View Full Version : drilling bi-metal bandsaw blades

02-05-2010, 07:06 PM
I am making some finger tooth rests for my TC grinder....I am using old band saw blades for the material..

What an evil material it is.... Hard as hell yet springy but it cannot seem to be annealed so it can be drilled..

What metal is it made out of and how can it be annealed so I can drill it???

02-05-2010, 07:09 PM
Use a die grinder with a cone point stone or a carbide end mill.


02-05-2010, 07:13 PM
It's air hardening. To anneal it must cool very slowly. Put them in a wood fire and let it go out normally or heat red and stick them immediately in a bucket of vermiculite insulation. Or, clamp between two pieces of heavy strap iron and heat the lot to red heat and let cool.

02-05-2010, 07:29 PM
No need to go through so much trouble!! ...Do it by electrolisis. Paint the blade with nail polish or any other insulating paint. scrap the paint where you want the holes, submerge it in salty water, get a 12V battery charger, conect positive to the blade, negative to a piece of stainless steel(coffee spoon) also submerged and swith power on. It will take about half hour depending on the blade thickness.

..can't claim this one for myself,I'm afraid.

02-05-2010, 07:37 PM
Don't anneal it, that destroys the springy quality that you were using it for in the first place. Get a carbide spade drill. They come in most sizes up to 1/2 inch. A carbide spade drill will sink right through hardened tool steel like a twist drill goes through mild steel. Where most people go wrong is to use cutting oil.
DO NOT use any oil, in fact make sure it is clean and dry (solvent and air hose).
I have drilled out many broken taps with those in the mill. They must be held rigid in a collet for doing taps, but you can use a drill press for a bandsaw blade.
Drilling a tap will sometimes bust up the drill, but it gets the tap out. Use a moderate spindle speed in the 500 to 1000 rpm range, even slower will work.

02-05-2010, 07:43 PM
After it is annealed all you need to do is tap it a few times along the length with a hammer. Instant springy.

02-05-2010, 08:34 PM
The easy way to drill it is with a carbide ball end mill of correct size . I use 3/16 and 1/4 ball end mills for drilling hard thin material works like a champ.

02-05-2010, 09:37 PM
Would Lautard's trick of running the head of a nail on it to in a drill press anneal it like he suggests for drilling and tapping a firearm for scope mounting? Or is that just stupid.

02-06-2010, 12:04 AM
Two ways I do it-

#1 method,hand held sheetmetal punch and
#2 sharpened up masonary drill.

02-06-2010, 09:14 AM
Punch it with a hand held sheet metal punch. Good excuse to buy one. You should be able to punch through .035 inch thick fairly easily. Thicker might be a problem for hand tools.

02-06-2010, 10:51 AM
I read somewhere to take a drill bit, chuck it upside down, while spinning push it down to the spot you want to drill and get it red hot and let it cool. That will anneal just that spot.


02-07-2010, 04:57 PM
I like the idea of being able to anneal just a spot, but it's possible that the surrounding material will cool the spot too quickly and it won't be soft enough to punch anyway. Too bad you couldn't combine the two functions- use something like a stellite shaft, spin it to heat the area, then immediately punch it through.

Not good for the drill press to crank down on the feed handle that much, but maybe on a mill/drill you could insert a pounding rod through the spindle, and have the stellite shaft free to move up and down a bit while still being driven by the spindle.

Probably a lot easier to just use a carbide drill bit.

02-07-2010, 05:14 PM
A solid carbide spade drill will cut right through it without heating it hardly at all.
I'm talking about about a small diam. piece of carbide with 2 tapered flats and a drill point, not a shank that a carbide end screws on to.

02-08-2010, 06:00 AM

Never mind the band-saw blades - PITA - as you've found out.

Use the ends of a hack-saw blade for the fingers/guides.

I know you have the CDF to sort it out.

Here are some pics of "fudged" set-ups for T&C grinding of end-mills etc. They were "posed" to show that an air-quill is not necessary and that a "Spindexer" and a bit of simple improvisation and lateral thinking can work wonders.
















Set up for cutting simple and compound angles for HSS etc.