Marking knives from bandsaw blades

[paulm]

Thought I might have a go at making a couple of marking knives using some old bandsaw blade that was otherwise heading for the wheelie bin.

Seem to remember though that it was nearly impossible to cut with a hacksaw last time I tried, even with a good quality blade.

Any thoughts on how I might do the initial rough cutting and shaping before getting to the grinder and files ?

Any other potential uses for old bandsaw blades ? Seems a lot of half decent metal to be chucking away !

Cheers, Paul.

 

[MikeW]

Easiest way to "cut" bandsaw blades is to make a score line with a file, place the blade into a metal working vise with the score line even with the top of the jaws and with a quick jerk, snap it. Do the other extent the same way.

Do wear gloves and safety glasses or a face shield.

After that, grind the teeth portion off. Do note that often bandsaw blades are not hardened at the back edge of the blade as hard as the toothline. So it may be best to keep the tooth edge as the cutting edge for the knife.

You can reharden if needed. Use a torch and heat it up to a nice orange color holding it with a pair of pliers and quickly drop it into a can of oil such as peanut oil that its level is deeper than the length of steel you are working. Then you must temper it by heating it evenly and letting it cool slowly. I do this in a little countertop oven to 350 degrees for about an hour, switch it off and let it cool down without opening the door.

Take care, Mike

 

[Johnboy]

Hi Paul, I made a marking knife from a jigsaw blade (not my idea, copied from Derek Cohen) and used a disc sander to do the shaping. Frequent dips in water to prevent overheating seemed to work for me.


John

 

[David C]

Paul,

We also score hard steel with a dremel, angle grinder or edge of Tormek or HS grinder wheel.

It is also a reasonable idea to wrap the blade with a cloth or paper towel when snapping off as this captures the lethal splinters that often fly off.

This is why Mike says it is essential to wear safety glasses!

I think making marking knives is a very good idea. There are virtually none available which suit me any more except Hock and other violin type knives.

David

 

[Alf]

FWIW I found clamping the score line level with a piece of hardwood on the bench more effective than the jaws of a vice - no idea why, but just in case anyone else finds it useful. ici.

Cheers, Alf

 

[MikeW]

FWIW I found clamping the score line level with a piece of hardwood on the bench more effective than the jaws of a vice - no idea why, but just in case anyone else finds it useful. ici.

Cheers, Alf

Might be because of the continuous contact at the break point. I should have mentioned I have lined my vises with aluminum jaws, and so they are smooth...Thanks Alf!

Take care, Mike

 

[paulm]

Thanks for the advice guys, might try and cut out some lengths as blanks tomorrow if I can get finished converting some more of my log pile into turning blanks first so that I've got some more room to work in.

Have been working steadily through a pile of sweet chestnut and spalted beech last couple of days, trying to instill some sense of order in the workshop, but got a way to go yet, so might switch to the marking knives later by way of a change and some light relief !

Do any of you have a particular preferred style/shape/size of marking knife that I could model my own efforts on ?

Cheers, Paul.

 

[paulm]

Had a few minutes at the end of the day after tidying up the workshop a bit to have a go at one of the old blades.

Tried the bench grinder first but found that a bit of a handful trying to manhandle the whole of the blade, although it was very effective, so tried the next piece (which was easier because I had already cut into the loop on the grinder and so was working with flat stock that behaved itself a bit better) with the dremel and cutoff attachment which was fine and more controllable if a bit slower.

So have a couple of lengths cut out and ground the teeth out on the bench grinder and all went much easier and quicker than expected.

Will leave the creative stuff till I'm less tired, but still open to ideas on favoured styles/sizes of marking knives ?

Cheers, Paul.

 

[Johnboy]

I like Derek Cohen's shown here which I shamelessly copied.

John

 

[David C]

I prefer knives with a long straight blade and no handle. Like Japanese or Violin knives. The green handle on the leather workers knives I used to buy are redundant.

Big shame that Barnsley (Sheffield) has ceased to exist. They had dozens of different knives for veneer, leather, rubber industries etc etc

The pretty turned handles make regrinding much more difficult. Flat scales might work.

Control of the knife angle is paramount so I grip the blade quite close to the tip.

Just my preference,

David Charlesworth

 

[Anonymous]

Thin 1mm cut off disks, in a small 4" angle grinder for me. Can do anything with them. Considerably less heat build up as well.

Get into all the tight areas.....I regrind all my profile blades that way, by mounting the larger disks on a regular bench grinder. Shouldn't be any fear of burning your blade.

 

[Anonymous]

I use an old 3/4" inch chisel with a skew edge.
No handle and the roundness of the neck fits snugly in my hand whilst my fingers have a firm hold.

Bit like the old style marking/striking knife without the pointed end.

 

[paulm]

Well, ground a V point on the blank today and then established the bevels on one side only, heated to an orange colour with my plumbers blowtorch, dunked in some veg oil nicked from indoors, then tempered in the oven at 190 degrees C for an hour and left to cool in the oven, (thanks Mike for the advice).

Have cut a couple of simple small slabs of purpleheart (just what came to hand, would have preferred cocobolo or something similar, might need another trip to Yandles soon !) and glued up with epoxy as a simple flat handle a la DC's suggestion.

Just waiting for the glue to harden fully and then I'll do some tidying up and try to make it look presentable. Will likely stay a bit on the chunky side though, think I'll make a couple of more delicate ones at some stage perhaps including a turned handle version.

Trickiest bit so far has been figuring out how best to hold the blade to establish the bevels on the Tormek and waterstones, still haven't worked out the best way to do it in a repeatable and accurate way.

Time for a break and a cup of tea while the glue goes off.......

Cheers, Paul.

 

[David C]

Paul,

Once ground I think freehand is almost the only viable option for honing.

David

 

[paulm]

Not very elegant, and the purpleheart came out a bit bland, but functional at least and not bad for a Mk1 prototype considering what it started out as !

Hope the pictures work as I have finally got around to having my first attempt at posting some.

Cheers, Paul. [/img]

 

[David C]

Paul,

Looks good to me.

David

 

[Johnboy]

Paul, looks good to me too. Handle epoxied on?

John

 

[MikeW]

Not very elegant, and the purpleheart came out a bit bland, but functional at least and not bad for a Mk1 prototype considering what it started out as !

Hope the pictures work as I have finally got around to having my first attempt at posting some.

Cheers, Paul. [/img]

Wow, Paul--nice job!

fwiw, marking knives and other small tools don't always show wood off to its best advantage. I like PH as a tool making wood as it is durable.

Again, nice.

Take care, Mike

 

[paulm]

Thanks guys. Looking forwards to making a finer, more elegant version at some stage, probably with a turned handle for a change.

Hi John, yes epoxyed the scales on with lots of 5min stuff and sanded clean on the belt sander before chamfering the scales with the LN block and hand sanding further, then a couple of applications of Danish oil (it soaked it up, the purpleheart was really dry and thirsty), then a couple of rubs of beeswax.

Not too much competition for Blue Spruce just yet, but will work on it ! :lol:

Cheers, Paul.