Dreesens Bicycles

Steel bicycles by Peter Dreesens

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Intermission of the Steel Frame Repair series for an introduction.  There’s a new Page here on Dreesens Bicycles. >>>>>>>>>>

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How to: Steel Frame Repair Part 8

The frame in the jig and fully silver-soldered with the Brown Hi-temp flux (an anti oxidation ‘paste’) on the areas heated.

Close up of the joint and the dried flux.

The flux removed (it is water soluble) showing the discoloration in the areas not covered with the flux.

The same area ‘Cleaned Up’ – polished and finished ready for paint.

The entire frame ‘Stripped’ of paint and ready to be dropped of at Spectrum for repainting.

 

 

How to: Steel Frame Repair Part 7

The mitered tube is fitted in the frame without the lug. The Bottom Bracket end will be scribed and trimmed.

The excess to be scribed, then removed.

Test fitting the miter to confirm the angle of the cut. The miter is much closer than the .005 of and inch maximum tolerance for the gap. For silver solder to have maximum strength the gap should be in that .001 to .005 of an inch range.

How to: Steel Frame Repair Part 6

The new tube: A  True Temper 34.9 (1 3/8″) HOXPLAT 10 of .7/,4/.7 thickness. True Temper created the PLATINUM tubing by taking an aerospace grade of air hardening steel and modifying it to enhance its properties for light weight bicycle frames. The tensile strength exceeds 195,000 psi.

Using a lug as a pattern the outline of the cut for the miter (shape of the tube to match the adjoining tube) is scribed on the tube using a dental pick.

The form of the miter is rough shaped using two angled cuts.

Using files and abrasives a shaped miter is achieved. This will match up to the head tube.

How to: Steel Frame Repair Part 5

Three Sections of the downtube removed.

The frame back in the jig for the mitering of the new tube.  The lug and head tube have been polished in preparation  for silver soldering which requires a ‘clean’ surface to ‘flow’.

The polished bottom bracket socket. The clean surface is necessary for flow of the silver solder (45 percent easy flow), a capillary action in the ‘sleeve’ joint.

How to: Steel Frame Repair Downtube Replacement Part 4

Heating the tube/joint to the temperature were the silver solder flows, the ‘Liquidus’ temperature.

Removing the cut section. pulling it straight out of the Bottom bracket lug socket.

Removing the bottom head lug from the section of tubing that was previously removed from the head tube.

 

How To: Steel Frame Repair Downtube Replacement Part 3

The center section of the tube is cut out to enable pulling the tube straight out of the joint.

The frame with cut out center on the damaged tube.