Shoe "last" From Plaster Casting, Weight On Foot?

[Softanvil]

Hi! I'm sort of following up on this idea: http://greencouple.com/2009/03/08/shoemaking-102-making-lasts/

However, I'm going to modify the casting to make it into a last and not just a foot replica. I might have the casting 3D scanned and then modify it in 3D studio and then remake it with a CNC mill, or I have some similar ideas. But first I need a cast of my foot.

Now, my question is, when making the cast, should I put my weight on this foot so that it is pressed against the floor like when I'm standing up? That will make it slightly wider and flatter.

Or should I suspend the foot above the floor and then make an impression of a "neutral" foot?

[electrathon]

Lasts are not really the shape of a foot, but a guideline to the shape for support. The best example of this is that a shoe is longer than your foot is so that your toes do not touch the end (at least they shouldn't) but they do touch the sides.

But to answer your question, measuring of the foot is done with some weight on the foot, for the reasons you said. I have othotics insoles that the Dr made from a cast of my foot and he did the cast with no weight bearing. They are not really the exact shoe size though, you often have to trim them depending on the shoes you wear.

[Softanvil]

Lasts are not really the shape of a foot, but a guideline to the shape for support.

Yes, that was my point with "I'm going to modify the casting to make it into a last and not just a foot replica"

But I don't understand your answer. If measuring is done with some weight on the foot, but your othotics were cast with no weight bearing, what does this mean?

The reason I'm asking it that those casting socks are kind of expensive, so I'd like to get it right the first time. Should I start my last making from a cast made from a neutral, free-hanging foot, or while standing on the foot?

[Softanvil]

And I do understand that it will be difficult and I'll be lucky if I make a decent last on my fifth iteration. There is no rational reason that I don't just buy a ready made last or indeed a ready made shoe; this is all for the hobby value only.

[electrathon]

When I took shoe making class we were told that measurement of the foot to properly fit the last the foot is placed on the floor to measure it. But, when I had orthotics made it was done with the foot suspended. Use tights/thick pantyhose as the sock that you cast over. Very cheap.

[Softanvil]

Ok, I'll try using some weight on the foot then.

I don't think you can use pantyhose in the same manner as the casting socks in the link in the first post? These STS Casting Socks are made from 5-minute PU. Alginate would be a much cheaper if making multiple moldings, but for a one-off, the STS seemed much less hassle and less cost. I got mine for £20 / 1 pair.

[electrathon]

To go low budget you can use pantyhose and cover your foot with plaster casting material just like old school broken bone casting. Even cheaper use 20 minute hot mud for fixing walls and dip stranded newspaper in it. You can treat it very similar to how he was working in the article. For a few dollars you would have enough material to do multiple castings.

[Softanvil]

Thanks! That is a great tip!

[electrathon]

Post updates as you proceed. I am interested.

[Softanvil]

By the way, I'm considering following another bloggers idea and making a "resin last", by sticking modelling clay onto a plaster casting of my foot, shaping it into a last, and then making a new negative mold from this. Then I'll fill this negative last mold with resin and extract a last.

Do you have any recommendations on what type of resin to use here? I'll probably stick a "wooden sole" onto it for putting nails into when using it as a last.

Edited July 28, 2013 by Softanvil