Taps and dies size choosing

[Amihai]

Hello,
Finally, decided to go down the kitless road...

(One of) My questions is this:
I'm looking to buy triple lead tap and die set for the cap, another single lead tap and die set for the section, and another tap for the bock size #5 pen nib housing (I prefer to make slimmer and smaller pens).

If I understood correctly, you don't want much of a "step" between the body and the section of a pen, aesthetically speaking. But on the other hand, you also need reasonable thickness material left between the top of the section thread and the bottom of the cap thread, which sits directly on top of it.

I thought about getting the M11x0.8 triple lead, and M10x1 single lead. If my calculations are correct, I should be left with 1.2 mm of thickness between the two threads. Is this enough, for a section made from Ebonite? I prefer to make the pen itself from wood.

Thank you very much, and sorry if I got everything wrong and messed up
Amihai Fishman.

 

[PatrickR]

I would choose a 12mm die. It is more versatile, you can make either a #5 or 6 pen. if you make a step-less design you'll have a 12mm barrel that is plenty small. If I could go back I wouldn't buy the 11 that I have. FWIW my favorite pen is made 12mm, step-less with a #5 wide shoulder nib

 

[Valleyboy]

I don't think your calculations are correct. Using m11x0.8 for the cap and m10x1 for the section would mean the major diameter of your section threads would be 10mm and the minor diameter of your cap threads on the barrel wood be 10.2mm. So you'd have a wall thickness in places of 0.1mm (where the two extremes meet) which isn't enough really.

In my opinion I would go for minimum M13, especially as you're just starting. The smaller you go the more accurate you will need to be (you'll get down to thinner wall thickness on the threaded part).

You could go m12 but if you did I'd recommend m10x0.75 for the section as that extra 0.25 makes quite a difference.

When asked I actually recommend m13 for starting out as it's a good standard size and allows you a bit of room to play with. Many commercially made pens are in this sort of size bracket. Also you don't need a step on the barrel. You can make the barrel smooth and have the end of the section register against a lip inside the cap to form the seal and to stop the cap over-rotating when screwing it on, in other words creating a positive stop.
Cheers
Ash

 

[Amihai]

I don't think your calculations are correct. Using m11x0.8 for the cap and m10x1 for the section would mean the major diameter of your section threads would be 10mm and the minor diameter of your cap threads on the barrel wood be 10.2mm. So you'd have a wall thickness in places of 0.1mm (where the two extremes meet) which isn't enough really.

In my opinion I would go for minimum M13, especially as you're just starting. The smaller you go the more accurate you will need to be (you'll get down to thinner wall thickness on the threaded part).

You could go m12 but if you did I'd recommend m10x0.75 for the section as that extra 0.25 makes quite a difference.

When asked I actually recommend m13 for starting out as it's a good standard size and allows you a bit of room to play with. Many commercially made pens are in this sort of size bracket. Also you don't need a step on the barrel. You can make the barrel smooth and have the end of the section register against a lip inside the cap to form the seal and to stop the cap over-rotating when screwing it on, in other words creating a positive stop.
Cheers
Ash

So, if I understood correctly, I calculated the distance between the two minors, when in fact I needed to calculate the distance between the female major and male minor. Thanks!

 

[Valleyboy]

So, if I understood correctly, I calculated the distance between the two minors, when in fact I needed to calculate the distance between the female major and male minor. Thanks!

Exactly!

 

[PatrickR]

You mentioned liking a #5 nib, most go to a 9x.75 section thread for this size nib. 13 is a very good option, allowing you to make a bigger pen if desired. It is my size of choice for most pens.
here is a quick and dirty pic showing a 12mm next to a 13mm step-less. (5&6 respectively). The 12 is as small a pen as I can make without going to a non traditional design.

 

[Curly]

I would suggest you get 11, 12 and a 13 x .75mm single start taps and dies and play with them. When you find the size that works best for the designs you want to try then go buy the triple start tap in that size.

You mentioned wood for the rest of the pen. You might find you need to sleeve the wood with Ebonite or resin of some sort to take the threads which might necessitate larger cap to barrel taps and dies.

 

[RobS]

@Curly is spot on with his recommendation.

Here is the thing, it all comes down to your skill in regards to wall thickness. Also remember you need to take the converter into account in your design. I find a 13mm body to cap thread is great for beginners, with a 10x.75 section which gives you more wall thickness than a 10x1. However, 10x.75 requires a custom mandrel.

You will see that there are several camps who will argue for one or the other and some argue for other sizes. This is where Curly's advice of playing with single point will help you develop your design while minimizing the R&D investment.

 

[Dannv]

FWIW< I have the Barry Gross beginner kit. It is set up for a #6 nib. Has a m7.5-0.5, m11-0.75 and m14-1 tap and dies for the latter two. I have since added a m14-0.8 triple lead to that. Makes pens on the larger size but works well and my wife likes the size of the pens, so they aren't huge. I do try to keep a 1mm wall thickness outside the threads, so with the 14mm threads, that means a 16mm minimum diameter to the cap. With some acrylics you could go thinner (and I have a little) but if they're brittle, they can break thinner, too. For the body, I turn my tenon and thread that, then screw on a nut I made from scrap and drill and tap the inside for the section to keep from breaking it.