Casting a perfect mirror image?

[mountainm]

I was very fortunate to be given a resin casting kit for Christmas and I'd like to create some unique knife scales. My thought was to work up one in wood and then create a mould. But then how to create its exact pair? I can't think of a way to cheat it.... But maybe I'm missing something?

Cheers

Mike

 

[Nomad]

I don't think you're missing anything. To the best of my knowledge, moulds can't be turned inside out (or whatever) to make a mirror image. All you can do is make the two bucks as accurately as you can manage.

 

[Ben Trout]

I don't know of any trick, sadly. Would one of these help: steel-profile-gauge

 

[crosslandkelly]

Shape the complete handle in wood, plastic, foam or whatever, then when you are happy with the shape, split it down the centre. Two halves of one whole.
et voilla.

 

[swright81076]

What about one of these?

http://www.resins-online.com/ecomme...ad)+Smoked+Case&utm_campaign;=ShoppingResults

touched by nature

 

[Niels]

It says Affordable

 

[WULF]

Can you not just make a pair with normal methods,,bandsaw/sanding etc mike??? or do you fancy playing with the kit?

 

[Nomad]

The profile gauge looks like pretty good way to go, albeit time consuming to get the second scale to match due to having to take things very slowly (sand a bit, check, sand a bit, check, etc).

Alternatively, you could start with existing scales and modify them, or make a mould from them, and then cast parts that will become the real bucks which are then modified.

 

[mountainm]

Can you not just make a pair with normal methods,,bandsaw/sanding etc mike??? or do you fancy playing with the kit?

Well my last resort is carving it completely from wax and creating a mold from that. But i was striving for perfect symmetry. May try the 3d printer at the Leeds Fab lab.

 

[jackcbr]

Ok, so I may not explain this too well, but here goes.

Think of it as making your own ply wood. Cut two identical perfect oval shape in a thin(ish) material, one will be left, one will be right. Now cut another pair slightly smaller and glue to the larger ones. Continue till you have the kind of profile you want. Now you can either fill the ridges with another medium of sand off the edges.

 

[mountainm]

Ok, so I may not explain this too well, but here goes.

Think of it as making your own ply wood. Cut two identical perfect oval shape in a thin(ish) material, one will be left, one will be right. Now cut another pair slightly smaller and glue to the larger ones. Continue till you have the kind of profile you want. Now you can either fill the ridges with another medium of sand off the edges.

I get you. I think that's as accurate as i'll get.

Ta

M

 

[jackcbr]

Just another thought, if you make one that is symmetrical both vertically and horizontally then wouldn't it work as left and right?

 

[mountainm]

Just another thought, if you make one that is symmetrical both vertically and horizontally then wouldn't it work as left and right?

It would. But it wouldn't fit the tang on the knife then

 

[Nomad]

If you have the means to do the 3D CAD modelling, getting a 3D printer service to make them would likely give the best accuracy (they generally seem to be +/- 0.2mm or better), certainly for the least effort. From samples that I've seen, the finish is okay but not great, but some light sanding should sort that. I gather they use thermoplastic, usually ABS, which wouldn't be my first choice for a final product, but should be fine for making a buck for resin casting (provided the required finish can be acheived).

The advantage of making the initial model in CAD is that you do get a perfect mirror, albeit with some loss of that perfection when the part is printed (depends on where the rastered deposition ends up with respect to the curves in the model).