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Making your own caps

Old 01-31-19, 12:42 PM
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Making your own caps

I'd like to make my own seat stay caps. What size steel would I use and where would I find it? I've looked around the interweb, but I'm not seeing anything good.

Thanks a lot.

Brandon
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Old 01-31-19, 01:26 PM
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I simply used sheet steel and brazed it in place on the face of the seat stay tubes, I had cut at an angle then brazed to the seat lug's sides..

I happened to make 1 piece wrap over and capped both seat stays.. it looks nice .. My 1 frame build was in the mid 70's..

concave ones are made from a scrap of the seat stay tubes themselves..

alternatives .. buy steel rod, same OD as your chainstays, turn it in your lathe to slip inside the seat stay tube, cut it off at an angle

if you machine both ends 1 angled cut will make 2 caps ..







....

Last edited by fietsbob; 01-31-19 at 01:39 PM.
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Old 01-31-19, 03:35 PM
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The traditional way is to use tube scraps from the build. Any wall/plate thickness might be used but I have gravitated to more then the thin stuff bike tubing usually is. One reason is my seeing so many Raleigh frames with cracks along the stay cap edges from over filing and thus thinning down the stay/cap joint. I'll use .049 or more walled tube or similar thick plate. I don't use stay end diametered tubing any longer due to a complaint that the "wings" can be sharp enough to snag shorts or cut skin. I'll use a tube around 1"+ for the cap if I want a concave /fluted look.

Here's a few shots of part of the process I've used. These are with flat plate and from quite a while ago. Today I might use thicker plate as mentioned.
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Old 01-31-19, 04:20 PM
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Thanks guys!

I came across this and wondering if it would work.
https://www.amazon.com/Online-Metal-...el+sheet+metal

Thanks again.
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Old 01-31-19, 04:34 PM
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The price is right and with good brazing and finishing the thickness is OK. Although I would be more comfy with the 16Ga. sheet, see link.

https://www.amazon.com/RMP-Ga-Stainl...KSVE92Y182C0T3

With SS sheet you'll need to use a silver filler. So when brazing the stays onto the seat tube's sides (or the lug's) a bit of temp care will be needed to not melt out the cap's filler. This is why I use non SS caps and brass to join then to the stay. Andy
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Old 01-31-19, 05:03 PM
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consider using a 1" top tube instead of a flat plate. Or pick your own radius.

Hardware stores sell sheet metal in appropriate thicknesses. Not much money. It would be easy to hacksaw out a plate of the right size.
Mcmaster sells sheets of steel. I think I wanted to put stainless caps on once and was disappointed they don't sell strips. Not sure if anyone else does.

Or you could do this, unwrapping is up to you:
img_0074.jpg by unterhausen, on Flickr

This is a frame I made back in 1980-ish img_0021.jpg by unterhausen, on Flickr

Last edited by unterhausen; 01-31-19 at 05:07 PM.
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Old 02-01-19, 10:33 AM
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Originally Posted by Andrew R Stewart View Post
The price is right and with good brazing and finishing the thickness is OK. Although I would be more comfy with the 16Ga. sheet, see link.

https://www.amazon.com/RMP-Ga-Stainl...KSVE92Y182C0T3

With SS sheet you'll need to use a silver filler. So when brazing the stays onto the seat tube's sides (or the lug's) a bit of temp care will be needed to not melt out the cap's filler. This is why I use non SS caps and brass to join then to the stay. Andy
I agree and would rather use non SS caps. I'll have to look around for non SS sheet metal in 16 ga.

Thanks Andy.
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Old 02-01-19, 01:23 PM
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I would use nickle silver for stainless caps. It's not much fun though. I need to practice and I'm probably at least a little allergic to it.

Home depot here has 16 ga weldable steel. 5 of them in stock at the local store. But I'm sure there are 4 other places in town where I could get it. https://www.homedepot.com/p/M-D-Buil...6038/100248617
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Old 02-01-19, 02:47 PM
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Originally Posted by BigPoser View Post
I agree and would rather use non SS caps. I'll have to look around for non SS sheet metal in 16 ga.

Thanks Andy.
DOn't know if you have one in Bakersfield but Doit Center carries a small selection of sheet metal
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Old 02-01-19, 03:40 PM
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Originally Posted by wsteve464 View Post
DOn't know if you have one in Bakersfield but Doit Center carries a small selection of sheet metal
We don't have a Doit, but do have Home Depot. I think this should work:

https://www.homedepot.com/p/Everbilt...-204225705-_-N
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Old 02-01-19, 03:42 PM
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Originally Posted by unterhausen View Post
I would use nickle silver for stainless caps. It's not much fun though. I need to practice and I'm probably at least a little allergic to it.

Home depot here has 16 ga weldable steel. 5 of them in stock at the local store. But I'm sure there are 4 other places in town where I could get it. https://www.homedepot.com/p/M-D-Buil...6038/100248617
Just saw this. Thanks I'll go grab some.
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Old 02-01-19, 04:03 PM
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The HD 16Ga sheet sounds about perfect IMO. That's about .060" thick.

BTW I've learned that different metals use slightly different thicknesses for the same gauge numbers. Here's a set of charts that I use to wade through the mud. Andy

https://www.metalsupermarkets.com/sh...l-gauge-chart/
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Old 02-04-19, 10:50 AM
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I was thinking about going with a flat cap for the frame I'm currently trying to finish. Found a sheet of AMS 5517 in about the right thickness in my scrap bin. That's 301 stainless to us hoi polloi. Maintains its mechanical properties up to 1550F, so I was a little worried you can't polish it. Turns out it will take a mirror polish, so I think I will use it and try to get the powder coater to mask it.
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Old 02-04-19, 11:30 AM
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Originally Posted by unterhausen View Post
consider using a 1" top tube instead of a flat plate. Or pick your own radius.



This is a frame I made back in 1980-ish
img_0021.jpg by unterhausen, on Flickr
The caps look great. I am going to keep this in mind for a build down the road. Thanks
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Old 02-04-19, 01:15 PM
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that frame has never been ridden. Sort of sad. I should probably get it powder coated and hang some parts on it. I am sure the rear end is 126mm spacing though.

I really like the way those caps came out. I have seen people that make them a lot stubbier, and I don't like that as much. When I was at Trek, someone brought in a (German?) frame that belonged to a friend. It was pretty amazing. It had similar style of caps, except the way they did it formed a hollow at the top of the stay. I have been thinking about doing something similar ever since. A couple of weeks later, Mike Apple made a frame with this style of cap and I never felt guilty copying him since I knew where he got the idea. I never saw it before that, but I think it's likely that someone had previously used this style. Nothing is new, same was true back in the '70s.
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Old 02-04-19, 01:19 PM
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Eric- I agree with wsteve464 that your old frame's SS caps are striking and nice looking. But a question about them. Have you had your thighs contact on then when pedaling?

I built a frame (a long time ago) for small woman with very strong thighs. I made a classic fluted cap using the end of a chain stay as the cap piece. This made for two interrelated problems. The caps's "wings" (the thin side of the flute) stuck out so far that her thighs made contact while pedaling and they were so sharp that they snagged her shorts. I removed the stays and reduced the caps significantly and also slightly shortened the SS placement against the lug. Here's two shots of that situation. One shows the original caps and the other the replaced ones in mid attachment.

Note of the second shot you can see a little bit of brass left at the flute's lower end. One might think that this should be filed away and you'd only see the thin line of brass. But having seen many Raleigh SS caps develop a crack at this exact location (from overly aggressive filing, thinning down the amount of joint thickness) I like to leave a little bit of extra brass, or do less filing right here. Andy
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Old 02-04-19, 03:26 PM
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these are low enough that it's not going to happen. That's another issue that might crop up with a stubbier version of this style. The bike I'm riding right now is too big for me. It has cast fluted seat stay toppers. The radius of the flute is larger than on your bike, so it doesn't stick out as much at the top. Still, my thighs hit them when I'm pushing hard up a hill. One of many motivations to replace that bike. On a bike that fits the way I like, it doesn't cause a problem.

For a short person or a person with robust inner thighs, a fastback probably makes more sense instead of side tacked stays.
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Old 02-04-19, 04:02 PM
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Originally Posted by unterhausen View Post
that frame has never been ridden. Sort of sad. I should probably get it powder coated and hang some parts on it. I am sure the rear end is 126mm spacing though.

I really like the way those caps came out. I have seen people that make them a lot stubbier, and I don't like that as much. When I was at Trek, someone brought in a (German?) frame that belonged to a friend. It was pretty amazing. It had similar style of caps, except the way they did it formed a hollow at the top of the stay. I have been thinking about doing something similar ever since. A couple of weeks later, Mike Apple made a frame with this style of cap and I never felt guilty copying him since I knew where he got the idea. I never saw it before that, but I think it's likely that someone had previously used this style. Nothing is new, same was true back in the '70s.
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Old 02-04-19, 05:40 PM
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I'm too old for that
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