Dreesens Bicycles

Steel bicycles by Peter Dreesens

Archive for January, 2011

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.