Front Sections

[PTownSubbie]

I have been playing around with sections. After watching George's video on threading, I still haven't had any success with threading like him though.....

I am contemplating the size of the threads between the pen body and the front section. Here is my train of thought. Other theories would be greatly appreciated. I am not necessarily looking for answers as I know everyone does things differently but looking for your train of thought on why you use what you do.....

Pen body uses a triple start 12mm x .8 die. This means theoretically the threads of the body extend from 12mm-11.2mm thickness on the pen.

I was originally going to use a 10mm x 1.75 tap and die to cut the threads between the pen body and the front section. My concern is this only leaves 1.2mm difference between the inner and outer threads. Is this enough "meat" remaining to not cause problems down the road with the pen? Is there any reason that the tap/die used couldn't be in the 8-9mm range?

What kind of thickness do you all have on your pen body between the inner and outer threads and what size tap/die do you use for the front section to body connection?

Thanks! Please discuss among yourselves...I would like to listen in....:biggrin:

Fred

 

[soligen]

M10 x 1.75 is REALLY course. Might I suggest M10 x 1 (same as El Grande) or better yet, M10 x .75 (what I use). At 1.75 you might not have room for a converter to slide inside the section

I think the answer depends on the material. With alumilite, I think you will be fine.

I tried it once with PR - Note that I said "once".

 

[Brooks803]

Lol...yeah I'm considering alumilite JUST for my kitless peices. PR is just evil when I made my 1st front section. For the one I built I used 12x.75 for the cap/body and then 3/8x24nf for the front section. 3/8 is 9.525mm so it's not far from your 10mm selection. It seems to me (no expert by any means!) that there's enough wall thickness that I'm confortable with it. You're drilling roughly 6mm into that same side for the feed threads so the outter threads need to be large enough to compensate for that thickness too.

 

[workinforwood]

1.2 mm will hold but will also break easy. 1.75 threads are way way too course, LOL. That's like the tap for the hose outside. .75 will be great. That will beef up the meat between your threads by a mm, so you'll have just over 2mm, that's pretty good, especially on a tubeless lower weight pen. I usually go with a 12 and 10 size taps if making a pen like you are describing, although I don't have triple start..to each their own...but also I use metal, so 2mm of metal between threads is not going to break without using a hammer.

 

[PTownSubbie]

Thanks for those that replied! I appreciate the feedback! Maybe this weekend I will have some time to play!

Anyone else have any inputs/recommendations?

 

[Timebandit]

Fred,

I have been using the 10 x 1mm for the front sections, but just recently started using a 9 x .75mm for my front sections. There is a little more work involved just because you are getting pretty thin down around the end of the threaded part on the section and you will need at least a 1/4 hole for the end of the converter/cartridge to attach to the feed. But it does work and it will get you some more meat on the body threads, but less meat on the section itself, so its kind of a trade off. I prefer the more meat on the body, because most of the times i drop a pen they are with it capped, so the force will be exerted on those body threads and not the section threads. Now if you were to drop the pen uncapped, you might have to worry about breaking the section. I havent done any durability tests on these sections, so i cant say which size is better. But for now i prefer more meat on my body threads. You will not be able to go smaller than a 9mm just because of the fact that you need a 8.8mm tenon or so and will need a 1/4 hole drilled through it for the cartridge and threads cut on the exterior for the body and the interior for the actual feed threads.

 

[Texatdurango]

Fred,

When I make a pen (from acrylic, alumilite or ebonite) using the triple start 12mm x .8 die, I cut a tenon .366" dia THEN cut the multi-start threads THEN drill with a "Q" drill bit THEN tap with a 9mm x .75mm tap THEN make my sections to match the 9mm x .75mm threads. I too found that the 10mm threads didn't give me as much wall thickness as I liked and I had several pens crack right at the inner/outer thread area. Switching to the 9mm threads, I'm sure I had failures, just can't recall when the last time was!

This has worked like a charm for a lot of pens. :wink:

 

[Texatdurango]

...There is a little more work involved just because you are getting pretty thin down around the end of the threaded part on the section and you will need at least a 1/4 hole for the end of the converter/cartridge to attach to the feed

Justin, Try making your sections about 1/4" longer giving you a tenon around .500". Thread the tenon as usual but when drilling the clearance hole for the converter only drill in about .250", just enough to grasp the converter or cartridge. That way you still have some material "under" the 9mm x .75mm hreads.

 

[PTownSubbie]

Justin/George,

Thanks! Those were the kind of things that I was looking for as far as guidance and what works!

Durability is key!