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Straightening a Seat Tube Ovalized by Shop Clamp

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Straightening a Seat Tube Ovalized by Shop Clamp

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Old 04-25-11, 04:51 PM
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23skidoo 
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Straightening a Seat Tube Ovalized by Shop Clamp

I'm buying a frame/fork from a fellow member that has a Reynolds 531 seat tube that was clamped too tightly into a work stand, slightly ovalizing the tube. I seem to vaguely recall discussion on the board about using wood blocks to round the bube back into shape. I'd really appreciate any information on how to proceed with this or a link to any previous discussion. I tried the advanced search feature but struck out.
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Old 04-25-11, 04:56 PM
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yes, a pair of hard wood blocks can repair deformations in a frame tube. The method has one greasing the damaged tube, the blocks placed around the area and in the jaws of a strong vice, then the frame is twisted to reduce the offense.
http://www.bohemianbicycles.com/tchotchke.html
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Old 04-25-11, 05:06 PM
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Here is one;
http://www.bikeforums.net/showthread.php/686936-Roll-in-Dents?highlight==

For a vintage seat tube you will likely need 1-1/8" (28.6mm) blocks. I recently made a set for myself using a chunk of 4"x4" lumber. I have not used them on a dent yet but they are also handy for securely holding the frame in a benchvise while working on it. I just drilled through the woodblock with a spade bit and then cut in half with a saw. Note that it is important to plan your drill& cut so that the cut is made parallel with the woodgrain so that the blocks dont split.
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Old 04-25-11, 05:38 PM
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How 'bout a BFH and some bondo.
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Old 04-25-11, 06:00 PM
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I have some you can borrow. Shoot me an email if you want them and I will dig them out.

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Old 04-26-11, 02:43 PM
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Thanks for pointing me in the right direction fellers!!

BFH and Bondo.... Right up my alley though.
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Old 04-26-11, 03:19 PM
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If the paint hasn't been damaged, try running an extra-long seatpost of the same ID down the tube. Might help some.

-Kurt
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Old 04-26-11, 03:38 PM
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Originally Posted by cudak888 View Post
If the paint hasn't been damaged, try running an extra-long seatpost of the same ID down the tube. Might help some.

-Kurt
That would be my suggestion as well. Grease up the seatpost well first.
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Old 04-26-11, 04:26 PM
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I had a repair done on a seat tube a few year's back, and the builder ran a steel rod down the tube to push out some of the material. He had an array of steel rods of different diameters for that purpose. I don't think an alloy post would be much of a match for that steel tubing.

Neal
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Old 04-26-11, 07:26 PM
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junkfoodjunkie is sending me his set of blocks, now if I can just find a nice long section of steel rod in 27.2 or do you think 27 straight might provide easy pushing? I also like the idea of a double-roller tubing cutter minus the cutting wheel. Who knows, my neighbor is part owner of a large, sophisticated metal design/fab shop so I'll ask him if such a thing exists or could be knocked out inexpensively. Once I get the frame and equipment I'll try to scheme on this a bit more with your help. One of the problems I see with the wood block/bench vise procedure is having a very limited swing of 90 degrees in the clamped position; turning the frame over would allow an additional 90 degrees of swing, so I'm also thinking wood blocks backed by some .25" flat metal stock and a C-clamp that would allow a full 360 turn inside the frame triangles. I'll take some pics and update the thread with results.
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Old 04-26-11, 08:09 PM
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Originally Posted by cudak888 View Post
If the paint hasn't been damaged, try running an extra-long seatpost of the same ID down the tube. Might help some.

-Kurt
+1 on this as the first option. I did this to a '73 Raleigh Competition with the same problem. Worked great. Paint didn't even flake. YMMV.
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