Moulding knife parts

[ZDP-189]

As you may know, I occasionally do castings in pewter, plaster and resins. I have tonight cast the little beauty on the left from the original on the right.



Before anyone mentions that it needs a flared base, it's a dummy knifehandle. I cast it to experiment with various textures/ milling/ chequering patterns that I will apply to the turned aluminium original. The handle was cast from polyurethane in a one-piece silicone rubber investment and I can produce a dozen or so in an evening without breaking a sweat.

But then I got to wondering: If I can make a good fibre-reinforced resin handle, could I cast knife handles directly onto the blades? This would be a quick and inexpensive way of making knives. I could even make training dummies based on production knives (though I would have to bulk the blades up with modelling clay or the resin blade would be too thin.)

Has anyone had any good or bad experience with PU or resin castings on knives? I'd value your comments (esp. Mushi) before I waste good blades.

[MushiSushi]

I haven't done it yet, but a lot of knives are done that way ... a mechanical fixing .. holes in the tang for the resin to go through .. would help .. go for it ... just make sure there is no moisture first or you will trap the moisture in ... it would help if you have a flange on the case mould for the silicone that tightens around the blade to hold the blade nice and central as it is setting .... some polyurethanes are brittle ... I am guessing that you used a fast cast for the prototype and that wouldn't sustain much impact ... shop around for some impact resistant resins ... one that comes to mind is easyflo60

[ZDP-189]

Many thanks, Sifu.

I used HEI-CAST 8012. Bl__dy stuff sets so fast you better mix quick or you'll never get it down the hole. I'll drop then hammer test the impact resistance.

The aluminium version is great, though. No impact worries there.

[MushiSushi]

easyflo 60 will give you about 2 1/2 minutes from mixing depending on humidity

more info can be found here

http://www.notcutt.co.uk/polyresins.htm

[dtalbot]

If it won't flow into the holes, how about putting short pins through them to give the same sort of mechanical fix. Not sure if it'd work, gust a top of my head idea.

[ZDP-189]

It sets solid like jelly, then like rock

[Kevin]

Damn good.



pm on its way.