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Author Topic: Duplicating Clear Parts - Part 1  (Read 366 times)

Offline MSgtUSAFRet

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Duplicating Clear Parts - Part 1
« on: March 07, 2017, 12:45:48 pm »
Fellow modelers,

Having some experience with duplicating parts, especially clear parts, I would like to share something of what I know in a step-by-step fashion.

A bit of background for those who may not know me. I spent 15 years as a Dental Laboratory Technician in the US Air Force. I got back into modeling approximately 2 years ago and noticed an uncanny parallel in the techniques and skills used to make and produce models and the production of dental prosthodontics.

While I was on active duty, I had to use basic materials to create everything that went into someone's mouth. I used a variety of techniques, three involving the use of acrylic, to make dentures, hard night guards and orthodontic retainers that would be helpful in my new hobby. To my limited knowledge of scale modeling, there are four techniques for making duplicate parts; maybe five.

1. The two-stage silicone mold making and resin pour method
2. Using Sculpy clay to make molds for parts
3. The two-stage plaster mold making and compression method
4. Paint brush build up
5. Sprinkle acrylic method.

Since I do not have a lot of experience with the first two methods, I will leave these to be covered by others. I will focus on techniques 3 thru 5.  This thread dealing with 5 "The Sprinkle acrylic method".

First a bit of learnin...the acrylic for this technique comes in two forms; a powder (polymer) and liquid (monomer). The polymer comes in a few different colors so be careful to pick up what you want. For the example below, I used clear nail powder. Be sure when buying your acrylic it is the "clear" as the powder and the containers for a variety of colors look very similar. Next, be sure to work in a WELL VENTILATED area; the monomer stinks! It will run everyone out of the room and maybe the house while you are working with it.

Best to use gloves as this stuff absorbs into your skin and, if used regularly, can do you some harm. So use Personal Protective Equipment (PPE).
 
You will need the following materials:
1.   Monomer (liquid)
2.   Polymer (powder)
3.   Liquid Squeeze bottle
4.   Squeeze bottle for powder
5.   Gloves
6.   Paper towels
7.   Clean large work surface

If you haven't done this before, please allow time, 30mins plus drying time, for your focused attention. These materials have a quick working time (1-2) minutes or less, so it will require some undistracted time.

I hinted at this process when I was building my NSEA Protector so I will re-use some pictures and augment where necessary.

I picked up the nail monomer and polymer at Sally's Beauty Supply. Here are some pics of the stuff I used:

The Clear nail acrylic...


The nail monomer or liquid...


Dispenser for the liquid...


And the dispenser for the powder.



1. You will need to make a mold. I used the stuff below. You can use whatever you want or with which you are familiar, but I would recommend using something every similar to this for the level of detail captured, the flexibility of the material and the release-ability of the material. I won't cover how to handle the material because there are tutorials online (and on the back of the box).  :P


 
2. A few pointers. When you are duplicating a part, one in which the underside will not be seen, make sure you duplicate the edges of the part as well. Take a look at the pic below. I tried to capture the border of the piece without trapping the piece in the mold. Back by the engine pods, you can see some tool marks where I had to "suggest/push" the material in place to capture the contours of the pod.

Third Dupe attempt by Steve Hartzell, on Flickr

3. Once the mold is set, gently twist/tease the master piece out. Check the mold for voids or defects.



4.  Using, for the lack of better term, a squirt bottle (something to control the amount of liquid you apply) and a shaker bottle (something to control the amount of powder you apply) (See pics above). I didn't use a mold release agent because 1) I didn't think it needed it and 2) I didn't want it to affect the set of the acrylic.

5. This is the actual application step. Taking the shaker bottle and gently tapping the bottle, much like you would carefully add salt to a steak, sprinkle a dusting of powder into the side of the mold; best to start in a small area and work around than try and cover the entire side at once. Gently tap the mold on the bench (we will do this a lot) to "settle" the powder. Then pick up the squirt bottle and carefully add the liquid to the powder. It is better to allow the liquid to flow into the powder and then allow the powder to wick the liquid into itself rather than to drop the liquid in the middle of the powder.  Gently tapping the mold will also assist the liquid to be absorbed by the powder.

PICTURES

As with painting layers of paint to get the coverage you need rather than one thick coat, layering with the powder and liquid will achieve the best results. Alternating powder, tapping, liquid, tapping, powder, tapping, liquid, tapping will maximize the density of the piece and minimize bubbles. If you see dry powder anywhere, try your best to get it wet. This entire process took me about 10 minutes to sprinkle so you kinda have to move quickly and steadily.

Occasionally, give a generous squirt of liquid all over the piece; you don't want it to dry out completely anywhere until you have finished adding acrylic to the piece. It should look like this, when you are done adding:


20170128_112211

Again, IT WILL STINK! Depending on the size of the piece, I would let it sit for a couple of hours or until cool to the touch. Another test for "done-ness" is to take a sharp object and scratch it. If it does little damage, it should be ready. If it makes a trough like warm butter, leave it a bit longer.

6. Then gently flex the mold and tease the duplicated piece out of the mold. You will have some flash to finish down, like you see in my pic, but more flash means you have something to finish. Weird, but it the "more is better" thinking.



And that's it! Until you get used to the technique, start out with something a bit smaller or less important. The Flux chillers, believe it or not, were more difficult for me to get an accurate dupe than was the Command module due to their smaller size and the amount of undercuts that were in the mold. But this technique is very forgiving and easy to use.

If you have any questions, or need help troubleshooting, let me know.

Also, let me know if I wasn't clear on something or you need more explanation! I love answering questions and comments!

LLAP!

Steve
« Last Edit: July 26, 2017, 07:35:59 am by MSgtUSAFRet »
"As long as there is injustice, whenever a Targathian baby cries out, wherever a distress signal sounds among the stars, we'll be there. This fine ship, this fine crew. Never give up... and never surrender."

Offline karve

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Re: Duplicating Clear Parts - Part 1
« Reply #1 on: March 12, 2017, 06:48:43 am »
Great post Steve...thanks so much for doing this!
  I don't know when, but at some point I may want to/need to do something like this and now I will have a reference.
  Thank  you! ;)
Kevin

"Look again at that dot. That's here. That's home. That's us."
    Quote from Carl Sagan's 'Pale Blue Dot'  1994

Offline Jimmypop57

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Re: Duplicating Clear Parts - Part 1
« Reply #2 on: March 12, 2017, 07:14:45 am »
Thanks Steve! This is good stuff, and thank you for documenting and explaining the process in such detail!
I play, I putty, I spray, and pray! Putty, sand, repeat...
All putty and no spray makes TOS models green and gray... All putty and no spray makes TOS models green and gray... All putty and no spray makes TOS models green and gray... All putty and no spray makes TOS models green and gray...

Offline Guns Akimbo

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Re: Duplicating Clear Parts - Part 1
« Reply #3 on: March 12, 2017, 12:18:49 pm »
Awesome post!

Offline AlW

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Re: Duplicating Clear Parts - Part 1
« Reply #4 on: March 13, 2017, 06:22:24 am »
Nice of you to write this up, Steve.  It'll definitely come in handy!

Offline MSgtUSAFRet

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Re: Duplicating Clear Parts - Part 1
« Reply #5 on: March 13, 2017, 07:09:37 am »
You are welcome, Guys! (and Ladies, too!)

I'm happy you liked the post. In thinking about this technique further, I had thought maybe I should make a video that better demonstrates the technique.

Till then, thanks for the positive feedback!

Steve
"As long as there is injustice, whenever a Targathian baby cries out, wherever a distress signal sounds among the stars, we'll be there. This fine ship, this fine crew. Never give up... and never surrender."

 




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