Homemade Parts!

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Homemade Parts!
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Posted: Feb 10, 2018 at 9:20 Quote
Pedro404 wrote:
RunsWithScissors wrote:
The urethane I'm using is a 2 part mix that I had leftover from an unrelated project. It's kinda cool stuff to work with because it mixes at room temperature and requires no extraordinary safety equipment to handle. It's a little on the hard side though for grips. You can definitely find squishier stuff if you go looking for it.

You fit all the mold parts together, then pour your casting material in the center. After that you insert the plunger and press down until it bottoms out. If you mixed and measured well you'll have just a bit coming out of the relief holes at the top. After that you put the cap on, chuck it in a drill for half a minute to spin any bubbles away from the outside and then walk away for awhile.

As for printing in flex filament... 3d printing is a pretty slow process if you want a lot of detail and finish quality, so if you'll be wanting to make several of something it's sometimes better to use the technology to make a mold rather than the actual product. It would probably take me 16-24 hours of machine time to print a pair of grips out of a flexible filament. I can cast a single grip every 2 hours out of just one mold, so that's 4-8 times faster, even making them one at a time. ...Also, this was mostly just a fun way to play with some leftover material Wink

Yeah, the time argument makes sense. I'm guessing the texture is from the print layers? Have you considered sanding the mold down to get a smoother finish?

And exactly how would you sand the surfaces of a negative mold?


Magura Smile

Posted: Feb 10, 2018 at 9:28 Quote
Pedro404 wrote:
RunsWithScissors wrote:
The urethane I'm using is a 2 part mix that I had leftover from an unrelated project. It's kinda cool stuff to work with because it mixes at room temperature and requires no extraordinary safety equipment to handle. It's a little on the hard side though for grips. You can definitely find squishier stuff if you go looking for it.

You fit all the mold parts together, then pour your casting material in the center. After that you insert the plunger and press down until it bottoms out. If you mixed and measured well you'll have just a bit coming out of the relief holes at the top. After that you put the cap on, chuck it in a drill for half a minute to spin any bubbles away from the outside and then walk away for awhile.

As for printing in flex filament... 3d printing is a pretty slow process if you want a lot of detail and finish quality, so if you'll be wanting to make several of something it's sometimes better to use the technology to make a mold rather than the actual product. It would probably take me 16-24 hours of machine time to print a pair of grips out of a flexible filament. I can cast a single grip every 2 hours out of just one mold, so that's 4-8 times faster, even making them one at a time. ...Also, this was mostly just a fun way to play with some leftover material Wink

Yeah, the time argument makes sense. I'm guessing the texture is from the print layers? Have you considered sanding the mold down to get a smoother finish?

That's certainly do-able, but the photo also makes the surface look rougher than it really is. The black shiny nature of the material makes it hard to photograph, so this pic is really close in and angled to show a lot of contrast. The layer height of the print is 0.06mm. That's pretty fine. If you wanted a really slick finish you could also print molds in ABS and vapor smooth with acetone.

What I'd really like to figure out though, is how to easily model a knurled surface on a grip. Anybody out there in PinkBike Land know how to do knurling in Fusion 360...?

Posted: Feb 10, 2018 at 11:41 Quote
Haven't worked with fusion 360 but I'd imagine you could swept cut a triangle around helices going opposite directions.

Posted: Feb 10, 2018 at 12:23 Quote
Mr-Magura wrote:
And exactly how would you sand the surfaces of a negative mold?

You're right, with the bad mofo grip that wouldn't be possible. RunsWithScissors has a picture of a mold in his profile where it would be possible, but it's a different grip with raised lettering on the finished grip. I got them mixed up.
But like RunsWithScissors said, acetone smoothing could work on ABS.

Posted: Feb 10, 2018 at 12:26 Quote
Easier to print a positive, machine the outer diameter, cast a negative mold......


Magura Smile

O+
Posted: Feb 15, 2018 at 17:04 Quote
It doesn't look that good with a knurl on it. rough and quick job though, with more work it might be ok.
Hard to read on an angle.
photo

Posted: Feb 16, 2018 at 4:55 Quote
latheboy wrote:
It doesn't look that good with a knurl on it. rough and quick job though, with more work it might be ok.
Hard to read on an angle.
photo

I like it Smile Looks like the lettering would be tough to print though for molds like the kind I've been making. It's a funny catch 22 kind of problem...

If you want inset letters you're gonna be printing them in thin air without support because the molds print vertically. so fine resolution is tough to get looking really good on the first couple layers of the underside of a letter. That first layer wants to twist/curl/warp. If you go the other route and use raised letters it's easier to print the mold, but harder to keep bubbles out of the raised letters when you add the urethane to cast a grip. Spinning the mold with a drill motor helps, but doesn't TOTALLY work every time.

Nice knurling, though. How did you model that? I'm thinking I'd like to try finer knurling like the checkering on a pistol grip or a rifle stock with raised letters or stars or some other simple shapes, but that might give me trouble to print, too. Sometimes there's a significant gap between what I can model on the computer and what will actually print nice....

O+
Posted: Feb 16, 2018 at 5:28 Quote
Do you plan on printing those grips with something like flexible pla, or ninja flex?

Also, has anyone printed jockey wheels yet? I've printed a whole bunch of tools, just never parts!

Posted: Feb 16, 2018 at 5:53 Quote
ArcherMatt wrote:
Do you plan on printing those grips with something like flexible pla, or ninja flex?

Also, has anyone printed jockey wheels yet? I've printed a whole bunch of tools, just never parts!

No, I've been printing molds out of ABS and PETG, then injection molding with 2 part urethane. Printing grips one at a time out of flexible filament sounds like a slow, frustrating, difficult proposition to me. Maybe I'm wrong, I dunno. Haven't actually tried it.

As for jockey wheels, I think that would be totally do-able and not even that difficult to either model OR print. ...Although I would expect one side to look a little ugly from support material marks.

Posted: Feb 16, 2018 at 6:10 Quote
I'm pretty sure someone posted 3D printed jockey wheels in this thread a few years ago. There are some models on thingiverse.

Posted: Feb 16, 2018 at 6:28 Quote
Pedro404 wrote:
I'm pretty sure someone posted 3D printed jockey wheels in this thread a few years ago. There are some models on thingiverse.

My next big idea is 3d printed rotor covers. I figure we can all benefit from not cutting a leg off every time we crash. A roadie gave me this idea. Guy must be some kind of genius...

O+
Posted: Feb 16, 2018 at 6:56 Quote
I can probably design some rotor covers and test it out. I've never had a need for them except when i accidentally touched my rotors with my leg after a hot lap at a downhill park. had a nice welt on my leg, haha

Posted: Feb 16, 2018 at 6:58 Quote
RunsWithScissors wrote:
Pedro404 wrote:
I'm pretty sure someone posted 3D printed jockey wheels in this thread a few years ago. There are some models on thingiverse.

My next big idea is 3d printed rotor covers. I figure we can all benefit from not cutting a leg off every time we crash. A roadie gave me this idea. Guy must be some kind of genius...
Does that actually happen to anyone, though? I think that's just UCI roadie paranoia.

For the jockey wheels, I think I still have a parametric Solidworks file floating around somewhere if that's useful to anyone. Just input the number of teeth and it resizes it automatically. Was for a chainring and cassette iirc but easy enough to change that to a jockey wheel.

O+
Posted: Feb 16, 2018 at 7:09 Quote
Arnoodles wrote:
RunsWithScissors wrote:
Pedro404 wrote:
I'm pretty sure someone posted 3D printed jockey wheels in this thread a few years ago. There are some models on thingiverse.

My next big idea is 3d printed rotor covers. I figure we can all benefit from not cutting a leg off every time we crash. A roadie gave me this idea. Guy must be some kind of genius...
Does that actually happen to anyone, though? I think that's just UCI roadie paranoia.

For the jockey wheels, I think I still have a parametric Solidworks file floating around somewhere if that's useful to anyone. Just input the number of teeth and it resizes it automatically. Was for a chainring and cassette iirc but easy enough to change that to a jockey wheel.

Where do you think that file is?

Posted: Feb 16, 2018 at 8:01 Quote
Arnoodles wrote:
RunsWithScissors wrote:
Pedro404 wrote:
I'm pretty sure someone posted 3D printed jockey wheels in this thread a few years ago. There are some models on thingiverse.

My next big idea is 3d printed rotor covers. I figure we can all benefit from not cutting a leg off every time we crash. A roadie gave me this idea. Guy must be some kind of genius...
Does that actually happen to anyone, though? I think that's just UCI roadie paranoia.

For the jockey wheels, I think I still have a parametric Solidworks file floating around somewhere if that's useful to anyone. Just input the number of teeth and it resizes it automatically. Was for a chainring and cassette iirc but easy enough to change that to a jockey wheel.

No, it NEVER happens. How many one legged former mountain bikers have you met? It's just a roadie paranoia thing that I like to poke fun at. Kinda like mountainbikers who are afraid of lycra Wink Each group has it's weirdos...


 


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