Homemade Parts!

PB Forum :: Mechanics' Lounge
Homemade Parts!
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flag RunsWithScissors
Posted: Feb 9, 2018 at 5:18 Quote
sherbet wrote:
Poulsbojohnny wrote:
Too many years fiddling with motorcycle chains in my book. Push pins always seem to break. So I moved to an angle grinder years ago. Not exactly pack friendly though!

So how does the grinder reassemble a chain?

Thank you so much. I was wondering what the hell he meant, too... Wink
flag crs-one
Posted: Feb 9, 2018 at 10:20 Quote
You just put the grinder in reverse.
flag macross87
Posted: Feb 9, 2018 at 10:29 Quote
crs-one wrote:
You just put the grinder in reverse.

Just like turning back the odometer?
flag cmcrawfo
Posted: Feb 9, 2018 at 11:14 Quote
you just grind off one of the links on the old chain to remove it ... it makes it easier when the old moto chain is rusted (rather than using a chain break tool).

to install the new chain, you would also cut the chain to length with the grinder, and then use the quick link to instal it on the bike.

Not exactly rocket surgery. Super common in the moto world. You could do it with a bicycle chain too, but the links are generally easier to push out with the tool. and grinders are not exactly looked upon as a stander shop tools in the MTB world, unlike in the motor world.... if you bump a frame on dirtbike with a grinder, things are usually ok .. if you bump a frame on a bicycle with grinder... not so much.
flag RunsWithScissors
Posted: Feb 9, 2018 at 11:53 Quote
I'd love to market these grips to the general public, but my boss would NEVER let me (for good reasons, I GUESS...), so these are just gonna wind up on a few friends' bikes.

Prototype grip for some friends
flag Compositepro
Posted: Feb 9, 2018 at 11:59 Quote
photo

that was my old truing stand design

photo

that was my original truing stand design

theres tons of machined stuff in here

https://www.flickr.com/photos/151761966@N05/albums
flag DC1988
Posted: Feb 10, 2018 at 2:36 Quote
RunsWithScissors wrote:
I'd love to market these grips to the general public, but my boss would NEVER let me (for good reasons, I GUESS...), so these are just gonna wind up on a few friends' bikes.

Prototype grip for some friends
I want a set, they're awesome!
flag iffy
Posted: Feb 10, 2018 at 3:40 Quote
I'm not sure he'd approve.


photo
flag DC1988
Posted: Feb 10, 2018 at 3:55 Quote
But wouldn't you love it when someone asks which bike is yours and you could say it's the one that says bad motherf*cker on it.
flag RunsWithScissors
Posted: Feb 10, 2018 at 4:08 Quote
DC1988 wrote:
But wouldn't you love it when someone asks which bike is yours and you could say it's the one that says bad motherf*cker on it.

That was prettymuch EXACTLY how these came into existence Smile Friends talking trash while we were building up a new bike. I had some urethane leftover from a project, so I decided to give it a shot. The urethane I had feels a little bit firm for the purpose, but not too bad. They'll probably last a long time. Wish we could market these, but I get where my boss is coming from. Some folks would be offended.
flag Grumposaur
Posted: Feb 10, 2018 at 4:13 Quote
sell it via a webshop seemingly unrelated to your main business: badmofo-bikeparts.com Razz
flag RunsWithScissors
Posted: Feb 10, 2018 at 4:46 Quote
Grumposaur wrote:
sell it via a webshop seemingly unrelated to your main business: badmofo-bikeparts.com Razz

You have no idea how tempted I am Wink If I didn't love my day job so much I probably WOULD do something like that. I'll probably just make a few for my friends and maybe sell the molds and modeling files to someone locally who wants to make 'em. It ain't rocket surgery, after all. Anybody could do this. I designed these on a cheap computer using free software and printed the first mold set on a printer that cost me less than $200. Anybody who really loves the idea can reverse engineer my design for free. Pics of the mold design are on my PB profile. I'm not patenting it or trying to protect the intellectual property in any way on this one. If you wanna run with the idea, go ahead, just don't try to sue anyone who steals the idea from YOU or I'll send Samuel Jackson to your house to collect my cut of the money... Wink
flag Pedro404
Posted: Feb 10, 2018 at 7:11 Quote
RunsWithScissors wrote:
Grumposaur wrote:
sell it via a webshop seemingly unrelated to your main business: badmofo-bikeparts.com Razz

You have no idea how tempted I am Wink If I didn't love my day job so much I probably WOULD do something like that. I'll probably just make a few for my friends and maybe sell the molds and modeling files to someone locally who wants to make 'em. It ain't rocket surgery, after all. Anybody could do this. I designed these on a cheap computer using free software and printed the first mold set on a printer that cost me less than $200. Anybody who really loves the idea can reverse engineer my design for free. Pics of the mold design are on my PB profile. I'm not patenting it or trying to protect the intellectual property in any way on this one. If you wanna run with the idea, go ahead, just don't try to sue anyone who steals the idea from YOU or I'll send Samuel Jackson to your house to collect my cut of the money... Wink

How and with what did you inject the mold? Wouldn't it be easier to straight up print them with a flex filament?
flag RunsWithScissors
Posted: Feb 10, 2018 at 8:28 Quote
Pedro404 wrote:
RunsWithScissors wrote:
Grumposaur wrote:
sell it via a webshop seemingly unrelated to your main business: badmofo-bikeparts.com Razz

You have no idea how tempted I am Wink If I didn't love my day job so much I probably WOULD do something like that. I'll probably just make a few for my friends and maybe sell the molds and modeling files to someone locally who wants to make 'em. It ain't rocket surgery, after all. Anybody could do this. I designed these on a cheap computer using free software and printed the first mold set on a printer that cost me less than $200. Anybody who really loves the idea can reverse engineer my design for free. Pics of the mold design are on my PB profile. I'm not patenting it or trying to protect the intellectual property in any way on this one. If you wanna run with the idea, go ahead, just don't try to sue anyone who steals the idea from YOU or I'll send Samuel Jackson to your house to collect my cut of the money... Wink

How and with what did you inject the mold? Wouldn't it be easier to straight up print them with a flex filament?

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
flag Pedro404
Posted: Feb 10, 2018 at 9:05 Quote
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?

 


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