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Saved from the scrap pile!

How I rescued these gears

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Stub Mandrel06/02/2012 20:28:36
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The drive train for my 0-4-0 shunter relies on a pair of bevels from a dead angle grinder for the final drive, with about 3:1 reduction (nice case-hardened bevel pinion as I found when skimming 1/16" off the back of it.
 
The balance of reduction and alignment with the motor will be through two pairs of 28 and 25 tooth gears which I've cut myself. I had two problems when making them: the mandrel started to escape from the 3-jaw chuck(!) resulting in a narrow tooth, and on a second gear I lost my place on the spreadsheet and cut a space 1.8 degrees out.
 
As cutting a gear takes about 1/2 an hour plus making the blank, I decide to try and rescue them, by silver soldering a steel 'chip' into the space. One gear I hadn't cut to full depth, so I just recuit all the teeth a little deeper, and then cut out the filled in gap in one go. The second gear was otherwise finished, so I sawcut and filed the gear to shape. the gears are 20DP, so the 28 tooth ones are 1.5" diameter. You should be able to spot the repaired teeth by the clear flux marks.
 

The gears are all from EN1APb, but I don't imagine running the wee loco weekly so they should see me out!
 
The two gears at the top  have extensions on the back for fxing screws, the two others will be keyed to a shaft.
 
I had lots of fun with bearings and bores - all my 5/16" drills, 8mm drills and my 5/16" reamer all cut dead to size at 5/16" (yes a 8.00 mm bar won't fit a hole drilled by my 8mm drill). In the end gears a push fit on 5/16" axles turned down a couple of thou to make the journals.
 
Neil

Edited By Stub Mandrel on 06/02/2012 20:33:41

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