balindamood

Tube blocks showed up friday, so off to the co-op today to either fix the dented top tube on the Mercian, or ruin it. Pictures:

Initial condition, dent in top tube a bit bigger than a quater, with a slight crease:



Bicycle Research 1-inch tube blocks from Biketoolsetc.com, cast aluminum, shown here after I worked some dents on some "practice" frames:



I should note that on the practice frames, the dents seemed to come a bit farther out without grease, but it also removed most of the paint. I might also note that the blocaks are cast aluminum (softer than steel), and that there was some scratching/gouging of the tube blocks without the grease.

Lubing it up:



No turning back now. I went to the co-op becasue they have a big-arse vice there, mine is much smaller.



Work it back and forth several times (about 200 degrees of rotation), tighten, back and forth several times, tighten...

The vise all the way closed:



I will note two things. 1). the blocks fit the none-bent tubes VERY tightly. 2), thought he vise was closed, and could not go any farther, the blocks seemed to deform slightly. Without the pressure, the blocks do not fit quite properly. I think unless one can find steel blocks, the aluminum one seem to flex too much to completely pop out the dent.



The dent was mostly out. Its size now is less than a dime.









I will be experimenting with body filler and paint over the next couple of weeks.

A couple of final thoughts. Before I started, I pinched the endes of the crease and actually felt the dent pop out a bit (531 DB tubes, kinda thin at the center of the tube). I belive that another, perhaps better method would be to take one of those C-clamp style pipe cutters and replace the cutting disk with a wheel of some sort, to truely roll-out the dent. I need to dig through the barn, but I may try to make one and mess around with that.

GrayJay

great progress, you probably eliminated the need for 90% of the bond that would have been required for the original dent. A sticker to cover the bondo would work to put off a re-paint.

you might be able to get a slightly tighter fit of the blocks by carefullysanding down the flat surface between the two blocks a few thousands of a inch.

Captain Blight

I've heard of framebulders just filling the dent with a puddle of braze and using that to support the area of the dent. This seems a lot simpler.

auchencrow

Very nice improvement balindamood - certainly worth the effort !

PS- I've done this myself with hardwood blocks I fabricated for an almost identical dent in a TT - and if wood is to aluminum, as aluminum is to steel, then harder steel blocks will not make a discernible difference, since my results were that same as yours.

(I suspect the reason is that some proportion of the deformation in the metal is inelastic.)

randyjawa 

I have thought about doing this myself. Give her a go and let's see what happens.

As for getting a dent completely out, I doubt that it is possible, in many cases. None the less, I need to start experimenting to figure out how to do this.

Finally where did you get your blocks? I have been looking at a set but cannot remember if they are steel or aluminum.

Poguemahone

Fascinating. Keep us updated. This is one of the best parts of this board, when people who really like bikes come up with ways to fix them most shops would never even try.

I'll be picking up a set of those blocks shortly.

due ruote 

Really significant progress. Well done. It looks as though the issue with the blocks deforming is that although the vise is a nice big one, the jaws are still smaller than the blocks. Perhaps if you could get your hands on a couple squares of 1/4" plate steel to put between the vise jaws and the blocks it would improve matters. Even wood blocks would probably help, especially if they were hardwood and you have the endgrain against the frame blocks.

jonwvara 

+1

cs1

Very nicely done.

illwafer

bumping to see how it turned out.

Tende

I too would like to see an update.

jeirvine 

Nice work. The way that dents are removed from brass instruments is to send a mandrel inside the tube. Here's an example of a tool:
https://www.votawtool.com/zcom.asp?pg...cific=jnmrqmi0

Or there are magnetic tools that can be snaked inside:

https://www.musicmedic.com/catalog/products/tool-d150.html

Might be tricky with a top tube or down tube - you'd have to in go through the BB or head tube. Someone should take a bike with dents to a good brass instrument repair shop and see if they'd be up for the challenge.

Chris W.

Wasn't there a post by "Frank the Welder" a while back, where Frank heated the tube and pressureized it with air to pop the dent out?

Cheers,
Chris

brockd15 

That turned out pretty well. I would have expected much more paint damage, more like what happened with Chuckk's frame.

Alan Edwards

Hey I was just on your site checking out your Raleighs Chuckk, having just bought a Super Course from Balindamood. I saw your work on the AutoDiamler and was impressed. Came back to BF and here Balindamood is pulling a dent, small internet.

NICE job on the Mercan, probably sold by now.

Wino Ryder

Great story 'Chuckk'. You worked those dents almost completely out and saved that beautiful Austro Daimler. The body filler was just the finishing touch.

You done well my friend

TimmyT 

Balindamood, really nice job on that dent.

So, this makes me wonder ....... I've got a Masi Team 3V frame, probably 1994. Looks like this one, but in rougher condition. I can't throw it out, but its got a dent in the top tube.

Sorry, I don't have a picture available.

Is a 1994 Masi in rough condition worth saving? I will try to post pictures, maybe tomorrow.

Thanks!
Tim

Grand Bois

Do they make French-size blocks?

balindamood

Probably. Depends upon how bad the dent is. Frankly, I would simply replace the top tube as a last resort. It would loose the Masi-value-premium, but the bike would still be just as good. I would liek to see pictures.

As for the Mercian, it is on my winter projects list. It is still hanging, un-assembled, in the shop.

MrEss

If they don't, it seems like it'd be an almost trivial job for your local CNC machine shop.

balindamood

I have not seen any. However, as French-sized tubes were simply the closest metric equivilent to imperial tubing sizes, I would think that they might be close enough to do some good. It may work that one of the tubes does not work as the top/seat tubes were different sizes than the down tubes, and the equivilent may be off too much one way or the other.

I may have to take a hammer to some old Peugeot/Gitane/Motobecane frames around here to see how they do. I have a 1972 TdF frame I cannot get rid of. Might as well use it for scientific purposes.

cudak888 

FYI to the OP: As good as frame blocks are, they don't generally remove the entire dent. The results in your original post is remarkable to begin with - I highly doubt you'd get a better result by changing the material of the blocks.

-Kurt

balindamood

Having done this 4 times now, I tend to agree. It also works ALOT better on thin walled tubing. I popped a SLX tube to where you cannot almost tell it was there, but had less success on a Champion No.5 PG tube. I have also played around with putting a dummy wheel in a C-clamp-style pipe cutter which also seems to work well if you have a defined point on both ends of the dent. It magles the paint much worse though. Ultimately, you are going to need some brazing material or bondo to make it go away completely unless it is a seat tube.

GrayJay

Frame blocks can also be made from a block of hardwood rather than aluminum. Hardwood blocks are probably an easier DIY project.

illwafer

since this thread came back to life, i found these from another thread:
https://www.paragonmachineworks.com/c...ion&key=FT4009

more sizes:
https://www.paragonmachineworks.com/c...&category=TB07