Drill Bits

[Richard Glenn]

Okay so I'm doing brilliantly (my opinion) on getting my first knife done. But I've gotten to the point of drilling the hole for the pains and I've reached an issue. I've snapped two drill bits and I still don't have a hole in the metal that'll fit the pin I have...
Firstly, I drilled a hole to small because the bits weren't in the right places in the box, when I tried to enlargen the hole I snapped two bits. I did my best to make sure they were straight in the hole and I tried to go slowly and yet still they snapped.

Mostly I haven't drilled in metal before as all my dad every did was wood working, this is 154CM stainless steel that has NOT been hardened yet...

So first, what am I doing wrong? And second, what would be a good set of bits for me to buy in the hopes of needing them for a second knife?

Thanks
-Richard

[Ray Rogers]

What are you using to drill your holes? If you're using a hand drill that makes it easy to snap a drill bit. You need a drill press and it is best to have you knife blade held in a vise or clamped to the table.

The drill itself needs to do the cutting - pushing too hard will snap a brittle drill bit. This is especially true when enlarging a hole. One trick I use for enlarging holes is to make sure you drill bit is perfectly aligned with the hole by first mounting a piece of plain drill rod the same size as the hole you already have. If you are careful, you can use a drill bit by chucking it in the drill upside down so only the smooth shaft is exposed. Make sure it spins smooth and true, then position your hole so that the spinning drill will enter the hole without being deflected in any direction. Clamp the blade in that position and change to the larger drill bit.

Another possible problem could be the drills you are using. Plain HSS drills are usually OK but only if they are very high quality and most these days are not. Cobalt drills, rather than HSS, will last much longer and they cost only a little more. I order mine from MSC in screw machine length. Enco and McMaster-Carr are also good sources for cobalt drills ...

[Richard Glenn]

Any chance a Lowes or Home Depot would sell a decent set of the cobalt drills?

I use a variable speed drill press and I try to use a clamp to keep the knife blank in place, perhaps I should try a different clamp and see if I can get something easier to work with for making sure the blade is in the right place and stays there.

I honestly don't know what they are.. It's my dads drill bit sets and I just know that he prefers I use the crap ones first and if they don't work then I can use the better ones until it does work lol. If I can find the money I'll try to get my own set.

[Ray Rogers]

Not much chance you'll find cobalt drills at the hardware store. Even so, the largest part of your problem is probably getting the hole in the handle properly aligned with the drill and then drilling with the correct speed and pressure. Try the technique I explained for the alignment. A cross slide vise helps a lot with this process if you can get one for your press.

Enlarging a hole is much easier if the original hole is much smaller than the new hole. If the new hole is just a little bit more than the original hole it is much easier for the drill to bind. In this case, you might want to just use a Dremel and grind the hole out a little larger ...

[Richard Glenn]

Dremel... Why didn't I think of that? I'll still have to look into the cross slide vise and drill bits but I hadn't thought to use the dremel to finish up that hole.. Thanks.

[Richard Glenn]

Well, instead of using the dremel as I found that I didn't have a bit for that... I just dropped by home depot and bought the only cobalt set they had and came home to try it out on the blank. The 1/8 was the one I needed. It wouldn't enlarge the previous hole that tiny bit so I just started a new hole. It seemed really slow so I figured drilling a pilot hole would help and so I switched it out and using one of the smallest in the set and it wouldn't even go all the way through the steel, and trying the 1/8 it wouldn't even get as far as the small one did in the same hole..
But when I switched to the 1/4 it cut through it like nothing and continued to do the second hole needed without any problem at all...

And since I should have two more blanks to drill holes in that I want them to be 1/8 I figured I'd ask if there was anything I could do that would help the bit work?

[Pelallito]

Look in the yellow pages for a machine shop tool supply in your area and buy better bits from them or, as Ray said, order from McMaster or Enco.
You might also consider getting a center drill to start your holes.
Fred

[NJStricker]

Glenn,

The only local hardware store cobalt bits I've found to work, at least on carbon steels, are from DeWalt. All the rest seem to have just a plating that scrapes off. For drilling metal you'll want the slowest speed possible on your drill press, unlike for wood. If you are using a lower end drill press the slowest speed might not be slow enough.

Also, try using a cutting oil used for machine work. It will help keep the metal a little cooler and reduce the chance of binding. Like someone else mentioned, don't put a lot of downward pressure on your bit, let it do the cutting. Especially on those smaller bits, if you are putting so much pressure that the bit is flexing then the first little bind will make it snap.

Good luck!

[Ray Rogers]

You keep saying blade 'blank' - is this a pre-made kit blade that you bought somewhere? If so, the steel is already hardened and no ordinary drill is going to go through it easily (if at all). For that, you would need carbide drills and the straight flute carbide drills are the best. If you decide you need those then you'll have to order them from MSC or McMaster unless maybe you have a really good machine tool supplier in your town. Someone may offer you carbide spade drills, they are more common, but they won't drill deeper than their diameter so if you want a 1/8" hole you can only drill through a 1/8" blade.

If this isn't a pre-made blade blank then what kind of steel is it and where did you get it? Even with cheap drills you should be having this much trouble unless that steel isn't fully annealed ....

[Richard Glenn]

It's one I've made from a piece of steel, I bought it from jantz knife supply and used a hacksaw to cut this small bit off before using an angle grinder and hand files to get it to the point that I could drill the holes for pins and then send it off to be heat treated.

It's 154cm. It should be annealed enough at least as even though the smaller bits wouldn't go through the 1/4 cut through it without any trouble what-so-ever.
Could just be bad bits, I mean it was just a little 30$ RIGID set, supposedly cryogenically treated cobalt bits.

[Ray Rogers]

Ya, I agree, sounds like the drills weren't all they could be ....

[WBE]

Cobalt drill bits are everywhere these days. I don't know of a hardware store that does not have them, including Lowes, and Home Depot. Dewalts are very good, but so are those from ACE hardware. I've never seen a cobalt coated drill bit. Cobalt bits are made of cobalt steel. Maybe you're thinking of the titanium coated bits. They are not much better than HS bits.

[Brad Johnson]

Glenn,
You should check your speed, if using HSS on 154 I like to use a slower speed. If I am using cobalt I use a higher speed and coolant.

[WBE]

I use regular kinda low speed, and never any lube. It makes a mess. Years back, I experimented with cobalt bits, and they seemed to cut better, and last longer with no lube. At the very least, lubed drilling did not do any better or make the bits last any longer.

[NJStricker]

Maybe it was the titanium I was thinking of, Wick. As for the cutting fluid, my thought was that the lubrication might cut down on the binding. . .