Adjustable thumb for InMoov

by Anar, published

Adjustable thumb for InMoov by Anar Aug 7, 2012


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These parts are to replace Hairygael's InMoov original thumb's base.
It gives more DOF by allowing the thumb's angle to be adjusted.
It uses the same wiring principle as for the fingers, and the knots will be hidden after gluing the tip part.

Updated 08/08/2012 : uploaded the parts for the right thumb

Updated 28/08/2012 : I made a new version of the base that is more respectful with the original InMoov's thumb angle. It's also stronger. Please read instructions.

Updated 16/11/2013 : after Balse's constructive comment (thanks!) I have corrected a few small problems. Only the right thumb is available ATM but I will also upload the left thumb soon.

Updated 24/01/2014 : I uploaded the new base that user Balse modified (left and right). Please read his comments to know why he made that correction. Thanks Balse !

For more information please visit http://www.reppersdelight.spacymen.com/index.php/post/2012/08/08/Thumb-UP!


  • Print using ABS and a 30% infill and supports set at 10-20 degrees.
  • After removing supports, fix the 2 biggest parts together with an M3 20mm bolt as axe.
  • Put 1 wire into each hole and make a knot on each
  • You can now glue the last part and it will hide the knots (you can use acetone for gluing).
  • take away the original thumb, remove the base part and fix it back to the new base.
  • put the 4 thumb's wires in place

Left version :
just print the left version of the base (balse version) and reprint the other two parts

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Is it possible to have the left version uploaded? Also, I haven't checked yet, but could the right just be mirrored? Thanks for this great improvement to InMoov!

Hi Adamj12b,
and thanks for your comment.
I will try to upload the left version ASAP but yes, the left version can be obtained by mirroring the right one.
I just don't remember on which axis the mirror should be performed. Probably XZ ? Not sure...
I also didn't have the time to check what user Balse has reported. Sorry Balse !

One more thing...
Gael has uploaded a new version of the hand that makes wireing simpler but I don't know if that new version has conduits for the 2 extra wires that my thumb derivative needs. I also have to check that.


Hi Anar
I found another little issue. If you install this Thumb with the covers on the wrist, it won't turn. This is because the original thumb base is rounded on the top and the bottom (im talking about the structure on the back side of the base, where the rod goes trough). Yours is only rounded on the top side.
I took the liberty to correct this little issue. I'm currently printing a sample to test it within the assembly. If everything goes according to plan, I would like to send my corrected version to you to publish here. I think it serves the users more if they find the complete Thumb under one roof, instead of creating derivates. (And I have absolutely no problem not taking credits by publishing it under your name!!!).
What do you think Anar???

Anar - in reply to Balse

Hi Balse !
I completely agree that all these derivatives are counter productive by adding ambiguity on what to print exactly.
That's why I have decided not to upload here all the corrections I make to the project and prefer to put them on my blog where Gael can come to pick them up and replace the originals part himself. This way leaving all the parts at one and same place under Hairygael's name and control.
So you're welcome to send me your correction and I will put it here with all credit you deserve.

Thanks again for helping at making InMoov even better !

There are a few issues detected by Slic3r with this design. Says there are self-intersecting facets.

Also, the V2 design cannot be printed on regular 3D printers, because the base part has a free standing hinges without any support to print it on.


I will check for any self-intersecting facets but I don't think there is any...

And I don't understand your remark about the non-printable part.

I've designed each part with ease of printing in mind and as you can see on the photos they have succesfully been printed on a "regular" FDM printer.

Balse - in reply to Anar

Same thing in Right_ThumbV2_base. Reversed normals.
If you open it with Makerware (9.9.9) you will see dark surfaces all around.
(But it will nonetheless print fine in most cases)

Balse - in reply to Anar


Maybe I can bring some clarity into this issue.
As I'm currently trying to print Right_ThumbV2, I discovered the following:

  • The self intersecting facets in Right_ThumbV2 are in fact Mesh Faces with reversed Normals. I only found this in one of the three Parts.

  • The second Problem luboudreau is talking about, is that one of the three Parts is slightly rotated around its X Axis. This results in the Part not standing perfectly level on the surface, witch then leads the Printer to print the bottom of the Part not in one but in three or so layers. Without support, this will results in a tanglement of the filament.

It would be great if Anar could look in to these Issues. I corrected these Problems using Blender. But I'm sure you would come to a much better result, as you have the original Files.

Hope I could be of some help...

Anar - in reply to Balse

Hi Balse,

for sure you are of some help !
Thanks for being so precise and with such a positive attitude.
Finally after nearly 3000 download someone report me the precise problem.

I will look at it ASAP and will correct the problem.
Thanks for clarifying and thanks to lucboudreau for reporting...
...and sorry I didn't pay attention at your first report.

Cheers !

Balse - in reply to Anar

Hi Anar

You are very welcome :-)
Keep in mind: I only checked Right_ThumbV2 and Right_ThumbV2_base.
I'm looking forward to print your V3 ;-) and if I can be of any more help, please feel free to contact me!!!

I cannot figure out which pieces are needed from each design (if printed new and not retrofit), nor do I have any idea what order the parts assemble in or how they should be fastened to each other. Do you happen to have a more detailed build guide?

Hi !
Please note that this is a derivative for InMoov's from HairyGael.
Or to be more exact, a derivative of the THUMB's BASE only ! (InMoov is a large project...)
So all the parts that are here are ONLY for replacing the original InMoov's thumb base.
To fully complete the hand (and eventually the InMoov's robot) you need to also download the files from the InMoov's project pages.
I hope it clarifies.

Anar, I dont see the file for the new thumbs complete. Is it (xxxx_ThumbV2.stl) and (xxxx_Left ThumbV2.stl)  and if so is that from your update on 8/28/2012 ?

 Hi pauliemagic and thanks for your interest in that thing !

Here are some precisions :

  • DOFThumb_left and DOFThumb_right are the first version with a small variable angle

  • Left_ThumbV2 and Right_ThumbV2 are the new version with a wider variable angle and should be used instead of the previous one.

But for those that had allready printed the version one, only the base of the thumb needs to be printed back. Therefore I have made them as separate file.
They are :

  • Left_ThumbV2_base and Right_ThumbV2_base

I hope it clarifies.

Anar,those 2 files Left_thumbV2 and Right_thumbV2 only contain the 3parts shown in your cad drawing above the one with the new angle and not all 6 of the pieces for the complete thumb. Could you clarify? Please pm me at [email protected]

 Hi Paul,

and sorry it is not clear enough but you need to also print the original InMoov thumb.

My parts are just a replacement for only the base of the thumb.

Yes, nice addition. You mention a v-shaped head screw. Do you mean a flat head?

  • In you photo there are only three wires/lines into the thumb. Is that right? And how does the finger action work - the sequence of movements????
Anar - in reply to bstott

bstott thank you for the comment !

Yes that's why I mean : a v-shaped flat head screw.

There is 2 new wires to animate the thumb's angle. So in addition with the two original ones that makes it 4 wires coming out of the thumb.

Both new wires are going on the upper side of the M8 bolt (back hand side) so that's why you see 3 wires
on the photo. The 4th one (responsible for closing the thumb) is on the other side of the M8.

And both new wires are going on the left side of the thumb's M3 axe (when looking at the photo).

I have tried several wiring but it seems this one was the best but you could try something else (wires on
each of M8 and/or M3).

I hope this will clarify a bit.

This derivative is for sure very usefull !! Could you modify it so we can still use the "topsurface" and "coverfinger"? As I see it, there is the attaching hole missing, and the M3 bolt added avoids contact for the "coverfinger" to be attached. Also there is an angle I gave to "thumb5" missing which allows better rotation once "topsurface" is fixed on. :)

I have just uploaded a new version that should have a much better angle. I have adapted just the base to allow for more angle. On my CAD it now has the exact same angle as the original.

Sorry I haven't look at the top surfaces problem yet...

@Hairygael - I've been using double backed tape to hold on my covers. I was thinking I'd cut screws and glue them in place to give the bolted together impression. The double backed tape is really tough stuff. You have to want it to come off with effort so, I use that. And I can place the cover to the position required to compensate for the prints from my machines. But, probably need screws when your hands are every where. :)

@bstott,Double side tape, of course! I's a good choice for one that doesn't have screws.

@Anar, this means we might need to add a servo someplace...Aaargh

I was sure for the "Aaargh".

I could allmost hear you saying it when I uploaded this thing ;)

I understand it might not be easy...

Hi and thanks for comment !

Yes that's why it is still WIP.
It's a first version to check it could work.
I will modify it again to include your predefined angles as one extreme.
Concerning the M3 nut it could be replaced by one with a V shaped head to allow for the top plates.
I will also add the holes for the top plates as
I didn't plan to use the top plates but will print them just to check that my next design is corrrect.

Cheers !