How To Make Shoe Lasts

[ABurchIV]

I know that this is an older thread butI'd like to add some information for those like me that came late to the discussion. Leather working for me is a hobby, my job involves observing body biomechanics and treating dysfunctions.

The reason why you can't make a perfect replica of the foot using any medium, is because it's a dynamic structure that changes shape constantly. The three arches of the foot (medial longitudinal, lateral longitudinal and transverse) all change shape. There is a difference between weight bearing and weightlessness as well as a change during every part of normal gait. Additionally the metatarsals and toes splay outwards during portions of gait and come back in during others.

I can understand the frustrations getting a properly fitted shoe, but casting the foot in any one static position would cause way more problems than it fixes. If you want to customize a last for better fit, then take all of the standard measurements in multiple positions. First seated with the feet flat on the floor but unweighted, then standing, then in the toe off position, midstance position and finally heel strike position and look at the variance. Some measurements will change almost insignificantly others more so. For those that have insignificant variance I'd recommend using the standing measurement as the feet are very pliable when not weight bearing.

The two measurements from Golding that are likely to change the most are Joint and Instep. The joint measurement takes place at the heads of the metatarsals which splay outward during toe off and the instep follows the transverse arch which widens from heel strike to midstance then narrows from midstance to toe off. For those two, I'd go for the mean of all combined measurements as the smallest measurements take place while no weight is on the foot and the leather will have a natural give to it that should accommodate the largest measurements.

Finally the shape of the toe box itself needs to blend the proportions of the style and the needs of the toes. Too many shoes have an unnaturally narrow toe box which jams the toes together and prevents splaying at all. If you want a narrow pointed toe, taper in a bit slower and extend the full length a bit further than what traditional styling would suggest and bond additional material between the lining and outer leather. The outside of the shoe will be about one size larger than your normal shoe size but the inside will remain the correct length and give the toes the additional space they need. It'd be like ordering one size larger and then stuffing the toes with paper, just a more permanent and much better method.

As for building better arch support,you'd be better off leaving that to the orthotics makers as youaren't measuring the real arches so much as trying to force them to where they should be which is a whole other can of worms. The three arches are made up of 12 bones, many ligaments and controlled by the actions of 15 different muscles. You have to craft a theoretically perfect arch that matches the anatomical structure of the one you are working with.

The whole reason I'm getting into shoe/boot making is because I spend all my day standing/walking and I have to wear dress shoes. I also have a difficult foot to fit, but more importantly, a lot of shoes just seem to ignore foot biomechanics entirely.

[Sixsmith]

Hi,

I just came across this thread. I make shoe lasts at Sixsmith in Lincoln, MA. We make custom lasts out of oak for some local designers, and have developed a fabrication method to make inexpensive lasts to incorporate into the shoe design system we'll be releasing this summer.

I agree that the book available from Walrus Shoes is very good. It especially does a good job of outlining key measurements needed to make a shoe last.

Basically, a last is not a copy of a foot, it is instead the form of the inside of the shoe that the foot would go into. When I measure a foot I find it more helpful to measure the client's foot while it is flat on the ground because it helps me identify how high an arch she or he has, as opposed to measuring the foot at the intended heel height and not getting as clear a picture of the shape of the arch height.

Because we have a complete fabrication lab, I'm able to make a CAD drawing of the last and then output it on our cnc machines. If you have access to a fab lab in your area, you should take a look at Delcam's e-shoe maker product. It is free and it allows you to customize a last model they provide, as well as heels and other patterns. You are only charged when you convert the file to an .stl format. Of course the .stl file can then be sliced and output on a cnc router, or milled on a cnc milling machine, or possible sliced and thin stock cut on a laser cutter and laminated together. I think Delcam also gives educational discounts.

One of the reasons people don't use most resins to cast shoe lasts is that the last needs to withstand some hammering, and also needs to be able to accept a nail. Many resins are too brittle for this and will either not accept a nail or will crack after a few uses. The other issue is that you really want to cast the inside of the shoe-not the foot. But resins poured inside a shoe are bound to stretch it and make the casting useless.

When we've been really stuck and have needed to quickly understand the relationship between the inside of an existing shoe and a platform or orthotic device, we've done the following:

Use a heavy pourable flexible foam like the #25 Smooth-On foam available from Reynolds. (Don't use rigid foam because it can crack). Pour it into the shoe you would like to copy. (Warning! This will ruin the shoe as you will need to cut and peel the shoe off the flexible foam once it sets.) Next, identify any area where the casting seems to have stretched, and sand it down to the correct shape. Then use Bondo to cover the foam and reinforce the foam. Sand it smooth. Wear a respirator.

This foam/bondo last will accept a nail and can be hammered and easily modified. It won't last forever, but will get you through a couple of shoes and prove your measurements. Since the foam has some flex, it has some self-healing properties with nails. It is also helpful in providing a starting point for modifications.

In addition to making our own shoe lasts, we also make custom insole boards for high heels using leather and a special technique for embedding a fiberglass shank. It's very popular with our students because leather provides an better foundation for hand-lasting a shoe.

Just my 2 cents,

Meredith

Sixsmith & Co.

www.6smith.com

[ElfNori]

I have some comments to make about creating your own last out of a foot casting. First, I wouldn't recommend casting your foot in a full weight bearing position. It produces a sloppy shoe. I have two sets of lasts from that sort of casting and I've modified them a lot to try and solve the sloppiness. It is much easier to make a different sort of casting to produce a better fitting shoe. The casting information for the full weight method is on this page -> http://norisstuff.co...waining/page/2/

After a bunch of trial and error, I've figured out a better way to make a casting for a last. I used a plaster bandage to wrap the ankle and the foot but not the toes, covered it with a plastic bag and then wrapped it with elastic wrap to hold it tightly to my foot. I was very careful to keep my ankle and foot correctly aligned with my leg and my ankle at 90°. I pressing only the forefoot into the floor with only a small part of my total weight until the plaster cured to leather hard. The more heel you need on your shoe (my goal is NO heel for a healthier foot and ankle), the more you should lift the heel off the ground when wrapping and curing. Full details with pictures are here -> http://norisstuff.co...ry/cordwaining/

You will need a mold release. Olive oil works but doesn't truly seal the plaster which lets it suck water out of the plaster you'll use for the casting. Glycerol with alcohol works better. You'll need to use two coats letting it dry completely between coats.

When the casting has set, peel off the original plaster wrap and set the casting aside to cure. When it's completely cured, use modeling clay to fill in the toe area for your shoe. If the casting isn't tall enough, fill in the top. You'll need to mold this newly shaped last. That's a whole other exercise.

Edited August 20, 2012 by ElfNori

[ruddhess]

Good information about "weighted casting". (One thing to consider is the amount of stretching of leather that is going on when making a boot or shoe on a last - also different people like their boots/shoes to fit tighter or looser than others; I prefer the a very loose fit and leave all laces shoes/boots very loose and knotted permanently for a quick slip-on - but I guess that's the "ol hippie" in me coming out again!) The shape of that casting looks quite a bit like some of the medieval lasts (except for the rounded toe).

I have some comments to make about creating your own last out of a foot casting. First, I wouldn't recommend casting your foot in a full weight bearing position. It produces a sloppy shoe. I have two sets of lasts from that sort of casting and I've modified them a lot to try and solve the sloppiness. It is much easier to make a different sort of casting to produce a better fitting shoe. The casting information for the full weight method is on this page -> http://norisstuff.co...waining/page/2/

After a bunch of trial and error, I've figured out a better way to make a casting for a last. I used a plaster bandage to wrap the ankle and the foot but not the toes, covered it with a plastic bag and then wrapped it with elastic wrap to hold it tightly to my foot. I was very careful to keep my ankle and foot correctly aligned with my leg and my ankle at 90°. I pressing only the forefoot into the floor with only a small part of my total weight until the plaster cured to leather hard. The more heel you need on your shoe (my goal is NO heel for a healthier foot and ankle), the more you should lift the heel off the ground when wrapping and curing. Full details with pictures are here -> http://norisstuff.co...ry/cordwaining/

You will need a mold release. Olive oil works but doesn't truly seal the plaster which lets it suck water out of the plaster you'll use for the casting. Glycerol with alcohol works better. You'll need to use two coats letting it dry completely between coats.

When the casting has set, peel off the original plaster wrap and set the casting aside to cure. When it's completely cured, use modeling clay to fill in the toe area for your shoe. If the casting isn't tall enough, fill in the top. You'll need to mold this newly shaped last. That's a whole other exercise.

[ElfNori]

My shoes are veg tanned kangaroo lined with chrome tanner bison outer. The full length counter is cow. They're water proof, which is lovely. My arch is too sensitive for grommet lacing so this pair has speed lacer hooks. The next pair will be a bit different.