zammykoo

I recently pulled a pair of SR pedals from the Box O' Crap with a missing dust cap, and thought it was the perfect opportunity to make a second. I haven't tried this before but has been on my to-do list. It was an enjoyable learning experience and I imagine is practical for many applications. It turned out well and overall I am happy with the outcome!

I documented my process for anyone interested in the details: https://imgur.com/a/m8GcN

Stevensb 

Well done!

Cheers.

Brad

steelbikeguy

Very cool! I love a fun project, and especially a well documented one!

Any observations about the cost of making the dustcap with this process vs. other processes? The only alternate process that comes to mind would be 3D printing, but that would require a scan of the dust cap (or drawing the part in a suitable application).

Steve in Peoria

JaccoW

Pretty good guide!

I've heard about the process before from mechanical keyboard forums:
Continued experiments in homemade key caps...with interesting results.
Capcraft Hub - Updates & Tom Foolery Herein
Sculpting Keycaps - :~$ynth & Green Stuff

There is a lot you can do with it, especially if you want to colour code your small parts.

Drillium Dude 

Nice tutorial - thank you! One of us should make a bunch of Campy pedal caps; could retire on the proceeds

Btw, I like the clear look better than the original.

DD

zammykoo

Thanks guys! I will be experimenting with different resins and colors to refine my process. @Drillium Dude, if I can get my hands on a Campy pedal cap I'll definitely try it. The clear does look nicer but you can see the bubbles inside. I'd have to build a degassing chamber to help clean it up.

@steelbikeguy, funny that you mention 3D printers. I am actually getting one to play with soon. 3D printers are nice for designing custom parts and printing with ease, but the downside the resolution is not high enough to make production ready parts. There will be a lot of sanding to get the final piece to be presentable.

If you are asking about cost to produce these caps in bulk, I think the best way is to use an original part as a starting point. You'd need to make a mold with multiple slots, almost like an ice cube tray so that you don't have to wait too long before casting the next batch.

bnewberry

Impressive!

steelbikeguy

Regarding 3D printers, they are pretty neat gadgets, especially if you have to make internal structures or features that are hard to machine. For prototypes, they are about the only way to get a quick part made.
Resolution is certainly an issue; more so if you are using a low cost version. If you need to make a half dozen parts, it might be worth it to use a 3D printer and then sand/polish the output. For a one-off like the dust cap, your molding process looks easier & cheaper.

When I think about what parts are on my bikes that are made of plastic and don't require much strength, I'm struggling to think of anything beyond pedal or crank dust caps. Maybe feet for frame pumps??
Even for pedal dust caps, the MKS caps make a nice replacement for the old Campy caps.

It's still a neat process for making a replacement part! I just need to figure out a good excuse for doing this myself.

Steve in Peoria

zammykoo

You’re right about that! I can’t think of anything else either that doesn’t require higher strength materials.

For more rigid applications I have considered trying to cast with pewter. It has a relatively low melting point and should be easy to work with. I think the silicone rubber that I have should withstand pewter’s melting heat range. We’ll see!

Chombi1 

Might you have to consider the particular plastic material used resistance to solvents and oils? Some plastics tend to craze and crack apart if exposed to these.....

noahwayout

Now that's cool! I'd imagine this would be great for recreating other NLA parts like the plastic insert button on the front of some Cinelli quill stems.

Hudson308 

I keep thinking somebody should die-cast metal copies of that infernal Simplex FD plastic clamp assembly. There has to be a way to reproduce those in metal somehow at a reasonable cost.

qcpmsame 

PM me an address, I'll be glad to loan an original Campagnolo pedal dust cap, If it gets some in the pipeline just remember me when you sell some of them. I'll even enclose a pre paid envelope for return of my original dust cap.

Bill

zammykoo

@Chombi1 - That's a good question. I have not looked into that yet but it would be on the checklist.
@qcpmsame - Bill, I appreciate your offer and will keep that in mind! I wanted to check with my local co-op first and will get back to you.

qcpmsame 

Anytime you should need one, I will take one of mine from duty. The plastic dust caps are going for upwards of $40.00, and the original metal items have reached some BIN prices around $90.00+. I would happily purchase some of your clear ones.

Bill

gearheadgeek

Interesting timing. I just spent some time over the long weekend to 3D model the Simplex front derailleur body (broken of course) from one of my PX10s. With this exact idea in mind.

The original is a poor design for a plastic part. I have always blamed the Delrin material but when you look closely at the design you can see that failure was inevitable for any plastic.

I have a 3D printed prototype en route. Just a cheap plastic prototype for now. I am going to get some quotes for a small production run in aluminum. I also have an improved design in process, about 85 percent done. My goal is to make that one out of plastic, but designed to last.

Unfortunately with my schedule that remaining 15 percent of the revised design may take a while.

- John

Hudson308 

WOO HOO!!!
I didn't mean to hijack this thread, but your efforts are exactly what I was thinking about. I suppose this deserves a new thread!

zammykoo

Very cool! Do share some pics with us once you get it

Salamandrine 

That is awesome! I was hoping somebody would do a 3D model of that part. While I don't have a Simplex front derailleur at this time, I'm still looking forward to hearing how this story plays out. Please start a thread for sure when you get the prototype!

I've always felt that they were unfairly maligned. Prestige FD shift fine if you know how to properly set them up. Also, Delrin is awesome stuff. Too bad its name has been besmirched. It's one of the coolest polymers around: high strength, high MOE, built in lubricity. I agree that the problem had more to do with design deficiencies than the actual material. That said, making one from aluminum would probably fix it...

pcf

I need one of those SR dustcaps! Please PM me if you can make another one!

oldschoolbike

I wanted some of those concave spacers used to fit rear brakes to a round seat stay bridge, for a tidy job of fitting fenders to the bridge of a U-brake bike. Do you think I could find a pair in my junk? No way.

Then I realized that they would not take much stress, drew one up, and printed a bunch in ABS at work. It would have been quicker to do one or two in a shop by old-fashioned machining methods, but I wanted to check off "intro to 3D printing" on my skills matrix and I didn't have access to a shop. For every solution, there is an ideal problem.