Help with printing prosthetic sockets

[Rburke1963]

I am a certified prosthetist who really embraces new technology. I bought and assembled my Rostock Max V2 in January off this year. Prior to this I had no 3D printing experience and still feel overwhelmed at times. I am sure everyone has seen in the news all the stories of 3d printed hands for children with no insurance. Awesome organization which I am a member of but have yet to be contacted about providing the service. While printing hands is impressive I also want to bring this technology to Lower limb prosthetics as well. I feel confident with some new filaments being introduced such as Bluprint from Taulman that the materials will hold up to the weightbearing forces applied to them. Ok let me get to my problem. I currently use a digital device to capture a persons residual limb shape and size. I have a prosthetic cad program which allows me to modify that shape for a comfortable weight bearing socket. Then I send it to my inhouse CNC carver which produces a positive model out of urethane foam. I either vacuum form plastic or laminate over the positive model to produce the socket. With the ability to 3d print I can eliminate a couple of those steps. Here is my problem. I export my shape as an STL file which would if I printed it give me the same positive model that my carver does which would be useless. What I need is the ability to print the model larger and be able to control the thickness of the walls. For example if I wanted my socket walls 6mm thick so that the original stl file would fit perfectly inside of it how would I go about this. When I read this post I realize how confusing I am. If anyone has ideas how to help me solve this problem I would be forever grateful. Thanks and I look forward to your responses. I have learned one thing from my short time on here that there are a bunch of smart people on this forum who are eager to help out.

[teoman]

You need a good CAD software to do that. I have never needed to do that, but i am sure it can be done.

STL files are not really that great to work with. What other formats can you output?

[DLS3141]

So, if I understand you correctly, what you really want is an stl file for a piece that would fit over the outside of the socket that you vacuum form, is that right?

I think that could be done in SolidWorks or Inventor, but I'm not exactly sure how, probably by abusing design tools for making injection molds.

[teoman]

I just checked the software I use. I am using fusion 360 and using it mostly in modeling mode. But it does have a "sculpting mode" where you can select surfaces and thicken them, split surfaces in to lines and then push and pull those lines (much like playing with playdough) to create your shape.

My grasp of the english language is not firm enough to paint a mental picture for you, so here is a video of what you can expect to do with "sculpting" type of modeling:

https://www.youtube.com/watch?v=OphzbTt4rKo

I have no relation to the video.

[Jimustanguitar]

Out of curiosity, where are you located? My dad is a new 3D printing enthusiast and a 1 year old below knee amputee. He loves being a guinea pig and would be all in for a project like this, even if he had to print the parts himself.

He's currently working with a prosthetist in Ft. Wayne Indiana (new this week) because he interviewed 4 or 5 offices and both doctors there had artificial legs, so he thought he'd get more experienced help.

Anyway, what you're doing is awesome. I hope it turns into a great opportunity for you and your practice!

[bot]

NetFabb can do this. Meshmixer can do this. Blender can do this. 3D Coat can do this.

I would advise going with Meshmixer first. Load the STL - Edit - > Make hollow. Lots of functionality. You may want to look into boolean operations as well, which I would use Blender for or NetFabb if you have the budget for it.

[Rburke1963]

You need a good CAD software to do that. I have never needed to do that, but i am sure it can be done.

STL files are not really that great to work with. What other formats can you output?

I can currently output as - AOP DXF XYZ IGES STL ASCII STL BINARY

[Rburke1963]

So, if I understand you correctly, what you really want is an stl file for a piece that would fit over the outside of the socket that you vacuum form, is that right?

I think that could be done in SolidWorks or Inventor, but I'm not exactly sure how, probably by abusing design tools for making injection molds.

Yes and no. I need to create an STL file of desired thickness that would fit over the socket to 3d print. trying to get away fro vacuum forming.

[Rburke1963]

NetFabb can do this. Meshmixer can do this. Blender can do this. 3D Coat can do this.

I would advise going with Meshmixer first. Load the STL - Edit - > Make hollow. Lots of functionality. You may want to look into boolean operations as well, which I would use Blender for or NetFabb if you have the budget for it.

I am currently using meshmixer as you have suggested but I can only hollow out to a max of 4mm wall thickness which is not enough. I am very new to all of this .Is there a way with meshmixer to get my walls thicker than 4mm.

[teoman]

Would you mind providing an stl, iges and dxf?

I can have a look at it in fusion to see if it is easy.

[Rburke1963]

Out of curiosity, where are you located? My dad is a new 3D printing enthusiast and a 1 year old below knee amputee. He loves being a guinea pig and would be all in for a project like this, even if he had to print the parts himself.

He's currently working with a prosthetist in Ft. Wayne Indiana (new this week) because he interviewed 4 or 5 offices and both doctors there had artificial legs, so he thought he'd get more experienced help.

Anyway, what you're doing is awesome. I hope it turns into a great opportunity for you and your practice!

I am located in Albany NY. When I have a viable solution that is safe for use I would love to get your dads input. I would be willing to collaborate with his prosthetist in Fort Wayne so that everything is on the up and up.

[Rburke1963]

Would you mind providing an stl, iges and dxf?

I can have a look at it in fusion to see if it is easy.

How would you like me to send the files? Email?

[teoman]

You csn upload them here if they are not confidential.

[Rburke1963]

Would you mind providing an stl, iges and dxf?

I can have a look at it in fusion to see if it is easy.

How would you like me to send the files? Email?

Jackman, Trevor.dxf

DXF

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Jackman, Trevor.dxf

DXF

(381.42 KiB) Downloaded 348 times

Jackman, Trevor.stl

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Jackman, Trevor.stl

(2.08 MiB) Downloaded 336 times

[TFMike]

Sounds like you need to enroll in a one week autodesk inventor course at your local community college, tell the instructor what yo uare trying to do and take a lot of notes. The software will come with the class price, or it should anyway.

[DLS3141]

Sounds like you need to enroll in a one week autodesk inventor course at your local community college, tell the instructor what yo uare trying to do and take a lot of notes. The software will come with the class price, or it should anyway.

It would be a good way to learn if and how exactly it could be done with the software, but the educational license for Inventor excludes any commercial use, so his use for learning the software in class would be OK. Using the software under the same license for his work wouldn't.

[Captain Starfish]

Can do this in FreeCAD but it takes a bit of stuffing around.

Your basic steps:
1. Import the STL.
2. Cap the mesh and turn it into a solid.
3. Copy and scale it.
4. Subtract the original from the scaled version.

Of course you could make your own limb solid and subtract the stump mesh from it, too.

[Generic Default]

RBurke, could you post a few screen captures of the parts you're trying to make?

For materials, any of the nylons will work great for prosthetics. Even blue trimmer line nylon is very wear resistant and strong. Just make sure you print your parts hot enough to get good layer adhesion.

[teoman]

My cadding skills were not quite up to it unfortunately. And fusion 360 says that there are a few too many triangles to run properly on my laptop

[Rburke1963]

Can do this in FreeCAD but it takes a bit of stuffing around.

Your basic steps:
1. Import the STL.
2. Cap the mesh and turn it into a solid.
3. Copy and scale it.
4. Subtract the original from the scaled version.

Of course you could make your own limb solid and subtract the stump mesh from it, too.

Since I am not very good or familiar with free cad would it be possible to provide some more detail how to do this. The only thing I have figured out is how to import it. Thanks.

[Captain Starfish]

Looking at it again, not what you want I suspect. This would end up subtracting your model from some other shape that you'd have to design.

Sorry for the bum steer.

Much better to be able to just thicken the mesh outwards, would be the equivalent of a vac form cup then.

Creo Parametric will do that nicely but, at $7k a licence, it's a bit much for experimenting.

[J.R. Spencer jr]

Sizing it up can easily be done by scaling it up in your slicer program.

[teoman]

Scale it up in cad and then subtract the original?

[J.R. Spencer jr]

My son told you about me last week. I am a bka and I am dealing with a prosthetist in Fort Wayne, In. This last week I had my second appt with him. He used
Lazer scanning on my stump. Within 2 hours he had my first test socket ready to test. I asked him about software to do what you wanted, he said its already out there. He didn't state any particular software, but his computer was running a software called tracer. His name is Shaun at 260-432-8886. Good luck J.R.

[Rburke1963]

My son told you about me last week. I am a bka and I am dealing with a prosthetist in Fort Wayne, In. This last week I had my second appt with him. He used
Lazer scanning on my stump. Within 2 hours he had my first test socket ready to test. I asked him about software to do what you wanted, he said its already out there. He didn't state any particular software, but his computer was running a software called tracer. His name is Shaun at 260-432-8886. Good luck J.R.

Thanks for the info. I have been using tracer for the past twenty years. It is awesome prosthetic cad software but it is set up for Cnc carving which I've been doing since 1990. The tracer software allows me to export my file as an stl but it doesn't allow me to modify the stl file to get the desired socket thickness for my 3d print. I have found some softwares which will allow me to do what I need but they are rather costly. Is your prosthetist Shaun involved in 3d printing ? Hope all goes well with your fittings. It sounds like you are with the right people now. I commend them on their utilization of cad cam in their practice. I still can't beleive how many practices choose to do things the old fashioned way. Anyways good luck to you and I will keep you updated on my progress in this 3d printing journey.