Palm Mesh

For design validation in preparation for merging into publicly released devices
hertfordkc
Posts: 25
Joined: Tue Feb 17, 2015 12:02 am

Palm Mesh

Postby hertfordkc » Fri Apr 17, 2015 12:07 am

I fastened a deformable PLA mesh to the palm of a Raptor Classic hand with a standard gauntlet. The tester rejected it because it wasn't as secure as his preferred model, a Raptor Classic with Velcro palm and an extended gauntlet. To draw some conclusion about the usefulness of a mesh for this tester, I need to refit his preferred hand with a palm mesh.
Should the palm cavity be formed to accommodate a full lining of either medical padding or leather? What sort of sock are the other testers using?

Peregrine Hawthorn
Posts: 64
Joined: Mon Feb 16, 2015 5:49 am

Re: Palm Mesh

Postby Peregrine Hawthorn » Wed Apr 22, 2015 1:30 pm

Yes, a palm cavity should accommodate some form of padding. This can be leather or foam, but leather is usually better. It shouldn't be difficult to make it potentially fit either. It's important that the user's skin doesn't actually make any contact with the printed plastic. Especially unfinished printed plastic can be abrasive and porous, resulting in skin abrasion and sanitation issues.

In addition to that, I always wear my hands with a sock under them. A simple poly-cotton blend ankle sock is enough. If you'd put it on your feet, it's probably ok on your arm. If a sock is causing discomfort, find a different one. Simple as that. Different materials can be more or less comfortable, tighter socks can compress your arm in unpleasant ways, or a sock that's too long can ride up and irritate the underarm. These aren't fun, but it's easy for a user to tell if it's not working for them. play around until you find some that fit well, and don't forget that there are cool socks with designs on them! (I'm pretty fond of my robot socks that put a big gear at my elbow. 8-) )
Heavy duty hand user, and co-designer of the Talon.

I break hands and then tell you how I did it.

hertfordkc
Posts: 25
Joined: Tue Feb 17, 2015 12:02 am

Re: Palm Mesh

Postby hertfordkc » Thu Apr 23, 2015 12:48 pm

Peregrine,
At the end of the day, doesn't your go-to hand have just a "heavy" leather palm? Or is it a mesh palm lined with leather? Are there circumstances where you might recommend the lined mesh over leather only and vice versa?

Peregrine Hawthorn
Posts: 64
Joined: Mon Feb 16, 2015 5:49 am

Re: Palm Mesh

Postby Peregrine Hawthorn » Wed Apr 29, 2015 3:18 am

The palm on my Talon is a thick piece of leather that my palm has stretched into shape. It serves as padding, and a pretty good but somewhat flexible around the edges structural bit. For a long time I've considered putting something in that was a bit more stiff around the edges by the wrist to reinforce the leather.

Moreso, however, I see this as a good, low cost and low skill prerequisite way to make hands that currently rely on velcro straps that are generally uncomfortable and have no padding and minimal stable structure to push against.
Heavy duty hand user, and co-designer of the Talon.

I break hands and then tell you how I did it.

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andreas
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Joined: Thu Feb 12, 2015 4:55 pm

Re: Palm Mesh

Postby andreas » Mon May 04, 2015 8:18 am

We should probably differentiate integrated thermomesh palms (Raptor Reloaded) and retrofit thermomesh palms (Raptor Original and Raptor Reloaded). I work with a recipient who has been testing an integrated thermomesh palm since February 18th and he's liked it so far, though we've made a couple of size adjustments (made it too loose last time around). One potential challenge we encountered is that the thermoformed PLA is still more brittle than ABS and will crack under a direct blow (a baseball in this case). I'm looking into integrating a ninjaflex/sugru gripping surface on the exterior of the mesh to help with functional grasping and to mitigate direct impacts.

VelcroTear.jpg
Velcro tear in traditional method of securing the residual palm.
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Feb18FitTest.jpg
The original palm geometry was the standard Raptor Reloaded with a re-modeled interior "roof" to allow it to be printed without support. This shaved a couple of important millimeters off the palm cavity, making the residual palm protrude a bit form the underside of the cavity, which impeded functionality.
Feb18FitTest.jpg (692.15 KiB) Viewed 4307 times

Cracking.jpg
Three small cracks are definitely grounds for replacement. They didn't cause any real trouble or harm, but likely form stress concentrations on the next elements of the mesh.
Cracking.jpg (718.79 KiB) Viewed 4307 times

full wrap 1.jpg
The deeper palm helped with fit and functionality. User was given the new palm on 4/29/15.
full wrap 1.jpg (508.89 KiB) Viewed 4307 times

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andreas
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Re: Palm Mesh

Postby andreas » Wed May 06, 2015 6:36 am

I modeled a better bolt-on thermomesh palm to integrate with the Raptor Reloaded. It prints separately, should be scaled to the same value as the palm, and requires nine flathead screws for attachment. I have not tested it with my beta tester yet, so test carefully, but it geometrically recreates the integrated thermomesh palm that has about 2.5 months of user testing behind it, so I think this is ready for user evaluation. Note below that the mesh add-on is being secured to Jason Bryant's promising dental elastic Raptor Reloaded palm and fingers.

Right thermomesh:
https://github.com/andreasbastian/e-nab ... 20palm.stl

Left thermomesh:
https://github.com/andreasbastian/e-nab ... 20palm.stl

I've also added them above.

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2015-05-05 17.41.57.jpg
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Jason M Bryant
Posts: 198
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Re: Palm Mesh

Postby Jason M Bryant » Wed May 06, 2015 10:39 am

Awesome!

Bolting the mesh on worked really well with my recipient. It was able to print the palm in ABS and the mesh in PLA, so the palm didn't change at all when I dipped everything in hot water. The only catch was that the first mesh I printed broke at one of the corners.

I also like the idea of it being a separate piece because that means I don't have to make a thermomesh version of the new hand! I'm rebuilding the whole mesh from scratch, but I'm making the palm inner space and the wrist hinges the same so that as much as possible can be compatible with the Raptor Reloaded. I'll make sure to keep the screw holes on the bottom consistent, as well.

Did you have to make the holes on the palm larger?

hertfordkc
Posts: 25
Joined: Tue Feb 17, 2015 12:02 am

Re: Palm Mesh

Postby hertfordkc » Wed May 06, 2015 11:34 am

How about more user feedback. Your research seems to bear out that an add-on mesh palm is a great idea. However, I'm still puzzled by my recipient's lack of enthusiasm for the mesh. As I said in the first post, his comment was that it was "less secure", but that may have really been a reaction to the short bracer on the test hand which I gave to him. However, he didn't care enough for the mesh to transfer it to the hand with the extended bracer and try that combination.

GreggDennison
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Joined: Mon May 11, 2015 1:36 am
Location: Falmouth, KY
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Re: Palm Mesh

Postby GreggDennison » Tue May 19, 2015 9:00 pm

Ok, i have some feedback for you.

Luke has been using this palm for a couple weeks now, almost every day. We have caught softballs, picked up numerous objects, dropped the hand, shaken dozen of hands, ran it thru airport security, etc. And I literally mean worn it daily, for hours at a time. It's a 130% scale, solid infill and we have had NO issues with it at all. Even now he says it is very comfortable, no rubbing. He loves the ease of getting the hand on. The old vecro would give after a bit of use and we'd have to retighten it or I even had one where the velcro started ripping at the screws. I would love to test one that was integrated onto the palm, further reducing the cozy because of the screws. Which have all successfully held up too. Let me know if you need pictures, but the palm, after 2 weeks, looks like I just printed it, if not just a bit dirty.

dallymeg
Posts: 1
Joined: Wed May 06, 2015 1:32 pm

Re: Palm Mesh

Postby dallymeg » Tue May 19, 2015 10:52 pm

Gregg and all,

That is great news. Was the palm thermo-formed with Luke to get a custom fit, or was it preformed before Luke received it?

I'm creating around 20 hands in 110, 120, and 135% sizes for a scout troop to assemble. I'm working with with Jan and Melena at e-Nable and leaving it up to them to distribute the hands wherever they're needed. I'm currently using either velcro or leather with binding screws for the palm cover. I'd like to switch to the Palm Mesh, but where the end users are unknown I wonder if it would be practical to do so? Also, I wonder if I could do some standard thermo-forming that might be comfortable enough for general use?

GreggDennison
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Location: Falmouth, KY
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Re: Palm Mesh

Postby GreggDennison » Wed May 20, 2015 3:39 am

Luke is my son. Also referred to as Little Cool Hand Luke. I printed the palm then heated it with a hairdryer and he stuck his sock covered hand in.

I'm thinking we need feedback from alot more kids to see if it should be a permanent fixture. The plus side is it's removable now if they don't like it, they'll just need to find velcro.

I know Luke loves his. I don't have anyone else to test it out tho.

hertfordkc
Posts: 25
Joined: Tue Feb 17, 2015 12:02 am

Re: Palm Mesh

Postby hertfordkc » Sun May 24, 2015 12:23 pm

As a fabricator, I'm firmly in favor of the bolt on mesh. It gives the recipient multiple options and it is much easier to fabricate. My original recipient is content with his Raptor Classic, so I can't add to the user experience for the mesh.

StephenDavies
Posts: 15
Joined: Mon Apr 13, 2015 1:25 pm

Re: Palm Mesh

Postby StephenDavies » Tue Jun 02, 2015 9:40 am

ImageI'm about 4 weeks in to using mine. Mine is a custom thermoform palm, with an access hole to allow for sensory feedback and easy access. I have had no problems so far, no problems with cracking or splitting.

gabemedina23
Posts: 5
Joined: Tue Jun 23, 2015 4:55 am

Re: Palm Mesh

Postby gabemedina23 » Fri Jul 10, 2015 6:49 am

So is what is everyone using for filament for these pla?has anyone tried tpu/tpe/ninja flex?

joecross
Posts: 80
Joined: Fri Mar 13, 2015 11:03 am

Re: Palm Mesh

Postby joecross » Mon Aug 10, 2015 1:57 pm

I tried printing the bolt-on version in PLA, but am having a hard time prying it off of the print bed. If I print directly on the bed, it sticks so well that I can't get it off without damaging it. If I use a raft, I can get it off of the bed, but then the raft sticks to the bottom of the print so well that I can't separate them. I tried decreasing the infill of the raft, but got to the point where it was too sparse to support the first print layer before I got to the point where it would separate from the print itself.

Any advice?

I'm printing to a metal heated bed with kafton tape and masking tape on top of that. I'm not heating the bed at all since it is 38C/95F right now :-)


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