I need to make a couple of brass filer plugs, the threaded part is 3mm standard pitch. One will screw into a 4mm ally plate and the other a 3m ally plate. How do I manage to thread right up to the shoulder? I am thinking of using a fibre washer to ease the problem, but it does sound like this can only be done with a single point tool inthe lathe and not fie cut?
TIA
Steve
Cut as close as you can with a die. If you try to do it with a tool in the lathe, you'll have to make a recess for the thread's end. And then you'll lose quite some length. Or have some collisions. :-)
It's much easier to countersink the thread in the plates so the filler can be screwed in flush.
Nick
Silver-solder a fully-threaded rod into a drilled hole in whatever you are using for the head of the plug.
Crafty!
Simplest method is to buy a couple of brass screws with sufficient thread length. Make the head part of the filler plugs and drill and tap part way through, about 4mm deep should suffice, for your 3mm pitch. Then wind the screws in using a little Locktite and once that has set cut the heads of the screws off. You can also use threaded rod of course and wind it in with pliers or two nuts locked together and then cut the excess length off.
Steve asks ........
Having cut the thread with the die, turn it around and run it down backwards.
The back side (without a lead in) should get you close enough to the head to be acceptable with a fibre washer in place. A slight countersink might help if you must.
Mike
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