Friday, August 08, 2014

Making two knives, the grips

When we left this the knives were being tempered in the oven.  Once they'd cooled completely, they went back to the belt sander to clean off the fire scale and oxidation.  Came out pretty well.

Those lines are to lay out the holes to drill.  I'm going to use brass pins and epoxy to hold the scales on.  I used the centerpunch to mark the hole locations, then drilled them on the press.
See that clamp on the left?  It's there as a safety: if the bit grabs- when it happens, usually just as it's breaking through the far side- it can start the piece spinning.  This is Bad; unsharpened, that point can rip you, and even with the back of the blade in the lead, it hits you it's going to hurt.  Some things I clamp in a drill press vise; can't do that here, so you put something in position so it's out of the way but will block the blade if it starts to spin.

Put a bit of cutting oil in each punch mark, use light pressure, and drill through.  When they're all done, you can take a larger bit and turn it in the face of each hole by hand to deburr the edges.

For the larger one I'm going to mark and drill some smaller holes(1/16") for more pins, so it'll match the big chef's knife already made.

By the way, on a knife like this I try to make sure the tang does not harden; makes drilling the holes a bitch.  Which is why I prefer to drill them before heat-treating.  If you plan to harden the entire thing, you WILL drill the holes before, or you won't drill at all.

Now we need the grip materials.  I've got a piece of walnut I'm going to use
Make sure the piece is thick enough, then on the side lay out the size you need to fit the tang, and cut it.  Remember, it has to be thick enough that, when you split it, the wood removed by the saw won't leave the scales too thin.

At this point you need to split the piece lengthwise.  Remember that the side you marked is not where you want to split; turn it 90 degrees and use that edge. 
Draw a line down the length and across one end(a square helps here), then clamp it in the vise.  If you start the saw at a diagonal on the corner, and keep it centered on both lines it'll make sure you're cutting straight down the center; once well started it's easy to keep it straight with just the one lengthwise line.  That gets you two scales.

To the belt sander, or to a flat surface where you can put down a sheet of sandpaper and sand the inside of each scale smooth.  Don't try to get it too fine; you want it flat to fit the tang, but that's it.  Say 100 or 120 grit will do fine.  That leaves a surface that's flat but still a touch rough, which means more area for the epoxy to get into and grab hold of.

Back to the drill press.  Line the tang up on one scale, and drill an end hole. 
Then stick a pin in that hole(I'm using 1/8" brass rod) to keep it from shifting, make sure the tang is lined up on the wood, and move down and drill another, preferably at the end, at least in the middle.  Then stick a pin in that one and drill the rest.  That'll give you holes nicely lined up.  In the case of the larger blade, I changed to a 1/16" bit and drilled those holes.

Take that scale off, and do the other.  That gives you the set.

Next step is to, one at a time and using a couple of pins to keep it aligned, mark around the tang with a fine-point pen or pencil. 

That will allow you to cut the excess off each scale right down to the line with a saw, or knife, or the sander.  You'll notice the front of each scale is a bit further forward than you'd want it to be, and that's deliberate; I'd rather sand it back a bit to fit than be looking at it a bit short and engaging in language practice.

Shape the profile of each, then use a couple of pins

to hold them together and shape the front as you wish it.  Go slow, check it frequently  so you don't overdo it.

At this point you can either glue the scales on as-is, or do a bit of sanding and shaping on the sides first.  I generally leave them pretty flat, as that gives a better surface for the clamps.  Also, if the clamps make any dings it doesn't matter, as they'll be sanded off.  I'm using a 'sets in an hour' epoxy, as I like to have enough time to get everything together before it sets, and if I can't do it in that time...

That's if all is ready.  Get all your pins cut, and use the sander or a file to bevel the ends a touch so they'll go in smoothly.  Make sure they're long enough to go through both scales and the tang and either be flush or stick out just a touch on both sides.  Count twice, be sure you've got enough(of each size in one case).  Get a place ready, have your clamps ready, and something to mix the epoxy on and with.  Note: if you're worried about time, get the 1 or 2-hour-setting epoxy; works just as well as the faster setting, and takes some of the time pressure off.  If you're confident, you can find 30-minute-set epoxy.  Be very confident before you do that...

Try the pins in the holes and make sure the damn things fit, no matter what the label says.  If they're a fraction large, now's the time to find out and either get some other material or sand these down to fit.

One more thing while setting up: either have some waxed paper to put between the clamp surfaces and the wood, or give them a coat of paste wax and let it dry first.  You do NOT want to find that one of your clamps has formed a bond with the wood.

Make sure the tang is clean, no traces of cutting oil, sweat or anything else on it.  I flushed these off with brake cleaner, and it wouldn't hurt at all to take some sandpaper and rough the surface just a bit.  Same as for the scales, more area for the glue to get into and grab onto.  I'd also suggest wearing some gloves, as you'll get the stuff on your hands if you don't.

Mix the epoxy. 
Take two pins and dip one end in the stuff and stick them in one of the scales.  Coat one side of the tang, the one matching the scale with the pins, put that scale in place and push the pins through the tang.

Coat the other side of the tang.  When I say 'coat', I mean it, don't be stingy.  You can mix some more if you need it.  Fit that scale on the two pins and push into place against the tang.

Dip each pin in the epoxy and push into place.  You can also use a toothpick or piece of wire to pick up a little and put it into the holes, then the pins.  Ideally a little epoxy will push out the far side as the pin goes through, you want the pin and hole to both get a dose.  Look everything over, make sure all's as it should be, then clamp.

Make sure the clamps are holding the scales snugly to the tang, but don't try to crush-fit it; you want there to be a fine film of epoxy in there, so don't squeeze all of it out.  Wipe off all the excess you can, especially on the blade, and then set it aside.  Whatever the label says, unless you're in a desperate hurry for some reason, let it cure until the next day.

Next day, take the clamps off and look it over.  Check for any cracks or splits in the scales, any actual problems with the fit.  If all's well, time to start sanding.
Yes, this is the smaller knife; I didn't trim the scales as well as the larger, and for some reason forgot to shoot a pic of the larger as it came out of the clamps.

If you cut the length of the pins so there's quite a bit sticking out one or both sides, no worry, just use a hacksaw and trim them flush.  Remember, when you start sanding those pin ends they'll get hot, push it and it'll be 'hot enough to make the epoxy soften' hot.  So use a light touch, and give it time to cool between cuts on the belt or disc.

Or, you can use a coarse file to do a lot of the shaping.  Wrap something around the blade to protect it from scratches, clamp it in the vise, and file away.  Completely removes the heat problem.

On the sander, I use a fairly coarse belt first so it does the gross sanding fast with less heat, but be careful not to take too much off.  Round the corners off, and remember you can use the belt at the rollers as well as on the flats or disk.  Keep trying it in your hand, and when it's close shut off the sander, and go to the vise and start using sandpaper.  'Close' being very subjective: when you get the hang of this you can get it very close on the power tools, until then I'd suggest leaving enough that you're certain of not removing too much.  Remember, power tools not only make a job easier, they make it possible to screw things up REALLY fast.

At this point I'll clamp the blade in a vise(use some padding, but not anything that'll give and let it move on you; it'll shift a bit just from the springiness of the steel, you don't want to add to that.

You can start off with a file(half-round here) or fine rasp where you have a lot to remove.  Then to to the sandpaper.  Or  abrasive strip.  It's 1" wide cloth with the abrasive on one side.  You can get it in just about every grit and different widths, just tear a length off and use it shoeshine fashion, or where you want to keep a surface flat wrap it or a piece of sandpaper around a fine file or a flat stick and use it that way.  Smooth the shape, and keep going until it suits you.  I'll throw in, it doesn't HAVE to be rounded; you can make sure the scales are even in thickness and just sand the corners off so you have a octagonal shape for the grip.  Works nicely for kitchen knives.

I'd suggest taking it to 220 grit for the finish, though you can go as fine as you'd like.  Remember, the finer you sand, the smoother the surface will be.  In the ase of a kitchen knife like this, I don't want it slippery, so I stop at 220.  For that matter, you could just go to 120-150 or so and stop there, though it'll take more finish to fill in the grain.  When all's done, the shape and finish are as you like it, time to finish it.

That can be as simple as linseed oil, getting some of the 'knife handle oil' from one of the kitchen supply companies, or a gunstock finish.  If the wood's pretty dry, might try a combination. 
For linseed, get some boiled linseed oil and wipe it heavily onto the wood.  Let it sit a few minutes; if a spot starts looking dry, put another dab on.  You want the stuff to soak in, so no rush.  When you think there's enough(I'd say ten minutes tops for thin pieces like this), wipe off the excess and set it aside for the oil to dry, I'd suggest either clamping the blade in the vise or otherwise security it so the wood is not in contact with anything.  Depending on weather, it can take a week or more to dry completely.  One thing I have known people to do is put the linseed on, give it plenty of time to completely dry, then do the other finish over that.  I'd not suggest it if you won't/can't give it the time to be absolutely dry, as if the linseed isn't when you put the other stuff on it can cause problems with the finish over time**. 

For the other stuff, follow the directions.  What I like best is Minwax Antique Oil Finish.  Doing it right will take a week or so(multiple coats, each needing time to dry), but it soaks into the wood, dries hard and is a good protectant.**

What happens if you check the work over and find a real problem?  A big crack, or split, something that can't be fixed in place, something that means you have to replace the wood?  Remember I mentioned heat making epoxy soften?  Turn the oven to 350F, when it's at heat put the knife in on a piece of foil or something and leave it a few minutes while you put on some gloves.  When the stuff gets hot enough it starts to soften, and you should be able to pull or pry the scales off.  Clean the epoxy residue off the tang and pins, and do it over.

And that's it.  Start off with good steel, take care while you work it, and you can produce a knife better than that available to most of humanity(including royalty) through most of history.

For sanding a truly flat surface, you can use either a surface plate, or, if there's a glass place around, get a piece of thick plate glass about a foot square.  Use a piece of plywood to make a base for it, maybe a piece of rubber tool-drawer or cabinet liner under it.  Stick a piece of suitable sandpaper on and start sanding.

*Same with gunstocks.  Linseed is often used as the first treatment on the stock, but if you're going to use something else to seal the surface, make damn sure the stuff has had time to dry.  I'd suggest a full two weeks, more if the weather is cool/cold and/or humid.
**First heard of this stuff on a thread at The High Road
which had the procedure for gunstocks.  You basically do the same with knife hilts.


Midwest Chick said...

Nice blades! Do you have a shop or someplace where one can purchase?

Firehand said...

No. Used to do a lot of smithing, had to give that up; these are the first knives I've made in a while.

If you've got something you'd like, shoot me an e-mail and we'll see if can do it.

Gerry N. said...

A few things I've learned in my 70 short years on this big blue marble.

Alcohol of any kind dissolves cured epox quite quickly, it will also wipe off latex paint(which never, ever dries).

Spent power hacksaw blades, usually to be had for the asking make wonderful knife blades. Easy to do too, hell, I've even done it.

Sandpaper of any kind glued to dry sticks of any shape with contact adhesive of almost any kind make wonderful, cheap, quickly replaceable files, sharpening stones, and nail files. See what happens when you sharpen a med. quality knife with 800-1000 grit paper cemented to a scrap of 1/4"- 1/2 Plate glass. Can you say "Scalpel"? Do it with the abrasive coated mylar sheet geeks use to finish the cut ends of fiberoptic cables and enter the world of "frighteningly sharp" as in obsidian ocular scalpels.

Some tools made of stone may be primitive, but in no wise could be considered crude. Field dress an animal with a competently knapped flint, chert, or obsidian knife.

Gerry N.

Firehand said...

Really? Alcohol? I'm going to have to try that