Making a multiprofile Drill bit

Somehow, chocolate teapot springs to mind...

Using one bit rather than 3 can save a fair amount of time, especially when I'll be drilling 46x 4" deep holes. And unfortunately if I do it without a multiprofile bit I'll have to change the bit no lses than 4 times for every single hole. Thats 184 drillings and 184 bit changes.

With a multiprofile bit it'll be 46 drillings and zero bit changes. And of course there will be future projects for it with further time savings. Still think its not worth spending 30 minutes on?

I had a go with the rod, and it was working but taking much too long. At the rate I could whittle the rod down at it would have taken hours. I've worked out another way to do it much quicker now. Buy a ready made bit of the middle width, grind the thin section down, which is a small fraction of the work, and add a small piece of drilled 10mm to the top. Hope to try that next week.

Regards, NT

I've got a tool and cutter grinder, the sort of machine that is designed to make special drills, and if I wanted a drill of the type you describe, I would get Drill Services at Horley to make one for me.

Colin Bignell

SHSHSHSHSHS!!

Better yet SDSDSDSDSDSDS :-)

Yeah, I could do. Another 2x 17 = £35, and it still means drilling 4x as many holes though. I'm going to have another go at the multiprofile bit :)

Regards, NT

You can't make it out of threaded rod, it's too soft, and can't be hardened. You need to learn about steels, what can and can't be hardened, and tempering/quenching.

Quite honestly, you will almost certainly not be able to do this in a manner that will last a fraction of the 184 holes, in less time than it would take you to drill them by hand.

However, if you gave some details of the hole profile, maybe suggestions could be made.

OK cheers. I knew it wouldnt last well but didnt think it would be that bad - and it can be resharpened easily. I wasnt going to bother with hardening, quicker to regrind the end, as long as it doesnt all buckle.

I'm getting a standard long drill bit that I plan to grind down: I would think that would work ok.

Basically I'm looking at some woodwork where if I drill all hole sizes in one shot its going to avoid having to keep dismantling and remantling things.

The bit will be as follows: length: 4" plus enough to go into drill chuck bottom end: 3.5-4mm middle: 5.5-6mm top: 9-10mm

Planning to make this from a long 6mm bit, screwing on a small lump of soft steel for the 10mm bit. I put this hybrid in one drill, and use the other for screwing. If this works it'll save me ages on this job alone.

Regards, NT

It's probably going to be easier to modify a 10mm drill bit. What tools do you have?

Couldn't you use a different screw that matches an off the shelf drill bit?

One way could be to grind a bigger drill bit down with an angle grinder while it's spinning in a drill. Might be worth doing a trial run with a cheaper bit first.

cheers, Pete.

Yup, thats exactly what I intend to do now. The first go with rod just took too much grinding.

Regards, NT

Going by experience with grinding the M8 rod, I think grinding a 10mm would take much too long. It went a lot slower than I had expected. Hence the next move tomorrow will be to try with a 6mm bit.

I've got no lathe, but can use a drill and angle grinder as makeshift lathe. Have all the usual property maintenance tools and more, including a 3.5mm tap: I plan to centre drill the small piece of 10mm rod, and drill a side fixing hole and tap it to give fixing. The 10mm will only be countersinking so it wont see much work compared to the other sections. I'll angle the sides with the grinder and cut notches in it so it cuts.

I couldnt think of any better ideas :) Am open to ideas though! Thanks for your input.

Regards, NT

Just regrind a spade bit with a bench grinder. This can be done adequately by eye. Keep the material cool by dipping frequently in water to stop it softening and make sure that the edge cutting angles are not too steep.

Regards Capitol

Recall turning something up from a bit of 3/8" stock with a drill as a lathe. Quite a complex little hinge pin, IIRC, but it didn't take long at all using files as cutting tools... Don't know if you might find they cut faster than an abrasive stone ??? Would use my best files on a drill bit mind....

Hi,

Might be worth grinding the bit with the flat side of the disc instead of the edge, making it easier to grind a constant amount off.

If you have a stand for the drill or can clamp it to something, even better.

cheers, Pete.

Doing it with the drill arranged vertically, so that you can take a cup of water and dip the whole bit in it every few seconds of grinding is a good idea.

I need a 4.5" bit 3.5mm and 6mm wide. I've never seen a 6mm spade bit with a shaft thin enough to be ground down to 3.5mm, nor one with a flat section at least 2.5" long. Thems is the problems.

Regards, NT