Knick's Prosthetic Finger v3.5.5

by knick Feb 14, 2016
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I found why my socket has not the right shape. I just used the stl file to print a prototype.
When I use openscad v3.5.5 I can see the new and good shape.

can you tell me how to setup in open scad if the finger is for a right or left hand?
I thing that the socket scallop is not on the same side for right or left hand.


I've added this device to the customizer I made for the e-NABLE community https://bymu.eu/customizer/?device=knicks-prosthetic-finger

The purpose of this customizer is to help recipients visualize their device in a 3D environment with the colors they want. The customizer has the ability to share a created color scheme with a short URL or save it as an image and thus can help recipients collaborate with those making the device.

The customizer is free to use for everyone!

Hi! After following the measurement instructions I opened the customizer and entered the following measurements:

Socket_width_bottom: 52-53mm
Socket_depth_scallop: 17-19mm
Socket_depth_top: 30-31mm
Socket_depth-bottom: 19-20mm

Middle_section_length: 19-20mm
Tip_length: 20-21mm
Base_extra_length: keep same

Linkage_length: 55-65mm (60)

Unfortunately, the .stl files that were generated seem to be scaled way off (like width and lengths of pieces being 100's of mm. I don't want to attempt to do the scaling myself because I have no reference. Is there a setting I missed (hopefully something obvious and easy to fix)

Edit: After closer review of the generated parts, the finger socket was generated as a solid cylinder. I think there is something wrong with the customizer.

I think I’ll need to significantly shorten the 2nd segment. My amputation left some bone above the joint, buts it’s useless for articulation. Are there any recommendations for modifying measurements for this type of case? .

Me and my woodshop teacher are trying to make him two new fingers, but we are having difficulty understating how to use SCAD or the customizer. Can anyone help?

socket_width_top : 65mm
socket_width_bottom : 67mm
socket_depth_scallop : 30
socket_depth_top : 40mm
socket_depth_bottom : 25mm
middle_section_length : 30mm
tip_length : 30mm
base_extra_length : .5mm
linkage_length : 100mm

Hello! Can I used a fishing line of 50 or 80 lb?

Comments deleted.

Hi peeps, I am having a problem figuring out how the base knuckle fit into the finger socket (the piece the stump goes into).

I printed the files from here to understand how the finger works, but the base knuckle is too big to slot into the finger socket. Is this a quirk with the files on here or is there a trick to getting it fit onto the finger socket?

You need to use a flexible material for both sockets or it won't work. Try ninja flex or something similar.

Am Buy This Please Help


when I put my measurements into the customizer, it changes how the bumber looks? what am i doing wrong?

Comments deleted.

I have printed the finger and is working fine but now i have request from a child missing two fingers. Please suggest .

Hello, great design! I'm waiting to print it now !. However, it would be ideal to have a file of the assembled model, it is somewhat complicated to understand the assembly. Thanks for your genius

Hi Seudo,

There are STLs of each part, but they are from my personal dimensions, and being a prosthetic, very unlikely to fit anyone else. Unfortunately given the required complexity of the design, there's no avoiding a fair amount of assembly. Best of luck!

  1. As a 3D printing enthusiast, I was thrilled to find this within the first few days of having lost my index finger... THANK YOU for sharing this!

  2. I have no experience with OpenSCAD and decided it was time to learn so I can use this (since the customizer no longer works), but immediately ran into a "Parser error in line 579: syntax error" that I can't figure out. Any suggestions would be highly appreciated.

Hi grtwht, I just tried and the customizer still worked for me - can you give me more details of your problem? try me at knick@dangercreations.com

Knick, you can disregard that comment about the customizer. It is working again (for a while it wasn't working on anything based on the other comments I was finding).

This is incredible sir! My boss hasn't had a middle finger for years! He showed me this and now I'm working on printing him one. I saw earlier in the comments that the top_socket_depth and bottom_socket_depth are not showing. I have the same issue. Have you updated recently? His measurements are pretty drastic.

hi.. am interested with the design.. :D what are the requirements for the length of the stump of the finger? hoping to hear from you.. thanks

Hi Knick, great work and we were successfully able to print the finger. We are currently working with a prosthetic doctor and his requirement is to print the entire finger in flexi material. Can this be done and if so any advice on the stringing of the same?


Hey, I'm trying to make the prosthetic for one knuckle. however, the customised won't let me download the files. Always get a runtime error. Could someone help me out with the files? For one knuckle...how would the finger base connect to the fingertip without the finger middle.

When opening the customizer I get the following error:

/usr/local/bin/openscad/openscad: error while loading shared libraries: libCGAL.so.10: cannot open shared object file: No such file or directory

How does this work? do I need to download something first?

Доброго времени.
Отрубило 2 пальца.
Хочу сделать для себя.
Не могу скачать со своими параметрами.
Вопрос как скачать с своими измерениями.
Все время выходит ошибка

Same here I messaged the owner I am trying to print one out too and the error runtime keeps coming up on multiple different computers.

Hello Mr.Knick!!! Can you tell if I' d be able to use these on my index finger and/or pinky? I have the first knuckle on both of them, just not much past that. Thank you!!!


I am French and I write to you because I try to adapt your finger for a person who is totally impregnated by his hand index without any cliff to adapt your system. If you know how I could allow him to fix it to his hand. As for the action of the finger, I think the racoder to the middle of the hand so that the prosthesis closes with the rest of the hand.


Mr. Knick
I like your dentures that you have done. I have a request from you. Could you send me the technical picture of this denture finger? I want to do it, but I'm making a mistake in the scale. Can you help me. I will follow the comments.
Thank you.
mail: nuzan_kbu@hotmail.com

Mr. Knick
Count Knick
Would you be willing to do this on your prosthetic finger measurements? I really need. please. thank you.

Working on putting together a finger and have found that ordering the metal pins from McMaster is faster and readily available.

We made 2 fingers, they are awesome. we thought it was an illusion. The only problem is filaments. In Poland are poor quality. Thanks a lot.

This is great, just lost my middle finger 2 months back, definetely going try this out!

the parts that i printed do not fit together. how should i resize them? the socket fits the finger well so i suppose the other parts in the archive should fit too

Can some one PLEASE help me make one of these for myself. I dont have a printer and i live in a small town so i do not have access to one anywhere. I amputated my left index finger right on the middle knuckle. Ive found it very difficult to do certain things and i could really use one of these. I would be willing to pay for one if its not too expensive. Can someone please help me?! If so please email me!!!! gavinaker25@gmail.com

Hi Colossus, did you manage to get your Knick's finger? If you haven't, by all means go to https://www.enablewebcentral.com and register yourself to receive one. That website organises volunteers to print and assemble devices for people who need them. I'm building one right now for someone in the UK. They will likely find a volunteer near your that could print yours - I will volunteer myself as well, although I might not be the nearest.

Hi there - others have had success bby reaching out to maker and 3 print shops to find someone willing to take on the project for time and materials costs. I wish you the best of luck!

Very nice! I'm one knuckle more on the same finger and hand (just lost the last one) and this is very similar to a design I was thinking of, only I was planning to have it anchor at the base of the finger. I just got a printer so haven't gotten around to it yet... Looks like I don't have to now! I do still need to make my design for a guitar slide, though.

yes! I've made a special one that helps adapt my stump to a slide. Also made one to close a chord. Key thing is that you can't have hinges, they are too unpredictable when trying to gauge where your finger will make contact with the strings when you don't have the benefit of touch feeling.

Do you think one would be able to play guitar (plucking the strings, not holding down chords) with these? Perhaps with something on the fingertips to help?

Either is possible, but generally work better as "fixed" fingers rather than with the hinges.

I still haven't made one, but I'd think think that a plucking prosthetic would be even more feasible than a chording one. I say this because length and flexibility isn't as much of a factor in plucking as it is on the fret fingers. They may benefit from having the design tweaked a little to give them a ridge to catch the string a bit.

I agree - a plucking prothetic is more akin to a pick holder, and shouldn't be too hard.

hi I really need one of these for my right pinky finger. I messaged you on youtube also. is it possible to use this for a replacement pinky, if so ill make me one. if not can you help me design my own, I have the printer just no good with the program for making my own stuff. thanks again

hi, it can certainly work for that. I'm unable to dedicate the time to making them (can barely keep up with my own and improving the design bit by bit), but others have had good success by paying 3d printing shops to take on the project


Thank so very very much for your work! :) I must do it for a friend, he lost only a single knuckle but in 3 fingers because of a cancer... So I need the version for when you lose only one knuckle. In your website you say "There is also a single knuckle mode – for folks missing only the first finger section,.." but where? I can't see it. In this "things files" I can only see the version for two knuckle lost.

Can you help me?

In addition, I am working in a prototype for my friend can play the guitar again :) but of course he is more easy because have 2 knuckles and I can work better in the prototype but maybe you can remix it to do it usefull to you.

Thanks so much.

hi, the things files are really only there as an example - the prosthetic is not useful unless it is carefully customized to your dimensions because everyone is so different. If you use the customizer, it will allow you to choose only one knuckle.

Has anyone offered help?

see comment above, single knuckle mode is supported in the customizer

I am in the same situation, trying to figure out how to build with just one knuckle. I thought maybe take away the middle part, but then the hinges don't fit together.

Hi - there is a single knuckle version in the customizer!

Is there any way I can produce these with an Ultimaker 2+ printer that I didn't realize only takes 3.0 filament? I read your comment below about using the 3.0 mm ninjaflex filament. Is that the best filament to use since my printer won't use 1.75 mm?
Thanks so much!

Hi there - the size of filiment really shouldn't matter, that's more of just a printer thing. More important is just your print settings to go slow and get high quality.

Comments deleted.

Nice! I am going to give it a try. I'm missing my left index finger. I really like your design.

Same here. I am going to a class to build a 3d printer and this will be my first project. Let me know how it works for you or maybe we can work on this together?

My thought was to have a magnet inserted under my skin since I don't have a stump to attach it to.

I'm looking forward to something like that some day. I'm skeptical a magnet could ever be powerful enough for the kind of pressure we'd like our digits to exert, but a titanium stud on the other hand :)

Hi there

I was just wondering if this would work for 3 fingers and a thumb? I have partial finger amputations on one hand due to septic shock. Thanks!

Hi there, sorry to hear about your accident. It does work for multiple fingers. Thumbs are more difficult, given the rotating nature of them.

Comments deleted.

Hi there

I was just wondering if this would work for 3 fingers and s thumb? I have partial finger amputations on one hand due to septic shock. Thanks!

Made one as a surprise for a friend who I thought had lost both joints on his index finger. They loved it but 'pointed out' that they'd lost only the upper joint! Has anyone worked on a 'shorter' version of this wonderful device? If not, I'll have a go and if successful post on the forum.

This design does do single joints (made one myself, see "Made" tab).

Hi, im new here, and saw this. I have had digital amputations to my right hand after necrosis. Would like to know more about your design. How can i contact you?

Could you post files to edit this in SolidWorks? I am having a hard time importing stl's and editing them. Thanks!

It's an OpenScad design, not SolidWorks. Load the file in OpenScad and see if any of the export file types helps you out.

Do you have CAD models for these other than STL? I am trying to bring it into solidworks and there is no way to get from an STL back to a solid model. Thanks

It's an OpenScad design. Load the file in OpenScad and see if any of the export file types helps you out.

This looks excellent. I'm going to print this as a surprise for a friend of mine who lost half his finger at work a couple of years back. Obviously if its a surprise I'll have to estimate the sizes, but I can always re-make it. I think he'll really appreciate this!

Super cool! We'd love to hear how it goes, and love to get pictures - either here on thingiverse, or we also have a facebook page too: http://www.facebook.com/dangercreations

i can't export as stl file.
error message :
Can't open file "C:/Users/���Ѿ�/Desktop/filename.stl" for export STL export finished.
are you solved this problem?

i solve this problem!
anyway, thank you~

Great, glad it's working!

Do do you change the measurements for a middle finger?

Yes, the measurements should be customized for every person's situation. There is a measurement guide that gives step-by-step on how to take the measurements, which get directly plugged into the customizer tool to generate for the individual's need.

Where is the guide

It should be in the downloads, but I keep the most up-to-date version on my site too:


hello. is this suitable for the thumb?

Hi - yes, you can configure for a single knuckle, in the event of missing one segment of the thumb.

There may need to be some customization to the linkage because of the way a thumb moves - it rotates much more than a finger, so the current linkage design might get in the way.

Can this design work for someone who is missing 3 fingers, or does this cause too much interference along the back of the hand?


Scott Collins
Instructor, Computer-Aided Design Programs
Ventura Adult and Continuing Education
Career Technical Education
Ventura Unified School District
5200 Valentine Road, Ventura, CA 93003
805.289.1744, Ext. 1205

Hi Scott. I've got some requests in my queue for that situation. I expect it to work just fine. It will probably require a new wrist linkage, which connects to bracelet in one spot and branches out with links to each hand, but that won't be too difficult.

Thanks for the reply, Nick. I'll see what I can come up with.

Great! I'll be happy to help or work with you, and incorporate it into the design so it can be easily configured by others in the future.

Can you tell me how to join Finger base and finger socket??


Hi there - if the socket is printed from elastic material like Ninjaflex or TPU, it should be fairly easy to join. If you wanted to do it all in PLA, then you could just combine the parts and slice them together to print as one part - but it's not comfortable to wear.

If you still have problems, make sure you've carefully removed any support material. There are also a couple settings for socket clearance that would help if you increase them, but too much will make it sloppy. Hope this helps!

this is so cool your awesome

Hi there - I'm interested in hearing from people who have printed these fingers for themselves. I am hoping to do some research into the use of 3D printed partial hand or finger prostheses. Would anyone like to share their experiences?
Thanks a lot!

Could you possibly give me some insight as to what I need to change on my Ultimaker 2+ to print the flexible parts using ninjaflex? I have 3mm sapphire Ninjaflex, and at current settings, the base does not fit the socket. What do I need to change? What settings do you recommend?

Hi - Sounds like you're getting the part to print, which is usually where people have problems with NinjaFlex - from binding in the feed gear and such. In which way does it not fit the socket?

It is a snug fit, and the support material needs to be pulled out of the inside of the socket ridge/interface point, should come out easy with needle nose pliers. Depending on how well it printed, you may want to clean up any extra material to make sure there's room for the ridge on the base to seat in the socket.

I print mine with little clearance, and firmly have to press the sides of the socket against the base to get it seated. You can also try raising the socket clearance, under advanced settings.

Hope this helps!

Update: The socket width settings which were not appearing, should now be fixed!

It says it can work w/ 1 knuckle instead of 2 ... so what parts to take away then ... it looks like you have to have the middle part regardless? Is there an STL file for just 1 knuckle to fingertip to fingersocket then?

There's an option in the customizer near the top that lets you choose the number of knuckles. In "1 knuckle mode" there is a segment that is a merge of the tip and middle section.

oh sorry i now see the customerize button lol!

Hi! I went to the customize page and just changed the finger tip cover and tip knuckle to "1 knuckle" and then "create thing". However, I've done it several times and it comes out as an error. What am I missing and are you getting the same thing? If you do happen to have the STL of both can you just e-mail it or put it the files on your thingiverse too? I'm not sure what I'm doing wrong on that customize thing.

I just updated, and tried again - still working for me. I'd be happy to send you the STL, but it will depend on your settings. Send them all to me, and I can generate it. Or, it's really easy to get OpenSCAD (free) and open the .scad file in it. Then change the values in the text editor yourself, and choose "render" (takes several minutes), then "export STL". Repeat for each "part".

In the customizer, choose Part: "Tip Knuckle". Then, after it appears, change from 2 to 1 knuckle, and you should see the new modified tip piece. This will work directly with the base, no need for a "middle" part.

knick - I just tried it again and pressed "create thing". It took 15 minutes and still came out as "error". Try it yourself as well.

chem20 - I found this issue finally! It wasn't always doing it for me, but I finally reproduced it and fixed for good.

Great news! I've printed a 1 knuckle for my friend, looks good so far!

Are you talking about on the SCAD file because I don't have the program. Is there an STL file you can put it for me? I have a person who just needs 1 knuckle! Thanks.

In the same boat as ezcorer - need to increase the width of the socket, but can't see where to modify the width in the customizer app.

Hi - see the reply I just put for him!

I must just be missing it but how do i get the socket bigger? i have been looking at all of the settings but im lost.
i need the top to be 20mm and the base to be 26mm and 35mm long.

Ok - should be fixed. There were some comments in the code that previously were ok, but it appears a customizer change didn't like them. All the settings should be working now!

I must just be missing it but how do i get the socket bigger? i have been looking at all of the settings but im lost.
i need the top to be 20mm and the base to be 26mm and 35mm long.

I see what you mean. I have no idea why those settings aren't showing up - I see them in the scad file:

/ [Socket Fitting] /

//diameter of the top of socket, roughly the diameter/width of the finger stump nearer the top
socket_width_top = 17.75;
//diameter of the bottom of socket, roughly the diameter/width of the finger stump bottom
socket_width_bottom = 19.25;
//Depth of the socket, roughly equates to the length of the stump
socket_depth = 27.25;

I'm currently traveling in India, and cannot fix from here - but will mess with this in a about a week and get it figured out. In the meantime, here's a workaround:

  • Install OpenSCAD
  • download my scad file and open it
  • directly change the values in the file
  • select the right "part" to print, in this case the socket.
  • choose render, this will take ~5 minutes
  • Export as STL

Hope that helps!

can I print this in all pla? or do i need ninjaflex (ninjaflex is a pain to print)
could you also design printable knuckle pins? and could i use regular fishing line?

For the other two questions - I've found that any thinner fishing line tends to dig/cut into the PLA and stick, same goes for mono-filiment. This particular kind has been far better.

If you wanted to use plastic pins, the way to go is to just reduce the diameter of the hinge pin hole (under advanced clearances IIRC) to about 1.9 mm to allow you to directly use a section of 1.75mm PLA or ABS filament. You could do it as-is, but the hinge will be a bit sloppy. I found that metal slides way way better - so if this is for real use, I highly recommend at least using the aluminum wire, if not steel pins - which I've recently switched over to.

Not currently, the tip and the socket are pressure fit, and so require something flexible. Regardless - I can tell you from experience that the flexible socket is the only way to go for any measure of comfort - my very first wearable design was a PLA socket and it's the very first thing I changed.

Lately I've been using SainSmart Flexible TPU, which I found on Amazon. It's cheaper than NinjaFlex (about same as PLA) and is also much firmer. As long as I print slowly I can print from my Flashforge/maker clone, or even my little PrintrBot simple, with no modifications. I use 20mm/s on the big printer, or 10mm/s for PrinterBot - which is more prone to kinking.

Comments deleted.

Is there someone that might be able to make a couple of these for me? I lost my pinky and ring finger but I don't own a 3D printer. I would be willing to pay for these as my insurance is giving me the run around about prosthetic fingers.



Hi Rob,

We can probably work something out! I have started to build them for folks that aren't equipped to do themselves. Hit me up at knicksfingers {at} gmail {dot} com, where I track my queue. I'm working up some standard instructions for taking measurements. I have a short waiting list, but working through it.

muy bueno gracias!.

Wonderfull work, it will be my masterpiece!!

: )

Trying to customize this for someone but I just can't get it looking right. He's a larger guy and according to his measurements he's got 1 7/16" long nub and 28mm wide, his other finger on his other hand is 3" long and 19mm at the tip. Now, that width might still be due to swelling as he lost the finger about a month ago but putting in those measurements the base always looks huge compared to the rest. I don't have as large a hands but I tried putting in my own measurements, 2 9/16" overall, 20mm width at the knuckle and about 18mm at the tip and while it looks okay it doesn't look as good as the model's hands in the picture. What am I doing wrong or what do I need to change? Should I just scale it up on the printer after I customize it here?

You definitely want the model to match exactly what you need, any resizing after is not parametric and it might not interface well.

The measurements you describe seem fairly reasonable.

The hands/examples shown, and default values, are all from me. My other index finger is 74mm long, so just shy of 3 inches. When measured with a caliper, my nub is about 16mm (without compressing skin too much).

You'd want to make sure the lengths here (base, mid, tip) add roughly to the amount he's missing.

If you post the specific values you're entering, that would let me reproduce what you're doing and I might be able to tell what is wrong.

Another overall suggestion; focus on the socket. Get that printed so it fits firmly (it should be snug at first, a little lotion helps). Get that so it fits well, since it is the interface point, and then worry about sizing the finger portion.

As you say, only 1 month later he'll still be very swollen, so that's part of it. I think my first one was 24mm wide, vs 16 now. You'll want to be prepared to occasionally make smaller sockets :)

For his I was putting finger size settings: Tip length = 25mm, Middle Section = 26.75, and socket settings: Socket Width Top = 26, Socket Width Bottom = 27. Would the base knuckle and the finger socket be the ones changing as the swelling goes down or just the socket? Also seems to be a problem with the plugs, I tried importing a version I was trying earlier and they were tiny in Simplify3D. Thanks for the help!

I'll take a look tomorrow to see how these settings seem.

I thought the previews generated for the plugs looked a little off too, I'll check it out.

The base knuckle wouldn't have to change- only the socket.

I think you're measurements are fine. In looking at the first finger I actually wore, about a month after accident, it was a similar ratio - with an oversized socket.

What will likely help is increasing the finger width, to better match his own digit thickness, and to match better with the socket. There are some advanced settings for this, but they aren't perfect yet - I'd focused much more on the length settings initially. Currently, adjusting middle-width or middle-diameter more than a small amount results in problems with the way the hinges come together. I'll do a little work and see if I can make it easier to adjust the width in a parametric way. I'll also take a look at the plugs. Hopefully can have an update this weekend.

Ok, uploaded a new one, sorry about the wait. This fixes the plugs, first of all. It also should let you configure the middle_diameter and middle_width up slightly as needed to make the finger thicker, just don't go too far. I like to print a base + mid + tip once I configure new settings, and make sure those 3 parts fit together well before moving on to printing the rest of the parts.

Awesome work! Can you upload the file for the hook?

Thanks! Oops, missed that one. Should be there now.

No, Thank YOU! Great Job with this!