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Turned my first pen....
sbwhart:
What a lovely bit of work well done Chris
:clap: :clap: :clap: :clap: :clap:
Thanks for posting.
Regarding making a Knib this may give you some ideas its about making musical box combes putting the splits in would be symilar to spliting the knib
http://chesteruk.net/store/don_busby_music_box.htm
Couple of questions about the threading as I've been giving this some thought.
1:- What Diameter would the thread be ?
2:- What thread form 60º or 55º or something else
3:- I take it the thread would be cut in the plastic in the case of your example acrialic or at some stage would you want to cut it in brass or steel.
This is what I've had in mind:-
If you are cutting the thread in soft material you can wind the lathe over by hand when you got the gear train set to give you the pitch.
For 36 tpi tristart you would set your lathe up to cut 12 tpi
To cut the thread you need a tool (correct term is chaser) that would cut the three threads at the same time, you can buy chasers that will do this or it may even be posible to modify a die to do it.
When you've got the male thread sorted it would be an easy step to make a tap for the female thread especialy concidering the soft material you want to work with.
Can any of the chaps comments on this it may be a load of rubish but at least its a starting point.
Cheers
Stew
raynerd:
Hi thanks for the reply.
1:- What Diameter would the thread be ? - a variety really for different pen sizes and shapes which is why taps and dies aren`t the way I want to go down. If I can learn to cut the threads then I won`t need to worry about the diameter. The internal diameter of a cap and barrel is about 0.37" but then if I wanted to make a more streamline pen it would be less and each section and barrel will also be different - but the barrel and section thread and any blind caps will just need to be single start/lead.
2:- What thread form 60º or 55º or something else? - standard 60
3:- I take it the thread would be cut in the plastic in the case of your example acrialic or at some stage would you want to cut it in brass or steel. - just plastics for now and I guess you could turn it by hand, it is pretty soft with a sharp tool.
I haven`t heard of a chaser - can you link me to one and explain how it would work? The only method I have seen is for a 36TPI tri lead in which a 12TPI is cut, the start rotated 120 degrees and the next cut is made....and one more. I haven`t got a CLUE how in reality this is done, I was just told that this is the method. This chaser idea seems interesting but is this a tool specific to diameter like and tap and die where I would need a whole range?
The link for the nib slit looks good but making the nib is certainly a pipe dream at the moment - the first thing is threading and then before the nib, I would like the make a cap clip like in the pictures. I think a clip is more realistic than making a nib (with a nib, I would also need to make a feed.)
Chris
sbwhart:
Hi Chris
Next question what thread pitches can you set your lathe to cut ?. 12TPI ?
Cutting a multi start thread as with all things ther's more than one way to do it, the first way I'd try would be
1:- set your machine up to cut 12TPI
2:- Set compound slide so that it moves parrallel with the lathe bed.
3:- With a single point tool cut your first thread when to depth Zero your cross slide dial
4:- Advance your compound slide 0.027" (1/36)
5:- Cut your second thread
6:- Adavance your compound 0.0.27
7:- Cut your third thread
With a chaser you'll cut all three threads at the same time so will be more accurate.
The only way for you to learn this is for you to start and do a few trials on scrap material, you'l product a lot of scrap at first but yoy will learn as you go along and only get better.
this is one site selling chasers http://www.cromwell.co.uk/category_page/393506
it'll give yoy an idea what they are as your requirements are a bit strange you may have to improvise by making your own simply cut up a dia, your thread pitch is covered by cycle threads, you can get them from Tracy
http://www.tracytools.com/tapsanddiesspecials.htm
Hope this helps I've certainly given you somthing to think about :scratch:
Stew
raynerd:
When you say - cut your second thread, cut your third thread - how do you ensure that is is 120 degrees around the piece? Do you need to somehow index it?
Yes, btw, my lathe can cut 12TPI.
I am really new to machining and I am sorry but I don`t understand how the chasers work - do you use them like a cutting tool so the diameter of the work doesn`t matter? ....and the bit about cycle threads and your second link totally destroyed me :scratch: sorry...I did have a search of the net for more info but didn`t get anywhere.
I am happy with your first method if you tell me how I should ensure the threads start at the correct roatations around the piece - really it is just like cutting a single thread three times right?
I am more interested about the chaser idea if you can give me some more details? - also the chaser cuts the external thread, but how would you cut an internal thread to match? I appreciate your time for the reply.
Chris
raynerd:
PS- just re-reading your post - what does increasing your compound slide 1/36 do in terms of the thread cut?
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