Osprey Hand: FEEDBACK/TESTING REQUESTED

For design validation in preparation for merging into publicly released devices
PeterBinkley
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Osprey Hand: FEEDBACK/TESTING REQUESTED

Postby PeterBinkley » Sat Jul 11, 2015 3:11 pm

Announcement edited on July 14:

Hey folks, the Osprey is ready for some beta testing. Are some volunteers willing to help me with this?

The files are here:
http://www.thingiverse.com/thing:910465

In an attempt to ensure better print quality, I'm not planning to include supportless versions of the Osprey. Apologies to those of you who prefer slicer-generated support material. This is an attempt at quality control after seeing a lot of print quality variation at large assembly events. So please print everything with no support, as support is included in the model. If you are printing in ABS, you can add a brim to control warping, although gecko pads in the palm and bracer models provide a good bit of warp management already.

Print proximals and pins last, and only after you've checked one proximal for tolerance. Once you find which proximal fits the knuckle block best (it should slide freely, but without too much wobble), print the rest of the proximals, and the pins of the same letter (A, B, C, or D)

The instructions need a lot of work, including photos and video. For now, I just need people to print and snap together the components. Here are the assembly instructions, but don't worry if there are some things here you don't understand yet:

https://docs.google.com/document/d/1xbf ... sp=sharing

For now you don't need any hardware. Just print the components and snap them together. Then let me know how things went. As this process moves forward, I'll make sure everyone who printed can finish making a wearable device.

Does everything print well? Did you have any failed prints?
Were the built-in supports helpful, or did they cause problems? Were they difficult to remove?
Do the parts seem to fit together well? Does anything seem too loose or too tight?
Do I need to add AA or DD pin-and-proximal sets (If the A set is too tight or the D set is too loose)?
Do the tolerances for the pin-and-proximal sets match up? (In other words, if the "B" proximals fit, are the "B" pins also a good fit?

Please let me know what printer you used, the scale of the print, and which tolerance set you selected.

I'll fill in this information as beta testers volunteer. I'm inputting myself as an example:

Print scale: 100%
Beta tester: Laird Popkin
Printer/material: Ultimaker Original+, PLA
Tolerance Set: A
Mechanical function: test print
Assembled to: printed components and assembled, no hardware
Notes: 1.75mm nylon is too big for a 100% build. 1.2mm is ideal.

Print scale: 115%
Beta tester: Peter Binkley
Printer/material: Ultimaker 2 / ABS
Tolerance Set: proximals B pins B
Mechanical function: Seemed to function very well. No concerns. A young client with little range or strength is having good success with his Osprey. He is learning cello and holds the bow with this device.
Assembled to: complete; device was fitted to a client.
Notes: Printed an older version of the bracer, so #8 screws were used.
Make sure to remove any brim material from the exterior wrist hinge nut, or it will generate friction in the wrist joint.

Print scale: 145%
Beta tester: John Diamond
Printer/material: RepRap I3XL / PLA
Tolerance Set: proximals A pins A
Mechanical function: Good function; very little friction
Assembled to: Complete mechanical function. No straps or leather.
Notes: John used standard hardware, including 1.6mm nylon mono leader and 10-24 set screws, with very good results.

Print scale: 150%
Beta tester: Laird Popkin
Printer/material: Ultimaker Original+ / Taulman 910 Nylon
Tolerance Set: proximals pins
Mechanical function: 1.8mm Bridge Nylon used as cabling with excellent results
Assembled to: Complete mechanical function, but no straps or leather.
Notes: Channels needed drilling; Thingiverse model was updated with wider channels.

Print scale: 155%
Beta tester: Peter Binkley
Printer/material: Ultimaker 2 / ABS
Tolerance Set: proximals C pins C
Mechanical function: Excellent
Assembled to: complete. Device was fitted to Peregrine.
Notes: 155% is a bit loose. We're going to make another at 145 or 150%.

Print scale: 200% (Demo Hand)
Beta tester: Laird Popkin
Printer/material: Ultimaker Original+ / Pins and proximals in PLA; everything else T-Glase (by Taulman)
Tolerance Set: proximals D pins D
Mechanical function: Excellent. Next time use more rigid cabling (like Taulman 910) or a 2.0-2.2mm nylon monofilament.
Assembled to: Completed demo hand
Notes: The Osprey works fantastically well as a demo hand, because the push/pull mechanism is very easy for people to work. Also, the small gauntlet (bracer) with straps is easy to adjust to a wide range of arm sizes.

1.75mm Bridge Nylon for the tendons. It's a little soft, but 3mm filament doesn't fit in the finger channels.

1.5 inch velcro strips (double-sided) work great. Turned so the 'soft' side is towards skin.

4 #12 1.5in metal screws to hold the velcro strips to the gauntlet. Laird printed some caps to screw onto the ends of the screws. He could have used shorter screws, but couldn't find any that were that large. So instead he printed caps to cover the pointy ends, which look cool.

10 socket head set screws ¼-28 x ¼. That is, quarter inch diameter set screws fit into the holes with just a little force, to hold the tendons in the gauntlet in place.

12 #6 x ½in wood screws through the 'template' then through the velcro, into the bottom of the palm. The template helps hold the velcro in place, so it doesn't pull on the screws so much. (The template is actually designed to mark, punch and cut a thick leather palm.)

Printed the palm, fingertips and gauntlet in T-Glase, and the pins and proximals using PLA, as it's a bit softer than T-Glase. Laird printed the 'D' size, which was quite tight, but with some encouragement (rubber mallet, pliers) everything fit into place, and there's no wiggling.

You may print at any scale, and I will include your data here.

Thank you!
Last edited by PeterBinkley on Fri Sep 18, 2015 4:16 pm, edited 9 times in total.

Jason M Bryant
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Re: Osprey Hand Beta Testing

Postby Jason M Bryant » Sat Jul 11, 2015 7:47 pm

Hi Peter.

I can't print one out right now, but I'll order the parts and take them back with me to China at the end of the summer.

You should put a link up on the Google+ group. Just show a picture of the hand, give a quick description, and then link to here. That always helps me get the word out about testing.

Good luck!

bosco2003a
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Re: Osprey Hand Beta Testing

Postby bosco2003a » Sun Jul 12, 2015 11:59 am

I am just finishing the printing and will be putting it together , the only thing I see so far and a few people have said is they would like to see the brace with just Velcro and the palm with some kind of open area

PeterBinkley
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Re: Osprey Hand Beta Testing

Postby PeterBinkley » Mon Jul 13, 2015 12:25 am

I'm not sure what you mean by an open area in the palm. Do you mean an opening for a user with a thumb?

You might be able to attach Velcro the same way the nylon straps go on. That is, make a hole in the material and attach the straps with flat-headed screws into the countersunk holes on the underside of the plastic bracer. The nylon (or Velcro) is sandwiched between the plastic and the leather.

I think the screw holes are an improvement over slots for straps, because the angle of the slots needs to be different for different-bodied clients. Otherwise the straps are tight along one edge and loose along the other. With screw holes, the straps rotate to any angle.

I also think that nylon straps will last longer than Velcro. Peregrine's Velcro has gotten fluffy.

Folks, don't even worry about the hardware yet. I'm still working on instructions, and I'll make sure you can assemble a device to completion. I have lots of hardware in stock and I'm willing to give away kits for free to beta testers.

For now, just print the hand and snap it together.
Last edited by PeterBinkley on Tue Jul 14, 2015 11:16 am, edited 2 times in total.

PeterBinkley
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Re: Osprey Hand Beta Testing

Postby PeterBinkley » Tue Jul 14, 2015 10:26 am

I just updated the palm. The thumb has been turned about 5 degrees to better oppose the fingers.
Thanks to Jason Bryant's Phoenix Hand, which showed the benefits of a thumb that more directly opposes the fingers.
There will likely be more changes to the palm in the next couple weeks, to further enhance opposition of the digits. No other components are expected to change, so you will only need to reprint the palm, the palm stencil, the upper stencil, and maybe a couple snap pins.

If you need access to the old palm, let me know.

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laird
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Re: Osprey Hand: FEEDBACK/TESTING REQUESTED

Postby laird » Sun Jul 19, 2015 2:08 pm

Print scale: 100%
Beta tester: Laird Popkin
Printer/material: Ultimaker Original+, PLA
Tolerance Set: A
Mechanical function: test print
Assembled to: printed components and assembled, no hardware
Notes:
- Channels (at 100%) in the proximals and distals are slightly too small to use 1.75mm filament (tried Taulman Bridge and 618). I also have some nylon coated wire (fishing line) that will work, but then there's an issue of how to tie it off. The nylon filament did fit through the palm channels
- Supports for front of fingers - Great idea! There are three supports. The two on the sides removed fine, the one in the middle was thicker and was harder to break off - I think it pulled material off of the finger that's supposed to cover the channel, as all of the fingers have two holes at the ends now, one on the "top" of the finger, and one at the fingertip. I'd suggest removing the middle support, since the other two would probably be enough support, or at least making it thinner like the others, so it's easier to remove and doesn't pull off material.

That's as far as I've gotten so far. I think I could drill out the channels a little bit to get filament through, but if you make them wider I'll re-print instead.
- Laird Popkin

PeterBinkley
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Re: Osprey Hand: FEEDBACK/TESTING REQUESTED

Postby PeterBinkley » Mon Jul 20, 2015 10:40 am

Yay Laird!! Thank you so much!

Yes, the "A" set of pins and proximals is what I would have chosen for your configuration. Small print scale (100%), PLA (which doesn't shrink as it cools) and an extrusion-heavy printer (Ultimaker) demand the skinniest pin and prox set. Did you find any particular pins too loose or too tight?

The fingers are still supposed to have two channels, even though I'm not using the dorsal "elastic" channels yet. So it sounds like your support material did what it was supposed to do, which is to snap off, exposing that hole. The fingertip of the dorsal channel is wide and hexagonal. There are fingertip/claw pins that insert into those sockets. Look at the images of the completed "Captain America" build on the Thingiverse page; the tip inserts are white. Right now, those dorsal channels are pretty much vestigial, (they were used for elastics) but I plan to keep them open for secondary mechanical components and/or for electronics (like led lights). More on that later, but for now I just want to make sure the components print well and fit together nicely.

1.75mm nylon printer filament is only good as cabling for builds above about 140%, and for that, I'd use Taulman Bridge because it is less stiff and has lower memory than most other nylons. But that stuff is way too thick and stiff for a 100% print. For a 100% build, you'll need 1.2mm nylon mono. And you won't be tying any knots at all.

I'll send you a hardware kit. Shoot me an email with your address. I'm putting together a kit for Gregg/Luke too. The hardware is different from the Raptor kits we've been using, but as you will see, it's quite inexpensive and easy to install, and the resulting device is extremely comfortable and durable. Once you build one Osprey, it's pretty easy to make another (unlike some other devices I've designed) as I've taken most of the guesswork out of the process.

I'm working to add photos and video links to the assembly instructions. I'll let you know here as I add media to the assembly document. Please ask questions as you proceed.

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laird
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Re: Osprey Hand: FEEDBACK/TESTING REQUESTED

Postby laird » Mon Jul 20, 2015 12:12 pm

FYI I tried using fishing lure wire, and it is not quite strong enough to push the finger open. I will pick up some 1.2 mm nylon mono and try that.
- Laird Popkin

PeterBinkley
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Re: Osprey Hand: FEEDBACK/TESTING REQUESTED

Postby PeterBinkley » Mon Aug 17, 2015 1:50 pm

Laird,

Here's the method for installing nylon monofilament in the fingers:

https://www.youtube.com/watch?v=cji0p_DsGxo

Did you find the support material hard to remove from the proximal phalanges? My Flashforge (Replicator 1 clone) handled it fine, but on my Ultimaker 2, the space between the object and the support was actually filled in where there should have been a gap. I had to remove the support with fingernail clippers. Probably something wrong with my retraction settings. If I can't make the proximal support work on my UM2, I may decide to remove it altogether.

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laird
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Re: Osprey Hand: FEEDBACK/TESTING REQUESTED

Postby laird » Wed Aug 26, 2015 10:14 pm

I printed one at 150%, and 1.8mm filament worked well. I printed the hand using Taulman 910 Nylon, which is fairly rigid, and used Bridge for the tendons since it's more flexible. I did have to run a thin drill bit through the channels in the gauntlet to clear them out a bit.

I attached the filament by melting the end into a ball and pulling it into the fingertip, like in the video.

For attaching the lines to the gauntlet I tightened down screws, then when the lines were all in the proper place added superglue - Nylon on Nylon is pretty slippery so I added superglue, one screw at a time, to be on the safe side. It's a demo hand, so I hope I won't need to adjust it.

Pictures at http://www.thingiverse.com/make:154352
- Laird Popkin

PeterBinkley
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Re: Osprey Hand: FEEDBACK/TESTING REQUESTED

Postby PeterBinkley » Fri Sep 04, 2015 1:58 am

Awesome Laird!

I took note that you had to widen the channels in the gauntlet for the cables and made them 10% wider in the model. I haven't published the changes yet as I'm working on a major remesh of that component. I'd like to turn the mesh into quads so I can smooth it with a subsurf or a massive "bevel". We'll see how it goes.
Thanks for your work.

droomurray
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Re: Osprey Hand: FEEDBACK/TESTING REQUESTED

Postby droomurray » Thu Sep 10, 2015 12:38 pm

Ahh so its not just me that had a problem with the gauntlet channel sizes, I will re-print a new gauntlet when these are released :)

Drew.

john.diamond
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Re: Osprey Hand: FEEDBACK/TESTING REQUESTED

Postby john.diamond » Thu Sep 10, 2015 1:44 pm

I'd like to volunteer to join the beta testing of the Osprey. I propose printing a 145% scale hand in PLA on my RepRap I3XL. What's the status of the design right now? Should I take the published STLs or wait for an update? Ideally, I'd like to have it ready to take to the World Maker Faire in New York on 26th September to exhibit on the e-NABLE stand.

PeterBinkley
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Re: Osprey Hand: FEEDBACK/TESTING REQUESTED

Postby PeterBinkley » Thu Sep 10, 2015 5:14 pm

I just updated the bracer on Thingiverse. The cable channels are now quite a bit wider. So it should work very well now. I'm also working on a remesh of the bracer that's much smoother. So I think the original bracer will end up on the Gamma Raptor, since it has the same "faceted" aesthetic.

john.diamond
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Re: Osprey Hand: FEEDBACK/TESTING REQUESTED

Postby john.diamond » Thu Sep 10, 2015 11:31 pm

I see the hexdistals (fingertips) have been provided with substantial supports under the curved overhanging section. I assume this is because you've had trouble maintaining print quality in this area given that the overhang is greater than 45' from vertical. I've had similar problems with the Raptor and Phoenix fingertips but, with Jason Bryant's help, was able to get fairly predictable excellent print results using no supports, no bed heat and an external cooling fan. This serves to stop the overhanging lip from curling up during the printing which results in a deformation of the curved overhang.

john.diamond
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Re: Osprey Hand: FEEDBACK/TESTING REQUESTED

Postby john.diamond » Sun Sep 13, 2015 6:25 pm

I'm a couple of hours away from having the fingertips reprinted. I didn't like my filament choice for the first attempt and have opted to change filament before the main assembly. I'm using the A sizing as the B was definitely too tight given my extruder settings. In the distals there are two identical medium, one short, one long and one fat. Am I correct in assuming that the long distal is for the middle finger and that the fat one is the thumb?

PeterBinkley
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Re: Osprey Hand: FEEDBACK/TESTING REQUESTED

Postby PeterBinkley » Mon Sep 14, 2015 4:41 pm

Drew, hold off printing the bracer for a day or two. I'd like you to see the new model so you can choose which one you like better.

PeterBinkley
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Re: Osprey Hand: FEEDBACK/TESTING REQUESTED

Postby PeterBinkley » Mon Sep 14, 2015 4:42 pm

John, thanks so much for giving the Osprey a whirl! I'd suggest printing the new bracer/gauntlet when I publish it, which will be in the next couple days. It's coming along nicely. I think the rest of the design is stable, at least until my might beta testers identify a problem. This design should print and function very well in PLA at 145%.

Yes, I'm including mandatory support structures with the Osprey. Because we have so many volunteers printing and shipping these devices, I decided to impose some quality control. I did remove support structures from the proximals, as it was causing problems on one of my printers. The overhang support on the distal phalanges is kind of necessary when printing in ABS on an over-extruding printer. Some printers default to over-extrusion in ABS, due to that plastic's tendency to shrink as it cools. Was any of the support difficult to remove?

Yes, the distals print in order, with the little pinky on one end and the fat thumb on the other. The middle finger is the long one.

I'm a bit surprised you had to use the "A" tolerance set, even at a print scale of 145%. At some point, could you try printing a hand at 100%? At that scale it should print pretty fast and without using much filament. If the "A" tolerance set is too tight for your configuration, I will need to release an "AA" set, which will be looser than the "A" set.

I really appreciate the feedback. Keep me updated.

john.diamond
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Re: Osprey Hand: FEEDBACK/TESTING REQUESTED

Postby john.diamond » Mon Sep 14, 2015 5:16 pm

All the supports were able to be broken away relatively cleanly either manually or using pliers. I then used a file and a heated tool to smooth off the remaining rough spots. I'm beginning to think I may have used the wrong technique to determine which fit setting (A-D) would be most appropriate. My proximals have a more sloppy fit in the palm than ideal ... does that differ between the fit settings? If I'm going to switch out the proximals I'll need to remove the knuckle pins. The best way I can see to do that is to drill out the center of one of them and try knocking them both out from that side using a suitable drift. Do you have a better suggestion?

Having tried to install 2.2mm weedwacker line instead of the recommended 1.6mm monofilament fishing line I can see why your suggestion would be preferable. I've now stripped out the oversized line and have ordered some 1.6mm fishing line from catchalltackle.com to continue.

Do the hex holes in the distals and the corresponding plugs have any functional purpose? I saw that you've wondered about installing LEDs ... is it related?

PeterBinkley
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Re: Osprey Hand: FEEDBACK/TESTING REQUESTED

Postby PeterBinkley » Mon Sep 14, 2015 5:46 pm

Laird, I'm so glad you're enjoying the Osprey Hand. I have a question and a suggestion. I'm assuming you used the Ultimaker Original+ for all the Ospreys you've printed.

For the 150% build in Taulman 910, which tolerance set did you use for the pins and proximals? I'm guessing the "B" set worked the best for your configuration. Maybe the "C" set if nylon shrinks at all as it cools.

The only thing I would suggest is that for the 200%(!) demo hand, you use cabling that's either thicker or more rigid. The Bridge is probably too soft, especially being so thin (for that build scale) but I'll bet your most rigid 1.75mm nylon filament would work great. Whichever is the stiffest of the Taulman 910, 618 or 645. If you use nylon mono fishing line, which is fairly soft/low memory, I'd suggest a cable thickness of 2.2mm.
Last edited by PeterBinkley on Thu Sep 17, 2015 11:35 am, edited 1 time in total.

PeterBinkley
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Re: Osprey Hand: FEEDBACK/TESTING REQUESTED

Postby PeterBinkley » Mon Sep 14, 2015 6:15 pm

I updated the announcement on the first page to reflect the data I've received so far. Let me know if I missed anything.

John, if by "sloppy" you mean wobbly, you should be using a higher letter, not a lower one. When selecting a tolerance, the rule is "Lower Letters are Looser". So if the "B" proximal was loose and wobbly, try a "C". If you've got extrusion reduced to help you print steep overhangs, I imagine you would need to use a higher letter, and not a lower one. Then print the pins of the same letter. The proximals should articulate with no resistance but only minimal wobble, and the pins should be a nice snug fit.

The knuckle pins already have a little hole in the ends to facilitate removal. Find a very small screw, and turn it into the hole. When the screw threads grab the plastic, pull straight out and the pin should come too.

If you have some 1.75mm Bridge nylon filament, you could use it to cable that 145% print, and it would work great. The 1.6mm mono from CatchAllTackle is also great stuff. I think Laird could use some of your 2.2mm weedwacker line for his 200% build. Truly huge.

The hex holes in the distals don't have any explicit purpose at this point. I'm leaving it up to designers to get creative. I have a version of the fingers that removes the dorsal channels completely, but I have a feeling that keeping those channels open will encourage some creative modifications, like LEDs, or even secondary mechanical components that mount either in the fingertips or on the flat surface on the back of the knuckle block. Secondary machines would actuate concurrently with the digits. So nothing yet, but hopefully we'll see some cool stuff soon.

PeterBinkley
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Re: Osprey Hand: FEEDBACK/TESTING REQUESTED

Postby PeterBinkley » Wed Sep 16, 2015 11:17 am

My own test prints were successful, so I just added the remeshed bracer to the Thingiverse page. Let me know what you think.

john.diamond
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Re: Osprey Hand: FEEDBACK/TESTING REQUESTED

Postby john.diamond » Wed Sep 16, 2015 5:32 pm

It'll probably be next week before I can download and try the new bracer. I'll also be trying the alternative fit settings for the proximals/pins. I need to dedicate my printing time right now to getting ready for a presentation that Justine and I will be giving on Sunday. The 1.6mm monofilament nylon fishing line that I ordered on Sunday has just arrived so I hope to be stringing up the Osprey later today and will report back.

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Re: Osprey Hand: FEEDBACK/TESTING REQUESTED

Postby john.diamond » Wed Sep 16, 2015 8:06 pm

I've installed the 1.6mm monofilament fishing line into my 145% Osprey and it's operating without any perceived friction. Here's how it looks:
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Osprey1.jpg
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PeterBinkley
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Re: Osprey Hand: FEEDBACK/TESTING REQUESTED

Postby PeterBinkley » Thu Sep 17, 2015 1:38 am

Oh wow John, that looks great. Well done sir.
It looks like the wrist nut might not be all the way on. The wrist pins should really snap into place in those nuts. If the base of the nuts have a bit of a brim, you might need to sand them down to make them seat properly. Squeezing the first print layer down onto the bed often creates a bit of a brim.
How did everything fit together? Can you identify any connections or features that need adjustment? Did the cables insert reasonably easily through all the channels? Are you planning to complete the device so it can be worn?

Thanks for helping with testing John. This is really great.

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Re: Osprey Hand: FEEDBACK/TESTING REQUESTED

Postby john.diamond » Thu Sep 17, 2015 2:05 am

Just checked the wrist pins and they are clicked in firmly. They can still slide in and out of the cap by about 0.5mm but the end of the pin is properly engaged. I'm probably going to wait till I reprint the bracer using the newly posted smooth design before moving on to adding the leather and nylon strapping. I also intend trying alternative fit settings for the proximals. With any luck I'll have this complete before the World Maker Faire in New York on 26th/27th Sep.

PeterBinkley
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Re: Osprey Hand: FEEDBACK/TESTING REQUESTED

Postby PeterBinkley » Thu Sep 17, 2015 11:32 am

John, I updated the data for your build on this thread's introductory post. Did you use the "B" set of proximals and pins for this initial build? That's what I put down for you, but I'll make changes if necessary.

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Re: Osprey Hand: FEEDBACK/TESTING REQUESTED

Postby john.diamond » Thu Sep 17, 2015 2:24 pm

I actually used the 'A' set for the initial build but now believe that was the wrong choice. When I get time on my printer next week I'll try the alternative settings to see which one fits best.

PeterBinkley
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Re: Osprey Hand: FEEDBACK/TESTING REQUESTED

Postby PeterBinkley » Mon Sep 21, 2015 2:40 am

I identified a couple issues with the new bracer today, fixed them, and swapped in the fixed file. I widened the cable channels and reduced the holes for the flat-headed screws. Everything should work very well now.

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Re: Osprey Hand: FEEDBACK/TESTING REQUESTED

Postby john.diamond » Mon Sep 28, 2015 7:17 pm

I completed the basic build of the Osprey using bracer version2.52 but haven't yet added the leather and nylon strapping. This a 145% build using 1.6mm nylon monofilament fishing line. I displayed it at the two day World Maker Faire in New York at the weekend and it was handled by many attendees during the event. The only damage that I noticed at the end of the event was that one of the tendons had kinked between the bracer and palm.
This was printed using the 'C' components. I filed the distal, proximal and palm joint mating surfaces smooth to ensure a smooth operation. There was very little sideways sloppiness on these joints when assembled even though the joints moved freely. I also drilled out the proximal joint holes on the distal end to properly accommodate the pins ... this allowed the pins to rotate smoothly in these joints. The finger tip pins were a little difficult to insert and I broke a couple of them in the process. Maybe the slot in the pins could do with extending further towards the head end. I did, however, have significant problems assembling the wrist hinge joints as the pins wouldn't go though the holes in the bracer cleanly. I ended up using the 'A' pins/caps and filed out the holes till they went through without damaging the pins.
The securing of the tendons into the distals went reasonably smoothly although a couple of them popped back out under tendon compression so I CA glued them back in.
I was able to adjust the tendon clamping to get the fingers to move fairly closely together but it's difficult fine tune the positioning with the current setscrew arrangement. Once the tendon has been clamped down on it becomes squashed at that point so undoing the setscrews and moving it slightly isn't easy.
I had to take both knuckle pins out to change the fingers from the 'A' to the 'C' versions. The first time I did this with 'A' knuckle pins fitted I was able to screw in a sheet metal screw into the hole in the end then pull it out with a pair of pliers. The second time, with 'C' pins fitted I had to resort to drilling one of the pins out. I'd suggest adding a hole on the underside of the palm between the middle and ring finger knuckle joints to allow the knuckle pins to be knocked out more easily for servicing.
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Osprey5.jpg (150.13 KiB) Viewed 6339 times

Osprey4.jpg
Osprey4.jpg (158.14 KiB) Viewed 6339 times

PeterBinkley
Posts: 48
Joined: Fri Feb 13, 2015 5:49 pm

Re: Osprey Hand: FEEDBACK/TESTING REQUESTED

Postby PeterBinkley » Sun Oct 04, 2015 6:39 pm

Awesome feedback John!

If your "C" pins don't fit when you are using "C" proximals, I think I may have calculated for ABS a bit too much. PLA is much more rigid, so bigger gaps are needed to allow the pins to snap in without breaking off. So I may decide to recalculate tolerances by reducing the thickness of the pins relative to the proximals. If I pair the current "B" proximals with the "A" pins, "C" proximals with B pins and so on.

You are the first person to report this problem.

Laird, when you printed the PLA Osprey at 100%, how were the tolerances of the pins relative to the proximals?

PeterBinkley
Posts: 48
Joined: Fri Feb 13, 2015 5:49 pm

Re: Osprey Hand: FEEDBACK/TESTING REQUESTED

Postby PeterBinkley » Sun Oct 04, 2015 6:44 pm

John, as for the long knuckle pins, I may end up just having a single very long pin that runs all the way through. I did that with the curved-knuckle Osprey (The Merlin) and it worked great. That way removing the pin is as simple as pushing a chopstick into one end.


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