Torch a 531 frame?
05-22-17 | 07:15 AM
#26
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Joined: May 2003
Posts: 4,056
Likes: 166
From: Mountain Brook. AL
To reiterate Andrew Stewarts comment, media blasting of such as 531 should be done cautiously. 531 tubing for
bicycles was in the 0.022 to 0.045" thickness range. Bike Tech magazine in the early '80s media blasted sheet
metal of various thicknesses (basically bike tubing) and measured before and after thickness with various media
and found that sharp sand (the most aggressive) could remove upto 0.006" of thickness. Since this removal
would be assymmetric the risk to the frame could be significant. Soft media only should be used for quality
frame paint removal.
bicycles was in the 0.022 to 0.045" thickness range. Bike Tech magazine in the early '80s media blasted sheet
metal of various thicknesses (basically bike tubing) and measured before and after thickness with various media
and found that sharp sand (the most aggressive) could remove upto 0.006" of thickness. Since this removal
would be assymmetric the risk to the frame could be significant. Soft media only should be used for quality
frame paint removal.
05-22-17 | 01:42 PM
#27
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Joined: Jul 2015
Posts: 7,494
Likes: 3,296
From: NW Oregon
Bikes: 1982 Trek 930R Custom, '91 Diamondback Ascent w/ XT, XTR updates, Fuji Team Pro CF road flyer, Specialized Sirrus Gravel Convert, '09 Comencal Meta 5.5 XC, '02 Marin MBX500, '84 Gitane Criterium bike
MEDIA blast only, IMO... if the tubes are double-butted, that means the CENTRAL sections of the tubes are THINNER... sand WILL remove material, and the results can hurt!
05-22-17 | 01:49 PM
#28
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Joined: Jul 2015
Posts: 7,494
Likes: 3,296
From: NW Oregon
Bikes: 1982 Trek 930R Custom, '91 Diamondback Ascent w/ XT, XTR updates, Fuji Team Pro CF road flyer, Specialized Sirrus Gravel Convert, '09 Comencal Meta 5.5 XC, '02 Marin MBX500, '84 Gitane Criterium bike
The metal Gods have spoken....
if you overheat high carbon steel, it changes the crystaline structure of that steel... the result is BRITTLNESS, and you must then reverse the process slightly by ANNEALING the steel... brittle is NOT a good thing, and the frame may very well CRACK... frames flex, flexing brittle steel makes cracks. Cracks lead to pain, both physical and emotional.
if you overheat high carbon steel, it changes the crystaline structure of that steel... the result is BRITTLNESS, and you must then reverse the process slightly by ANNEALING the steel... brittle is NOT a good thing, and the frame may very well CRACK... frames flex, flexing brittle steel makes cracks. Cracks lead to pain, both physical and emotional.
05-23-17 | 07:30 AM
#29
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Joined: Jan 2013
Posts: 3,151
Likes: 888
Bikes: too many sparkly Italians, some sweet Americans and a couple interesting Japanese
05-24-17 | 07:21 AM
#31
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Joined: Oct 2016
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