Casting an aluminum handle

[JD Bragg]

Has anyone tried to cast an aluminum handle around a steel object (the tang of a knife, in my case)? I'm just wondering if there's anything that would be a problem in trying this

[Frosty]

Welcome aboard JD, glad to have you. If you'll put your general location in the header you might be surprised how many of the gang live within visiting distance. 

Sure you can cast al around steel it's usually not difficult. However problems can always arise,  it depends on what you're doing. Thick al around thin steel easy peasy almost foolproof. Thin al around thick steel? Oh baby can that be a problem. 

Thinking knife hardware? Buck casts all it's guards and pommels on the blade. Casts the grip too but that's resin or ?

Frosty The Lucky.

[JD Bragg]

Thanks, Frosty. I actually live up in Alaska. And yes, it will be a fairly thin piece of steel compared to the aluminum. And I will be doing the full handle, guard and all

[Frosty]

Cool, where? The next club meeting is Saturday May 12. in Palmer at Arctic Fires Bronze. Pat is a professional caster and I believes teaches classes.

Aluminum casts well at around 1,100 f. which is guaranteed to kill the heat treat in a blade so chill blocks are necessary to protect the blade itself. Copper blocks against the blade will prevent heat from traveling past. We did some of this type casting in high school in the last millennium. You'd be far ahead talking to Pat, this is his meat and drink.

Frosty The Lucky.

[JD Bragg]

Down on the Kenai peninsula, in kasilof. Thanks again for all the tips

[Frosty]

Nice country, I like the Kenai. My pleasure, I'll ask Pat next time we talk. 

How about a drawing of what you have in mind, it might not need an expert and oh heck there ARE experts hanging on Iforge.

Frosty The Lucky.

[JD Bragg]

I haven't made a drawing yet, I'm still just finishing up my first knife. I got into this because I wanted to and I could get a highschool credit for it, so I thought it was a win-win scenario. I'll try the aluminum-casted handle on my next knife. I have read the foundry casting basics discussion

[Frosty]

Is there an aluminum casting unit in school? 

Make the tang wide though not a full tang. Drill or even saw holes in it so it's just a skeleton tang. That way when you cast the handle it doesn't even have to grip the tang, it can't go anywhere as it's ONE piece. Make the guard and pommel integral to the handle.

This would be pretty straight forward for green sand if you carved the form from Balsa wood. You need a couple reasonably heavy pieces of copper bar to clamp to the blade from the ricasso to the tip to stop the heat from conducting through the bade and drawing the the temper down. If the temper is drawn down you will NOT be able to re-harden the blade Aluminum's melting temp is well below critical temp.

Make sense?

Frosty The Lucky.

[JD Bragg]

I'm actually homeschooled through a private school up in eagle river, it's part of Until That Day church. So, I think this will count as an arts credit, or an extra credit. Thanks for the tips, I was thinking that making holes in the tang would be a good idea. Can I carve the form out of wax, or does wood work better?

[Frosty]

1 hour ago, JD Bragg said:

I'm actually homeschooled through a private school up in eagle river, it's part of Until That Day church. So, I think this will count as an arts credit, or an extra credit. Thanks for the tips, I was thinking that making holes in the tang would be a good idea. Can I carve the form out of wax, or does wood work better?

If you don't have someone available to show you how to make green sand molds you'll need to go the investment casting route in which case wax will work fine. Post some pics of what you plan on and we can give you some tips on the tang. 

There are patterns for removing material from the tang that can make it safer for the heat treatment. 

I've known home schoolers but don't know how the class credit works but I don't think just doing something counts. I had to write and teach to a curriculum for the one student who wanted credit for learning the craft. It was worth it in more than one way though, he was able to buy some of his tools and equipment  through the process.

Frosty The Lucky.

[JD Bragg]

Sorry, I guess I didn't specify. I am writing a paper of how I made my anvil and forge, and learning arc welding in the process. The knife I'm making now I'll give to my principal to show that I can make a knife. Then, my parents just have to sign something saying I did learn the forge a knife. 

 Below is what I'm thinking for the tang(bottom drawing). About a 1 in. width with two half inch holes on either side. The blade shape will just be a simple bowie shape, if you're wondering. Then, the cast handle (top drawing) will have the guards a part of it, like you mentiond. Sorry, I'm not a very good artist.

[OddDuck]

For a beginner, this sounds like an almost ideal scenario for lost foam. Probably the easiest way to do this, in my opinion. Either use Styrofoam or the blue or pink insulation foam (the stuff in the sheets, not the spray expanding foam stuff), glue two blocks around the handle and carve it to the rough shape you want. Add a long square section of foam attached to the butt end to act as your sprue (the hole you will pour the metal into.) clamp the copper blocks ( aluminum blocks would probably work as well) along the length of the blade, and bury this assembly in DRY sand, point down. Metal bucket, by the by, don't use a plastic one. have the square sprue barely poking up out of the surface of the sand. Set an empty soup can with both ends cut off around the sprue, pour some sand around it to hold it upright. Melt your metal, for aluminum you will have to pour on the hot side of things, somewhere in the 1400 to 1500 F range. Pour into the soup can, the aluminum will vaporize the foam and fill the resulting void with metal. Pour fast and steady, there will be a lot of smoke when you do this. It also stinks a bit, so be warned. Let the metal cool for a few minutes, and then pull it out of the sand and quench it. Saw off the sprue, and clean up the resulting handle. Nice thing about doing it this way is that you are pretty much only limited by your imagination and carving skills. Bad thing about doing it this way is that it's a one shot deal, if it doesn't work you are left with a blob of misshapen aluminum adhered to your knife blade. The surface texture may be a bit rough, use as fine of a sand as you can locate. You can also dip the foam in thinned drywall compound and let it dry thoroughly, this helps by keeping the sand away from the surface.

[JHCC]

It's not a how-to, but there's a great little video online about Ruana Knives in Montana, which uses cast aluminum handles with elk antler inserts. The section with the casting starts at 4:00.