

 

Answer is to just get good'uns to begin with.

[thespannerman]

Get my drill bits from ScrewFix, they call them jobber bits? Buy them in packs of ten of whatever size you want for peanuts.

[Guest Alan_builder]

If you can; buy HSS drills by Dormer; 25+ years of selling these & they were one of the best. Superstores drills may be called High Speed Steel but they won't cut like Dormers. N.B. -- HSS does not mean run at max. revs. around 200-500rpm is fine dependant on diameter & as above moderate pressure to ensure drill is cutting all the time,or else you'll be workhardening the job, cutting fluid by Rocol if poss. DOn't know of a good drill sharpener for below 4mm; I sharpen these by eye; roughly O.K. gets a bit more work out of them.

 

This post and the post below by SHAFT hit the spot.

 

The Rocol smells like cats piss but it is superb, mains electric drills are often too fast for drilling with, battry one are often better. Sharpening drills is simple on a bench grinder, look at the tip and stroke from the cutting edge towards the next flute, the angle of the drill should be the same as the drill point, lift the contact point on the drill as you rotate it about 120 degrees, this gives the cut relief angle. The cut relief angle and the point angle change for different materials, so when you buy a new drill the first thing an expert dose is sharpen it for the job in hand. Oh yes on small drills you can flat cut when sharpening and on big ones back cut the flute.

 

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