# Cap Threads - Section or Barrel?



## LL Woodworks (Jun 5, 2012)

As I study and admire the craftsmanship of our pen makers, I've noticed different techniques in cutting the external threads to attach the cap.  Some place them on the grip section and some of you put then on the barrel.  Is there advantages or dis-advantages of either? Is one method  harder to make than the other?  For variety sake I think I'd like to make pens both ways!  Thanks for the opinions and feed back.


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## Andrew_K99 (Jun 5, 2012)

Interesting question.

I can't be of much help but one thing I read somewhere is if the cap threads are on the section (aposed to the body) there is a chance you'll unthread the section instead of the cap which could get annoying.  I believe someone suggested using left hand threads in this case to prevent this.

AK


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## joefyffe (Jun 5, 2012)

That could be interesting the first time one forgets about the left hand threads, or someone who doesn't know (yes I realize you are not supposed to loan a custom fountain pen) attempts to take off the cap by turning cc and blows up the cap or twists off the end of the bbl.


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## Timebandit (Jun 5, 2012)

Andrew_K99 said:


> Interesting question.
> 
> I can't be of much help but one thing I read somewhere is if the cap threads are on the section (aposed to the body) there is a chance you'll unthread the section instead of the cap which could get annoying.  I believe someone suggested using left hand threads in this case to prevent this.
> 
> AK



This is the main reason i see against it, other than esthetics, i dont prefer the look of the threads on the section. As for the left hand threads, i would avoid it as well. This will probably be the only pen your customer has ever had in there life that had left hand threads and the first time they go to unscrew the front section they are going to resort to muscle memory and go to unscrew it to the right and when it wont unscrew they are going to think its stuff, so they are going to crank it harder and you are going to be lucky if they dont twist off the section threads and break the section. I would avoid this at all costs. I prefer the old method of barrel threads.


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## Timebandit (Jun 5, 2012)

Double post


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## Dalecamino (Jun 5, 2012)

For the sake of stability, thread the barrel. Consider how thin the threaded area on the section is. JMO!


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## Robert111 (Jun 5, 2012)

I plead guilty to having mentioned the left hand threads, but I only mentioned them. I didn't recommend them, and I don't think anyone has. 

I brought them up in the context of a possible solution to the problem you mention--accidental unscrewing the section with the cap. 

On that subject, I made a pen this week with the cap threads on the section. It works fine, in that the section doesn't unscrew with the cap. I made the section threads tight by maxing the tenon diameter for the section threading into the barrel. To thread in the section, you have bear down a little on the last turn as you seat the section into the barrel. The cap-section threads had a smaller tenon before threading. Even with the cap screwed on tight, you don't uncrew the section when you loosen it from the barrel.

For the record, I usually size a tenon about .2 mm under the nominal size of the die; e.g., the tenon for a 12 x .8 would be 11.75-11.8. I believe Ken (Drgoretex) mentioned this standard and I've followed it. A loose-fitting thread would then call for a tenon of about 11.6 mm. Tight threads would get 11.9. Bear in mind I'm a novice at this and I'd be interested in the comments of the experienced pen makers on this.


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## Robert111 (Jun 5, 2012)

On the subject of the possible risk a section breaking because of having cap threads on it, I may regret this but I doubt it's going to happen. I think I have more meat under the section-cap threads than I would have on a barrel when there are cap-barrel threads right over section-barrel threads. 

Of course, you can move the the cap threads back on the barrel to avoid that, and then the issue becomes one of aesthetics: Where do you want to see the threads--forward near the nib or backward on the barrel?

Another aesthetic issue is the ratio of cap length to barrel length. I like a shorter cap, and putting threads on the section allows that.

Again, this is a novice speaking. I'd appreciate the opinions of the guys (I don't think there are any women in this category) with the experience.


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## Curly (Jun 5, 2012)

*Why does everyone think the cap has to turn backwards?*

Maybe it is just me and the way I think , but if I wanted cap threads on the section I would put the left hand thread on the section to barrel and not the section to cap. That would give you a pen with a conventional threads that muscle memory would like. You would only need to remember to turn counterclockwise if you needed to take the section out of the barrel for changing cartridges or working the converter.


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## Timebandit (Jun 5, 2012)

Curly said:


> Maybe it is just me and the way I think , but if I wanted cap threads on the section I would put the left hand thread on the section to barrel and not the section to cap. That would give you a pen with a conventional threads that muscle memory would like. You would only need to remember to turn counterclockwise if you needed to take the section out of the barrel for changing cartridges or working the converter.



Thats what were talking about, the left hand threads on the section so that it doesnt unscrew when you unscrew the cap. But again you have to worry bout someone turning it the wrong way and breaking the section threads off. Not left hand threads for the cap. I dont think left hand threads are a good idea at all on brittle items. If it was on a metal pen, maybe(i still wouldnt)but maybe. Not on brittle resins though.


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## IPD_Mr (Jun 5, 2012)

Many of your vintage and successful lines (Parker Vacumatic) had the threading on the section. Two big reasons for this. Many times the area of the body was used as an inkview. Threading over an inkview doesn't work.  :wink:  Now if you are designing a pen and you are putting threads on the section, what does that do to the threading on the cap?  For the most part it allows the cap threading to be higher up in the cap.  Why do we want the threading higher?  What is the most fragile part of the cap?  THE EDGE  You do not want threading anywhere near that, especially if you do not use a centerband (also known as a girdle, which was its initial purpose, to renforce the cap)


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## watch_art (Jun 5, 2012)

Well - except for a very few pens with threads at the front of the section - like Ancora and the custom pens by Oldwin, NONE of the pen companies put cap threads on the section OR left hand threads.  I don't see why we should be doing it any differently, either.
I've never handled the Oldwins, but I had about 10 of the Perlas last year and the sections are plastic over a metal sleeve with an o-ring to hold things in TIGHT.  I actually got really sick of taking them apart to clean ink out of them after using and tuning the nibs.


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## Curly (Jun 5, 2012)

Timebandit said:


> Thats what were talking about, the left hand threads on the section so that it doesnt unscrew when you unscrew the cap. But again you have to worry bout someone turning it the wrong way and breaking the section threads off. Not left hand threads for the cap. I dont think left hand threads are a good idea at all on brittle items. If it was on a metal pen, maybe(i still wouldnt)but maybe. Not on brittle resins though.



Doh! For some reason I took it as right hand section threads and left on the cap.  Thanks.


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## watch_art (Jun 5, 2012)

IPD_Mr said:


> Many of your vintage and successful lines (Parker Vacumatic) had the threading on the section.



Show me this.  I've never seen it.

{--- Review Index ---} - The Fountain Pen Network


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## Russianwolf (Jun 5, 2012)

What has been the experience of people who have made the Presimo pens from PSI? They have the threads on the section. Any issues with unthreading when uncapping?

And to answer the question of "if everyone else does it like A, why should we try B?", because innovation rarely comes from doing things the way everyone else does.


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## Robert111 (Jun 5, 2012)

I'm going to make a carry pen with section-cap threads on the section and see how it goes. I want to see if it'll hold up over time.


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## soligen (Jun 5, 2012)

I've made almost all my kitless pens with threads on the section.  Unthreading the section has not been a problem for me since I went to .75 pitch.  Its simply a non-issue.

I did have one pen with an section un-threading issue, but it was 1mm pitch, and I did a particularly poor job on the threads, so I consider that pen an anomoly (teh other 1mm pitch sections have been fine).  All the rest have been a non issue, but I did change to .75 pitch just to be sure.


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## Timebandit (Jun 6, 2012)

IPD_Mr said:


> Now if you are designing a pen and you are putting threads on the section, what does that do to the threading on the cap?  For the most part it allows the cap threading to be higher up in the cap.



 I can do this with the threads on the body as well. I dont see how the threads on the section are going to allow that any differently. Moving them forward 1/4" isnt going to change much. I can get the threads just as high in the cap and keep the cap the same length as one with the threads on the section, with the threads on the barrel. This is more an esthetic thing (putting threads on the section) than a functional one. Can anyone give a truly functional purpose for this other than esthetics?


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## Russianwolf (Jun 6, 2012)

Timebandit said:


> IPD_Mr said:
> 
> 
> > Now if you are designing a pen and you are putting threads on the section, what does that do to the threading on the cap?  For the most part it allows the cap threading to be higher up in the cap.
> ...



If you put the cap threads on the body and the section threads on the inside, you get to a point where the material can get pretty thin and fragile. I'd hazard to guess that sometimes its fragile enough that one could break the pen screwing the section in too tightly.

Moving the cap threads to the section can relieve this somewhat. You can design a section that has no overlapping thread portions.

|cap threads|nib holder threads|section threads|

thus not stressing the material as much. I think it also makes making the pen easier since the tolerances aren't as important.

I made one pen with no section just to see if I could. I could tweak the design a bit and have the cap threads on the body (currently there are no cap threads) with no chance of breakage. But I'm working on other things right now.


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## Timebandit (Jun 6, 2012)

Russianwolf said:


> Timebandit said:
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> > IPD_Mr said:
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Il be honest, i have broken a section screwing it in before, but never a barrel, and i highly doubt this will happen. A breakage is going to occur at the weakest link. In this case it is the threaded area of the section, not the threaded area of the barrel. This area of the barrel has 2-3 times more thickness than the section area. I would be flabbergasted if the barrel broke before the section did. I cant ever see the barrel breaking due to screwing in the section to tight. At least not on my pens. I leave enough material here where this is a non issue. Others may make this area thinner, so this may be of some advantage to them, but not in my instance.

Why would the tolerances be less important this method?


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## glycerine (Jun 6, 2012)

Timebandit said:


> Russianwolf said:
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> > Timebandit said:
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I think he just means that without having to thread the "section end" of the pen body on the outside, you could make it thicker if needed.  You're not constrained to a specific size...


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## Timebandit (Jun 6, 2012)

glycerine said:


> Timebandit said:
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> > Russianwolf said:
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You couldnt make it any thicker than the cap threads that are on the section or else the barrel wont thread into the cap any farther than if the threads were on the barrel. Your constrained by the cap to barrel thread size. Just because the threads arent there doesnt meant that you can increase the size of the barrel, it just means that the cap threads wont be in that location on the barrel, leaving that much more material. But to me it wont be a large enough gain in material to warrant it, and i dont think that is a fragile area anyway. The section itself is the weak link.


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## glycerine (Jun 6, 2012)

Timebandit said:


> You couldnt make it any thicker than the cap threads that are on the section or else the barrel wont thread into the cap any farther than if the threads were on the barrel. Your constrained by the cap to barrel thread size. Just because the threads arent there doesnt meant that you can increase the size of the barrel, it just means that the cap threads wont be in that location on the barrel, leaving that much more material. But to me it wont be a large enough gain in material to warrant it, and i dont think that is a fragile area anyway. The section itself is the weak link.


 
Yeah, but there's no reason the cap has to screw on past the threads.  If you're not concerned about that, then you could make the cap and that end of the pen body a little thicker if you wanted.  I'm not saying it's necessary, but if you're considering the advantages/disadvantages of putting all the threads on the section, then that could be one adtvantage...


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## watch_art (Jun 6, 2012)

So basically you're talking about creating a step from the barrel down to the threads?


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## Timebandit (Jun 6, 2012)

glycerine said:


> Timebandit said:
> 
> 
> > You couldnt make it any thicker than the cap threads that are on the section or else the barrel wont thread into the cap any farther than if the threads were on the barrel. Your constrained by the cap to barrel thread size. Just because the threads arent there doesnt meant that you can increase the size of the barrel, it just means that the cap threads wont be in that location on the barrel, leaving that much more material. But to me it wont be a large enough gain in material to warrant it, and i dont think that is a fragile area anyway. The section itself is the weak link.
> ...



True, if you just wanted it to screw in as far as normal, but if you wanted to do like Mike was saying and have the threading higher in the barrel, then this method wouldnt work, as the pen barrel would be to thick to screw into the cap. But, that is one advantage though, just a slight amount of extra material in that area of the barrel if you are worried about the thickness of that area.


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## Russianwolf (Jun 6, 2012)

Timebandit said:


> glycerine said:
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> > Timebandit said:
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Sure you can make it bigger. You can make it the same diameter as the cap with the cap threads on the section. You could even make the body larger than the cap if you wanted (Just to be different). In order to do that with the threads on the body, you have to make a step in the body.

In my experience the hardest part of making these is when you have overlapping external and internal threads. unless the size difference is pretty big between them, its pretty easy to mess them up. At least when I'm working with plastics.

Granted I'm not as good or experienced at this as you are.


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## Timebandit (Jun 6, 2012)

Timebandit said:


> You couldnt make it any thicker than the cap threads that are on the section or else the barrel wont thread into the cap any farther than if the threads were on the barrel. Your constrained by the cap to barrel thread size. Just because the threads arent there doesnt meant that you can increase the size of the barrel, it just means that the cap threads wont be in that location on the barrel, leaving that much more material. But to me it wont be a large enough gain in material to warrant it, and i dont think that is a fragile area anyway. The section itself is the weak link.





Russianwolf said:


> Sure you can make it bigger. You can make it the same diameter as the cap with the cap threads on the section. You could even make the body larger than the cap if you wanted (Just to be different). In order to do that with the threads on the body, you have to make a step in the body.
> 
> In my experience the hardest part of making these is when you have overlapping external and internal threads. unless the size difference is pretty big between them, its pretty easy to mess them up. At least when I'm working with plastics.
> 
> Granted I'm not as good or experienced at this as you are.



See post above. You can make it larger as long as you dont want to make the threading higher in the cap, and then it wont work. And yes to do it with the threading on the barrel you will have to cut a shoulder. But that same shoulder is still there with the threads on the section, you just dont have to cut it on the barrel. Its between the barrel and the section. Are you having trouble threading your barrels because of wall thickness there?


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## Russianwolf (Jun 6, 2012)

I've broken a few while threading because the outside diameter was too close to the inside thread diameter. Here, let me try a picture.

Top shows cap threads on the body. Red lines are the internal threads on the section  (for the nib holder) and body (for the section). The yellow line is the external threads on the section. In the body, two sets of threads are right on top of each other. The black line below shows the minimum cap depth.

Below it shows the same for threads on the front of the section. No overlapping threads anywhere and a MUCH smaller minimum on the cap length.

Last shows threads on the back of the section. With this a shoulder had to be made, or the section would have to taper, one or the other. This would allow for no overlapping of threads with a little planning and a minimum cap length longer than the second, but still shorter than the first.

Beneficial? you decide. From my experience not having overlapping threads may make things a bit easier. As long as the section isn't coming off when I'm trying to unscrew the cap.


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## Russianwolf (Jun 6, 2012)

Timebandit said:


> Timebandit said:
> 
> 
> > You couldnt make it any thicker than the cap threads that are on the section or else the barrel wont thread into the cap any farther than if the threads were on the barrel. Your constrained by the cap to barrel thread size. Just because the threads arent there doesnt meant that you can increase the size of the barrel, it just means that the cap threads wont be in that location on the barrel, leaving that much more material. But to me it wont be a large enough gain in material to warrant it, and i dont think that is a fragile area anyway. The section itself is the weak link.
> ...



Hold it..... rereading I think you may be talking about posting the cap on the back of the body. I'm only talking about capping the pen. We may be talking about two different ends here.


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## Timebandit (Jun 6, 2012)

Russianwolf said:


> I've broken a few while threading because the outside diameter was too close to the inside thread diameter. Here, let me try a picture.
> 
> Top shows cap threads on the body. Red lines are the internal threads on the section  (for the nib holder) and body (for the section). The yellow line is the external threads on the section. In the body, two sets of threads are right on top of each other. The black line below shows the minimum cap depth.
> 
> ...



No need for pictures. I understand what you are saying and I understand all about threading, was just asking where you were having trouble? What size are you using? Most here use around the same sizes, and most dont have this problem. I suspect a problem somewhere else. Maybe your tenon is to small or your using to large of a bit, to much force maybe? Your barrel tenon and the hole drilled internally should never be as close as you are saying, which is why i suspect something else.


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## Timebandit (Jun 6, 2012)

Russianwolf said:


> Timebandit said:
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Nope same thing:biggrin:


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## Russianwolf (Jun 6, 2012)

Well, I was using M10 for the section and M12 for the cap. but I bought an M14 more recently, just haven't tried it yet.


The threads may have been a little too course also, adding to the problem. got the finest threads that victor had on the shelf for both the M14 and M12 at the same time.

But moving those threads may be another answer to the same issue.


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## Gilrock (Jun 6, 2012)

I'd like to make threads like a Jr Statesman.  They look much nicer without sharp edges and they don't look so dense.  I think I followed one of the threads around the pen and it made 1 revolution.


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## Russianwolf (Jun 6, 2012)

Gilrock said:


> I'd like to make threads like a Jr Statesman.  They look much nicer without sharp edges and they don't look so dense.  I think I followed one of the threads around the pen and it made 1 revolution.



The Jr series uses a triple start thread. so there are really three threads that circle the piece an even distance apart. 

Mike Redburn sells triple start taps and dies on his site. www.Silverpenparts.com

The Baron used a quad start thread. Just FYI.


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## joefyffe (Jun 6, 2012)

*I'm so confused!*


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## Gilrock (Jun 6, 2012)

Russianwolf said:


> Gilrock said:
> 
> 
> > I'd like to make threads like a Jr Statesman. They look much nicer without sharp edges and they don't look so dense. I think I followed one of the threads around the pen and it made 1 revolution.
> ...


 
Yeah I bought my 12mm x 0.8mm triple start tap/die from Mike.  I use it for my cap to body threads and it looks nothing like a Jr Statesman.


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## Andrew_K99 (Jun 6, 2012)

Gilrock said:


> Yeah I bought my 12mm x 0.8mm triple start tap/die from Mike. I use it for my cap to body threads and it looks nothing like a Jr Statesman.


 
I just pulled out a Jr. Statesmen and I think what you want is a flat topped thread.  I think you'd have to reduce the tennon size to be able to achieve this or attempt to turn off the tops after threading.  I'm not sure how this would affect strength or wear of the threads.

AK


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## Russianwolf (Jun 6, 2012)

Gilrock said:


> Russianwolf said:
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> > Gilrock said:
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yeah, and I want to make threads like this.... casine_floral_1 but it ain't gonna happen this week. :tongue:


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## Gilrock (Jun 7, 2012)

Russianwolf said:


> Gilrock said:
> 
> 
> > I'd like to make threads like a Jr Statesman. They look much nicer without sharp edges and they don't look so dense. I think I followed one of the threads around the pen and it made 1 revolution.
> ...


 
I didn't double-check a Jr Gent II but I know all my Jr Statesman pens can only have the cap put on 2 ways so I don't think that's a triple start thread.  If you look at the pen below....there is no way to screw that cap on where the blue stripe isn't lining up...so I'd call it a double start 180 degrees apart.


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## Russianwolf (Jun 7, 2012)

You sure about that? Every Jr. I've ever gotten has been a triple. Unless they've made changes recently. I have a Jr. Stateman, a Jr. Emp and the Stretch (which is based on the Jr's) in my case here. All are triples.


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## glycerine (Jun 7, 2012)

I've got a jr Statesman on my desk from several years back and it's a quad.  Not sure about the newer ones though, I believe all of those are at the house...


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## glycerine (Jun 7, 2012)

Interesting, just found a newer model and it is a double...


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## Andrew_K99 (Jun 7, 2012)

The one in my desk is triple ...


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## Russianwolf (Jun 7, 2012)

glycerine said:


> Interesting, just found a newer model and it is a double...



guess they are making some changes. It's been a while since I got any.


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## glycerine (Jun 7, 2012)

In my best Forrest Gump voise: "threads on pen kits are like a box of chocolates... you never know what you're gonna get."


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## Curly (Jun 7, 2012)

Gilrock said:


> I'd like to make threads like a Jr Statesman.  They look much nicer without sharp edges and they don't look so dense.  I think I followed one of the threads around the pen and it made 1 revolution.



They are some kind of square thread like the ones you see on clamps and vise threads. An Acme thread is an example. If you want to make them you will most likely have to cut them with a metal lathe or make a tap and die with one.


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