The GIANT HAND thread

Heya, i've been meaning to make this thread for awhile. First to try and collate as many different styles as possible help[ing giant hand builders moving forward, and second, I'm hoping someone smarter than me can get me over the final couple of problems i've had with my versions.


First, here is my journey with giant hands https://www.therpf.com/showthread.php?t=276706
During my journey I got in touch with MWiggs whose Raynor I think we all know but just in case here is his thread https://www.therpf.com/showthread.php?t=239205 at the time I asked if he had released the files for his hands and being the generous human he is, he had, and you can find them here on thingiverse https://makerware.thingiverse.com/thing:1822981
They are great hands and I have seen a number of oversize suits using them here on the rpf and on social media in general and they are a fine solution.
However, for me, I was fairly sure I was going to enter a competition and I felt using his design wouldn't be right and I should make my own or design my own.
So I had some goals I wanted to hit-
1) I wanted the hands to have tensile strength so I could pick things up specifically the hammer
2) I wanted the fingers to hang more naturally. bungie cord hands spring back to full extension and if you're not directly controlling them then sometimes it looks like you have 'jazz hands', this could be solved by simply preventing them from fully opening and having the bungie short, but if you do this you can't give a peace sign or flick the bird or whatever floats your boat ie. you limit the movement range.


In looking for inspiration I naturally came upon Alphatech's thread https://www.therpf.com/showthread.php?t=253279&page=4 the hands start on post #91 his work and research here was fantastic and a good base for my mind to start thinking of what I wanted.
My travels also found Torch Art Lanterns

https://www.facebook.com/people/Torch-Art-Lanterns/100009407195261 I find his work really nice and he does so many varied things, well worth a look but here is the specific post https://m.facebook.com/story.php?story_fbid=1866674363656119&id=100009407195261


My first efforts were fairly quick, i needed hands for a con so went the bungie route made out of Sintra, they were ugly and a bit clunky but they did the job for the day.
After this I watched youtube, specifically Lars Christiensen https://www.youtube.com/channel/UCo29kn3d9ziFUZGZ50VKvWA and I went from never modeled a 3D print to pushing out test mdoels in just a few days. I highly recommend his channel if you want to learn Fusion 360.
I kept going ...
a outdated vid..i never used that interior joint system
Eventually, I got there...
I really only designed one finger and then to change the finger length i had the middle part of the digit in 3 different lengths and it was this that made me different sizes. So the part below that is 100mm i also did in 85mm and 75 mm for the pinky, for the thumb i just used 2 segments instead of 3.

I was learning Fusion all the while so my save files are a mess, I kept restarting every time i came across a problem.
By moving the end of a pull rod only 2cm i could close the entire finger.


So, what went wrong? Well, they look great and they do move and have strength but there are 2 issues.
1) They somtimes 'lock' when fully extended and no amount of force will make them close by pulling the system, yet a simple knock to 'unlock' them makes them functional again. Until they lock again. I have sanding and cleared everything mltiple times, they aren't catching on anything and there is no friction that i can see preventing them closing, when they reach that maximum extended pose it's like they have gone over the edge so to speak and the amount of force to birng them back vis the angle i'm pulling on is just not physicallt possible.
2) The pulley system of poles up the arms doesn't transfer the action cleanly, pulling closed is ok (assuming the problem in 1 is not happening) but pushing on the poles there is wobble and the force doesn't always get transferred back directly.
3) I have just in the last few months started getting arthritis in my hands so actually using the hands became painful.
4) The thumb, i tentatively connect to the 3rd finger as in general when you close your third finger you are also generally clsing your thumb so it seemed like a nice solution but the angle is sometimes less than ideal.


So, that said one hand still has the old system of wooden rods while I attempted to move over to servos in the left hand.
So, i'm trying not to repeat to much from my original thread but here are some shots of me trying to retrofit 3 servos into the hand.

In case it's not clear there is a 3d printed rod that attaches to the finger and then is looped over the threaded rod. 3 strong servos also have an arm connected to the rod and the combined strength of the 3 servos pull the rod back closing the entire hand (i'd given up on indicidually controlling them at this point, i was in a hurry and just wanted closure lol).
So, the servos are only controlled by a servo tester with 3 outputs
Near where my thumb sits in the suit I put a power button, and then i made a sort of bike bell thumb switch that i can easily swivel with my thumb that turns the servo controller nob that in turn turns the servos.
Because this is retro fitted into a handmade scratch built hand nothing even remotely lined up and activating it does nothing but you can feel it almost wants to rips the hand apart from the force. So at this point it was con day and i had to smile and leave it.
Afterwards a nice person in reddit pointed me in this direction https://hackaday.com/2013/06/03/hardware-store-robot-hand/ it's wonderful and i feel i can take some idead from it and it's certainly moving in the right direction and solves the thumb movement really well.
I guess the ultiimate goal would be this http://www.instructables.com/id/DIY-Robotic-Hand-Controlled-by-a-Glove-and-Arduino/ but at the moment the flex sensors are $20 each so that'd be $200 .. i'd like to keep it within a budget. I guess if was going to accept that that each movement was going to close each hand then i could have one sensor in each hand and call it a day.


I think, if we could create a rock solid 3D printable module of one mechanical finger (with the middle of the digit being able to be shortened for different finger lengths) that can be controlled either manually or by servo's no matter how far up the arm the user's hand was then i think that's the goal of this thread.


So, if you see a thread here with awesome hand designs, please link, if you come across something beautiful on the net i'd love to see it. Thanks

Nice write up!

I nearly thought this was your new build . (I promise I am not stalking you). The only thing i have to add: don't forget to put the fingers in an arch, it makes the whole look waaaaay better then all of them being on a flat plane. I think I saw an example somewhere in MrWiggs build...
Here it is:



Didn't know so much work went into those hand extensions. Also I don't know if you ever saw Sylgian's build, but he build a nice Powerglove with a similar system like your first. It lacks the 'power' to pick something up tho.

Anyway keep on crafting!

-Hopli-

Yep Read Sylgian's build some time ago but couldn;t find the link so thank you for that.
The curve of the hand I have slightly on my Rein which is why the 3 servo's won't align to pull the threaded bar and the curve is soooooooo slight too.
We'll get there, MWiggs is watching and has something new up his sleeve.
When i'm sitting in front of my main PC i'll screen shot my fingers properly and see if i can upload my save file somewhere so if someone is interested they can delve in and have a look around.

Hoplitespear said:

Nice write up!

I nearly thought this was your new build . (I promise I am not stalking you). The only thing i have to add: don't forget to put the fingers in an arch, it makes the whole look waaaaay better then all of them being on a flat plane. I think I saw an example somewhere in MrWiggs build...
Here it is:

https://i.imgur.com/tqXc5dW.png

Didn't know so much work went into those hand extensions. Also I don't know if you ever saw Sylgian's build, but he build a nice Powerglove with a similar system like your first. It lacks the 'power' to pick something up tho.

Anyway keep on crafting!

-Hopli-

Click to expand...

Just came across this http://slsa.3dn.ru/load/mechanical_hand/1-1-0-1 incredibly interesting, in particular the hand controller. You could connect the controller to the arm shafts of your large build and ...wow.

Although this will probably come back to bite me - as this site is a very noble use of 3d printing resources (when compared to cosplay).

But if you study the designs on the site, you see that it may maybe possible to adapt some of them as the basis of a cosplay giant hand.

http://enablingthefuture.org/

GasmanR said:

Although this will probably come back to bite me - as this site is a very noble use of 3d printing resources (when compared to cosplay).

But if you study the designs on the site, you see that it may maybe possible to adapt some of them as the basis of a cosplay giant hand.

http://enablingthefuture.org/

Click to expand...

Thanks for adding them to the list ..this is the V2 version of the one linked in post #4

It's been a little while since i've added to this thread but i've been working on things in the background.
Firstly, here is the link to the file in the video below https://a360.co/2wTt6ro
The file in the video above is the master version of my fingers, I haven't touched it since October 2017 so it's as is, but these are all the individual components that I printed to make the fingers... it's not perfect though, some of the pivot points need to be changed for the middle phalanx.
View attachment 841976
Where the 'tendons' attach for the middle phalanx, points 3 and 4 in red in the image should be more in line vertically with the chicago screws that form the joints.
Technically, the 1 in green would be better over the chicago screw over the knuckle as well however, it seems to still work fine for the first joint it just seems to have trouble for the second movement so that's what i'm working on at the moment.
Thanks to @HulKhokie on instagram for helping me pinpoint the spot causing me issues and taking the time and effort to show me in diagrams the basic mechanics. I've pointed out this thread to him and with any luck he'll add his considerable knowledge on the topic of mechanical hands here, and if not there's still alot you can learn from having a look at all the awesome images on his insta.
So, the conversations regarding the pivots came about as I was ripping my Reinhardt arms apart for the last time. He has one last stage appearance then he's being retired and I really want his hand to be fully functional for it.
So, here's where the hands were.

The fingers were either broken, or non functional, i had stopped reaching for them and they were held on mostly by tape and cable ties for the last few photo shoots still poseable but not moveable.

So i ripped them off in tact, stripped out my awful attempt at running struts up the arms and got out the aluminium.
I'd never really thought about this part which may have been a major error, making the fingers is one thing, transferring that 80cm or so up an arm that you only grip just above the elbow is something else.
So i took 2 screenshots from the video linked in previous posts to help me think about how I should tackle it.

This is 2 different version of the hand system both very different but both very good. The first one is simpler and i understand the 'why's' of it better than the second one so i'll use that as my inspiration.
One of the reasons, among many, that my hands have never worked properly is that there has been too much lateral movement and in having that it lost alot of the direct transfer of the movement..so they sucked.

I have no special tools, no CNC machine or anything fancy so i'm just doing this with a normal drill, a hacksaw and a rivet gun from the dollar shop.
So i made an aluminium frame that will slot into the hand casing.

I put a threaded bar through and bolted it either side then cut some strips and drilled some holes through. I then slid a pipe onto the thread and measured across it and cut it into sections to use as spacers to divide up the linkages. I then took one of the fingers to get right and started to work on this one before moving on to the rest.
This is where I came across the problems with my initial design, I knew they were there I just needed the courage to peel off the cosplay parts and get back to the mechanics.

This is the fingers still intact, I took off the tendons and replaced the first one with an aluminium strut.

Here's the older PVC frame and i'm measuring where to put the second stage of the mechanism, the aluminium section will sit on top of the pvc frame, there's plenty of room in the arm.

Here's the second stage with one finger connected

So far the aluminium has been pretty easy to work with, there was probably a better way to make a loop on the end but i put it in a vice and wrapped it round a crowbar with my pliers, nothing fancy and it's far from perfect but it'll do the job. I then added the rest of the struts to stage 2.

Next i'll connect this structure to the pvc and from there i'll measure out the lengths of the finger pulleys properly and fingers crossed it'll function correctly.
Thanks for reading and if you come across and 'handy' stuff feel free to add to this thread

Did a little bit more...

I made 4 more loops for the fingers, i bent the aluminium around a crowbar then adjusted it with pliers. I've got 3 out of 4 fingers re-attached now, they need some steadying, there's too much lateral movement here and there but nothing a few washers won't fix. The fourth finger needs a new knuckle which i'm going to try to make out of aluminium instead of 3d printing it. Quicker and stronger.
Anyway, getting there.