# Cap Thread Plastic



## soligen (Apr 16, 2011)

I have some black alumilite blanks that I've turned down to make threaded plastic inserts for kitless work. It works great, but i'm wodering if there is a more common (less expensive) alternative that threads just as well.  I want the part to be black, or at least a very dark grey. 

So, what else works well?  I imagine Delrin would work well, but I haven't seen it in anything but white.

I'm curious how well PVC would work for cap threads.  US Plastics has it in dark grey at an atractive price.  Has anyone tried it? 

I also am thinking I could use the material to make essentially tubes with integrated threads.

My requirements are:

Color is black or dark grey
Holds fine threads that are durable (cap threads)
Can be turned to a tube that has a very thin walls


Thanks


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## collectric (Apr 16, 2011)

*Black Acetal ... Delrin*

I use Delrin alot and get it from Enco. Usually can find a free shipping code.
www.use-enco.com

Tom


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## chrisk (Apr 16, 2011)

Last summer I bought Acetal (Delrin) in black and white rods.


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## KenV (Apr 16, 2011)

Dennis -- Have not used PVC for threads on pens, but it its the "go to" practice and inset materials for thread chasing on the lathe.  It will cut and hold good threads in that envrionment and should work with either a die or metal cutting lathe with appropriate lubrication to prevent galling.


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## soligen (Apr 16, 2011)

I didnt know Acetal was the same as Delrin. Now I have a plan  Thanks


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## Texatdurango (Apr 16, 2011)

Perhaps I don't understand what you are doing but if you are going "kitless" why not just thread whatever material your cap is?  I have made caps from ebonite, acrylic, truestone and alumilite and all threaded just fine.

I don't see the need for a threaded sleeve, what am I misisng?


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## soligen (Apr 16, 2011)

Texatdurango said:


> Perhaps I don't understand what you are doing but if you are going "kitless" why not just thread whatever material your cap is? I have made caps from ebonite, acrylic, truestone and alumilite and all threaded just fine.
> 
> I don't see the need for a threaded sleeve, what am I misisng?


 
Kitless wood pen, or a blank that is not opaque enough that the threads won't show through without a painted tube. I also like to make pens from my home cast PR blanks, but I dont trust PR is strong enough by itself for a cap.


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## KenV (Apr 16, 2011)

Dennis -- this is a "tool opportunity".   You should be able to thread the PR blanks if you use a CNC mill with a thread mill.   The incremental cuts are so small that it will not stress the resin blanks --  and with the programming, you can get multiple start threads.

Only take $3500 or so to get one of the micro CNC mills up an running with a 4th axis.  ''

(Been there and looking at those but cash flow keeps getting in the way and the programming will take a few hours.....).


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## Texatdurango (Apr 16, 2011)

soligen said:


> Texatdurango said:
> 
> 
> > Perhaps I don't understand what you are doing but if you are going "kitless" why not just thread whatever material your cap is? I have made caps from ebonite, acrylic, truestone and alumilite and all threaded just fine.
> ...


 
I suspected you might be using wood blanks, may I share some experiences that might save you some troubles.

A while back I tried using Acetal (Delrin) for threaded sleeves in my caps.  They thread like a dream and you can make some really nice looking threaded inserts.  I used my metal lathe and made some sleeves that fit really snug in my blanks.  Where I experienced my problems was when I tried adhering the inserts in the blanks.  Every adhesive I tried failed sooner or later as nothing wanted to stick to the acetal.  I tried cutting grooves in the sleeves, scuffing up up the smooth surface, but nothing worked so I soon abandoned the use of acetal and went back to alumilite.

I would be interested in hearing of your successes.  Here was a good source for me...... http://www.usplastic.com/catalog/item.aspx?itemid=23672&catid=439


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## soligen (Apr 16, 2011)

George,


Thanks for sharing your experience.  I guess I'll scratch delrin off my list.


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## Dan_F (Apr 16, 2011)

I talked to Ed at Exotic blanks some time ago, he didn't think it was a good idea to thread their PR blanks, as he didn't have much confidence that they would hold up over time. I have heard as well that Truestone threads break down over time. I have no personal experience with either, and suspect that longevity may depend on style of threads, how threads were cut, and the ingredients of the individual blank. I have threaded garden variety acrylic blanks with good results. All of my threading has been with tap or die, none with a metal lathe. 

George---Have the Truestones you've threaded seen a lot of use?

Dan


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## Texatdurango (Apr 16, 2011)

soligen said:


> George,
> 
> 
> Thanks for sharing your experience. I guess I'll scratch delrin off my list.


 
Please don't give up with your idea just because I couldn't get anything to work, I just wanted to share where I had my difficulties.  Acetal is a nice material for making threads and is very similar if not identical to what is used in kits.  The problem is getting the parts to stay put without using the traditional kit parts compressing together.  You might just come up with a clever way of making it work.

*Dan,*
Most of the truestone pens I made are sold and I have no feedback.  The ones I still have are for sale so spend their lives in pen cases.  None of my daily users are truestone.


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## KenV (Apr 16, 2011)

Has any one tried this glue --  It was recommended to me but I have not gotten my hand on any yet --  

Claimed to glue delrin and UHMD Polyethelene and others.   The recommender advised he has yet to have a glue joint fail.  Interesting some of the applications -- and it is a bit expensive, but may be well worth it.

http://tech-bond.net/


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## Texatdurango (Apr 16, 2011)

KenV said:


> Has any one tried this glue -- It was recommended to me but I have not gotten my hand on any yet --
> 
> Claimed to glue delrin and UHMD Polyethelene and others. The recommender advised he has yet to have a glue joint fail. Interesting some of the applications -- and it is a bit expensive, but may be well worth it.
> 
> http://tech-bond.net/


 
Interesting find Ken, I'm going to order some and see how it works.

*Dennis*, This might be your answer!


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## KenV (Apr 16, 2011)

George --  I have some on order -- but as long as it takes to get to Alaska - you will have it before I get mine off the slow boat.


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## leestoresund (Apr 17, 2011)

But will it work as good as CA for a finish? LOL

Looks promising.

Lee


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## PenMan1 (Apr 17, 2011)

George:
I am going to try 3M marine sealant 5200. It is formulated to hold wood, plastic rings and even silicone boat parts to fiberglass boat hulls.

It should work to secure Delrin into PR or wood. I'll know it a few days. 5200 has solved many similar boat issues in the past. 5200 dries hard but remains somewhat flexible.


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## workinforwood (Apr 17, 2011)

If I was gluing in Delrin sleeves, I would grab a rotary tool and make a few shallow L shaped grooves in the outside of the delrin. I'd do that with any sleeve really. The glue gets trapped in there, giving a stronger bond...it's like a locking point.

A cnc sure would be awesome. You can not just thread anything, but you can invent your own threads. I found a used Haas super mini with 4 axis on ebay, and it was only at $2500 ..so I bid $9000 and wouldn't you know I was outbid in 10 minutes. Darn things are expensive, but if I'm going to go in, I'm going in big! You just never know what you might need to do down the road. I'm just biding my time and saving my money till the right machine comes along that I have the cash to cover.


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## monark88 (Apr 17, 2011)

I have a delrin rod, about 1 1/2 x 16". Yours if you want to pay shipping from Oregon.
Russ


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