Thread: Drill bits for knife making

Good evening,
just a question to all the knife makers here..
What kind of brand / maker drill bits are you using for cutting/ drilling through old saw blades? unknown origin and steel composition.
I tried several bits,- Bosch, HSS, and Carbon bits bought from Mitre10 on the drill press using cutting fluid.
The bits where in size from 4mm-6mm.
Most bits cut alright two or three holes, one burned up, probably the speed was too high? the other ones just stopped cutting.
Neighbor gave me a masonry drill of all things and that one cut a couple of holes through the steel the other ones didn't even put a scratch on the surface..
Any advise would be much appreciated

Annealing before drilling would greatly help your cause.
Otherwise some cobalt drills ,low speeds and high feed pressure with cutting oil.

good HSS drills initially then try carbide.
Sharp and if you think its going to be a tough steel cut your revs down and once you start cutting keep a good weight on the feed. Don't let it rub and keep the coolant or more likely in your case some decent cutting fluid up to it.
Rocol, RTD and if you know a plumber with the ridged pipe threading machines see if he cab furgle you a cup of the fluid they use in that. Its pretty good too. Or the same with the stuff they make the coolant from for turning. It will work neat too (without water) but is water soluble.
As an example for turning and this also relates to drill speed as its the speed of the cutting edge, a 10mm drill through mild steel should be doing 1000rpm.
20mm =500rpm
5mm=2000rpm . get my drift? Carbide can be 3x that
This is for solidly held steel and good tooling. Your gearing etc might be off so you pick the closest low one.
high tensile steel/tough or stainless steels could be half that. If in doubt go slow but keep the feed and fluid up as suggested before.
Id try really slow maybe 2-300 rpm and follow the rules above,

Assuming that you are only drilling the handle/tang for pins, and you are trying to keep the original saw blade heat treat, your cheapest and easiest solution is to spot "temper" where you are going to be drilling (ie take the harness out).

Key with the spot tempering is to NOT heat up the section of the blade that you want to remain hard, and to heat the spot temper location as localised and as quick as possible with as little heat as possible. Best way to do this is to immerse the cutting section of the knife blade into a coffee tin of saturated wet sand which will act as a heat sink to protect the blade heat treat, and it will hold the knife in a vertical position while you spot temper. Then use a oxy/acet set with a small cutting tip or a largish welding tip to heat the drilling locations. Normal annealing temps would be around the 800 deg C, but you are not really aiming to anneal (refine grain structure etc), you are just trying to kill the high hardness heat treat, so you could probably get away with 500 deg. Heat it quick and localised, then take the torch away and let it cool in still air while the knife sits in the wet sand.

Then follow all the drilling advice above for maximum effect.

How are you cutting your templates? The couple of s as blade knives I've seen wouldn't hold an edge for shit as they had tempered during profile cutting with a grinder.

1075 or 1084 is cheap and easy to heat treat

Thank you all for good advise!
I will try spot temper and then HSS drill first then Cobalt, see how that goes.
Yes I used a grinder, so it is probably buggered..
Try to get 1075 or 1084 steel and do heat treatment.
Or maybe use a chisel to cut out template and keep the temps down?
Picture added of first knife made from old saw blade, not sharpened yet.



Where do you fellow knife makers source your 1075, 1080 steel?
Cheers

why cant you do a rudimentary heat treat after profile cutting?

sounds doable, will do some research on home built furnaces

Lovely color and grain in the handle...what is it?

Not sure what kind of wood it is.
I used my wife's old wooden bowl she kept walnuts in..
Now she wants the knife..

I had the job of replacing a number of cutting blades on the river weed cutters down here. A couple of hundred holes through each of the spring steel blades (did 4 with 2 blades each). I used masonry bits that I first sharpened. The key was to avoid heating which caused the weld to melt releasing the tungsten tip. Use a bit of cutting fluid, press down a couple of seconds, lift tip a couple of seconds, repeat over till through being careful as you break through. Managed the last two on one drill bit.

Then came the job of hammering all the rivets.

Originally Posted by csmiffy

why cant you do a rudimentary heat treat after profile cutting?

You probably can. Depends what's going on in the steel though. With a saw blade you are really making a guess as to the type of steel and to the hardening process. Pays to anneal and normalise first though. Much nicer to work with a softer piece of steel as well and basic hc steel is cheap enough that you aren't saving much by re using the old stuff

@ Diana2 , I am new to the knife making scene as well mate so like you it's a learning curve .
I get my steel from Creative man in Oz. They have a good variety of different knife making materials and the prices / freight are ok.
I landed some stainless and with freight I think it was around $60 NZ to the door and enough to make two knives.
The annealed stuff is easier to work for the profiling , beveling , drilling etc and then get it heat treated after .

For steel, have a look at Artisan Supplies. They have a NZ based store as well, so if you place an order on the Aust website, you will be dealing with the NZ based team.

For standard size knives, a 3.2mmx38mm section of flat bar is the best place to start, in either 1075 or 1084 as they are supper easy to heat treat (no soak time required). Just heat to non-magnetic and quench in canola oil, then temper in your oven.
https://www.artisansupplies.com.au/p...c=dab83b10fbbe
https://www.artisansupplies.com.au/p...c=dab83b10fbbe

O1 Tool Steel!
Can be bought in very knifemaker friendly sizes (4x40x500, 3x30x500, 3x50x500 etc)
It is sold as gauge plate (fully annealed and precision ground) from a few different companies. I mostly dealt with Special Steels in Auckland. Email them for a price list of all their sizes. I was buying 4x40x500 for around $23 a piece a few years ago.
I started knifemaking using old sawblades but once I started using gauge plate I never looked back.
O1 is very easy to heat treat in the home workshop using nothing more than a map gas torch ($100 from Mitre 10) a few fire bricks, a few liters of canola oil and the kitchen oven for tempering.
Many of my early knives were heat treated with very basic equipment until I build a PID controlled electric furnace.
https://www.facebook.com/Guildford-K...6427120825057/