Cast Urethane Wheelchair Push Tabs

Cast Urethane Wheelchair Push Tabs I use these push tabs on my manual wheelchair since I can't grip the push-rim. I had originally printed tabs using Ninjaflex and they worked very well but over time some broke as the layers delaminated. I needed more and since my 3d printer was down for a while I asked a friend if he could print some. He made one print and suggested it would be much faster to print a mold and cast them from urethane. We altered the tabs design by adding draft angles to some surfaces so the part could come out of the mold. Then my friend designed and printed the mold and cast the tabs. Another friend installed the tabs and they are working very well. They are a little harder than the Ninjaflex but that seems to be fine. We did have a hiccup. Originally we had a nut buried in the tab body and the screw ran up through the bottom but when we attached them and applied pressure the rubber could not hold and the tab popped off the push rim. So the friend who was installing them drilled the hole all the way through and bolted them from the top. This is solid and I like seeing the button head M5 screw. In the end the result is great and another reason to love 3d printing. And thanks to my friends for making and installing these! [attachment 108869 push_tab_1.jpg] [attachment 108870 push_tab_2.jpg] [attachment 108871 push_tab_3.jpg] [attachment 108872 push_tab_4.jpg] [attachment 108873 push_tab_5.jpg] https://reprap.org/forum/read.php?166,842110,842110#msg-842110 Sun, 13 Sep 2026 03:35:50 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?166,842110,850771#msg-850771 Re: Cast Urethane Wheelchair Push Tabs https://reprap.org/forum/read.php?166,842110,850771#msg-850771

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Ohmarinus
Unless you like to experiment, which I think you do ;)

You read me well. :-) Sometimes it's difficult to know when to stop iterating.

I will keep looking on the Smooth-on site for materials. I don't have much experience with PU but will try to learn more.

Have a good day!]]> Garry Bartsch Look what I made! Sat, 06 Apr 2019 17:08:27 -0400 https://reprap.org/forum/read.php?166,842110,850564#msg-850564 Re: Cast Urethane Wheelchair Push Tabs https://reprap.org/forum/read.php?166,842110,850564#msg-850564

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Garry Bartsch

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Ohmarinus
I can imagine making a 3-stage mold where you first cast some softer PU, then remove a mold piece to cast the rest of the harder PU. These two should be able to bond together so you have the construction with hard solid PU and a softer part where your more fragile skin/hands have to touch it.

I like this idea very much. Maybe in the future I will try that. Can you recommend a soft PU? We used Smooth-on material for this.

Ahhh Smooth-On is actually already quite a good solution by itself. We used it on the tools on the art academy I worked some time ago. In that case I'm not sure if it's worth going through all the trouble of making a new mold. Unless you like to experiment, which I think you do ;)]]> Ohmarinus Look what I made! Wed, 03 Apr 2019 10:49:53 -0400 https://reprap.org/forum/read.php?166,842110,850395#msg-850395 Re: Cast Urethane Wheelchair Push Tabs https://reprap.org/forum/read.php?166,842110,850395#msg-850395

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Ohmarinus
I can imagine making a 3-stage mold where you first cast some softer PU, then remove a mold piece to cast the rest of the harder PU. These two should be able to bond together so you have the construction with hard solid PU and a softer part where your more fragile skin/hands have to touch it.

I like this idea very much. Maybe in the future I will try that. Can you recommend a soft PU? We used Smooth-on material for this.]]> Garry Bartsch Look what I made! Sat, 30 Mar 2019 19:33:08 -0400 https://reprap.org/forum/read.php?166,842110,850241#msg-850241 Re: Cast Urethane Wheelchair Push Tabs https://reprap.org/forum/read.php?166,842110,850241#msg-850241 Ohmarinus Look what I made! Thu, 28 Mar 2019 13:40:50 -0400 https://reprap.org/forum/read.php?166,842110,842236#msg-842236 Re: Cast Urethane Wheelchair Push Tabs https://reprap.org/forum/read.php?166,842110,842236#msg-842236 Garry Bartsch Look what I made! Sun, 23 Dec 2018 14:36:57 -0500 https://reprap.org/forum/read.php?166,842110,842206#msg-842206 Re: Cast Urethane Wheelchair Push Tabs https://reprap.org/forum/read.php?166,842110,842206#msg-842206 imqqmi Look what I made! Sun, 23 Dec 2018 08:07:27 -0500 https://reprap.org/forum/read.php?166,842110,842110#msg-842110 Cast Urethane Wheelchair Push Tabs https://reprap.org/forum/read.php?166,842110,842110#msg-842110
I had originally printed tabs using Ninjaflex and they worked very well but over time some broke as the layers delaminated. I needed more and since my 3d printer was down for a while I asked a friend if he could print some. He made one print and suggested it would be much faster to print a mold and cast them from urethane.

We altered the tabs design by adding draft angles to some surfaces so the part could come out of the mold. Then my friend designed and printed the mold and cast the tabs. Another friend installed the tabs and they are working very well. They are a little harder than the Ninjaflex but that seems to be fine.

We did have a hiccup. Originally we had a nut buried in the tab body and the screw ran up through the bottom but when we attached them and applied pressure the rubber could not hold and the tab popped off the push rim. So the friend who was installing them drilled the hole all the way through and bolted them from the top. This is solid and I like seeing the button head M5 screw.

In the end the result is great and another reason to love 3d printing.

And thanks to my friends for making and installing these!

[attachment 108869 push_tab_1.jpg]
[attachment 108870 push_tab_2.jpg]
[attachment 108871 push_tab_3.jpg]
[attachment 108872 push_tab_4.jpg]
[attachment 108873 push_tab_5.jpg]]]> Garry Bartsch Look what I made! Fri, 21 Dec 2018 20:18:00 -0500