3D print unicorn hoods (bracket covers)?

Veloo · #1 05-21-2024, 07:18 AM

Calling on 3D print and CAD experts.

Came across this last night as the bike search has taken me down the path of 9 speed Ultegra. Ironically, I've bought a good half dozen 9 speed hoods to catch and release here, avoid 9 speed like the plague cuz of the rotting hoods and now find myself in potential need of them.

Blew my mind when I saw this but I'm still skeptical.
How the hell did this person figure out the 3D drawing? Is it not as complicated as I'm thinking it is?
Friend just got a 3D printer last week so I may try his out with him but would a TPU print really stand up to the forces of installing hoods?

Printed on a Creality Ender 3 V3 KE

https://www.thingiverse.com/thing:5019040/comments

JAGI410 · #2 05-21-2024, 08:07 AM

I'm guessing that was a scan-to-mesh modeling workflow. Even the newer iPhone can do lidar scanning, and with the right app, you could scan that hood fairly easy, then do some smoothing to get that final result. Other purpose built scanners exist as well, so modeling these odd, complex shapes can be made easy with some investments.

Now could it handle the stress of being installed if printed with TPU? That's a whole other story. I don't have a lot of experience with TPU, but I've installed hoods a time or ten, and I don't know if I'd trust it. It would be worth the experiment though! But honestly, I'd use ABS/PLA and use that for a mold for a proper rubber material.

rccardr · #3 05-21-2024, 08:11 AM

Check out this guy's web site: https://racevelo.com/?v=7516fd43adaa

He's been making a bunch of older hoods for vintage levers and the reviews are excellent. He's even done some one-off stuff.

bahyow · #4 05-21-2024, 01:06 PM

I can't say I've printed much TPU, most of the stuff I print is ABS, PLA, ASA. I would not think that TPU holds up as a brake hood material...I've had it split along the layer lines (FDM type printer).

I'd definitely look to making a mold and pouring some rubber/silicone material in.

prototoast · #5 05-21-2024, 01:12 PM

Quote:

Originally Posted by bahyow

I can't say I've printed much TPU, most of the stuff I print is ABS, PLA, ASA. I would not think that TPU holds up as a brake hood material...I've had it split along the layer lines (FDM type printer).

I'd definitely look to making a mold and pouring some rubber/silicone material in.

That was my first thought as well.

unterhausen · #6 05-21-2024, 05:14 PM

That's a fairly impressive model to me. Assuming it fits.

Veloo · #7 05-21-2024, 10:44 PM

This was the first pass without any supports.

Veloo · #8 05-21-2024, 10:51 PM

Then the software calculated some supports.

rmhurley · #9 05-21-2024, 10:53 PM

Along similar lines, I have dreamed about a retrofitted hood for say an old dia compe lever that would have some extra material on the ramp section where it would help flatten out a bit more and make it a bit more of a modern hand fit. I know that sort of kills the full on old-fashioned feel, but I like those brakes but the perpendicular connection hurts my wrists.

Matt92037 · #10 05-21-2024, 11:13 PM

Make sure you really dry out the TPU before printing. It absorbs A LOT of moisture and will print terribly if not dry.

Quote:

Originally Posted by Veloo

This was the first pass without any supports.

Veloo · #11 05-22-2024, 07:04 AM

Before.

Veloo · #12 05-22-2024, 09:46 AM

After.
The hood is 19 grams. The supports total 17 grams.
Still gotta tidy it up a bit. It does have "SHIMANO" on it.

Will report back on how install goes.

Joe Cyclist · #13 05-22-2024, 09:58 AM

Wow, that's impressive. Looking forward to hearing about the install

kppolich · #14 05-22-2024, 10:17 AM

Nice first draft. TPU is tricky with temp/speed/cooling.
Layer height look OK too, but I'm sure you'll dial it in future versions to reduce blobs/stringing.

Veloo · #15 05-27-2024, 05:22 AM

So as I kinda expected, it didn't work out. Maybe operator error?
Of course it's no where as stretchy as an actual rubber hood.
I even put hair dryer heat to it as I tried to force it on. Thought about boiling it in water but I wasn't quite in the mood to take it that far.
I could hear the snap/crack of the strands giving as I pulled/pushed. I entered from the rear cuz there was no way it was going over the lever and that pointy cap.
Just to check the actual fit, I cut i open and while I wasn't able to get the top section seated into the slot, the rest of it did fit quite well. I recorded the process on my phone. I'll try to post it up later today.

Maybe for kicks I will put it in boiling water to see just how flexible it gets.