MadModder
Gallery, Projects and General => How do I?? => Topic started by: raynerd on April 18, 2009, 11:50:20 AM
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I`m trying to set up my new gear (well infact John (bogstandard) has offered me a visit to his house this week to take a look at my lathe) and although I am a long way off being capable of internal threading, I just want to know what is possible. Basically, I have sucessfully threaded a brass bar with 20TPI external thread using a 60 degree tool. I expect threading internally will be more difficult but I can image the physical limitations of the tool can cause some problems. The parts that I am interested in turning and threading are quite small and therefore so is the internal diameter.
1. Using a 60degree internal threading tool, what will be the smalles diameter hole that I will be able to thread? I presume it is case of finding a small headed tool - the threads will not be deep and less than 1 inch of threading starting close to the enterence of the hole .
2. I haven`t yet purchased an internal threading tool for my lathe (clarke cl300m) a 12x7, can anyone recommend a UK supplier and a suitable internal threading tool?
Chris
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Chris,
Aren`t all the smaller size threads, (under .5 or 12mm), covered by easily available taps? :wave:
David D
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Yes - but I want to learn screw cutting as a skill because ultimately I want to cut multi-lead threads - the one specifically is a quad lead 36TPI. Will any tap and dye set allow me to achieve this thread? - also even if I could achieve this with taps and dyes I need to buy a range for each thread type and size - I want to have flexibility without having to purchase a huge collection. Does this sound sensible?
Chris
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Sometimes if it's a special it's as well to make the tap, tap making for odd sizes isn't hard, just different skill sets.
JS.
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I`ll be more specific - one of my hobbies is fountain pens and pen repair. With my lathe I have started turning them from scratch but I need to figure how to thread the barrel and cap with a multi-lead thread - each cap and barrel (pen) is slightly different so I need to learn how to thread both external thread on the barrel and internal thread on the cap - and the calculations I will need to make. Because each one is slightly different, I really need to figure out how to do it on the lathe. It isn`t that the threads are necessarly different - infact I could get away with doing just one or two thread types - perhaps a quad lead 36 TPI and then just a single lead 20 TPI.... but at different sizes of holes!
I hope this makes sense.
Chris
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What you are asking Chris, is the same as 'how long is a piece of string'.
When you start to cut your own threads, only then will you know just how small you can make the screwcutting tool.
I have made boring bars, very similar to a screwcutting tool, as small as 1mm, out of an old drill, but using it for a production job and very intricate work is only a thing you can do yourself, by trial and error.
As John said, you could most probably make up your own multi start screw cutting gear, I am sure the pen manufacturers don't do it by single point, but again, because it is so specialised to your hobby, you would have to do it all yourself.
I am sure there is a toolmaker somewhere that will make just what you want, but even on the cheap side, I wouldn't see you getting a set made for under a grand a pair, maybe a lot more. Those sort of chappies don't work for peanuts.
Bogs