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September 5, 2020 at 9:53 pm #8341
Quick update, the prototype, using foamcore, is complete and will be delivered tomorrow. Regrettably, with the pandemic, I can’t test fit so user will fit an take photos and suggest any changes. Unsure of final materials as there is a large unsupported section and a thin neck on the joystick side. Thinking of adding metal reinforcing strips or T connector to the underside in order to keep material thickness and weight to a minimum. Will make next model out of 1/8″ hardboard to test.
![lap desk prototype|588×500](upload://qgGZtbTOBYrdnUrOiG5o18ENnBs.jpeg)September 5, 2020 at 9:53 pm #8342
You’re the best! thanks for this great update and photo! Let us know how it goes and don’t hesitate to ask for feedback if you need it! We can tag other people in the community who might have expertise in this!September 5, 2020 at 9:53 pm #8343
@marchache1717 your tray design is looking great. I was talking to a few rehab engineers over the weekend who mentioned the frequent need for wheelchair lap trays. I look forward to seeing your finished product.September 5, 2020 at 9:53 pm #8344
Thanks. Met with the health care aide and got some feedback. Working on V2 of the prototype now for delivery Wednesday. According to the aide part of the challenge with these trays is that the chair configurations tend to be unique to the individual so a standard one is difficult.September 5, 2020 at 9:53 pm #8345
Plywood could be an option here. Could be cut with a jigsaw or a laser or CNC if that is available. (Laser would provide some nice customization options). That would be relatively easy to glue up and finish in a way that is easy to clean.
Acrylic is another commonly used material, and probably the easiest to clean. Downside being it is harder to cut cleanly without access to a laser/waterjet and is far more expensive. Making the lip around the edge in pieces could cut down on the material required.September 5, 2020 at 9:53 pm #8346
Prototype V2 is complete and delivered to the aide. Made from 3/16″ hardboard. Nice and light. Considered (and may yet go to) plywood. Concern there is the weight. The front section is unsupported so needs to be as light as possible so the lever effect is minimized. Acrylic would be good but that stuff is really expensive. Don’t know what it’s like now but in the early days of the pandemic you couldn’t get it anywhere. Everyone and their brother needed sneeze guards.
Decided to go with buckle straps (https://www.princessauto.com/en/detail/brown-strap-with-clip/A-p8903494e) instead of Velcro as I felt they could be cinched down tighter. The client also indicated this would be nice as Velcro tends to snag on clothing. $2/ea
3d printed trim pieces for the cup holder and the strap slots.
Couldn’t find suitable edging so designed and 3d printed f-channel. Had the added benefit of not cutting into the tray real estate. Photo only shows corner piece as I wanted clients approval on height, colour, etc. before completing.
To reinforce the thin neck on the joystick side and to provide support on the tray I affixed some metal U-channel on the underside ($6 for 48″). They’ll test tomorrow but I think it will work well. May need to duplicate on the other side which will require a redesign on the cup holder.
I may CNC the final design. We’ll see what the feedback is. Trim pieces hide a lot of sins. :grinning:
Aide thought the client will be super happy it’s this far along.September 5, 2020 at 9:53 pm #8347
@marchache1717 your tray looks excellent. The 3d printed f-channel was a clever addition.September 5, 2020 at 9:53 pm #8348
@marchache1717 @ZKv If you guys ever receive any more of these we have had partner adaptive design programs who have had good luck with triple wall cardboard (or stacked and glued single/double wall). It’s lightweight, affordable, durable, and easily manipulated with basic tools. The whole thing can then be painted and polyurethaned to become more watertight.September 5, 2020 at 9:53 pm #8349
Thanks @brentcourson, @ConnorM That is a FANTASTIC idea! Client has now decided she’d like it out of acrylic as the wheelchair will be in motion, with tray attached, more than anticipated and she needs to be able to see where her feet are. Otherwise would be doing that for sure. I still need to do a final prototype or two. Acrylic isn’t cheap and want to make sure we have everything dialed in before lasering.
Learning lots about things that need to be considered when building these. For instance, the cushions on the chair are almost $400 so important that the tray edges don’t go anywhere near for risk of wearing on them. Same with the armrests, need to keep the straps from contacting.
I had thought about building a frame with a clear, thinner acrylic surface to reduce cost and weight. Have it sit on top of and bracket either side of the armrest but risk of wear is high and I have to be super careful that nothing touches the client either as she has no sensation below the chest.September 5, 2020 at 9:53 pm #8350
Almost at the end of the runway on this project. Got the cardboard prototype laser cut using the dxf file that will be used for the final acrylic version once test fit.
Could use some ideas for the cushioning. I need to find something to protect the torso on the inner edge of the tray (see picture). What’s on there now is 3/4″ foam backer road with a slit cut in. This might work (dropping off at aides place today) but I have a suspicion it’s going to interfere with the armrests. Ideally I’d like to adhere just to the inner edge (1/4″) with maybe a small lip over the top.
There are u shaped foam edge protectors but none that I’ve found are thick enough. She needs about 1/2″ padding.
Any ideas or solutions that have worked in the past ?
![tray|373×500](upload://ejalCudNXxZfBeU1JXGsIF0Z8Jw.jpeg)September 5, 2020 at 9:53 pm #8351
Some may already be familiar with this technique, but just in case.
I need to print a full sized paper template to ensure the CAD file was correct based on the template the aide provided
![tiled pdf|303×404](upload://kPTsXd5Pu3UTBtcPfxX7QDcJBL3.jpeg) .
Borrowed a technique from sewing patterns. Creating tiled PDF’s in Inkscape.
Process I used can be found here:
Creating Tiled PDFs in InkscapeSeptember 5, 2020 at 9:53 pm #8352
Just an update to show the design so far here! @MMC_Suzanne sent the photos. Great job @marchache1717 so modern and simple sleek!!
![tray-glass|666×500](upload://n1adacK5NL95LQFKvV87QVgVKGi.jpeg)September 5, 2020 at 9:53 pm #8353
![tray|363×484](upload://wPAAjNLUI3FlSn39AKm64W84ZBK.jpeg)September 5, 2020 at 9:53 pm #8354
Thanks, not *quite* there. The front edge of the tray needs support. Have designed two swing down legs, using hirth joints, to rest on the footrest attachment points. Should be finished end of week. I’ll post a little write up. May be some things other can use.September 5, 2020 at 9:53 pm #8355
Oh yes! Please send an update with your tweaks Marc! Looks Fab so far!
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