The Quest for Perfect Fingertips 3 Prusa XL and Colorfabb

in this video i let you know how its going using the prusa XL and colorfabb filament to print the new version of the fingertips. I've also discovered a new issue that i'm dealing with, tackifiers. thats the chemical compound that makes things slightly sticky, theres a whole science that im figuring out with this part of the project.
@prusa3d

[@FinalSparkLux]

If there's a single person on youtube that deserves the sponsorship/free toys from a company, it's you. Preface: I have no idea if any of these ideas would work. Idk how you're currently printing things (in terms of how the g code, orientation, etc) but if possible, you could try applying some form of mold release onto the support piece before the TPU is printed to aid in it's removal. Maybe let the support piece cool a bit (wait) before printing the TPU onto it to reduce layer adhesion? Maybe print the initial layer of TPU that contacts the support at a lower temp for reducing layer adhesion between the two? Anywho, love your work. Looking forward to seeing your process evolve. Keep it up 🙂

[@D-S-9]

I really enjoy these videos so please keep making them. I also appreciate that you support suggestions from the armchair experts such as myself, who know so much less than you do about this. And on that note, I saw a video once about this Geko Material that might tick all your boxes for an outer skin layer. Not sure about durability, though.

[@missingpartsclub]

And there it is, you answered your question. I imagine you're talking about the veritasium video. Getting that tiny enough of a profile to cast into the silicone was very hard and time consuming. Aside from the tooling only lasting a dozen or so pours. It worked by the shear amount of flat on flat contact area. Organic fingertips have a relatively small contact area, compared to how and what he was picking up in the video. Also, that would work amazing in a lab setting, but not so much out in the wild.

[@420spacecadet]

Honestly, i think most of your viewers and then some will be happy with anything put out. Your thoroughness in explaining everything you do makes a good learning experience for anybody with half a brain. And even some without lol. Keep doing what you love, and we will all love to watch you thrive as you find new ways to improve your prosthetic. Not only that, but also improve the lives of many, many people in the process.

[@TheBehm08]

Prusa made the best investment by sending you, a popular KZbinr who’s literally building his own hand using metal and 3D printed parts a machine. I pray it pays for itself in sales for their contribution!

[@FrostCraftedMC]

i for one definitely enjoy the side quest videos just as much as the major accomplishments. the whole process is interesting

[@Repkord]

Yes!! Ian this has to be one of the best overviews of Multi-material application on XL specifically with flexibles! Thank you for such a concise overview of your process and I cant wait to see what you do next! -Pooch

[@nikitanugent7165]

Definitely enjoy these sidequests. It's nice to have a more focused video to go back to later, instead of trying to remember which (larger) video that information was in.

[@josuelservin]

Gecko tape or nano tape would be an excellent tackyfier because it isn't reliant in chemical adhesion to provide the effect, I know it would not be ideal to be incorporated into the printed part, but I feel it is an interesting alternative that meets the requirements you outlined.

[@simon_far]

Another vote from me to look into using nanotape for the fingertips, although the geometry might have to be tweaked to get it to stick in all directions

[@MrNostars]

i found this channel randomly through youtube recommendation, and although i can barely follow what you're talking about, as an artist i really appreciate the craftsmanship and dedication you have put into creating your hand and all of the problem solving you've done to try to find answers your design problems. i appreciate any and all videos you upload and watch them not only to support, but also to catch a glimpse into a world i don't think i'll ever fully be apart of (engineering) but still find fascinating. keep doing you!

[@jelek_pl]

I work as a cow milker and I use one of those pvc gloves that are made by dipping a cotton glove in pvc they are very durable sticky and wash very easily and I've been using this one pair for a month now, and they are still in perfect shape I'd recommend buying one of those and glueing the fingertips from them.

[@Evinosx]

I love your content. I always wanted to mess with prosthetics. You inspire me.

[@thenaniboi9659]

I want you to know I’ve been using your Prosthetic as a art reference, it’s beautiful

[@theavaliengineer]

This seems like the perfect application for a generative CAD type process, e.g. working in Rhino and Grasshopper. Excited to see where this goes!

[@missingpartsclub]

You say that. Recently, I purchased a license for Plasticity. It's a nurbs cad. Less parametric, more artistic. It does organic shapes so much better than traditional autocad.

[@theavaliengineer]

@@missingpartsclub Ooo! I've been eyeing Plasticity for a good while myself to try making organic shapes in. Seemed like it could be a good compromise between CAD and NURBS workflow. Definitely show off how that goes. The reason I mentioned Grasshopper specifically is because of the node-like geometry generation system which I thought you may be able to use to generate fingertip parts using one filament, perhaps by varying thickness or density of a mesh. I'm curious if Plasticity has the same functionality.

[@o0kaelas]

i love seeing your content, major accomplishments, sidequests and all. its fascinating.

[@isaacthedestroyerofstuped7676]

I wonder if you could replace the tackifier by replicating how gecko's stick to surfaces? I've seen a few science youtubers show that even just molding rubber to a diffraction grating can get you substantial grip! Further, you could look into other surfaces like the self-cleaning microstructure of cicada wings.

[@insertphrasehere15]

Yup. Get a diffraction grating, then hit the print with a blowtorch to soften it up and then press to the grating?

[@josephpipe7445]

I've had a small amount of experience using silicone 2 in 1 and having a TPU part that it gripped onto. I did this using a PLA mould and pouring it in the placing the TPU part where I wanted the silicone to grip on to. Problem is that the TPU needs to have multiple holes/ bits that the silicone can mould around. The benefit of it is that it cleans off in water. It also doesn't need a rough surface and can work very well with the silicone being smooth. I did this on an airless tire for a RC car.

[@hallion5591]

I think its good to showcase the side projects on the channel. We end up getting a holistic view of everything that is involved in the production of it all.

[@woomynation]

Came for the engineering prosthetics journey, stayed for the cat clips

[@Moose370]

I love my 5 extruder XL, The real game changer for me is printing with multiple plastic chemistries at once. PLA makes an amazing support material for PETG prints and literally falls right off even in super complicated geometries. I'm never using PETG as its own support material ever again. The 5 color printing is also really nice!

[@terminalvalence9871]

Purely a random thought, but what if you used a very small nozzle (0.2mm?) to add a bunch of micro siping or hairs on the surface of the part, using the same TPU material? Might be hard to tune in, but I could see it adding friction/grip without relying on a chemical agent. Awesome work you're doing, love your channel!

[@jamesfowley4114]

Maybe a washable silicone like used on dashcam suction cups. The thin lines are a good idea. I don't know how the silicone would be added, maybe a thick spray, then heated a little bit or air cured.

[@zachvalenti]

Can’t wait to see your review of the Prusa Core One

[@TMmodify]

If you look at an organic hand, tactile feedback and skin durability are just as instrumental as the more mechanical aspects of it. It may be less exciting from an outside perspective but it's anything but a side quest to me. ultimately that's what's going to be in contact with stuff,

[@Bo-kq8tn]

This is so excellent, I can definitely see the advantage of the multi headed 3d printer now, the tactile surface and multiple hardnesses inside were really impressive! Also hell yeah getting a free printer from prusa, very well deserved! WRT the tackiness/grippiness, after seeing your explanations and some comments, it can maybe be reduced to these few variables, and trying to find some combination of them that works? 1. Sticky surface additives (like the sprays. TPU is a porous material, is there any liquid you could dip or soak the fingertips with that it would absorb and slowly release over time, like sweat or skin oil? Have you explored different waxes and gum powders for the cooking and ceramics industries? Vaseline/paraffin wax blends? Is it possible to soak them in something and then put them in a pressure cannister to force more tacky liquid into the TPU?) 2. Surface texture (I've noticed on a bunch of silicone things around the house that the tackiness/grippiness of it changes drastically whether it's matte or shiny. Not the same material, but TPU might behave similarly. Not sure what's achievable with your 3d printer though. Is there a way to roughen or smooth the surface after it's printed by using something that dissolves TPU? I see people using acetone vapor to smooth 3d print lines somtimes, so wouldn't necessarily have to be a spray or a soak) 3. Structural grippyness (Other people mentioned fractal vises or gecko feet, is there some macro structure you can print that might behave similarly? more surface contact with more pressure, or pinching the touched thing's surface in some way?) Also, I really enjoy the side quest videos :)

[@missingpartsclub]

Thanks for the reply, I've tried a couple of soluble compounds, natural pine sap dissolved in alcohol to try to get it to flow into the porous surface of the cf on the tactile side. Also, dissolved gum Arabic. Both with limited success. The main issue is kept running into with thus method was repeatability. If I'm going to turn this into a product I need to be able to reliably reproduce the fingertips without needing to get a pile of time into each set. Ultimately they are consumables.

[@martylawson1638]

Fabric template adhesives are the best source of "post it note" sticky spray adhesives I've found. I've used them for sticking printed templates to parts. I had some parts reaction injection molded in a 65A 2-part silicone rubber. Very grippy and soft while also very durable. As a 2-part rubber, it should stick to other things better than most silicone rubber. But afik some of the acrylic and PolySulfone 2-part rubber sealants stick a LOT better. All would need to be brushed on or thinned for dip coating.

[@miguelcarunchod.1493]

6:33 Great video, but just a doubt: Have you already considered, to place a miniaturized "fractal vise" on each fingertip? It should hypothetically solve the dilemma you just described but with solid materials, flexible ones a always kinda tricky.

[@missingpartsclub]

Omg, I haven't. Could you imagine how tiny you'd need to make the segments?

[@miguelcarunchod.1493]

@@missingpartsclub Resin printers needed?

[@deroz9960]

Whatever adhesive is used on Cricut cutting mats may be interesting to look at. I believe it can be washed with soap to restore some tackiness

[@shpadoinkle_wombat]

Foaming TPU is easy to print and can be very soft but, in my experience, it has low friction to most surfaces. I think for this application soft TPE would be better, it could allow you to not use tackifiers. TPE is usually sold as TPU so it's not super easy to look for. I can recommend Fiberlogy Fiberflex 30D, it's harder to print but still manageable but, it's soft, squishy and has a friction like soft overmonding on many tools. Also check out CNC Kitchen video about printing flexibles it has great comparison between couple brands of flexibles kzbin.info/www/bejne/anrRd5dredSNl5Y

[@SianaGearz]

Are TPU and TPE miscible, do they exhibit cohesion when printed together? In my mind they should be...

[@Bash_Minimal]

Why use a chemical adhesive/tackifier instead of a naturally tacky rubber thimble of some sort?

[@missingpartsclub]

Rubber thimbles, and continuing down that line, rubber cement, plasti dip, and silicone, don't actually bond onto the surface of the fingertip. They will just peel off. With this design I'm trying to use the semi rough and porous topology of the print to act as a tooth for the tackifier to bond to the surface of the fingertip.

[@Bash_Minimal]

@@missingpartsclub Ah, that makes sense

[@davidgutting4317]

Try hairspray, it comes in different “holds” and can clean off dirt that loads up in the recesses. Also check out Mythbusters gecko episodes. They were able to mold the micro tabs that electrostatically stick the pads on their feet.

[@dadsfriendlyrobotcompany]

It would be interesting if you can eable fuzzy skin on just the fingerpad side to give more surface area for the variashor conform and grip

[@eliassimon666]

Have you ever looked at Dycem non-slip mats? My dad used it while he was nursing a hand injury. He could do things like set a small non-slip mat on the counter, then set a pickle jar on the mat, then twist the lid off with one hand. It's really impressive stuff, in that it has a surprisingly high coefficient of friction, without any "stickiness", so it wouldn't stick to the object you were taking off of it. Perhaps you could contact Dycem and get the stuff in un-cured form?

[@malthegregersen731]

Hallo Ian i have a Washable silicone Lint roller at home and its about as stiggy fingers and it can be washed and cleand with warm warter. i don't know what type of silicon it uses but it can mabe be taken of and used for testing on the Fingertip prints. It is always a plescure to watch you're videos :)

[@khubba10]

Have you thought about some sort of wax/waxy material? You are really looking for increased friction and not just "sticky" like surfboard wax or some other kind.

[@bengineer8]

I finally have found the name of the opposite of a lubricant!

[@benspellman2603]

Have you considered using micarta as a material for your fingertips? It doesn't have much give at all, but it's plenty durable and won't scratch anything you try touching. Peter brown has a really good video of him making denim micarta you could check out

[@Cabin2N]

I wonder if something like geckskin would be a good choice. Having used other products it works great on smooth surfaces at least and renews easily with soap and water.

[@TheSuperBanana1000]

Have you thought about printing a finger skeleton of sorts that you can then mold a rubber around it? I think that ELASTOSIL® LR 3003/60 US A/B (no affiliation) would be a qualifier based on specs.

[@missingpartsclub]

If you look at some of the earlier fingertip videos, you'll see I have spent quite a bit of time chasing the overmolding process using alumalite silicone. I do like the feel and squish of the silicone, where it fails for me is that it doesn't bond to the material that i use for the cores that attach to the aluminum distal. And casting fingertips without including a core yields a fingertip that won't stay in place. Also, silicone is damaged very easily during real-world scenarios. What I'm finding is that it is unlikely that I'll find "the perfect setup" what I'm more likely to find is a balance point with a design and process that yeild a product that is reliably reproduced at a reasonable cost and wears well enough out in the wild.

[@TheWindGinProject]

What about a finger tip that has hard little spikes or grips under the flex filament. Just a thought not sure its a good one. When you apply pressure to the flex material maybe the harder grips underneath could kind of protrude causing more grip.

[@ChannelRejss]

I highly recommend you to try Fiberlogy Mattflex 40D. It's a matte and thus grippy TPU that doesn't vary in hardness but it prints incredibly well, like seriously easy and clean. You could use it for the parts that don't need to be super squishy. Varioshore has its uses but from my experience with it (I also own a Prusa XL) it's really hard to print cleanly with it due to the constant oozing as you probably found out yourself. Even perfectly dry spools of Varioshore do that unfortunately... must be the quirk of the foaming which creates constant pressure within the nozzle which even retraction can't minimize effectively.

[@missingpartsclub]

It always seems to leave strings, no matter how long and much you dry it. I like the adjustability of the firmness. The main reason I'm trying to stay with it is because if I can print the whole thing in cf, then chemically it's all the same material and I won't have the issues with delamination like I have in the past. I've reached out to Recreus to find out more about their filaflex 60 filament.

[@Jagdtyger2A]

I like your builds because they have sort of a "Steam Punk" kinda vibe. This can be increased by the use of Aluminum Bronze on the metal parts and extending it up to the shoulder

[@josuelservin]

It would look amazing, but the weight would make it impractical for daily use

[@Jagdtyger2A]

@@josuelservin That is a shame

[@esk8jaimes]

I love the side quests

[@gfx8391]

print, mould, then pour silicone, there are many silicones with different properties and you can colour as you want, I'd have thought a silicone with shore hardness of 20a would be about right (they don't need to bond to your mechanic, they can be removable and washed)

[@josuelservin]

I'm pretty sure he has tried that in the past, the parts tend to peel off, break and simply dislodge and get lost, so not suitable for daily use, especially in a shop environment like he needs.

[@Howema]

would making a finger tip "cup" out of metal or slightly weaker sacrificial material to break first before the main hand components and fill the "cup" potion with a type of rubber where any squish or pressure against it when picking up heavier objects would push it deeper into the finger tip cavity and you could replace just the grip material as it wore instead of the tip itself? for example "push in rubber feet" if the grip is strong enough.

[@hbeau1900]

If the search for a chemical tacifier proves fruitless, there are some great micro mechanical structures that can provide a similar effect. A sort of toned down gecko foot

[@simoncleret]

It'd be hard on an FDM printer, but you could hypothetically use a resin printer to make a rubbery surface with lots of little suction cup features all over it.

[@SianaGearz]

I have used contact cement as a sort of tackifier, as a high friction surface. Unfortunately, it has a habit of peeling up at the edge and then balling up, so it is very situational and i don't think it's going to work for you. I too am curious of what other things i can use! I was of the impression that the fingerprint ridges are sort of how we hold onto things, so a bit like a little bit of gecko effect. I think Ben Krasnow has demonstrated some methods to create a master surface from which a gecko effect casting can be pulled. I imagine putting a master on the buildplate, and orienting a print such that you'd have the fingerprint on the bed. But i think it's more likely to damage the master than make a good imprint because the forces from extrusion are much higher. Maybe some of those holographic PEO and PEY build plates could help?

[@SianaGearz]

Gecko effect surfaces are fascinating. You can always wash them and they regain their tackiness when clean and dry or wet, so this corresponds to your design requirement. No chemistry, only structure. I have a 25 year old mousepad where the bottom is gecko surface, i still can't get over how mad it is, it absolutely still works.

[@SianaGearz]

Another tackifier i can think of is grip tape that is sold for use on gaming mice. Unfortunately it's intended to be put on hard surfaces, it's probably going to fall right off a soft fingertip print or casting.

[@alaaaboahmed8803]

الله ينور عليك يا هندسه ربنا يكرمك ويوفقك ويرزقك ويسعدك يارب العالمين

[@scooterman103]

Maybe some sort of elastomer insert like the material they use for re-usable lint rollers

[@gembocobo9484]

Good luck with this project

[@insertphrasehere15]

Could you try adding a 'fingerprint' texture to the fingertip to increase the CoF? Maybe blast it with a blowtorch and then press to a silicone mold of your right fingertip? Or as another commenter pointed out, using a diffraction grating as the tool to press into. there are some other vids on youtube demonstrating how to replicate gecko grip using a plastic molding of a diffraction grating.

[@BerserkeR_031]

Def want silicone molds or some sort of soft rubber for the finger tips

[@daysejones968]

would gecko tape be a usable concept to increase the friction on the fingertip?

[@96MManuel]

maybe 3d printing molds and then over-molding the fingertips with silicone or rubber could work!

[@BurnabyAlex]

what about the gecko tape from geckomaterials? it has its stickiness be directional due to how the surface is shaped and flexes.

[@VampireSquirrel]

you try a fingertip swirl texture with varying levels of hardness in the folds?

[@Weretyu7777]

Hmmm...what about pulling a gecko? Line the tactile side with lots of very thin ridges. Not sure of the difficulty, but it might be an option.

[@maxmaloney7547]

Wait what about that material that football wide receiver gloves are made of?

[@SuperMartimusPrime13]

What about glue dots or maybe it’s called fugitive glue? When not in dot form. Might work

[@baldeagle5297]

Use water-soluble filament for supports and wash it away at the end.

[@entokyado568]

have you tried rubber? just to make sure

[@Onni-]

Have you tried water soluble filament for support?

[@Eugensson]

Maybe i have missed it. But has leather already been excluded from the list of the options?

[@missingpartsclub]

Sorry, yes. About 2 videos ago.

[@jazzjazzrick7055]

Can you please make tutorial of how make prosthetic hand

[@qaon5748]

is there any way i can buy a hand that is attached to a pole so i can use it to do work remotely without using a ladder?

[@SianaGearz]

If you have tasks that don't require advanced dexterity, there are gripper reacher tools, claw-like. You can get them from sports supply and gardening supply. If you have tasks that require dexterity, this is going to be an issue, but ask around animatronic fursuit makers, i'm sure someone of that community had built a hand extension device, i saw several but don't remember any names. Not something you can just buy but perhaps you'll find a construction that is easy enough or you or perhaps you can commission them to build one for you.

[@qaon5748]

@@SianaGearz ya they have those but this one really grips

[@gsestream]

tpu 95a?

[@missingpartsclub]

Creality makes it. amzn.to/3A4bbms

[@Bullfrogerwytsch]

Geko tape finger tips?

[@raylenn4444]

Why not make the fingetips in the same metals than the rest of the hand,save for the inside of the fingetip, where you could use softer polymers to reproduce the feeling? That would cut costs while ensuring that the immortant part have normal feeling into them.

[@joefresco1738]

Make a foot. My dad needs one!

[@missingpartsclub]

If you have access to a 3d printer, you could always help your dad out and build him one. I'm sure that he'd appreciate it even more from you.

[@grndzro777]

3M double sided clear mounting tape.

[@frank8193]

Philadelphia

[@the_ant_guy]

gecko finger tips

[@MrWetstone]

Pine sap

[@missingpartsclub]

I have accidentally tried pine sap out. (There's a sugar pine in front of my shop next to where i park). It is tacky. But it is absolutely terrible at the same time. And it gets everywhere.

[@KM4OOS]

silicone molds

[@joefresco1738]

Gtfo his prosthetic even perfectly does hand grstures.