Poseidon Thread Size?

[Alex D]

Hello! I am working on a graduation gift for my Goddaughter and really want to use a Poseidon kit I have from woodpenpro. It is the perfect fit for the blank I chose.

However, I really want to make her a fountain pen, and ideally a convertible rollerball/fountain.

Despite the Poseidon looking a lot like a Churchill, the threads are definitely not the same and I can't just thread in a Churchill or El Grande section. That's not the end of the world and I'm prepared to make a custom section for it and buy a custom die if needed. However, I can't seem to figure out what the section to body threading is. Does anyone happen to know?

I broke out the calipers and what I'm getting is: In US: .3440 (very close to 11/32) for the diameter and 32 TPI. If I try in metric, I get .873 x.8. The threads almost look acme style in that they don't have much of a peak, but seem a little squared off, but it is more likely that they were just cut a bit off.

Clearly neither of those are anything standard, and I fully expect I'll probably need a custom die, but I don't want to order one and it turn out I've ordered the wrong thing.

Is there any way to get a better idea of whether these are metric or US threads? And, assuming that the major diameter is probably a bit smaller than it started out due to machining, am I really looking at more like 11/32 or 9mm? If it's 11/32, I did surprisingly find that 11/32 x32 is a stock die size that I can pick up from MSC.

Thanks!
Alex

 

[Alex D]

Hello! I am working on a graduation gift for my Goddaughter and really want to use a Poseidon kit I have from woodpenpro. It is the perfect fit for the blank I chose.

However, I really want to make her a fountain pen, and ideally a convertible rollerball/fountain.

Despite the Poseidon looking a lot like a Churchill, the threads are definitely not the same and I can't just thread in a Churchill or El Grande section. That's not the end of the world and I'm prepared to make a custom section for it and buy a custom die if needed. However, I can't seem to figure out what the section to body threading is. Does anyone happen to know?

I broke out the calipers and what I'm getting is: In US: .3440 (very close to 11/32) for the diameter and 32 TPI. If I try in metric, I get .873 x.8. The threads almost look acme style in that they don't have much of a peak, but seem a little squared off, but it is more likely that they were just cut a bit off.

Clearly neither of those are anything standard, and I fully expect I'll probably need a custom die, but I don't want to order one and it turn out I've ordered the wrong thing.

Is there any way to get a better idea of whether these are metric or US threads? And, assuming that the major diameter is probably a bit smaller than it started out due to machining, am I really looking at more like 11/32 or 9mm? If it's 11/32, I did surprisingly find that 11/32 x32 is a stock die size that I can pick up from MSC.

Thanks!
Alex

Just following up in case anyone else ever needs the info. I have both a stainless and gunmetal version. For whatever reason, they gunmetal does not thread into the stainless one, so I thought they must be different sizes. I just made a test section using M9 x .75 and it worked in both.

On close inspection it's clear the stainless collars are machined in a different manner than the gunmetal ones. I think the result was that the threads in the stainless collar are probably just a touch off and while the metal threads bind up, the acrylic ones maybe have just enough give to thread into both.

So...bottom line, M9x.75

Thanks,
Alex

 

[duncsuss]

Glad you were able to figure it out - good sleuthing!

 

[Alex D]

Glad you were able to figure it out - good sleuthing!

Just wanted update this in case anyone else wants to use a fountain nib on this kit.

You definitely can make your own section, but the length is critical because of the cap tube length and you will need to have a decently short section (less than 30mm) which can get dicey if the feed threads get into the tenon for the body threads. There just isn't a lot of meat there. I think I'll be able to pull it off, but I'm not positive.

As a back up, and definitely an easier route, is to use an El Grande section (Beartooth Woods has them). They come threaded for M10x1, but there is plenty of meat on the tenon. I turned down the existing threads until I got to 8.93mm and then used the M9x.75 die to cut new threads.

Worked like a charm. I used a chuck to hold it, but in hindsight, I think I would just turn the threads down between centers. I ended up marring the section in the chuck so I had to sand and polish that out.

Hope this helps someone

Cheers,
Alex