General Category > General Discussion
Thread chasing
crazylegs:
A bit of help and knowledge needed. I am going to try thread chasing but am struggling to know how to size the two parts. Do i just make them a tight fit or do you need some play. If I make the male and female parts the same size will the chaser cut enough to allow the thread to work or do I need it a little smaller?
Percy:
Size the piece with the male thread by cutting a small spigot that just fits inside the piece with the female thread. Then cut a slightly larger diameter spigot (ideally about the height of the thread you want to cut more than the first spigot) just behind this one and chase the male thread onto this. A little adjustment might be required, but you should get a very good fit. There is an excellent old video somewhere on youtube of Allan Batty teaching hand thread chasing which is well worth a watch. He explains it much better than I think I just did!
The Bowler Hatted Turner:
Crazylegs Percy's discription is pretty good, I always chase the female thread first and as he said cut a (very small) spigot to fit snuggly inside the female thread, then on the male thread increase the diameter further up the spigot by 2depths of the thread plus a bit. Cut the thread and it will be a little tight, reduce the diameter a smidgeon leaving the thread visible and chase again, to strengthen the threads I take the tops off a little and also you can coat them with super glue or friction polish or similar. Once done rub a bit of candle wax on the threads. You may also explore tapered threads but that is a bit different. I would also recommend using an arm rest for the female chasing as it saves moving the tool rest all the time.
One last bit of advice, get hold of some plastic pipe and practice on that.
Buzzbee:
The problem with the double spigot method is that it interferes dramatically with any attempt to grain match.
crazylegs:
Thanks for the replies. I think I have my head round it.
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