Vintage WorkshopServices for Brough Superior motorcycles and their contemporaries
| Vintage Workshop Services for Brough Superior motorcycles and their contemporaries |
Castle forks front leg tubes last update: 1/2004
| Well, cleaning up the end and turning the diameters for the thread and end are nothing special, nor is cutting a 1"*26 tpi thread, but it all needs doing. |
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| Cutting the slots for the spring abutments was a bit
more demanding, however. My first attempt (after devising a suitable way of clamping the tube) was to run two successive cuts with a 1/16" slitting blade up the tube. Unfortunately I had to find there is some residual stress in the tube, leading to a slight expansion of the diameter after slitting. Which can be corrected by considerate application of the vice jaws, but this makes the slit a bit too narrow again. Thus, for a second go, I set up two 1/16" slitting blades at a 1/8" distance. This worked quite fine. I could have used a 1/4" disc cutter, but I did not like the big cutting area on a thin-walled item. And I did not have one, to be honest... |
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| I made a few more tubes, as I learnt that usually
setting up the machine takes much longer than doing the
job. Yes, I have cleaned the swarf out in the meantime.... |
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| And I made a few top nuts. In stainless steel, of course. |
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| Drilling the big hole isn't too much fun, but what
can you do? Screw cutting the internal thread on the lathe was a bit exciting, as you don't want to run the tool against the blind end of the bore. But I did not dare to ask how much a 1" * 26tpi plug is...
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| Ok, that starts looking like a pair of Castle forks.
To be continued..... |
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