# Material for practicing threading



## Texatdurango (Mar 23, 2010)

So you're starting down the road of "kitless" pens and are starting to do you own threading now. One problem is that you have to practice and experiment then experiment some more then once you are happy with a particular diameter, you decide to make the body a bit wider so you have to try different threads which means more experimenting!

Over the past few years I can't remember how many $3 - $4 blanks I ruined because I used them to experiment with! This was until I realized there is a better alternative! 

I started using clear acrylic rods which, compared to acrylic pen blanks, are dirt cheap AND you can order a 6' rod and saw off a few inches to experiment with instead of wasting a 5" pen blank. This really came to be a cost savings when I started cutting threads on my metal lathe, I was going through lots of acrylic trying out different threads, pitches and blank diameters. Now I make all my mock up pens from clear acrylic before using colored material. Not only do you save money, you can see what's going on inside your pens with your threading and drilling!

I'm placing another order today for supplies and thought about sharing this little tidbit since some of you might want to save some money yourselves.

This stuff doesn't warrant a group buy since it's so cheap and the quantity discounts don't amount to much. Here is the deal.....

United States Plastic Corp, http://www.usplastic.com/ sells clear acrylic rod in different diameters but are all in 6' length rods but a 1/2" dia rod is only $.51 a foot and the 5/8" dia is $.80 per foot. That's a LOT cheaper than $3 or $4 for 5"!

Drilling and tapping this material is just like using a typical acrylic pen blank and you can even make some nice clear "demo" pens or pens with ink windows!

*Edit:* As mentioned below, I use the *extruded* rod, see post #5 for the reason.


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## glycerine (Mar 23, 2010)

Thanks for the info!!  Do you know what the difference is between the cast acrylic rods and the extruded acrylic rods.


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## workinforwood (Mar 23, 2010)

I Do, I DO !  Cast acrylic rods are cast, where as extruded acrylic rods are extruded. :smile-big:


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## Russianwolf (Mar 23, 2010)

workinforwood said:


> I Do, I DO !  Cast acrylic rods are cast, where as extruded acrylic rods are extruded. :smile-big:



smacks Jeff in the back of the head.

That's for being a smart aleck........... that's my turf.:tongue:


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## Texatdurango (Mar 23, 2010)

glycerine said:


> Thanks for the info!! Do you know what the difference is between the cast acrylic rods and the extruded acrylic rods.


 
Cast rods are about 5x the cost of extruded.  They are supposed to excel in clarity, machining and glueing but when I placed my first order, I ordered some rods of each type and for my needs, the extruded are working just fine.

I have cut, threaded, drilled and reamed both and can't tell the difference so I choose to use the extruded.

Placing a cast rod beside an extruded rod and holding them to the light you have to have better eyes than mine with these bi-focals to tell which is which!


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## Jim15 (Mar 23, 2010)

Thank you George.


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## Sylvanite (Mar 23, 2010)

glycerine said:


> ...what the difference is between the cast acrylic rods and the extruded acrylic rods.


Cast acrylic has better clarity than extruded, but you have to get a pretty thick piece to really see much difference.  They also engrave differently.  Extruded acrylic engraves mostly clear whereas cast acrylic engraves frosty white.  If you're using the rod to experiment with threading, get the cheaper extruded acrylic.

Regards,
Eric


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## bitshird (Mar 23, 2010)

glycerine said:


> Thanks for the info!!  Do you know what the difference is between the cast acrylic rods and the extruded acrylic rods.



The cost??
sorry just had to come up with a smart A$$ comment and the good one was taken

George that sounds like a much better way to figure threading out. Thanks for the suggestion.


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## mbroberg (Mar 23, 2010)

Thank you George.  I've been practicing on blanks I picked up on sale, put not as cheap as what you use.  Thanks for sharing!!


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## bgibb42 (Mar 23, 2010)

Wow, they've got some cool stuff.  This thread came along at a great time.  I've been learning to make my own threads recently, but had to quit for awhile because I don't like wasting expensive material.  

Of course, I could slap myself for not thinking of looking for a cheap alternative on my own...sigh.:redface:


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## Texatdurango (Mar 23, 2010)

bgibb42 said:


> Wow, they've got some cool stuff. This thread came along at a great time. I've been learning to make my own threads recently, but had to quit for awhile because I don't like wasting expensive material.
> 
> *Of course, I could slap myself* for not thinking of looking for a cheap alternative on my own...sigh.:redface:


 
That's why there are members like me, we're glad to slap you around!:biggrin:

The timing of this little tidbit is right as I noticed Skip has a nice tutorial going on showing the ins and outs of threading and I can just see perfectly good pen blanks being tossed in trash cans left and right across the country as folks practice threading!


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## RichW (Mar 23, 2010)

The extruded rod is slightly softer and more plastic than the cast. The biggest difference is that extruded rod has a significantly lower melting point. When turning, extruded rod will sometimes melt right at the cutting tool resulting in waste that collects in little piles on the tool instead of flying off in threads. I think the finish that can be achieved on cast acrylic is superior to extruded, but at the same time, the harder cast rod is more likely to chatter and pit if you get too aggressive with the cutting tool.

For practice cutting threads, none of these factors really matter. At low speeds (like cutting and tapping), the materials behave essentially the same so why not save the money? Just drill slowly and at lower speed than you normally would. If you drill too fast or put too much pressure on the bit, you WILL get melting. This not only affects the waste, the softening and re-hardening of the walls of the hole affects how the material will take an internal thread.  It will get brittle and tend to chip and flake. 

When it comes time to make a finished product, I think I would switch to a cast material.


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## cnirenberg (Mar 23, 2010)

George,
Wow this post did come along at the right time.  I just ran out of the "practice" alumilite casts I made, which I was using to thread.  I haven't gotten so far as to cut them myself on the metal lathe just using the die holder.  I did pick up some Delrin to use for threading and bushings, but I like the extruded clear idea much better for practice, cheaper too.  Once again, you're the Man. Thanks.


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## btboone (Mar 23, 2010)

I do the same when I try out new threads.  I get my acrylic rod from MSC.


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## Manny (Mar 23, 2010)

Plus you can dissolve the mess ups in acetone and stabilize your blanks with it!
Manny


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## RAdams (Mar 23, 2010)

How does this material compare to PR and alumilite? One of the issues I am having as a rookie thread cutter, Is that if i change materials, the characteristics all chage as well, so practicing on one material and then switching to another seems almost pointless. 

I understand practicing the sizes, and diameters and what have you, but if PR and alumilite are different in workability characteristics than this rod, then wouldnt practicing in a different material be futile?


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## j.d.sackett (Mar 25, 2010)

i dont think so. when i was learning to cut threads i used pvc pipe. cheap and if you screw up your not out much. when i was comfortable with cutting pvc i went to metal and cut them just fine. i think even though the material is different, if you can cut threads, you can cut threads. just watch the cut and pay attention to what its doing and work from there. just my .02 and worth what you paid for it. regards, j.d.


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## frankhp (Mar 25, 2010)

Great tip George. Just placed an order and you are correct-again. That stuff is cheap.


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## Texatdurango (Mar 25, 2010)

j.d.sackett said:


> i dont think so. when i was learning to cut threads i used pvc pipe. cheap and if you screw up your not out much. when i was comfortable with cutting pvc i went to metal and cut them just fine. i think even though the material is different, if you can cut threads, you can cut threads. just watch the cut and pay attention to what its doing and work from there. just my .02 and worth what you paid for it. regards, j.d.


 
Jeff, Good point about practicing on pvc pipe, I went through some of that as well but sometimes I have trouble conveying my thoughts and I think I stressed the term "Practicing" too much, please allow me to elaborate my thoughts.

We are now diving into the world of custom pens and no longer have to rely on size constraints such as brass tube lengths and diameters, kit component diameters, etc and have the freedom to make any size pen we want.  There is a lot more to making a nice "kitless" pen than just grabbing a tap and die and cutting a few threads.  There is a lot of trial and error (and waste), at least for me there is and that is why I suggested the clear acrylic.   I used to use lots of delrin rod until I realized it was several times the cost of clear acrylic. 

When I have an idea in my head about making a new pen design, first I doodle the pen design on paper then go through what measurements I_* think*_ I want to use.  When satisfied with what I _*think*_ will work well, I grab a piece of clear acrylic, turn it to size, drill and thread it, both cap, finial, nib section, and inner and outer threads of the bottom.  If all works well, I end up with a clear acrylic pen "demo pen" but sadly it's usually not on the first try or even the first few tries.  I have more clear "shop pens" floating around my shop these days!  

Once I finally have a pen that I like the shape and look and everything threads together just fine and I was successful at jotting down all the final dimensions and thread info, THEN I will make one out of the good stuff.

Trying different ideas, I go through a lot more clear than nice acrylic blanks, ebonite or truestone, etc.


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## RAdams (Mar 25, 2010)

LOL....


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## j.d.sackett (Mar 26, 2010)

points taken and agreed with george. i do pens in metal because i have worked with metal my entire working life. i practice on cheap sticks of aluminum. once the bugs are worked out i do them in brass, copper, etc. you have no idea how many shop pens and small diameter scrap i have spent hours creating, lol. regards, j.d.


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## Kaspar (Mar 27, 2010)

Anyone ever use this?


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## KDM (Mar 29, 2010)

workinforwood said:


> Cast acrylic rods are cast, where as extruded acrylic rods are extruded. :smile-big:



Wait... No... That can't be right?


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## barkisini (Mar 29, 2010)

Thank you, George!

I appreciate your sharing this!


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