Kitless Pen Threading

I thought I would show a pen I have in progress at present, following up on the thread about taps and dies for kitless. Might help a penny or two to drop into place!

First, you should note that I use brass for my pen components (which I then 'skin' with timber much like a kit tube). I don't like plastic and don't work with it if I don't have to. However, the principle would be identical if you were tapping acrylic.

So, the components:



There are three key parts: Section, Cap, Barrel. Ignore the two down the bottom, they are for a bulb filler and are unnecessary for a normal cartridge/converter kitless.

The die is used to make 'outside' or 'male' threads. I highly recommend that you get hold of a tailstock die holder (about £30 from RDG tools or the like). This helps to ensure that you apply threads at right angles to the component centre line:



The tap is used to make 'inside' or 'female' threads. Again I highly recommend that you get hold of a tap guide that you can mount into a Jacobs chuck in the tailstock, to ensure that your threads are 'straight'. I use a second tap for pretty much everything - I'm sure Grump would disapprove but it's never been a problem. Brass and acrylic are waaaaay softer than steel or stainless!



One final point: There are two approaches to placement of the cap-to-barrel threads. I make the section about five mm longer and the barrel correspondingly shorter, and thread the cap threads onto the section immediately in front of the section-to-barrel threads, so strictly speaking the cap screws to the section rather than the barrel:



The advantage of this is that I don't have to worry about the remaining thickness of material on the front edge of my barrel (if you do the math, the remaining solid wall thickness between a M12 x 0.75 and an M10 by anything is about 0.6mm), while the disadvantage is that it is possible to unscrew the section from the barrel while trying to remove the cap.

If you refer to the photo showing the tap you will see that I have marked the alternative position for the Cap-to-Barrel threads. If you go down this route remember to shorten the section and lengthen the barrel by corresponding amounts to allow for the change of position of the cap-to-barrel threads.

I hope this helps.

Jimjam66 said:

(if you do the math, the remaining solid wall thickness between a M12 x 0.75 and an M10 by anything is about 0.6mm)

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Sorry! Just re-done the math, it's actually about 0.25mm! I thought 0.6 sounded generous ...

I'm sure Grump would disapprove but it's never been a problem.

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Young David that is a nice tut and thanks for doing it.
I have nothing to disapprove of you are quite in order to do what ever you want.
I may do same myself but would never tell anybody to do it the wrong way, if I am giving instruction I would give the correct methods in that instruction.
If I am explaining how I do things that is a totally different kettle of fish.
The way I see it is we have both acted correctly and cannot be sued for our syntax init?

Had this before with somebody teaching to use cloth on a spinning lathe.
Wouldn't accept he could be made liable for accidents from his teachings.
Difference being do as I say nt as I do init?
Good luck and thanks again for a great tut init?

This I like David. One day I will have a go at this. Nice work mate

thank you David, thats excellent. I've threaded a bullet today as per Brians instructions so tomorrow... I might just have a go at this.

Thanks a lot its a great tutorial.

Grump said:

I may do same myself but would never tell anybody to do it the wrong way, if I am giving instruction I would give the correct methods in that instruction.

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Good point and one I hadn't thought of.

Interesting, thanks you for posting David
One day, in the future, I may attempt this

Very interesting David, thanks you for posting.

That's really useful, especially with good labelled pictures, thank you !
Regards Terry

Thanks for that David, one to keep for sure ..

David is this for a pen of your own design or are you modifying a kit?

Are your M10 x 0.75mm and M12 x 0.75mm tap and dies triple start or gut the standard ones?

Hi Mark - yes, it's my own design. I started with brass bar and turned and drilled on my metal lathe to produce what you see in the photos. This thread started as a follow up to this one by InkyFingers relating to taps and dies, in that thread I mentioned that yes, these are all just standard single-start taps and dies. I don't (yet) have the money or the incentive to invest in triple-start stuff. Bear in mind that the only thread you might want to be a multi-start one is the Cap-to-Barrel. Section-to-barrel really has no need to be multi-start.

I produced the following as part of a leaflet I give to customers. It might help those who are a little unclear as to the 'whats and whys' of multi-start threading:

What is a Multi-Start Thread?
When you screw the cap onto your precious new fountain pen or rollerball pen, it helps to be aware that it uses a multi-start thread. A single-start thread, as seen in the diagram below left, can only screw on one way and takes six full rotations to fully close. A multi-start thread, as illustrated below right, actually has a number of different parallel threads running alongside one another, which drastically reduces the number of rotations it takes to fully close.
In the illustration a two-start thread halves the number of turns required, from six to three.



Most fountain pens have three-start or four-start threads to make it easier to screw on the cap.

Why Do I Need to Know This?
Because multi-start threads actually consist of a number of separate threads running parallel to one another, your cap can screw onto the barrel of your pen in a number of different orientations. We as pen-makers work very hard to present our pens as perfectly as possible, so we have chosen one start which best matches the patterns between the cap and barrel, or which best shows off the natural grain of the timber used.
While there is nothing wrong with screwing your cap on using any of the starts, you may end up with the effect shown in the second diagram below, where the patterns or the grain don't match up.



If you wish to ensure that your pen is always perfectly presented when capped, this can be easily accomplished. If you screw the cap on and the patterns or grains don't align, simply unscrew the cap while maintaining slight closing pressure on it. As it reaches the end of the threads it will 'click' over to the next start. (You will more likely feel than hear the click!) Screw it down again and observe the pattern or grain. If it is still not perfect, repeat the process. You may have to do it as many as four times depending on the number of starts in your particular cap thread.

Brilliant explanation once again young David.
I have found no need for a triple start either.
I did see a tut by Skiprat somewhere some time ago, a how to of making a triple thread with a standard tap.
Never tried it myself, can't be arsed as I don't wanna faf about that much.
This might be it but it's not hard to search for

Thanks for that Brian. It's a great tutorial, but then Stephen (Skiprat) is an engineer and makes it look easy. Having tried it I can tell you it's not easy! Aslo, this doesn't solve the problem of needing a die (female thread) to match. What Skippie does is to make up these rods, use one piece as a tap and drill out another piece to mount as the male part of the joint. No need for a tap then!

Sorry David I must have misthunked it.
I am sure somewhere he did a tut of using a standard tap and making 3 threads.
Perhaps I dreamt it, I am getting on a bit, make allowances init?

Thanks for your explanation David.
I found some fine thread taps and dies quite cheap.

Grump said:

Brilliant explanation once again young David.
I have found no need for a triple start either.
I did see a tut by Skiprat somewhere some time ago, a how to of making a triple thread with a standard tap.
Never tried it myself, can't be arsed as I don't wanna faf about that much.
This might be it but it's not hard to search for

Click to expand...

Thanks for the link Brian he makes it look easy.

Bit pricy for me.

Triple lead tap and die sets

M 11 x .8 x 3 lead set

1 inch die and plug tap 2 piece set

$135.00