Making bicycle grips molding/casting?

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bikewhorder

bikewhorder

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Sorry if this topic has been covered on here, I searched around a bit and came up empty handed. I have a custom grip I'd like to make. I've been watching Youtube tutorials on how to do casting but I've never done it and was wondering if anyone had much experience with this and could steer me in the right direction. I'm mostly just a bit stumped on what products to use, there seems to be quite an array of materials and manufacturers. I just want to make a grip that has the same look and feel of an original grip from the 30's/40's. I'm not looking to make a grip that is so authentic that it is the same chemical composition, it just needs to be convincing. I'm also not 100% sure what the mold for a grip should look like. I have a plan for how to do it but since this is something that has been done a million times I'd love to see what the most proven method would be. Any advice from people with real world experience in this field would be greatly appreciated. Thanks
 
RustySprockets said:
Maybe liquid silicone molding? That's where I'd start my search.
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I've never made grips before, but I use liquid silicone to make molds of other pieces like switches, lenses and things like that. Currently working on a mold for a fender ornament, but is proving to be a little difficult due to the shape.

I imagine silicone could be used to make a mold for grips relatively easy, but take your time it dries slow.
As far as material to use to make the actual grip, that would be something to research. Everything I replicate is plastic.
 
The two-part stuff is supposed to set up quickly, like 20-40 minutes, depending on the mix. I thought maybe use the silicone for the grip itself. You'd first have to to carve a form, then make a mold of the form.

Watch some YouTube videos--the steps don't seem too difficult. The magic is in doing those steps WELL. You may be the only guy attempting this...blaze a trail!
 
I didn't think about the two part stuff. I use to use an amalgam that my father in law used in his practice, but it got expensive. Magic mold putty might be the way to go, just make sure you have enough to pack inside the grip to avoid air pockets.
 
This is not an easy topic to address in this format, but maybe I can point you in the right direction. (P.S. I'm an expert moldmaker and caster with an MFA in sculpture :))
I would imagine the toughest part would be the actual casting of your grip. Commercially available grips are most likely injection-cast. This is because they're so thin. You can replicate the technique on a limited scale with some kind of giant syringe. I use turkey-injectors for small stuff, not sure if they would hold enough material for a grip.
As for products....though I've never used it, Polytek makes castable rubber. I do use their other products, and they're really great. All their stuff is the wrong color for your application, but they also make dyes for the rubber.
http://www.polytek.com/products/liquid-castable-rubbers/poly-pt-series/
 
If the turkey squirter doesn't hold enough material by itself, why not employ two of 'em? I have a pretty nice acrylic injector that I use as a poor man's grease gun--it's perfect. Now that Thanksgiving is over, time to stock up on those gadgets.
 
Rockit! said:
This is not an easy topic to address in this format, but maybe I can point you in the right direction. (P.S. I'm an expert moldmaker and caster with an MFA in sculpture :))
I would imagine the toughest part would be the actual casting of your grip. Commercially available grips are most likely injection-cast. This is because they're so thin. You can replicate the technique on a limited scale with some kind of giant syringe. I use turkey-injectors for small stuff, not sure if they would hold enough material for a grip.
As for products....though I've never used it, Polytek makes castable rubber. I do use their other products, and they're really great. All their stuff is the wrong color for your application, but they also make dyes for the rubber.
http://www.polytek.com/products/liquid-castable-rubbers/poly-pt-series/
Click to expand...

Thanks for the info, why do you think the pour in products wont work? Are they just not the right material? I was thinking about placing an order with this company http://bjbenterprises.com/index.php/polyurethanes/castable/ but its just a random choice really.
 
bikewhorder said:
Yes i actually own a set of the ball end grips, I'd be curious to know if he's making them or importing them. I'm not looking to infringe on his business I just want to learn how to do it myself because I have a few design ideas I want to experiment with.
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I think he is making them in the Northeast.
 
bikewhorder said:
Thanks for the info, why do you think the pour in products wont work? Are they just not the right material? I was thinking about placing an order with this company http://bjbenterprises.com/index.php/polyurethanes/castable/ but its just a random choice really.
Click to expand...

Well, you'll still use the pourable stuff, just pouring it with a little pressure. My concern is that with a viscous material like that, with a thin wall casting like grips, will increase the likelihood of air pockets and things like that.

Taking a class from them will definitely get you pointed in the right direction. You'll definitely need some kind of demonstration to get you started.....grip casting is a little advanced for someone who's never done moldmaking before.
 
bikewhorder said:
I've been in contact with Derek from Polytek and he's been incredibly helpful. He says he will make me a demo video on Monday showing how to add an insert to a mold like I would need to do to create the bore for the handlebars.
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It's always cool when a company is willing to go above like that, they probably figure in the long run it'll help make more money, but still cool that they'd do things like that to help out.
 
bikewhorder said:
I've been in contact with Derek from Polytek and he's been incredibly helpful. He says he will make me a demo video on Monday showing how to add an insert to a mold like I would need to do to create the bore for the handlebars.
Click to expand...

Perfect. That's the part that would probably be the most trouble. Sounds like you're well on your way now!
 
Not sure if this will help you. I did some work for a place that was making parts using a two part very thick material and a rubber mold. To help with the air bubbles we mounted one of those vibrating hand sanders to a board and placed the mould on it. While very slowly pouring the vibration helped dislodge most of the air bubbles. Was not 100 percent perfect but a lot better then not doing it.
 
Have you considered 3-D printing your mold? Not sure if that would work, I've been tossing around the idea of molding some grips as well and thought of the 3-d printing.
Can you post a link to the video Derek was making?
 
I'm not an expert, but I would make a blank/use an original old grip with the end of a handlebar in it, then make the mold around it, then reuse the handlebar covered in mold release within the void when recasting (or I guess if you want to be really fancy, you could cast right onto the handlebar you intend to use if you don't plan on removing them). There's casting rubber in varying durometer. I did something similar to cast this Iver Johnson replica badge, substituting a PVC piece in the correct diameter for a head tube. Going around the tube on three sides will be more of a challenge, but I would think it would be doable.

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