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Since I started learning to make shoes in 2004, there has always been talk of the promise of 3D imaging – the scanning of feet – and how this would greatly simplify the work of making shoes, mainly by facilitating quick and easy last customization. The idea was that a scan of a foot could be used to derive a last and make a shoe that would fit perfectly.

While “scan-to-shoe” hasn’t really panned out, thanks to a Make|Learn|Build! grant from the Oregon Regional Arts and Culture Council (RACC), I have been able explore first hand over the past year how 3D imaging and CAD software might fit in a custom shoe making workflow.

Scanning

Grant funds were used to purchase a Structure Sensor Pro and an iPad, since the Structure Sensor Pro requires an iOS device to run. This scanner is based on infrared light, similar to the Kinect and other structured light scanners. With this handheld scanning setup, I acquired scans of 5 pairs of feet from clients who consented to participate in my pilot study. I also scanned lasts I modified.

Scans of feet must be manipulated in some way to make them fit into the digital last models. Most feet are scanned on a flat surface, but most lasts are not flat. A lift of the heel is needed and some lifting of the toes as well. This already requires some assumptions about how a foot might behave when manipulated in this way. Even though I could manipulate the scan of the foot enough to make it fit inside the bounds of the last, the scan data do not provide the right kind of information to know if this is actually possible for the given foot, or if it would be a comfortable and pleasant fit.

In practical terms scanning feet using a handheld infrared scanner is pretty fussy. It can take quite some time and the results vary in accuracy. It is difficult to capture the feet from every perspective in order to obtain a complete 3D scan. I used the same scanner to scan lasts, but the edge detection is not good enough to get clearly defined edges especially around the feather line.

CAD

My original plan was to use a customized CAD program offered by the German last manufacturer Spenle. They offered a stripped down last-only CAD environment and access to a library of their lasts, however this was not available to me despite my efforts to purchase a license. As an alternative, I used grant funds to purchase a copy of Rhinoceros 7, a very capable CAD program that is also well represented in the footwear world. This also meant I had to learn CAD for real in order to make a usable model of a last to send out for production.

I manipulated and adjusted the foot scans using Rhino’s robust mesh editing tools. I also used Rhino to align and orient the images in a way that might approximate the way a foot might sit in a physical last. I built last models with a combination of parametric and subdivision (SubD) modeling.

Lasts

Typically lasts are purchased from a manufacturer’s catalog of existing shapes and selected on the basis of simple length and width measurements, which in themselves do not account for many of the idiosyncrasies of individuals’ real feet. In order to streamline the custom shoe fitting process, I wanted to see if lasts carved from a modified digital model of a last, with help from the scans of feet, could offer a better starting point. I did indeed do this, but only for one individual. Because I did not have access to the library of lasts from the last manufacturers, I had to buy scans of lasts and build my own models. For this individual, I built the model in Rhino based on a standard length and width and then modified it significantly using the scan of the feet as a guide. I sent my model out for carving and the lasts look good. Final fitting is in progress.

I also modified the physical lasts to fit and then compared the modified last with the scan of the feet to visualize feet in a last that fits according to the subjective judgment of the wearer.

Visualizing the Fit

For each person, trial shoes were made and the lasts adjusted as needed before the final shoes were made. The real test of whether the last fits is whether the shoe fits. Since I have some experience fitting feet, lasts and shoes, I thought it would be interesting to see how this fit is visualized.

The visualization of feet and lasts is not intuitive. While most people might imagine that a foot fits inside a shoe, and therefore should fit inside a last, when visualized on the computer the foot protrudes in all sorts of ways. An untrained observer trying to assess these superimposed images might assume a particular combination of foot and last does not fit when in fact it does. This is a limitation of computer modeling of elastic forms. The real world is elastic in ways that a surface scan is not. This is not to say that the computer can’t model elasticity, but that the wild variation of mobility and flexibility in human feet can’t be captured by a surface scan and modeled using only that. It’s important to set realistic expectations and know the limitations of the medium.

Below are images of feet and lasts and the shoes made on those lasts. Can you tell which of these fit to the satisfaction of the wearer?

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Click for Fit

Excellent from the start.

Same foot, same last, but cordovan is usually thick and takes time to break in. After some wear, it was a good fit.

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Excellent from the start.

Same foot, same last. The cordovan vamp was a bit too thick for this toebox. When the material creased, it was hard on the joints.

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A good fit. This boot features a thickly padded insert, which is not really modeled in the last because it was incorporated during construction. Still, it affects the fit.

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I made this shoe for demonstration purposes because it’s the standard size used for men’s shoes – EU 42/7. Most automated systems and manual methods measure my foot to be about this size, but I find it just a bit short and tight along the ball mount.

Many Kinds of Fit

To state the obvious, shoe size alone does not determine the fit. The fit really depends on the shoe. Not just the shape of the shoe, but what the shoe is made of and how it is put together. Shoes of the same size but different materials and/or different construction techniques will fit differently. One person may also have many fit preferences. Sometimes they may want a loose fit and other times a tight fit. Shoes are designed and used for many types of activities and occasions. For some occasions the fit is as socially constructed as the look. None of this is readily visible even in a really good 3D scan of a person’s foot.

3D Imaging in Custom Shoe Making

With the examples I’ve provided here, it is possible to see how the digital images of feet and lasts can be combined to visualize the fit. With some insight and knowledge of anatomy and biomechanics, feet, and shoes, it’s possible to make sense of these images and discern the ways in which a particular fit might be displayed. The difference between a shoe that fits really well and one that does not fit all that well can be very small, and may not even be visible in the digital images.

Facial recognition software can do a decent job of identifying landmarks of a face, but it can’t tell you anything about the personality behind the face. Likewise, 3D images of feet on their own are not enough to tell the whole story. In many ways the blueprint, or Harris Mat print, provides more useful information than a surface scan of a foot. To get a complete picture of fit, you have to know more about the feet, the person, and the shoes they want.

In the vast array of information needed to successfully make custom shoes, 3D imaging of feet and last can play a part. Given the affordances and limitations of surface scans of feet, infrared scanners might be serviceable enough. Improved resolution can’t provide more information about what is happening beneath the surface. For capturing images of lasts, however, a more accurate scanner is needed. The most promising role for 3D imaging, in my opinion, is the ability to capture and reproduce lasts that have been modified to a wearer’s preference. To make adjustments to digital last models and to be able to compare these changes is valuable indeed.

If you’ve ever wanted to sew your uppers for sneakers like the pros, but don’t have access to a Strobel sewing machine, don’t give up. Sew your kicks by hand!

How to hand sew “Strobel” construction.

1. The needle goes all the way in, then pulled back slightly which creates a loop in the thread.
2. Pick up the loop on the kerf side (very important!)
3. Pull some thread to make the loop bigger (this pulls the thread from the spool up the grooved side of the needle)
4. Pull the loop over the insole and upper.
5. Gently press the needle in to the loop for the next stitch, but don’t cover the eye.
6. Pull out the slack from the loop to set the stitch.
7. Repeat!

What exactly is a strobel stitch?

Strobel sewing the insole to the upper is actually a chain stitch. In many types of hand sewing, regardless of double or single needle, you have to measure out the thread ahead of time. With a chain stitch like this, like the Strobel machine itself which has no bobbin, the needle is fed directly off the spool. The good news is you can very likely sew to your heart’s content without running out of thread. The bad news is that if you drop your awl, kick your spool, turn away or pull the thread at the wrong time, you can easily pull the whole thing out. Ok, being able to pull the stitches out easily also means you can easily fix a section that you might have liked to sew differently.

When Strobel sewing an upper with a machine, the fancier models have a differential feed (one feed wheel turns faster than the other) so you can gather the upper at the heel and toe. Sewing by hand, you have to be cognizant of the need to do this and gather as necessary.

To make shoes this way, the perimeter of the upper and the perimeter of the insole have to match exactly. Compared to designing uppers with a lasting allowance, designing uppers for Strobel construction requires a high level of accuracy in locating the feather line and a lot of finesse to deal with the toe and heel. Components are handled differently and the last is typically just stuffed in once the insole is one.

Often there are at least 6 registration marks to make sure the insole and upper align properly in production. I drew a line connecting the center of the heel and toe and eyeballed it as I went. It worked out fine, but it means as I approach the center line, I know how much to gather, but after passing the centerline, the amount needed is ambiguous. Experience with uppers helps, or add all the registration marks.

Ok ok, these boots above aren’t actually sneakers, but the process is the same. One of these days I’ll make some sneakers.

This is a picture of my first usable 3D scan of a last displayed on my “Mac” using Meshlab. This is a mini progress report of sorts. Back in July, I received a Make|Learn|Build grant from the Oregon Regional Arts & Culture Council (RACC) to explore the ways in which 3D technology might appropriately fit into the custom shoe making process.

While it has never been an area of focus for me, 3D scanning and printing technologies have been a steady companion topic since I took my first shoemaking class back in 2004. My instructor, Alan Zerobnick, created one of the very early 3D foot scanning systems – Digitoe. My reason for learning to make shoes was to get out of technology, not deeper into it, so I have kept the 3D stuff mostly at arm’s length. In 2010, when visiting Ortho Baltic in Lithuania to learn more about the company and the lasts I purchased from them, I had my feet scanned using the Easy foot scanner which they manufacture themselves. It makes an extremely accurate scan of feet or lasts in seconds. Many early studies of using 3D scanners to scan feet focused on whether they actually work. Here’s a meta study of foot scanning from 2010 which mentions that scanner and was published not long after my visit (totally unrelated). Did they accurately record the measurements of the foot? Yes. We know that the scanners, scan quickly and accurately. Interestingly, the paper notes that the actual obtaining of measurements is a bit more nuanced than you might think. There’s more to it than just the the linear circumference of the foot as a cross-section of the mesh.

Over the past 10 years, more scanners for feet have become available. Some new ways of obtaining scans have been developed as well, including different types of structured light, infrared and LIDAR. None currently compare to the old Class 3 red laser for accuracy and speed. It’s clear, however, that this technology is being used extensively now in the development of orthotics and prosthetics. I am wondering, “How useful is this for the custom shoemaker?”

This question was asked in a research study commissioned by the EU and published in 2003. In that study, however, the emphasis was really on integrating 3D scanning and customization and large scale custom production of footwear. As you may know by now, almost 20 years later, we are not strolling through the foot scanners and picking up shoes made just for us on the way out. The report from IDEA-Foot (2012) summarizes a pretty comprehensive approach for scan to shoe at smaller scale. Despite a fairly comprehensive understanding of what this might take, the scan to production at any scale has mostly just fizzled. What you see now is more of a digital Brannock device. For roughly $7,000 you can have a system that will match scans of feet with shoes you carry. In theory, that’s why you might organize your shoe inventory by size, but hey, it’s out there. It’s really a system to aggregate demographic information that could be used to inform shoe shapes and sizes, but it’s not scan to shoe customization large or small.

The chatter and hype around 3D scanning and shoes never seems to diminish. It’s like 20+ years of the self-driving car discussion. These are some of my questions:

• Are some of these newer scanner types useful?
• Can they improve the custom shoe making process as it is?
• How and where is this sensible to apply 3D scanning and where is it just a time-wasting exercise in new technologies?

To start with, there is plenty of time wasting. It’s been months of struggle to get one usable scan. Let’s say you’re already a seasoned shoemaker who has previously developed applications for mobile platforms – they taught you that where you studied shoemaking, right? For example, to get this scan I had to complete the following steps.

1. Install a UEFI bootable installation of the latest Macintosh OSX operating system in order to compile an application for a non-Macintosh operating system (iOS for iPad).
2. Download and run the most recent version of XCode in order to compile the app for the most recent version of the iPad. (This assumes you already know how to use a beast like XCode to do anything.)
3. Get the C++ SDK for iOS.
4. Write some new C++ routines in order to simply save the obtained scan to the device.
5. Sort out depth-sensing calibration issues.
6. Arrange fixturing to get 360 degree access to the last.
7. Scan!

Now I can officially get started gathering real data for my exploration. Stay tuned!

During this time of pandemic and business closure, when I’ve been unable meet with clients as usual, and trapped inside due to fire and smoke, I have explored some techniques for using new materials to make composite shoe parts. I’m working with basalt fiber and epoxy. Below are my initial trials and some details on how I made them.

Background and Back Burner

I first tried to make carbon fiber parts when making prototypes for a pair of bicycle touring boots requested by a client. 10 years ago when I visited Ortho Baltic (a Lithuanian company where I buy some of my lasts), I was impressed with their ability to produce a wide range of very high quality carbon fiber parts. I contracted Ortho Baltic to make the carbon fiber midsoles for me.

Ortho Baltic can make such high quality parts because they are cured under vacuum in carefully controlled high temperature ovens. Because making custom shoes means never doing the exact same thing twice, I wanted to see if I could develop the facility to make custom carbon parts on par with Ortho Baltic when needed, but with less equipment. The fact remains that carefully controlled heating and cooling is really the only way to produce these kinds of parts.

Without using ovens, I’ve found that the next best thing is to use vacuum resin infusion. I watched videos on this over the years but kept the idea on the back burner because I was never excited about working with epoxy and carbon fiber. Epoxy is considered non-toxic, unless you sand it and inhale the dust. Carbon fiber is very dangerous to work with. When cut or sanded, particles of carbon fiber float into the air and get everywhere. Fibers can become embedded in your skin, eyes and lungs. Carbon fiber’s tiny particle size makes it an inhalation hazard. After carbon fiber has been set with resin, it can make splinters (like fiberglass) which make the parts no fun to handle. The coatings used on the fibers are often toxic as well (OHS Safety Sheet). Yikes. It’s enough already to do all the things needed to make custom shoes without also becoming an expert on plastics and producing custom composite parts. Nonetheless, my curiosity remained.

Front Burner

In the summer of 2019 I visited one of my students at his shop in the Shriner’s Children’s Hospital Orthopedics and Prosthetics lab. There I saw vacuum resin infusion used to fabricate all kinds of prosthetic devices, and that’s where I learned about basalt fiber. Basalt fiber is way less dangerous to work with than carbon fiber.

In August I finally started gathering the basic materials for a vacuum infusion setup. My first goal was to make a midsole which would provide some relief to a stiff big toe and ease toe-off. It is intended to be a combination of rocker bar, spring, and shank – all in one piece. Using the insole with a 1cm inset as a template, I covered the entire area using one basalt fiber braided sleeve. Since it’s a tube, the sleeve is equivalent to two layers of the same type of fabric.

The braided sleeve format means you only need to cut it to length – no fraying edges. It can be shaped easily without coming apart. If you could get a vacuum seal with the upper, the part could be made directly on the last. I was unable get a vacuum seal with this upper. There are a staggering number of places an air leak might occur, but I still think a vacuum seal with the upper on a last is possible.

Maximizing Green Stage

Since getting a good vacuum seal is so difficult, I decided try to keep my setup as simple as possible. I made a flat mold and transferred the part to the last before it has completely cured. If you get it at the right time, the epoxy will be cured enough to keep the part together as a unit, but also sticky enough to make a decent bond to the insole. This is also known as “green stage.” In green stage you can cut the part with scissors or a knife, if needed, which also saves you from sanding a too-big part. This also means I didn’t have to make a matching pair (left and right) of the much more complicated compound curved mold of the last bottom.

Using rubber cork, I made a mold for the part on a rigid piece of ABS plastic (4mm thick was the minimum). The base has to be rigid enough or it will bend under vacuum if the bagging film pulls on the perimeter.

With the film applied and tubing to pull the vacuum and let the resin in, it only takes a minute to actually infuse the fabric with epoxy and make the part.

So little resin is used to infuse the part that the vacuum changes hardly at all. The resin trap provides enough of a stored vacuum that you don’t need to have the vacuum pump connected to complete the infusion. It takes hardly 2 minutes to infuse. On the second run, I infused it much more slowly. Here’s about 13 minutes sped up to about a minute and a half.

Infusion – The Movie

Recap and Plastic Waste

To revisit the pieces pictured at the top of this article, different vacuum levels, or none at all, produce very different results. Looking at the four pieces above, and starting from the left:

1. 1. Using a two part mold to squeeze out the extra resin made a very nice looking part that felt good to handle and was quite strong. The extra resin provides a lot of strength, but adds extra thickness and weight.
   2. This part had a leaky vacuum seal, which is similar to using very low vacuum. More resin is allowed in and the whole assemblage is allowed more space for both air and resin. The resin saturation and thickness is not very consistent, but it is strong and functional
   3. The product notes for basalt fiber will tell you that 30in/Hg vacuum will result in a part that’s a bit too dry, or “starved.” 20 – 24in/Hg is recommended. I wanted to see what “starved” looks like. The part is very thin and light, but brittle. There is not enough resin for the part to maintain integrity and it can easily be broken.
   4. 20in/Hg worked well for me, and I would consider even 15in/Hg. In making this last part, I tried a two-step infusion – first infusing under full vacuum (30in/Hg), then releasing more resin with the vacuum set to 20in/Hg. The fabric is fully saturated, strong, light, and not breakable.

Sometimes you want a stiff part, sometimes you want something flexible. Sometimes you want a bit of both. Using a braided sleeve, the irregularity of the insole shape naturally creates stiffness in the shank and flexibility in the forefoot. It does this simply by narrowing and condensing the material in the shank area and spreading it out in the forefoot. More fabric can be added as needed to make the part stiffer overall or stiffer in places.

I’m already able to make parts without the need for flanges or other fabrication artifacts to be cut, sanded or otherwise discarded. My biggest challenge right now is trying to figure out how to develop ways to reuse the molds and setup materials.

When working with plastics and composites, I’m always shocked at the prevalence of single-use materials. For example, the plastic film that covers the mold is thrown away after one use. It’s difficult to remove it without destroying it, even though it’s quite tough. Bleeder cloth and infusion mesh are also not easy to re-use. A failed part is a genuine failure – there’s literally nothing other than the experience to be recovered and reused.

Movement, Clothing, and Shoes in Early Tango.

Presentation in two parts by Manda Levie, Master of Dress and Textile Histories, University of Glasgow and Jeff Mandel, Shoemaker. A free seminar as part of the Valentango 2020 tango festival.

Date: Saturday February 15
Time: 5:00-6:30pm
Location: Alaska Room, DoubleTree Hotel, Portland

Beginning with an overview of women’s fashion from 1905 to 1925, this portion of the presentation will explore how tango influenced mainstream fashion, with particular focus on the easing of strict Victorian social mores and the increasing need for freedom of movement. Original apparel, shoes and hats from the era will be modeled and discussed.

Learn the anatomy of tango shoes. This portion of the presentation will cover how women’s tango shoes were made – from the early days through the present. Discover how innovations in shoemaking during the 1930s are still with us today. There will be real-time shoe deconstruction!

When I first read the book Handmade Shoes for Men, I saw this picture: Der Leistenbauer (the last maker). I was struck at the time, and for many years to come, by the utter otherworldliness of the man, the tool and the activity. How was it that such a refined and beautiful shape was crudely hacked out of a piece of what appeared to be basically firewood?

While visiting the shop of Berluti in Les Rosiers-sur-Loire in April, I unexpectedly received a paroir (aka stock knife) as gift from Anthony Delos. (A famous shoemaker in his own right who’s business was purchased by Berluti.) Stunned, I thought about that picture and I really wanted to find out what it is like to make a last using this tool. It was pretty rusty and I have no idea when it was used last, or when it was made. Using one of the polishing wheels on my finisher, I cleaned it up and sharpened it.

First I had to make a handle. Thanks to my friend Greg, I learned a bit about how to turn a piece of wood on a lathe and how to make a T handle. We used maple for the shaft and T, and copper pipe for the front of the haft. The T was fitted to the shaft in much the same way that a leg or spindle is fitted to a Windsor chair – tapered shaft to tapered hole. It was pinned, but also set with epoxy.

I decided to copy a last that I already had. Using rough outlines of the profile and the bottom pattern as guides. Going primarily by eye, I chopped away. After 2 days and about 10 hours of chopping, I was totally wiped out and figured I had gone about as far as someone would with that tool.

Throughout the carving process, I used my existing last to compare the shape and size, length and width, toe and heel spring. I did not use a profile gauge or take the dimensions too seriously.

My guess is that a last maker would put it in a vise and clean it up with a file and spoke shave. I sanded and did the final shaping on my finisher.

The heel height and toe spring looks right and the lengths are the same. I could have spent days working on it to get it exactly right. Ok, I did spent 3 days on it. I’m just going to stop and call it good.

Learning which cuts were hard and which were easy was very interesting. I would definitely mount the paroir on a lower table next time. I managed not to cut or otherwise injure myself. While my right hand was really tired and sore, I did not get any blisters. I’m quite happy with the shape of the handle, and ultimately with the last I carved totally from scratch.

After spending time with shoemakers in France and the Netherlands and visiting Texprocess, the Spenle last factory and Pfaff’s industrial machine showroom, I have a lot to share!

Please join me for an evening of shoe talk and catching up.

Date: Friday June 28, 2019
Time: 5:00pm – 8:00pm
Location: ExIT Shoes in Union Station

Light refreshments served.