Silicone finger tip mould

[Ew Chee Guan]

Hi,

This is the substitute for Lee Tippi which I mentioned before , in G+ and I finalised the stl files. , I use normal acidic silicone with a little bit of corn starch ( mixed well, need to work fast to avoid too dry to work on ) 1:5 , and it dry within an hour, and cure 100% and ready for use the next day. Acidic smell will go away once dry 100%.

I can make 12-15 sets of silicone tip with a new tube of 300ml acidic silicone .

The mould can be scale up for larger size. I coat a layer of dish washer soap on the mould before I apply silicone on it, beeswax works too.



https://www.youmagine.com/designs/silic ... able-hands

[Jason M Bryant]

Neat.

How about if they were molded right onto the fingers? We could make a version of the fingertip model the has some of the tip removed. The fingertip would fit into the mold, and the silicone would replace the missing tips of the fingers.

Here's a quick version that I threw together.

mold ready finger.jpg (20.19 KiB) Viewed 5991 times

finger and mold.jpg (22.79 KiB) Viewed 5991 times

[Ew Chee Guan]

Yes, I'm thinking of this also, my idea slightly different, I'm thinking of moulding a half portion of finger tip as you described, but try to make it detachable, so that I can replace it when needed.

Yours seems like a great idea too, are you going to try it ?

[Jason M Bryant]

I'm getting a little backed up on ideas that I need to work on.

How about I make the models, then send them to you. You can try it and compare it to your own version. That way the same person can make the same silicone gel and make a direct comparison between the different versions.

[Jason M Bryant]

Here's the finger mold and the finger with the recessed area. I based the mold off of my remolded finger, not the standard RR finger. If people prefer the standard RR finger, I can make a mold for that.

https://www.dropbox.com/sh/g9hynjh1u8f2 ... 6ft2a?dl=0

There's a little space between the finger and the mold. I wasn't sure if it needed a little space to let the excess silicone escape. If you want a mold with a tighter fit, let me know. I can do that pretty easily.

I can also make the little holes a little bigger, if the silicone mix isn't getting in them.

Try this out. See how it compares to yours. Even if it doesn't work great, maybe it will give us some good data.

[Ew Chee Guan]

Hi,

Thank you for your fast file .


I will download, print it and post the result here. I'm very slow on 3D cad, still new .
Thank you.


Ew

[Ew Chee Guan]

Hi,

I print it out 100% last night. I forgot to keep my black old PLA in dry box for quite some times, , (I'm using camera dry box for my filaments. ) The black filaments degraded and looks ugly.
The silicone mould looks good, take some time to apply silicone but I'm satisfied with the result. about the edge that I pointed, I can feel its a little bit loose and maybe you can add some kind of structure so that the silicone can hold it in place.

The touching feel just exactly like human skin.

I will try to print another one at 160% size .

[Jason M Bryant]

Wow, that looks great.

I'll think about the shape of it. Maybe I can make it hold better at that joint.

[Jason M Bryant]

Here's one other thing.

You mentioned replacing the silicone. Could you try cutting it off the finger? The little "girder" holding the silicone is flat on both sides. It might not be too hard to just cut it off and put new silicone on it.

[Ew Chee Guan]

Bon't worry about the silicone replacement problem , I think it's easy, just peel off the old silicone and re-apply new one ,
Don't know how long it can last , I will try to use it in one of my recipient's hand and see how long it can last.

[Ew Chee Guan]

Hi ,

Just wish to inform you that the silicone can be easily peel from the finger.
I think we need to find out a better solution to hold the silicone.

[Jason M Bryant]

Let's try one more thing. I just finished finger_recessed_v2 before I saw your message. I think it will hold the silicone much better. Maybe that will be enough.

I've uploaded that, so you can give it a shot.

[Ew Chee Guan]

No problem , I will print and try again.


Thanks!

[Ew Chee Guan]

I printed V2 120%, and I can feel its much better now, the silicone can hold on its place far better than the previous one. My first attempt failed, because silicone didn't fill in the small holes and it can't hold on its place.
Since the mould need to press from its top, maybe small holes from top will help on this issue, as seen on the picture I pointed.


Ew

[Jason M Bryant]

Okay, I put up some new files. One has the holes you suggested. The other two have a different structure. I printed them out and they seem pretty sturdy. The question is how well they hold on to the gel and how nice they feel.

These new ones would definitely be harder to clean out if you needed to replace the gel tips.

Anyway, give them a try and see what you think. They're in the same dropbox folder, labeled as v3.

[Jason M Bryant]

By the way, if this works, I've got another idea. I think I can shrink the area taken up by the tie-off bar a little. That would allow room to put gel on the sides of the fingers. Then we'd have added grip on the middle part of the finger, not just the tips.

[Ew Chee Guan]

Thanks for the V3 and the test files, I'll print it out for testing.
I'm thinking of using this in one of my recipient and see how long it can last.

[Jason M Bryant]

Ooh, I'd love to get it to a recipient.

I'm working on a new finger design. Even if I can't expand the area of the silicone, I think it will be an improvement. Plus, I can get you a thumb with a soft tip, too. I really like having a thumb that is wider than the fingers.

We should have something really awesome by version 5 or 6.

[Ew Chee Guan]

Hi Jason ,
Sorry I forgot to reply here. Tested all the design , the best one is the one you modified from V2. It works perfectly.
Maybe you can make a flange around the edge where the fingers and silicone touches?

[Jason M Bryant]

Okay, Version 4 is in my dropbox. I based this design on my new finger designs, so there is a finger *and* a mold.

I put in a flange. On the 100% finger there isn't a lot of room, so see what you think. It also might print better or worse on a larger hand.

The mold is a little more substantial. I was afraid the walls might break off on the first one. However, the walls only come up one millimeter past the recessed part of the finger. Let me know if you need it to be deeper.

If this works out, I'll make you one for the thumb, too. I like a nice, wide thumb.

[gabemedina23]

Jason... I was wondering if this project was scrapped. Was there any testing done on a recipient? Can I use this on the phoenix hand?

[Jason M Bryant]

The fingers so far are for the Raptor Reloaded, although it could be done for the Phoenix as well. Ew Chee Guan has been busy with work, but last I heard he used these fingers with a recipient. I'm waiting to hear how that has gone.

[gabemedina23]

I can see now that i printed it, that this would not work for the Phoenix, ty. would it be possible if you have time to design one for Phoenix?

[Jason M Bryant]

Sure, I just made a note of it.

[Ew Chee Guan]

Hi Guys,

Sorry for super long wait. Really busy recently.

I'll visit one of my recipient in x'mas holiday. I will report in detail then .

Regards,
Ew

[Nicholas Hall]

Here is a link to similar work that Andreas Bastian did last fall on a fingertip mold for the Raptor. He had a similar approach, but he used Sugru. Might be some useful info.

https://plus.google.com/+AndreasBastian ... HVXxsC4KZn

Here is the instructables page:

http://www.instructables.com/id/Sugru-O ... ted-Molds/

[Nicholas Hall]

Also here is a link to some work I did on gluing Oogoo (that's the generic name for silicone mixed with corn starch).

https://plus.google.com/110736851786370 ... 1CGjvCNDNr

This is really terrific stuff. I allows you to "paint" silicone anywhere on a finger or palm to get extra grip.

I tried dozens of glues, but the only one that will glue oogoo to plastic is DAP All Purpose Adhesive Sealant. It's food safe, and it sticks like a champion. Oogoo made from it will not stick directly from plastic. The easiest solution is just to use it straight out of the tube, it dries adequately in overnight at 1/4" in thickness. If you want to make oogoo with it for some reason, it is first necessary to spread a thin coat of this on the plastic like a primer. Then glue the oogoo to the plastic.

20141106_012955 (1).jpg (1.43 MiB) Viewed 5015 times

[Nicholas Hall]

Also here is a link to some work I did on meshes and oogoo (cornstarch mixed with type 1 silicone). Laird Popkins wrote an open scad program for me that allows for the creation of any mesh you can imagine in any size. The bonding is incredible with oogoo. It's probably overkill for your application, but it would allow you to remove the fin with holes in it to capture the oogoo. the reason this is advantageous is that it makes the fingertip more compressible like real human fingertips which aids in gripping.

https://plus.google.com/110736851786370 ... GLzGvVbmyG

https://plus.google.com/110736851786370 ... XiFVSB4wZm

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