Tandem Tom

So I have decided on a Zefal pump, I have it on the bench, that will be mounted on the seat tube from the chain stay up.
I have the "L" shape peg, already mitred to match the seat tube .
So my question is how much should I compress the pump to determine the peg location?
Thanks!

Doug Fattic 

You want to compress it is much as possible still leaving just enough left so the pump can be removed. The reason for this is that the tighter the pump is in the frame, the less likely it is to accidentally get bumped out while riding.

Tandem Tom

Thanks Doug!
All water bottle bosses are in and I am working on the dump wire access.
Next will be making a jig to hold the pump peg.

bulgie 

1. grind the teeth off the jaws of a small narrow-nose vise-grip pliers, clamp the peg in the pliers lightly so as not to mar it.
2. hold the pliers in the bench vise with the miter of the peg facing up.
3. flux and braze a little dab of filler on the miter.
4. Take the pliers out of the vise and hold it in one hand, torch in the other
5. hold the miter against the tube and heat until the filler melts and wets out on the tube.
6. hold the pliers still until the filler freezes, then release them.

Maybe not as good as a dedicated fixture, but versatile and quick. Works for many types of BOs

Mark B in Seattle

Tandem Tom

Just saw this post now that I have finished!!
I took a piece of barstock and ground a groove in the end. That and a hose clamp kept the peg in position.

Nessism

What's a pump peg?

unterhausen

it's the thing that holds your pump so you can use it on another person's bike when they run out of CO2 cartridges. See also: one extra tube you'll probably need to lend to them.

Andrew R Stewart 

Pump- It's what you do with your fore arms to look hyper male before your date.

I've brazed a rod/wire to a braze on and bent it to hold the bit with the wire clamped to the tube to locate a braze o0n. Andy

calstar 

Here's how Brian Chapman does it, holds the peg with needle nose pliers or vise grips. "Picture worth 1000 words..."

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Cynikal 

Probably important to note that he is not using 56% silver for this. Read through the notes on the instagram post. He mentions what he uses.

unterhausen

I wouldn't go out and get 38 percent silver just for this. 45% is just fine.

Tandem Tom

I just did mine and used 56%. Am I looking for problems?

Cynikal 

Don't think so. I was pointing out the the technique used above where he built up the silver then placed the peg was not possible with 56%.

unterhausen

I'm pretty sure the reason he uses 38% is because he got a lifetime supply of it cheap and uses it wherever he can. You can make a decent size blob with 56%, but it's easier with lower silver percentage.

calstar 

"You can make a decent size blob with 56%, but it's easier with lower silver percentage."

After seeing the Chapman vid I tried a few practice pegs using his method with 56%(all I have, didn't know he used 38%), it was more difficult than I thought it would be, doable but not able to get a "blob" close to his size. Where is 45% generally used/prefered over 56?

thanks

Cynikal 

Anywhere where you would need to build up a fillet. I haven't used 45% but I have used Harris 50N on a small stainless rack repair.

Doug Fattic 

I do not recommend using 56% silver when there is such a small contact area like a pump peg. 56% is designed to flow between metal and not be used as a fillet although on low stress areas it can work. How about someone doing a test to see? Braze a pump peg on some scrap with 56% and see how hard it is to try to take off with pliers. If you have Fillet Pro and brass that would make a great test to try all 3.

Here is my back story to my suggestion for using brass on a pump peg. On a prototype Ukrainian transportation frame I brazed on the kickstand plate with 56% silver. I did this because our Ukrainian maker was not a world class brazer and it was easier for him to use silver than brass. However after some use, it started to break off even though it had been brazed well with a decent sized fillet. Of course the kickstand has extra leverage to put stress on the boss. Fortunately this happened early enough in the process so we could braze all the rest of them on with brass and none of the 50 in that batch of frames has failed since. In the same way a pump peg can be extra stressed if the bike falls over and something hits the pump.

I would estimate that less than 5% of my frame building class students have the coordination to put on a pump peg like Brian did. Even coordinated people can have trouble using both hands simaltaniously at just the right time. I got my pump peg holder when I acquired a lot of frame making equipment from master builder Johnny Berry from Manchester UK. It was a simple long piece of thin flat stock with a U shaped notch filed into the end to fit around the peg . His had like a pump spring clamp attached to the flat stock to hold it to the frame. I think Tom used a simple hose clamp around the flat stock to hold his pump peg in place.

unterhausen

I would definitely burn myself using that method and probably not get the peg where I want it. I feel like I am pretty competent at brazing.

I generally use stainless braze ons, so 45% or fillet pro for most of them. Pump pegs are a special case because they are long and don't have much surface area. And also, I am not sure there are stainless versions. I forget what I used on my travel bike pump pegs, which were definitely steel. I can't imagine using anything other than brass for that. I think it all goes back to Brian having a batch of (nearly) scrap silver lying around.

Tandem Tom

One of my fringe benefits of taking Doug's class is his willingness to answer my questions!! He suggested that I practice with some nails. So I got out a damaged frame and practiced brass brazing a nail on to the seattube.
Went well. So tomorrow I will redo it.

calstar 

These are pics of the 56% silvered peg I did yesterday after seeing the Chapman vid, soaked with the flux removed. I couldn't break it off with pliers, hit with a hammer(not king kong style but pretty decent blows), the peg bent deforming the tube, then I broke it trying to remove it with vise grips. Pretty unsuccessful trying to build a bit of a fillet like Chapman did.



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These are from today, same thing, I couldn't get it loose with pliers, bent it hitting with a hammer. I'll soak of the flux and them try to get it off again. The one pic shows the blob of silver(with a little burned flux), I added a little more by gently heating the blob till shiny, then melting the silver just above it so it fell on top, did it in rapid succession hoping it would stick and not run away and it did. I think the key is to have a decent size blob and setting the peg on with the blob just before it goes liquid but I really don't know.



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Notice the plier marks on this last pic, I only had the two pegs so couldn't test with brass, had plenty of scrap tubes cause I'm practicing fillets(still).

unterhausen

In today's experiment, you have a big blob of solder under the peg, which isn't great. Silver does have pretty good mechanical properties though, basically equal to brass. Looks like you cooked the peg, which is one good reason the silver didn't go up onto it.

I don't see any big advantage in using the Chapman method (also suggested recently by Mark Bulgier). Figure out some simple way to hold the pump peg where you want it. I think I used a bent up piece of welding rod.

calstar 

I agree his method has no advantage, I'm not planning on using that method when I need to braze a peg, especially with 56%. I tried his method because I saw it done(and shared the vid here), "nothing ventured nothing gained". Absolutely I cooked the peg the second time(trying to remelt the blob, if I had another peg I would have repeated it), but it still refused to break off, just like the first one.

Doug Fattic "...How about someone doing a test to see?..."

What I posted here is the result of Doug's request to test the strength of the 56%; he asked someone to do it, I did it, the method used doesn't matter. The result(IMO) of this very limited "experiment" is it can be done with 56% and seems relatively strong given the load/stress on a pump peg.

regards, Brian

Andrew R Stewart 

Nails- Serotta way back when uses a Common nail (looked to be a 10D?) as a pump peg on at least two frames I've worked on. On both the subtle rings around the nail head hadn't been sanded off. Andy

Doug Fattic 

Thanks Brian for doing this test! I would have tried it at my shop but I'm visiting our daughter and 1st brand new grandson so I couldn't do it myself. Tom had already brazed on his pump peg with 56% and I recommended he take it off and do it with Fillet Pro or brass so it wouldn't potentially come off after the bike is together. The pump peg is one braze-on I have always done in brass so I wouldn't have to worry about a painted frame with a broken off pump peg coming back for a time consuming and expensive-to-me repair.

Andrew R Stewart 

General comments- 56% is a poor filleting filler. As I understand it, 56% looses strength rapidly as the clearance gap opens up. And fillet has a BIG gap of sorts.

What Brian C shows is just a version of wetting/priming the joint surface first before adding the second element. One would want to be pretty precise in placing the drop of filler with so little flow out/puddle depth. But that's one of the marks of a skilled guy I guess.

One of my few frame failures was a rear drop out eye braze on with silver. The eye (a commercially available M5) was attached to a short stalk/stand off to allow for rack and fender hardware clearances. The eye/stand off was silvered onto the drop out.

A few years after the build the bike was used on a credit tour requiring boxing and UPS shipping. The (double) boxed bike suffered a serious impact that broke off the silvered eye stand off. As I am a belt and suspenders guy the fender eye missing was backed up by the rack having it's own eye that worked for the fender strut. The tour wen ton without issue. But the failure stuck with me. I strongly suspect if I had brassed the eye's stand off onto the drop out it wouldn't have broken off. maybe bent but not cracked off. This was just one reason I have moved to more use of brass. Andy