From Digital Design to a Wood-Like Finish
3D printing is changing the way orthopedic shoe lasts can be designed and produced.
Instead of starting with a physical wooden last and modifying it step by step, the complete process can be moved into the digital world.
And that changes more than just how the last is manufactured.
Why 3D print a shoe last?
There are several advantages to 3D printing orthopedic lasts.
Less material waste.
A traditional last is typically machined from a larg block of wood. 3D printing only deposits material where it is needed, resulting in significantly less waste.
No milling dust.
There is no need to turn a large block of material into a last by removing most of it. That means less dust and less cleaning in the workshop.
Local and on-demand production.
With a suitable desktop 3D printer, lasts can be produced directly in the workshop. There is no need to manufacture them elsewhere and ship them across the country, or even across the world.
Fast iteration.
Perhaps one of the biggest advantages is that the physical production of the last can be postponed until the digital design is right.
A different workflow
The digital workflow for a 3D printed last can be quite different from the traditional process.
In a traditional workflow, you might first produce a wooden last. A test shoe is then made from that physical last. Based on the feedback from the fitting, the physical wooden last is modified, and the process may be repeated.
With 3D printing, the order can be reversed:
- You can design the last digitally and 3D print a test shoe directly from the digital model.
- The fitting can then be evaluated and the digital last adjusted accordingly.
- Only when the digital model is right do you print the final last.
This means that, ideally, there is little or no need to physically modify the final 3D printed last.
That opens up another interesting choice: what material should you print it in?
PLA, or something more like wood?
If the final last does not need significant physical modification, a standard and cost-effective material such as PLA (Poly Lactic Acid, a bio-polymer) can be a perfectly practical choice.
But there is another consideration.
Orthopedic shoemakers are used to working with wooden lasts. Wood is easy to sand, shape and modify, and many traditional workshop techniques are based around working with wood.
So what if you could have the advantages of 3D printing, while retaining some of the characteristics of a wooden last?
That’s why we developed our wood filament for 3D printed lasts.
It is designed specifically for printing orthopedic shoe lasts that can still be worked with using familiar techniques.
But does it really look and behave like wood?
We decided to put it to the test.
Solid or hollow: 2 ways to make a 3D printed last
There is another choice to make when designing a 3D printed last: how you build the inside.
One option is to print the last with a substantial outer wall and an internal structure that provides the required strength and mass.
For example, you could specify a 5 mm wall thickness around the last and fill the inside with an appropriate infill structure.
The advantage is that the complete last is produced in one printing process. There is no need for additional filling material afterwards.
The downside is that this takes more time and uses more filament.
There is also a practical limitation to keep in mind: the wall thickness determines how much material you can remove during manual finishing.
If you print a 5 mm wall, you can only sand away up to approximately 5 mm before you reach the internal structure.
This is something to consider when designing the last and deciding how much manual modification you expect to do afterwards.
Hollow and foam-filled
An alternative is to print the last as a hollow shell and fill it afterwards with last-making foam.
This can be faster and may use less filament for the printed shell.
However, it introduces an additional production step and involves mixing and handling a chemical filling material. It is therefore a more messy and chemically intensive process.
So there is a trade-off:
Printed structure:
More printing time and more filament, but no filling step afterwards.
Hollow + foam:
Less printing time and potentially less filament, but an additional chemical filling process.
Which option makes the most sense depends on your preference, taking time, costs and process into account.
Need help choosing a printer?
Not every 3D printer is equally suitable for printing orthopedic lasts, especially if you also want to print test shoes.
If you are considering bringing 3D printed lasts into your workshop, we can help you choose a suitable printer and advise on the printing process and recommended settings.
Need help choosing a 3D printer for orthopedic lasts and/or fitting foils? Get in touch.
Check out our 3D printing filaments for orthopedic lasts and choose the one you prefer: https://www.footprint3d.nl/shoe-last/
