threading a 7mm nose cone

[DME72]

has anyone threaded a 7mm nose cone? i tried to thread one with a 1/4-28 die which did not work. maybe i did not go slow enough. i have some schmidt a3 refills on order which are cross size but with a small collar to use a spring. would like to use a ready made 7mm nose cone that i could thread with taps and dies. try to make a slim click pen with that refill and a schmidt shm192 click mech. i might have to make it where the click mech comes apart on top, but would rather have the nose cone unthread. any help or input would be great.

doug

 

[magpens]

@DME72
Not sure what you mean by saying it did not work. . Please could you explain a little more fully. . I can appreciate that it would be quite tricky.

I assume you used a standard nosecone for a slimline and tried to thread the "stub" that normally presses into the brass tube. . That stub has a diameter very close to 0.249", so you might be able to put 1/4-28 threads on that with a die. However, the ID of the brass tube is only a bit different (close to 0.248" ... measurement is a bit difficult with calipers) ... so you won't be able to thread that with a 1/4"-28 tap. . Is that the situation you are working with ?

I think you might have to fasten a brass ring inside the brass tube for the "stub" to thread into.

I hope I am not totally out of the ballpark in these statements ... please correct me in any way necessary ...

The brass ring I am referring to, after threading, would have to have an ID large enough for your whole refill to pass through. I am not sure about the size of the ID of a female thread for 1/4-28 .

I am very interested in this topic !

 

[Roger Schlenz]

I am interested too! PSI makes a no press Comfort pen kit where the components are screwed together instead of pressed together. The nose cone is threaded, and screws into the threaded lower tube. Maybe that would be a way to go.

 

[DME72]

i am trying to use an slim line nose cone that is modified to thread on instead of a press fit so the refill can be changed. i tried a 1/4-28 die and broke the nose cone. maybe i went to fast or something. the reason i want to use a slim line nose cone is it is already made and does not cost alot, plus i have alot of them already. as far as the brass tube goes i have several feet of really thick brass tube i was going to use and turn drill and ream as needed. i may give up on a slim line nose cone and try something different, or make one from scratch on my taig lathe.thanks for the input.
doug

 

[magpens]

If you are planning to use a Parker refill in a 7 mm tube and also be able to replace the refill through a removable nose cone, that is a tricky proposition.
Although the refill fits fine in the brass tube, there is not quite enough clearance between the refill and tube wall ID to squeeze in a (home-made) brass coupler to which you would screw the nose cone. . I am currently struggling with precisely this problem.

 

[More4dan]

If you are planning to use a Parker refill in a 7 mm tube and also be able to replace the refill through a removable nose cone, that is a tricky proposition.
Although the refill fits fine in the brass tube, there is not quite enough clearance between the refill and tube wall ID to squeeze in a (home-made) brass coupler to which you would screw the nose cone. . I am currently struggling with precisely this problem.

Could you add an external sleeve to the tube with threads on the OD that threads into to nose cone's internal threads? That would leave the entire ID of the 7mm tube for the refill.

You would have to make a custom nose cone.

Danny


Sent from my iPad using Penturners.org mobile app

 

[magpens]

@More4dan
Yes, Danny that is a possibility that I have considered and could very well be the way to go, but there is a problem unless you custom make nosecone.
The standard slimline nosecone does not have enough depth of material for threading at that diameter. ... Ideas or hints welcome !

 

[DME72]

that is the problem i have run into, not enough metal on the nose cone for threading. i am trying to make a really slim click pen with the schmidt A3 refill. the a3 is like a parker but almost cross refill size with a shoulder for the spring. thinking about 6.5mm threads but i dont want to spend a ton of money on custom taps and dies. same thing as magpens any ideas or thoughts welcome.
doug

 

[GaryMGg]

What if you epoxy the nib to the barrel, split the barrel above it, and put the threads higher up—maybe 1/4 to 1/2" higher so you're threading wood to wood?

 

[magpens]

@DME72
Let's keep in touch, doug.
You suggested 6.5mm threads. The Jowo #5 nib section has threads M6.5x0.5mm (single thread) and that might do the trick for you. . You can buy that tap from mredburn, a member here ... he has a website called sliverpenparts.com (I believe). I don't know if he has the die.

But I don't think it will work for me, since I am trying to use a Parker refill, which needs a little more clearance.

Please can you tell me the max. diameter of the Schmidt A3 refill that you want to use ... and the length ... I might have to give up on the Parker.

 

[magpens]

@GaryMGg
That is a good thought, Gary ... it has gone through my mind also. . The threads could be in the barrel material ... acrylic should work ok for that but I am not sure about wood. ... . Doing things this way, It would be a rather different design.

 

[DME72]

i might just turn one from aluminum on my taig metal lathe. i could make the clicker unthread to change the refill, i think it would be best if the nose cone unthreaded.i am probably not going to be able to use a standard 7mm nose cone for this pen and keep the slim profile i want due to the threads.