Framebuilders - Blocks to repair dent in frame?
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Hello all, has anyone ever actually used those aluminum or wooded blocks to remove a dent from a frame tube? I have read many, many references to them, but not from anyone who has ever done it. Bicycle Research sells them. All I read it "try those blocks - but for sure it will damage the paint" or "I saw those blocks, maybe those will work" or "I know of this guy who used them, I will ask him how it worked"
HAS ANYBODY USED THEM? PLEASE HELP!!
I have an 85 Trek 770 that I just bought, it was shipped to me and durring shipping received two small dents in the underside of the downtube where the wheel hub got jammed into it. The dents do not appear to have done any structural damage, but certainly cosmetic damage. Otherwise the frame is in wonderful shape and I would really like to repair it.
Please do not tell me sand it down, weld it, and repaint. Please do not tell me to not worry about it. Please do not tell me to bondo it and repaint it. Please do not tell me to weld rods on and pull the dents out. I know all those options. I simply want to know if the anyone has used the block method. You would think that Bike Research would not sell the tool if it did not work.
Thanks so much for your help.
12-26-08, 08:19 AM
I've used "Bicycle Research" aluminum frame blocks quite a number of times to try to remove dents. My experience is that it may help to minimize a dent but it has never eliminated them. It always destroys the paint. Cheers, Mark
12-26-08, 07:05 PM
In my opinion you are better using something like permatex liquid welding or something better than bondo (a lot of stuff in the market that it is better than bondo)
sprry my bo bo liquid steel filler
12-26-08, 07:15 PM
Fill it with some brass. I fill dents for free for anyone who needs it if you are in the area.
Thanks Mark for the reply, not sure what I am going to do yet. The 770 I have has been repainted a couple times but the current paint job is pretty nice - would prefer not to ruin it, but any dent repair seems to ruin the paint - if the blocks minimize the dent then maybe they are worth it. Did the blocks ever do an additional damage?
12-29-08, 05:45 AM
Correct technique for frame block dent removal is to grease the inside of the blocks and grease the frame; place the blocks around the frame and place the blocks in a bench vise; add slight pressure; rotate the frame back and forth a couple of times; increase pressure; repeat; repeat; repeat; until the blocks are secured firmly against each other in the vise. This pushes down the high points around the dent and theoretically pops up the low point, but it never does it completely; and it is obvious that there is extensive "collateral damage" to the paint in the affected area. Now you can clean the area and apply Bondo or other dent filler material and sand smooth. Don't bother trying this if you don't want to ruin your paint; it will. Live with the knowledge of the dents, and plan for your next repaint.
Cheers, Mark Beaver, Tamarack Cycles, Halifax NS Canada
I got the frame blocks (1-1/8") for the down tube and set them on the frame to check fit and found that they seem a touch small for the downtube(I tried to hand press them on but clearly would not press on). I checked them on the seat tube (because I think the seat and downtubes are the same size) and I found that the blocks seem to fit differently based on the side of the tube they are on. They fit perfect on the side of the tube and are a touch small when set on the inside face of the tube(though I can press them on)? This is true the full length of the seattube. Do you have experience with this? Is it possible that the tube is not round but oval or is it simply paint thickness?
Any further advise?
01-05-09, 08:38 AM
Sounds like a combination of paint thickness and the tube being out of round. I assume you made sure your down tube is not 1.25"?
Well, I do not have calipers but I measured it a few times and it always looked right on 1.125" and 1.25 is big jump. Of course, I will measure it again now!
01-27-10, 01:11 PM
Has there been any further development on this project? I'm in a similar situation with I bike that I'd love to bring back to life, but don't want to spend a lot to do so (tube replacement is not really an option) and I'd rather not repaint. I'll be measuring the tubes and see if I want to invest in the blocks.
I read somewhere on BF before (but of course can't find it now) that someone made their own wooden blocks and assume that would cause less paint damage if used.
01-27-10, 03:20 PM
The BR frame blocks are pretty good, but they seldom completely remove a dent. Fill any depression with a low-temperature filler (I prefer lead solder) rather than putty.
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