Best drill bit.

[DuffyBB]

Trying to drill 6mm holes in I/H beams for a job at work. Its to secure thin metal sheets at the loading bays.

They had tried before but were struggling to get a drill to make more than a few holes. I went today and got these. Took it easy and kept spraying the bit, but they stopped cutting after 5-6 holes.

The steel must be about 15-20mm, not sure if beams are hardened somehow?

Next option is cobalt drills, are they going to be up to the job? Toolstation sell individual size Heller cobalt ones.

 

[PhillipM]

When you say you took it easy, do you mean you didn't put much pressure on it or you slowed the drill down?

 

[DuffyBB]

Steady firm pressure and kept the drill speed slow. It drilled the first holes no bother at all...then seemed to hit the proverbial wall.

 

[hareng]

Or maybe look at the carbide, not cheap but careful on breakout.

 

[garethp]

I've not used DeWalt metal drills before but a few years ago I bought some of their masonry drills and they were garbage, I use Heller masonry bits now and Dormer split point bits for metal (A002 I think)

 

[scott0031]

Look at using split point drills, they reduce the load a lot compared to a standard chisel edge. If you are drilling by hand keep as square as possible this helps a lot as drills are not designed to drill on an angle and causes excessive wear. A turned pilot bush is a very good thing to use and gets a hand drilled hole started off squarely, especially if you are doing a lot for them and if they are fairly deep which yours are. I am of course assuming you are hand drilling these by the way you describe the problems you have.

I would not buy these drill kits, some are ok i guess, but a lot or not, they are cheap imports. Get some decent own brand drills from J and L industrial or Cromwell tools or any reputable engineering supplier..... this does not mean machine mart or screwfix!

Again speed, if you are spinning the thing about 1500 rpm slow it right down to about 500 or so you will get to a point where it feels right.

If you are using a spray oil as was indicated, bin it. Yes yes i know everyone has used it for years and it worked for them blah blah........... get a washing up bottle and fill with soluble, friction is your enemy. Friction causes heat which you don't want. Whilst oil is brilliant at lubricating is useless at cooling, unless you can flood it, it's ineffective oil lubricates for a second then boils off, then its not working at all. soluble can be flooded easily, removes heat a hell of a lot better and flows down the hole far superior than any oil due to the viscosity. It will also allow for better chip evacuation. Don't get me wrong oil is brilliant if it can be used in the right application, but a spay of oil for drilling is not it! Try what i have suggested and you will see


Kind regards,


Scott

 

[gordon stephenson]

Getting the drill speed correct will prolong the bit life,You will be able to google for drill speeds for various sized drill bits, Also keep on a good pressure when drilling, drills like to cut and not just rub, and keep up with the lubrication.

 

[brightspark]

use rocol cutting compound or trefolex or templars i cut 20mm holes through half inch steel beams with hole saws using it no problem just buy good quality hss twist drills . nothing fancy presto sherwood guhring or dormer ad keep a good pressure on drill

 

[striker]

I have used the heller cobalt from toolstation. I was using 4mm high speed steel at first. Poor quality though. I have drilled over 800 holes in 16g shs steel in my spaceframe teardrop camper with the same heller cobalt bit thats a lot of rivets!!! With hss I was spendng more time sharpening than drilling. The same 4mm cobalt bit hasnt been near the grinder. Doesnt seem to bend either like the hss ones.
So the heller cobalts get the thumbs up from me. I bought four 4mm but am still on the original one!!!

Paul.

 

[Hitch]

Can you not just use tek screws?

If not, another vote for the dormer a002.

 

[DuffyBB]

Cheers for the replys.

I see toolstation have a Tectane cooling liquid, might try that a heller cobalt and take the speed down a bit more.

It is tek screws im using, they wont drill into the beam though will they?

 

[Welderpaul]

It is tek screws im using, they wont drill into the beam though will they?

If you get the right screws they will do. I've had some that drill through 20mm flanges. They have a very long drill bit end.

 

[Hitch]

Fine threaded ones, for heavy section should go in okay.

 

[armalites]

I've used the Dormer jobber coated on stainless without issue with some cutting fluid.

Great drills in the lathe or pillar drill but pricey.I never use them in a hand drill and as I don't want to break them

I have recently bought some Heller cobalts from Toolstation and they seem pretty good for the money.

 

[nwallace]

Does anybody rate wurth drill bits? I use them for drilling stainless flanges, one 9mm bit went through 9 holes per 10mm flange times 8 flanges. It was however knackered after that.

 

[DuffyBB]

Got cobalt drills, and they drilled 1 hole. Thats when i realised 6mm was too big a drill bit(had been drilling the first lot, and the guy i was working with said it was 6mm we were using...turns out it was 5.5).

So, decided to try and see if the screws would self drill...and they did