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| Locking a screw thread? |
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| philf:
--- Quote from: chipenter on February 03, 2015, 03:59:17 AM ---For a fixed wheel sprocket there used to be a locking ring available , if not turn down another sprocket as a lock ring . --- End quote --- Jeff, You can still buy the fixed wheel locking rings but they have a left handed thread. The locking thread is smaller than the 1.37". Phil |
| steampunkpete:
There is a standard that covers locking threaded components used in certain safety applications - that is where the threaded component becoming loose or detached would cause a hazard. The standard does not preclude bespoke solutions, but there are a number of pre-approved locking methods. With one exception, the methods are characterised by being both positive and visually inspectable. Castellated nuts + split pins and wire-locking come to mind from memory. A single fixing relying on a thread locking compound is not accepted, being considered too unreliable for safety purposes as well as not being inspectable. I'm assuming that the sprocket is held onto the shaft by a screwed collar (I'm not familiar with bicycles - a photo with the post would be good). Taking the safety standard as a lead, personally I would go for wire locking the collar to the shaft or a split-pin through the shaft. Alternatively, a pin through the sprocket into the shaft flange behind the sprocket - again difficult without seeing whether there is such a flange. Does this thing need to come apart again - for repair or maintenance? If not can it be brazed? Come to think of it: :worthless: |
| awemawson:
--- Quote from: RussellT on February 03, 2015, 04:12:13 AM ---In my experience it's a waste of time trying to bore the thread off or trying to turn another sprocket down. They're very hard. Make a plain unthreaded close fitting hub and weld the sprocket on. Take your choice of how to fix the hub. Russell --- End quote --- Carbide tool would have no problem whatsoever. (If the sprocket is fully hard (ie untempered) it would soon crack in use) |
| John Hill:
Thanks for the comments. Yes, I will be making a hub for each sprocket. There are three to do and having bought then new from the local cycle shop I am taking very good care of them! :coffee: I think I will put extra thread on the hubs then screw on the sprocket followed by a lock ring followed by a dab from my welder then if I have to take a sprocket off the hub I can grind the weld off. |
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