# Threading Silmar or Alumalite



## Simplex (Jun 29, 2011)

Has anyone tried tapping or running a die over Silmar or Alumalite?  I was wondering if they will hold a durable thread.  The acrylic blanks I get from Woodcraft thread pretty well but since I don't have direct experience with Silmar or Alumalite I'm not sure if they hold up equally well.  Thanks!


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## Manny (Jun 29, 2011)

Both thread well. Alumilite getting the nod because it is slightly softer. search in the advanced pen making and SOYP forums for the kitless designs. Many use both of these materials

Manny


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## Texatdurango (Jun 29, 2011)

Manny said:


> Both thread well. Alumilite getting the nod because it is slightly softer. search in the advanced pen making and SOYP forums for the kitless designs. Many use both of these materials
> 
> Manny


Totally agree, Alumilite threads easy AND the threads hold up very well.  I use pens I threaded two years ago and the threads look and feel as if they were made yesterday!  Can't speak to polyester resin since I have no desire or need for it.


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## Manny (Jun 29, 2011)

One more thing be sure to use a lubricant when threading to make nice clean threads. Many use Pam or Canola


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## cnirenberg (Jun 29, 2011)

Gary,
I've threaded Alumilite and love the way the way it machines.  I haven't worked with Silmar specifically so I can't say.


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## MesquiteMan (Jun 29, 2011)

Manny said:


> Both thread well. Alumilite getting the nod because it is slightly softer. search in the advanced pen making and SOYP forums for the kitless designs. Many use both of these materials
> 
> Manny



Actually, Alumilite is NOT softer than PR.  This is a common misconception.  It is less brittle which makes it possibly feel softer when working with it.  Alumilite Clear has a shore D hardness of 80 while PR is 78-80.  The big difference is in the % of elongation.  Alumilite Clear has an elongation % of 8% while PR is something like .3%.  In other words, Alumilite will flex and give more without breaking.


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## IPD_Mr (Jun 29, 2011)

MesquiteMan said:


> Alumilite Clear has a shore D hardness of 80 while PR is 78-80. The big difference is in the % of elongation. Alumilite Clear has an elongation % of 8% while PR is something like .3%.


 
This is funny to me.  10,000+ members and I bet you could count on one hand the number of people that knows what this means in a practical application.  Thanks Curtis you made me smile.  :smile-big:


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## Texatdurango (Jun 29, 2011)

If I were deciding on whether to buy polyester resin or Alumilite blanks with threading being a concern, another thing that would weigh heavily into the decision is brittleness.

Having used polyester resin on and off for 40 years I know what one or two drops too many of catalyst can do to a small pen mold size batch.  A brittle blank means a blank which is not too "thread friendly" and quite a few home made blanks I have received from members, while turning and polishing nicely, will fall into that category.


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## Manny (Jun 29, 2011)

MesquiteMan said:


> Manny said:
> 
> 
> > Both thread well. Alumilite getting the nod because it is slightly softer. search in the advanced pen making and SOYP forums for the kitless designs. Many use both of these materials
> ...




Wow good to know I stand corrected. I always assumed brittle = hardness but I see that is not correct. Thank you. 

threading brittle materials is very difficult.


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## TomW (Jun 29, 2011)

You should'a seen Seamus' face when I did the "alumilite is not brittle and won't break" demo at N. Texas Chapter meeting.....priceless.....

Tom


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## MesquiteMan (Jun 29, 2011)

MesquiteMan said:


> *In other words, Alumilite will flex and give more without breaking.*





IPD_Mr said:


> This is funny to me.  10,000+ members and I bet you could count on one hand the number of people that knows what this means in a practical application.  Thanks Curtis you made me smile.  :smile-big:



Not sure what is funny about it.  I gave the technical information and then presented it in practical terms.


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## Texatdurango (Jun 29, 2011)

MesquiteMan said:


> MesquiteMan said:
> 
> 
> > *In other words, Alumilite will flex and give more without breaking.*
> ...


 
It was your presentation and timing!  Some got it.... some don't :biggrin:


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## MesquiteMan (Jun 29, 2011)

Texatdurango said:


> MesquiteMan said:
> 
> 
> > MesquiteMan said:
> ...



I guess I don't get it!  Must by an inside joke of some kind!


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## IPD_Mr (Jun 29, 2011)

Curtis - If you leave of just this last line 
_*In other words, Alumilite will flex and give more without breaking.*_
It is just rather very technical for the common person to grasp.  To me it was kind of like asking the difference between 2% and whole milk and getting a technical breakdown of the chemical composition of each and not having a clue what it means.

Didn't mean to foul your Cherios today. :frown:


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## MesquiteMan (Jun 29, 2011)

IPD_Mr said:


> Didn't mean to foul your Cherios today. :frown:



Mike,

You did not foul my Cherios, my friend.  I did not mean for my reply to come across that way or that I was offended in any way.  I was not at all.  I was just curious as to what was funny, that's all, nothing more!  That's the problem with the internet, things written can be taken a number of different ways.

I am certainly guilty of being just a little bit technical on most things I do!  I guess it is a character flaw but I like to know how everything works and the technical details and specifications of things.  Rather than just say it was less brittle, and just as hard, I tried to back that up with the technical details to show I was not just pulling stuff out of my butt!


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## Simplex (Jun 30, 2011)

Thanks for all the responses (and the humorous back-and-forth between Indy & and Mesquite).  Based on what I am hearing, it looks like the Alumilite is the way to go for what I am doing.  Thanks again!


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## PenMan1 (Jun 30, 2011)

Simplex said:


> Thanks for all the responses (and the humorous back-and-forth between Indy & and Mesquite).  Based on what I am hearing, it looks like the Alumilite is the way to go for what I am doing.  Thanks again!



Well... Maybe yes, maybe no. Alumalite IS easier to thread, although PR threads just fine with a little patience. One advantage that PR has over Aluma is the depth of gloss that can be achieved. 

The only way that I can get Alumalite to shine like PR is to put CA over it. Using CA over threaded pieces requires another skill set that I don't currently pocess.

While Trying to make a gloss black "kitless" pen recently, I experience this issue. The Alumalite was easier to machine, but the "gloss" factor I was after just was not acceptable. Finally I went back to PR and just took my time threading.

I suspect that this will be different in every shop, as everyone has their own favorite materials.

Respectfully submitted.


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## Simplex (Jun 30, 2011)

That is good information.  Just out of curiosity, did you try taking it (Alumilite) to a buffing wheel?


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