12-11-2018, 06:12 PM
Having digested all the ideas and advice in this thread, I managed to get up to my shed and try to sort out the binding front brake.
Firstly, I established as best I could that the drum was round and not distorted. Then I checked the profile around the central hole that Gary Edwards mentioned. This was fine, too.
Satisfied that the drum was not at fault, I tried Reckless Rat's method of chalking the shoes to see where they were binding. On tightening the three screws, I encountered exactly the problem that Steve Jones mentioned in the previous post, and so I chamfered the edges of the linings. This didn't completely overcome the problem, and the chalk indicated that the top sections of both shoes were binding. At some time in the past, the pivot has been repaired by drilling and tapping through its axis, and then bolting through the backplate. Perhaps this was slightly off centre, raising the shoes slightly.
I would have liked to make an adjustable gauge like Ruairidh's, but just didn't have the time, so instead I made a slightly less elegant copy of Derek Sheldon's sanding drum, but using a strip cut from cloth-backed sanding belt rather than emery cloth. A few turns, a little packing and a few more turns, and voila! problem solved.
Many thanks to everybody for their help
Firstly, I established as best I could that the drum was round and not distorted. Then I checked the profile around the central hole that Gary Edwards mentioned. This was fine, too.
Satisfied that the drum was not at fault, I tried Reckless Rat's method of chalking the shoes to see where they were binding. On tightening the three screws, I encountered exactly the problem that Steve Jones mentioned in the previous post, and so I chamfered the edges of the linings. This didn't completely overcome the problem, and the chalk indicated that the top sections of both shoes were binding. At some time in the past, the pivot has been repaired by drilling and tapping through its axis, and then bolting through the backplate. Perhaps this was slightly off centre, raising the shoes slightly.
I would have liked to make an adjustable gauge like Ruairidh's, but just didn't have the time, so instead I made a slightly less elegant copy of Derek Sheldon's sanding drum, but using a strip cut from cloth-backed sanding belt rather than emery cloth. A few turns, a little packing and a few more turns, and voila! problem solved.
Many thanks to everybody for their help