The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Frame => Topic started by: RichardL on 03.02. 2018 21:31
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Guys,
Trying to decide what to do with a dent in my A7 frame before powder coat. It's just a dent in the tube with no bending. I don't believe it represents a structural issue, but as long as I'm rebuilding I thought it would be nice to have it out. Is this just a matter of welding some rod to the center of the dent to create a slide hammer, then heating the dent to red hot during the slide impacts? Should I just Ignore it? Other ideas?
Richard L
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I'd get the brazing torch out, fill and file or grind back.
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Yeah. I know how to braze. That's much easier. This may come as a surprise, but I have a tendancy to overcomplicate things. Thanks, Andrew.
Richard L.
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As a last resort, I'll suggest ;
When I was forced to crash my Gutzzi a few years ago and busted the rocker box, I patched it with Selleys 'Liquid Steel '(I'm fairly sure) , 'cos I didn't have time to chase up another cover. I painted it and then forgot about it until a few years later had it powdercoated and it handled that ok, and ten years later it still looks fine and I can't remember which box it was...maybe if I look at them closely....also good for patching fuel tanks in emergency
But obviously if you have, or can access brazing, much better
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This post link below has some pics which may assist. I used home made “frame blocks” as used on push bikes to get rid of most of the dents on my frame. The blocks only really only work where the frame is pretty straight, so that technique may not be much use to you.
https://www.a7a10.net/forum/index.php?topic=3775.msg27478#msg27478
Google “bicycle frame blocks” to see how they work, the key is rotating the frame in a vice as this applies the enormous pressure needed on a bsa frame tube, more than you can apply using the vice handle itself. You need a strong vice *work*
I didn’t expect the quite flimsy frame blocks I made to work on my frame, but they did *smile*
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Literally 10 minutes work with the MIG set and grinder will see that sorted, and as much less heat is involved it wouldn't affect the other joints nearby, either.
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Rex,
My small and cheap arc welder is just a wire-feeder type (no inert gas). My skills with it are crude, so creating a solid build-up the depth of this dent would probably leave something that looks like a mound of pebbles glued together then ground off. Nevertheless, it's an idea worth a practice run on a piece of scap pipe. I might just have to break down and pay a professional welder to do the job. Cheaper than buying real MIG or oxyacetylene gear, for sure. ("Buuuuut, I sure could use a real MIG outfit for other things around the shop," he said, trying to justify the expense and wondering if it would somehow make him a better welder.)
Richard L.
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hi guys, you could drill and tap hole opposite dent then heat dented tube while tightening suitable bolt from other side,, when dent is sufficiently pushed out braze/weld over cut off bolt, cheers
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Ah! I had a similar idea involving pounding a drift from behind, but I like the screw "from the opposite side of the pipe" (in favor of saying "from behind" *shh*) as a better idea. Though, the idea of some kind of filler, weld or braze, is sounding easier.
Richard L.
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I wouldn't weld as this involves melting the parent metal. If there is any latent strain on the tube it could distort. I've filled dents like this with brass filler and you can achieve a perfect result.
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Like I said, I'm a lousy wire welder (with a lousy welder) but I'm OK with brazing. So that's to be the way.
Thanks Andrew and all for the advice. Now, to get the time to do it.
Richard L
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Like I said, I'm a lousy wire welder (with a lousy welder) but I'm OK with brazing. So that's to be the way.
Thanks Andrew and all for the advice. Now, to get the time to do it.
Richard L
hi guys, Richard with a few basic rules/correct heat and plenty of practice welding is not that difficult, problem is if one has not needed to do it for a long while it takes time to sort the method needed, a good tip i was told with `brazing`is always beware of `the melted metal goes where you put the heat, good luck,cheers
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Well, it's only been four months *eek* since I first asked about how I should repair the dent in my barn-find A7. Of the suggested solutions, I went with Beezermacc's recommendation for brazing.
This probably turned into the most expensive dent repair possible. I wanted to do it myself, so I needed to get an oxyacetylene outfit together. I had my dad's professional-grade 40 or 50 (or?)-year old acetylene regulator and torch handle professionally repaired, along with an eBay-bought oxygen regulator to match. Then, I needed tanks. I bought new ones so I would have something to swap with the local gases supplier (they don't fill on site, and buying or renting from them was not as economical). My dad's old hoses proved to be in decent condition once new end fittings were added. OK, once all together, I bought professional-grade leak detector fluid. It turns out just soapy water is not a good idea, even though I've always used it in the past for other purposes. Here, it's a safety matter for house and family.
Anyway, I was able to get into the brazing groove pretty easily, even though I don' think I've torch welded in 35 or 40 years. Obviously, I have other intentions for the rig than just the dent repair.
Hopefully, the attached pictures don't yield responses like, "Next time try it with your eyes open." *smile*
Richard L.
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G'day Richard.
Not bad for a mug. So she'll be on the road about Xmas. *whistle*
Cheers
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You're being very optimistic.
Richard L.
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Which is the brazed bit ? *smile*
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That looks great Richard. I used to have an oxy-acetylene kit; very useful. It wasn't getting used much and the gas cylinder rental was just too expensive to justify. I gave the hardware to my sister, who restores vintage cars, and I ceased the gas account. I have a cheap MIG set now but rarely use it.
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I haven't tried brazing since high school metal shop (1971). If you were closer I'd ask you for lessons. Looks good!
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Based on the replies from folks I respect (all of you), I guess I did OK. To be honest, I'm pretty happy with it, though it must be told that it was a braze-grind-repeat process that wasn't particularly fast.
Anyway, we have a vintage-centric forum here, so I figured, "Why not show the vintage welding gear?"
Richard L.
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This is the sort of set I had.
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Très moderne.
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Could I do this to a heavily pitted frame? Wondering if I could get away with doing this or chop the section out and weld a new section in after having the difficult task of bending it to the correct angle.
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G'day bd.
If it's BADLY pitted on the outside I wonder what it's like on the inside! Rust pits I just hit with converter and then bog and sand. Wait a week or so before painting. If not the bog will show through a few months later, it has to be dead dry. Super bad pitting I'd cut and shut.
Cheers
Ps: I can rebuild a motor/geadbox/diff in my sleep but show me rust or paint and I run a mile. LOL.
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Got a picture?