Drill bit questions

G

guaps

Joined
Jun 2, 2009
Messages
9
Let me start by saying I know next to nothing about metal working. So no answer is too basic for me.

The handle to my large kitchen knife recently broke (the wood scales). So I thought I would make a new handle out of some maple scraps I have laying around with some simple brass pins. However the holes in the knife tang are very small. So I want to drill them out to a little larger diameter. I tried putting the knife on my drill press and quickly destroyed an old bit. (I used an old bit knowing this could happen). So I need to buy a metal specific drill bit, but I have no idea where to start. Is a step bit the right tool? Or do i need some other specialty bit to get through this hardened steel?

What's the best technique to do this? I can slow my drill press down and use oil, but other than that, are there any other tips?

Thanks!
Jeff
 
It is dangerous to drill a sharpened blade because of the consequences of a "helicopter". Chasing an existing hole often leads to the dreaded spin and it's easy to loose parts of your hand, so the work needs to be clamped solid.

A straight flute carbide drill would be the "right" tool for cutting hard steel, but since you're opening an existing hole you might use a reamer. I like a right hand cut, left hand spiral, reamer for this because they don't tend to bind.

A standard HSS steel drill won't do well in hard steel.

This is dangerous with the wrong setup, but simple with the right setup. If you were local I'd invite you to bring it by the shop and I'd open it up for you with an old scrap carbide tool.
 
Thank you for the concern - I need warnings like this. When I tried this last night, I set the blade so that if it helicoptered, it would be the back side of the knife spinning towards me. But the point could still get me, so I'll take your advice and clamp it down good next time. And thanks for the offer to help do it! Too bad I'm several thousand miles away...

I looked up the straight flute carbide bit and reamers. After shipping, it might be cheaper for me to stop by a welding shop nearby and see if they will open it up for me.

Thanks for the help!
 
I can recommend Bosch MultiConstruction drill bits for opening up holes. Carbide Reamers are expensive and take only a little off. Straight flute bits are also expensive and easy for a beginner to break...don't ask how I know. :( The Bosch bits have carbide tips, ground with a sharp scraper form, so they are not so prone to grabbing at the point of break through.

http://www.boschtools.com/Products/Tools/Pages/BoschProductCategory.aspx?catid=1143
 
C_Claycomb said:
I can recommend Bosch MultiConstruction drill bits for opening up holes. Carbide Reamers are expensive and take only a little off. Straight flute bits are also expensive and easy for a beginner to break...don't ask how I know. :( The Bosch bits have carbide tips, ground with a sharp scraper form, so they are not so prone to grabbing at the point of break through.

http://www.boschtools.com/Products/Tools/Pages/BoschProductCategory.aspx?catid=1143
Click to expand...

Perfect! And they are only a couple bucks at the hardware store. Good place to start.
 
Where are you located? I would be willing to help as well If your near me. If you take it on your self make sure to cover the blade edge very well before beginning the work.
 
clamping is better than nothing for sure. a good drill press vise is a solid base. use a stud in a t nut as a block and orient the back of the blade against this vertical block. it will not helicopter with this setup.
 
A drill press vise clamp or hold down can be invaluable, and better than a drill press vise for thin and/or irregular shaped profiles. I have something like this.
http://t.harborfreight.com/9-inch-drill-press-locking-clamp-36221.html

You can put spacers behind the stuff you are drilling to get clearance if there is a bolster, and if you use steel, or aluminium, but steel particularly, the drill gets to bite into the backing spacer as you break through, rather than jumping into open air. Gives better control, and doesn't damage the drill table :)
 
Last edited:
Thanks everyone. Finally did it successfully, and with no trips to the emergency room. I used the bit Claycomb recommended. It was cheap and got the job done. It might only be good for drilling balsa wood at this point, but I'm not complaining.

I wrapped the blade in a small towel, taped it to the blade, clamped it to the table (with a piece of wood under to save my table), then put a C clamp right behind the blade so if it did helicopter, the C clamp would act as a backstop. Everything went really smooth.

Thanks again for all your help. I'll post a pick of the finished handle (and all ten of my safe fingers) when I am done. The handle might be ugly as this is my first attempt.
 
You must log in or register to reply here.
Back
Top