The Shop > Wood & Stuff
Banjo Build
vtsteam:
Simon I posted my drawknife pics in "Tools":
http://madmodder.net/index.php/topic,10747.0.html
S. Heslop:
The files softened. I was able to file them with another file.
Finger for scale, they're pretty tiny teeth. I think a more solid support (there's a table leg underneath this vise but I cut it too short, and it's supported by a wedge that tends to work loose) and a bigger hammer I should be able to get bigger teeth. Not sure how happy this high speed steel will be getting whacked though. Wish I remembered to look for some wee cold chisels at the boot sale.
I sort of assumed you'd want the teeth to lean forwards a bit so they bite the wood, here they're all over the place.
Did a little test and it seemed to cut this walnut fairly okay.
I've got two softened files and now i've got to decide which one I want to turn into a curved rasp. I've got some other dull ones I could use too, but the teeth on them are so mighty that it'd take alot of effort to grind them off.
This is all the easy part though. I've gotta find a good place to keep that compressor, then pressure test it to reassure myself that it won't detonate, then start fussing about a sand blasting setup.
The other thing i'm thinking about is how i'd best go about preventing the teeth from burning off when I harden it. I was thinking about perhaps dipping them in plaster of paris, but then that'd probably rust them. Maybe I could try something like cladding them in window putty, which as far as I know is just linseed oil and chalk. Alternately I wonder how well a heavily reducing flame would prevent the teeth from burning.
Edit: I found a photo of some rasp punches, as the guy called them, that i'm putting here mostly so I can find it easier.
vtsteam:
Cool Simon!
Well, those are some of the questions I was having, too about old ways of protecting the teeth while hardening. Looks like immersion in a molten table salt bath is the way it's done, now. Linseed oil will burn up. Plaster of Paris might work for the heating phase, but plunging to harden would maybe be too slow with an insulating layer of poP. Lautard in the Machinist Bedside Reader mentions using hand soap rubbed on cutters to prevent scale when heat treating. I've done that and it seemed to work fairly well. Heating the file as much as possible without oxygen would help prevent burning and scale, so burying in hot embers might help as opposed to a burner/blower in air. Maybe a rich torch flame would hep some. Just all maybes, here.
S. Heslop:
Got the forge set up and ended up using it right away. Picked a helluva day to do it because it's pretty hot.
Made a... swaging block I think you'd call it? Ground the bulk material out with an angle grinder and filed the rest to get a good shape.
It took a while to get the forge working. I kept rearranging the bricks (not a good idea when they're glowing hot!) to get a good shape, and this one seemed to work well for heating the whole thing up at once. It probably also just got better as the bricks got hotter.
The shape looks pretty good in this photo, but from the side it kept curling up. It was also twisting a bit which was spooking me since I had no idea how to try correcting that. As it's finished, i've got the top of it more or less flat I think. Or flat enough to finish up with a grinding. But the bottom of the file, towards the tang, is still a bit curly. I don't think it'll matter too much but it looks a bit silly.
I had problems with the brick barbeque I was doing this on falling apart from the hammer blows. Plus I gave myself a few burns, and singed a bunch of my hair off. And I wasn't too excited about having to heat the entire file up instead of just heating the areas i'm gonna shape. Ideally I probably should've shaped the forge to have a slot the file could pass through, but with the thing hot I couldn't rearrange it so heavily.
I also stuck another big rasp in with the file so hopefully that'll soften too. I was intending to cover it with bar soap to test that idea but I was so busy juggling all the problems I just forgot.
S. Heslop:
You can see the bendyness here. It also seems to have developed a sideways bend while cooling too.
I was thinking about hitting it with a hammer to straighten it out, but I think there's enough of a straight section to be useful. I can just pretend its some sort of exotic rasp for specialist work.
Had a go at smoothing it. I'm having the same problem I had with the helmet, where I can't find a way to remove material fast while grinding. I think it's mostly just the belts i'm using, but i've tried a few brands of belts and not found one that doesn't go blunt very quick. Maybe because they're intended for use with wood.
As a result, there's a bit of a dip inwards at the tip as well as some erosion pitting from the flame that would take alot of effort to grind out. Actually, thinking about it, the steel is soft enough to file...
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