Progress on new tensioner box: Paperclip based Gripper Box

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Jason M Bryant
Posts: 198
Joined: Mon Feb 16, 2015 1:59 am

Progress on new tensioner box: Paperclip based Gripper Box

Postby Jason M Bryant » Wed Feb 18, 2015 4:51 am

I like how my Gripper Box works, but I'm still looking for improvements in size and simplicity.

The next experiment is using a paperclip instead of snap pins. This eliminates the need for wheels, since the smooth metal will hold up fine against the wire rubbing against it.

Basically, the cap, base, three snap pins and two wheels have been replace by just a cap, a base, and a paperclip. I snap the cap and base together, then run a straightened paperclip through the holes. There are grooves on the top and bottom to hold the wire. I have to use two pairs of pliers to pull the wire through, shape it, and cut off the excess.

Pluses: Without wheels, it is much smaller. I can make the whole box much smaller with this design. I feel fairly confident of the strength, I tested it out with the fishing wire, and the wire broke with only a tiny bit of bend in the paperclip wire. There just isn't much room before the cap and the base for the wire to bend, so it can't deform enough to weaken the wire.

Misuses: It requires two pairs of pliers. More importantly, it requires a fair amount of strength. I've seen videos of children assembling eNable hands, and I don't want to lose that.

I love the results of the finished product, but I'm not sure the strength requirement is reasonable.
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Jason M Bryant
Posts: 198
Joined: Mon Feb 16, 2015 1:59 am

Re: Progress on new tensioner box: Paperclip based Gripper Box

Postby Jason M Bryant » Wed Feb 18, 2015 9:04 am

Next experiment, using the snap pins as wheels.

Snap pins are back, but this time the holes for them are completely round. Thus, the snap pins can spin, and there is no need for wheels.

Theoretically. Printed at .2mm, they don't spin. These are at 100%, so a bigger scale would have more tolerance and leverage, and they might spin at that scale. I also tried printing them at .1mm, but they still didn't spin.

Even without spinning, they seem to work. When I pull the fishing wire around them, it slides pretty well. The original reason for having a wheel was that I was afraid the wire would eventually saw through the pins. Hopefully, if they have enough friction to saw, it'll make they pins spin, instead.

There's nothing between the top and the bottom, so the top cap just lays on top of the wires. I did this for printing simplicity. I considered putting a spacer on the plates to hold them apart. However, the holes on the plates are bigger on one side than the other, and the side that would need the spacer is opposite the bigger holes. Since one side or the other has to be flat, I didn't put in the spacer. I think it should work fine even with the cap lying on top of the wire. There's a millimeter of space built into the snap pins, so even with thick fishing wire, it shouldn't be a problem. Obviously any hand that is bigger than 100% will also scale up that space.

The reason I can make the gap so small is that neither this design nor the paperclip wire design will have a swivel pin for the back hole. The idea is to have a post behind the balancer and tie the back snap pin to the post with fishing wire. It should rotate around that just as easily and that will save a lot of verticle space.

As you can see from the pic, it's smaller than the current gripper box whippletree. It's about halfway between the current design and the paperclip design, but both of the newer designs take up about 5mm of vertical space.

One disadvantage is that getting tiny, tiny snap pins into the plates is a little difficult. However, if you use pliers and the right trick, it's not too bad.

I'm going to make a box for this design and see how it works when it is all put together.
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droomurray
Posts: 69
Joined: Mon Feb 16, 2015 4:04 pm

Re: Progress on new tensioner box: Paperclip based Gripper Box

Postby droomurray » Wed Feb 18, 2015 11:38 pm

Jason,

I'm watching this with great interest, unfortunately due to work the last few days I have yet to print the now fixed box parts.

Drew.

Jason M Bryant
Posts: 198
Joined: Mon Feb 16, 2015 1:59 am

Re: Progress on new tensioner box: Paperclip based Gripper Box

Postby Jason M Bryant » Thu Feb 19, 2015 12:26 am

Haha, don't worry about it. The only reason I had time to make these things in the first place is my university is on a break for the winter. All the students left town, and suddenly I was productive!

I've finished version 2 of the Gripper Box, which uses the wheel-less snap pin design in my second post. You can find the parts here: Gripper Box V2

Jason M Bryant
Posts: 198
Joined: Mon Feb 16, 2015 1:59 am

Re: Progress on new tensioner box: Paperclip based Gripper Box

Postby Jason M Bryant » Thu Feb 19, 2015 1:53 am

Now for a quick tribute to iterative design.
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droomurray
Posts: 69
Joined: Mon Feb 16, 2015 4:04 pm

Re: Progress on new tensioner box: Paperclip based Gripper Box

Postby droomurray » Thu Feb 19, 2015 11:43 am

Jason M Bryant wrote:Haha, don't worry about it. The only reason I had time to make these things in the first place is my university is on a break for the winter. All the students left town, and suddenly I was productive!

I've finished version 2 of the Gripper Box, which uses the wheel-less snap pin design in my second post. You can find the parts here: Gripper Box V2


Awesome work, if i stayed snowed in with work for a few more days you will be up to v3 ! :)

Drew.

Nick
Posts: 4
Joined: Mon May 04, 2015 5:12 pm

Re: Progress on new tensioner box: Paperclip based Gripper Box

Postby Nick » Sun May 10, 2015 2:05 am

I like the idea of metal bits for these to slide on, just maybe not paperclips. Heavy gauge solid core wire (12 or so?) would give you a slightly bigger, smoother radius for the string.

To secure them without using a bunch of force, I'm a big fan of using a wood burning iron (or a soldering iron you don't care about the tip on) to modify printed parts. Just print the holes a bit oversized, insert your metal pins, then melt over the top and bottom of the pins a bit with the iron. They'll be nice and secure with no protruding pointy bits.

hamyamys
Posts: 1
Joined: Tue Feb 26, 2019 11:30 am

Re: Progress on new tensioner box: Paperclip based Gripper Box

Postby hamyamys » Tue Feb 26, 2019 11:56 am

Nick wrote:I like the idea of metal bits for these to slide on, just maybe not paperclips. Heavy gauge solid core wire (12 or so?) would give you a slightly bigger, smoother radius for the string. V Tight Gel | Penomet | Bathmate | Bathmate| Vigrx Oil | Semenax

To secure them without using a bunch of force, I'm a big fan of using a wood burning iron (or a soldering iron you don't care about the tip on) to modify printed parts. Just print the holes a bit oversized, insert your metal pins, then melt over the top and bottom of the pins a bit with the iron. They'll be nice and secure with no protruding pointy bits.



Those are the things you can't justify with because those wood burning are the best things among iron or tip


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