Threadless Cebloplast

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dgscott

dgscott

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I wanted to create a pen with an unbroken line in the barrel -- no threads and an "unshaped" section. That meant fabricating a cap that would fit by friction. I wanted to be able to line the cap with something both durable and pliant so that the cap wouldn't scratch the barrel when taken on and off, so I put in a Delrin plug and turned to size. I found that even though Delrin is a greasy plastic, you can bond it to other surfaces with Loctite Plastic Bond (a two part process that uses an activator then a different formulation of CA).

The material is cebloplast, the section ebonite.

Thanks for looking.
Doug
 

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Awesome! I just started a project using a stick of this material and it certainly isn't the easiest to use. You've done an excellent job and I love the threadless concept!
 
Doug - great looking pen. Does the cap friction fit to the section and that is why you did an "unshaped" section? I am just trying to se the reason for the section with no shape unless it was just a personal preference.
 
IPD_Mr said:
Doug - great looking pen. Does the cap friction fit to the section and that is why you did an "unshaped" section? I am just trying to se the reason for the section with no shape unless it was just a personal preference.
Click to expand...

Thanks! This was just personal preference. I never felt that the curve or lip on most sections really did much to improve comfort or grip unless the "unshaped" dimension of the section was large (like 14 mm or so). I really wanted to create a pen shape that was a continuous, smooth line.

Doug
 
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OK that makes sense. So where is the friction fit for the cap then. Is it just on the first part of the body behind the section or is part of the section used in the friction fit as well. What do you think in regards to the derlin wearing down over time? Do you think this would be a future problem? Obviously you didn't think it would be too bad or you would not have done it. I am just trying to picture where the friction hits and if it does wear down, does that mean the cap will continually slide further onto the body and risk the nib bottoming out or does it have a shoulder to prevent that?

Frisction fit caps have been discussed on here before but I don't think that derlin was ever a thought of or discussed option, so I am trying to get a feel for any pitfalls.

Thanks
 
IPD_Mr said:
OK that makes sense. So where is the friction fit for the cap then. Is it just on the first part of the body behind the section or is part of the section used in the friction fit as well. What do you think in regards to the derlin wearing down over time? Do you think this would be a future problem? Obviously you didn't think it would be too bad or you would not have done it. I am just trying to picture where the friction hits and if it does wear down, does that mean the cap will continually slide further onto the body and risk the nib bottoming out or does it have a shoulder to prevent that?

Frisction fit caps have been discussed on here before but I don't think that derlin was ever a thought of or discussed option, so I am trying to get a feel for any pitfalls.

Thanks
Click to expand...

A bunch of really good questions. First, the inner Delrin liner in the cap is shaped to fit about 1/2" of the barrel just below the section, and it's pretty snug -- doesn't wobble like it would if it only engaged a small part of the circumference.

The inside of the cap is "stepped" so that there is an inner shoulder that rests about where the nib fits into the section, so it would never go down further than it was intended to.

As to eventual wear of the inner sleeve, Delrin is pretty high on the Rockwell scale as well as having much higher abrasion and wear resistance than either nylon or polyethylene. I imagine that if anything fails, it's likely to be the Loctite Plastic Bond that holds the Delrin in place, but I suspect that unless it is exposed to extremes of temperature, it's likely to wear pretty well. Even if the sleeve does eventually come loose, it can be easily replaced.

Time will tell, I guess....
Doug
 
Doug, I was talking with Dawn on the phone on Tuesday or Wednesday and mentioned making a pen with almost the exact concept, threadless. Funny how different people come up with similar ideas right around the same time. Mine will be slightly different, hopefully I'll get it finished tomorrow.

Great looking pen.
 
Russianwolf said:
Doug, I was talking with Dawn on the phone on Tuesday or Wednesday and mentioned making a pen with almost the exact concept, threadless. Funny how different people come up with similar ideas right around the same time. Mine will be slightly different, hopefully I'll get it finished tomorrow.

Great looking pen.
Click to expand...

You suppose it's something in the water supply? Phase of the moon? Or just great minds.....:wink:
 
dgscott said:
Russianwolf said:
Doug, I was talking with Dawn on the phone on Tuesday or Wednesday and mentioned making a pen with almost the exact concept, threadless. Funny how different people come up with similar ideas right around the same time. Mine will be slightly different, hopefully I'll get it finished tomorrow.

Great looking pen.
Click to expand...

You suppose it's something in the water supply? Phase of the moon? Or just great minds.....:wink:
Click to expand...

have a look....

http://www.penturners.org/forum/f56/threadless-celluloid-96394/
 
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