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PostPosted: Tue May 30, 2017 11:50 pm 
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Joined: Thu Jan 17, 2008 4:40 am
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Location: Canberra, Australia
http://i.imgur.com/zkrzFp0.jpg

In answer to Martin's post concerning 3D parts and paints on the main board, here are some pictures of Shapeways 3D printed FUD parts that have been finished in enamel paints after using the 'UV post-cure' method that has been described by PatMat (and to whom the credit should go). They are in 1/144 scale and are being used on Revell's Fletcher. This is not a review of the parts used, just a description of how they were painted.

The equipment for doing this is very simple, just a UV bulb: http://i.imgur.com/fIQWQ5b.jpg

and desk lamp placed into a cardboard box: http://i.imgur.com/VqrD0Dr.jpg

The cardboard box doesn't add to the curing process at all, it just allows you to avoid personal exposure to UV light.

I started by cleaning the parts to remove wax and oil residue, then placed the parts in the box, turned on the light, and left them there for about six hours. I turned the parts over occasionally, to ensure every surface was directly exposed to the UV, this was probably unnecessary as the parts are pretty near transparent anyway.

I did some surface finishing work on the gun mounts by sanding and using an air eraser (none at all on the smaller parts), and added etch and made gun mantlet canvas bags from Vallejo Acrylic putty. I used Aber turned barrels as well. I only mention this to indicate that the mounts have had some work done on them, but I don't think anything that would impact one way or another on the paints used or the chemistry of the plastic.

The first coat of paint was Mr Surfacer 1500 Black, to match the paint modulation technique I am using on the rest of the model: http://i.imgur.com/zkrzFp0.jpg

Followed by Colourcoats 5-N Navy Blue, a little 5-S Sea Blue to fade and highlight, and 20-B Deck Blue for the turret roofs. All paints dried as normal, completely flat, using a regular enamel thinner. Colourcoats do take a little more time to become completely tack free than some other enamels, but the paint on the 3D parts behaved exactly the same as the paint used on other parts of the model.

http://i.imgur.com/1MfyusT.jpg
http://i.imgur.com/niXbQ6j.jpg

The sheen you can see on the smaller parts is AK Gauzy intermediate shine enhancer, an acrylic gloss used as an overall barrier coat before oil -based filters and drybrushing.
http://i.imgur.com/Pq4oCRn.jpg
http://i.imgur.com/IC7x45h.jpg
http://i.imgur.com/IC7x45h.jpg

Most Shapeways parts have little sprues or blocks to support them during the printing process; it's easy enough to test your results on these before committing to expensive parts. I am very pleased with the results and will do the same for any further 3D parts that I buy. So, lacquer, enamel, acrylic and oil paints, all cohabiting happily together on 3D printed parts.

cheers

Steve


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PostPosted: Wed May 31, 2017 7:35 am 
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:big_grin: :big_grin: :big_grin:

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Catalog: https://modelmonkey.wixsite.com/modelmonkey

On the ways:
1/350 USS Saratoga CV-3 ('44)
1/350 USS Yorktown CV-10 ('45)
1/192 USS Missouri BB-63 ('45)
1/350 HMS Duke of York ('45)


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PostPosted: Wed May 31, 2017 12:03 pm 
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Location: In the hills of North Jersey
This is excellent, and very much appreciated. Thank you!

PS - your Fletcher looks awesome!

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"Tomorrow is the most important thing in life. Comes into us at midnight very clean. It's perfect when it arrives and it puts itself in our hands. It hopes we've learned something from yesterday." John Wayne

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PostPosted: Wed May 31, 2017 1:48 pm 
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Location: San Tan Valley Arizona
It all works well as long as you don't use MEK for a thinner. It will be interesting to see these results in 6 months. That's about how long it took for my stuff to crystalize using MEK as a thinner with Tamiya Acrylics. Hopefully, yours won't as you went through a lot of trouble to ensure a seamless finish and paint adhesion.
Thanks for sending this along, good tips.

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PostPosted: Wed May 31, 2017 5:17 pm 
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Location: Canberra, Australia
Mark

No MEK used.

Martin

I will post a separate WIP thread on building the Fletcher. Things have progressed a bit since that photo was taken and I have photos of various stages of construction and painting.

Steve


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PostPosted: Tue Jul 04, 2017 2:09 pm 
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Location: Wallburg, NC
Steve,

Thanks for this very important tidbit of painting info. I have just received my FLETCHER kit (from MGunns) and am getting the planning in place for a future 1960s era build. To be able to use enamels on the Model Monkey or other Shapeways 3D parts is great news!! I have some M_M 3D parts on my current build that still need painting - so, why not go for the enamel???

Now to look for a UV bulb!!!

Hank

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Builder's yard:
USS NEW JERSEY (BB-62) 67-69 1:200
USS PENNSYLVANIA (BB-38) Late 1940 1:200
USS STODDARD (DD-566) 66-68 1:144
Finished:
USN Sloop/Ship PEACOCK (1813) 1:48
ROYAL CAROLINE (1748) 1:47
AVS (1768) 1:48


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PostPosted: Tue Jul 04, 2017 3:08 pm 
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Location: Phoenix, AZ
I sprayed a Shapeways ship hull (printed in FUD) with Mr Surfacer out a a rattle can last week and it went on and set just fine.

Prior to painting, I set the part outside in the AZ sun for an hour to ensure the material cured fully. Did a great job melting excess wax on some other parts as well.

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PostPosted: Tue Jul 04, 2017 6:03 pm 
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Location: Yorktown, Indiana, USA
I have also used Mr. Surfacer thinned with lacquer thinner on printed parts with no ill effects. Prepped with UV on the windowsill for a couple weeks first, then scrubbed with a toothbrush & dish soap and rinsed with a diluted vinegar solution.


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PostPosted: Fri Jul 21, 2017 1:44 pm 
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Joined: Sat Feb 28, 2015 9:09 am
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Location: Aberdeenshire, Scotland, UK
I finally got round to trying this myself.

My Model Monkey 1/200 HMS Hood funnel was printed in the cheaper stuff on the basis that it will be wrapped with the Pontos PE anyway. It has stood on a windowsill for two very dull, rainy days, washed with washing up liquid and hot water, dried and painted 1 hour ago.

I used a half-used old tin of RN02 which came to hand. This was thinned 50/50 as I always do with Colourcoats thinners. I do not (and have never) recommended the use of MEK as a thinner and do not take any responsibility for the performance of the paint when thinned with anything at all other than Colourcoats thinners. I can't control what diverse liquids end users pour in with Colourcoats to thin it, so I can't possibly test the paint for all possibly concoctions that end users see fit to try. Cellulose thinners work ok with Colourcoats but are too hot for some plastics. I personally avoid household white spirits for thinning enamels due to excess smell and long drying times. Colourcoats Thinner is a proprietary enamel thinner designed specifically for the enamel base we use in Colourcoats and it gives a very good combination of adhesion, good drying times and minimises odour.

It's dried on the funnel already.

Clean the 3D printed parts with detergent, expose it to UV light for a couple of days, mix the paint properly in the tin (all of the complaints we've ever had have been traced to inadequate mixing before use) use the correct thinner for the paint and job's a good'un.

Don't know what all the fuss was about :)

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Sovereign Hobbies Ltd
http://www.sovereignhobbies.co.uk


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PostPosted: Mon Jul 24, 2017 9:50 am 
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Thank you, Steve, Mark, Scott and great news, Jamie!

I have changed the product preparation advice found on the cover page of my catalog to reflect Jamie's experience with Colourcoats on his Hood funnel.

Modelers who prefer enamels: the Sun is your friend.

Thanks also to Pat Matthews for his sage advice.

Although many of us have been modeling for decades with polystyrene plastic or other resin plastics, please be aware that 3D-printed acrylic plastic behaves differently than polystyrene. Our past modeling experience may actually be working against us when it comes to this new technology.

1. Leave your parts in the bag, uncleaned, until you are ready use them on your model.
2. Please be sure to clean your parts only with a mild, water-based detergent like "Dawn", "Fairy" or "Simple Green" in water. Let them soak for a while.
3. Give your parts a good dose of UV light (more is better).*
4. Paint soon after cleaning with appropriate primer, paints and thinners following the manufacturer's guidance.

Do not use any paints, primers or thinners containing acetone, acetate of methyl ethyl ketone. Those products are known to attack acrylic plastic or leave a nasty residue spoiling the paint. Cleaning with acetone can leave your new part looking more like cauliflower than a turret.

Welcome to the New World.


A bit more advice: if you receive a warped 3D-printed part from Shapeways, that likely means there is liquid resin present in your part, which permitted the part to bend during packaging and/or shipping. Fully cured acrylic plastic does not bend, it breaks. To cure the warp, fix the product to a flat surface or otherwise set it to the position you want it to be in and expose it to a lot of UV light. It will cure in the position you set. No need to apply any heat, just a good dose of sunlight.


* The reason UV light works has to do with the liquid resin used in the 3D printer. Liquid resin naturally seeks to quickly harden but solid resin can't be extruded by the 3D printer. A chemical inhibitor is added to the liquid resin to keep it in a liquid state so the resin can pass through the printer. UV light breaks down the inhibitor, permitting the resin to naturally harden. Heat does not cure 3D-printed acrylic resin. Only UV light does.

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Have fun, Monkey around.

-Steve Larsen
Catalog: https://modelmonkey.wixsite.com/modelmonkey

On the ways:
1/350 USS Saratoga CV-3 ('44)
1/350 USS Yorktown CV-10 ('45)
1/192 USS Missouri BB-63 ('45)
1/350 HMS Duke of York ('45)


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PostPosted: Mon Jul 24, 2017 3:55 pm 
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"* The reason UV light works has to do with the liquid resin used in the 3D printer. Liquid resin naturally seeks to quickly harden but solid resin can't be extruded by the 3D printer. A chemical inhibitor is added to the liquid resin to keep it in a liquid state so the resin can pass through the printer. UV light breaks down the inhibitor, permitting the resin to naturally harden. Heat does not cure 3D-printed acrylic resin. Only UV light does."

Are you sure ? As far as I knew, pulses of UV-light are used to selectively induce the polymerisation at the wanted places within a tank of liquid monomere. But Shapeways may indeed use a different process.

Depending on the size of the part, you may considering a small hend-held UV-LED, as used to cure acrylic cements, or one of those cheap UV-hardening stations as used in 'nail-art' (using the word 'art' in this context makes me shudder ...) studios for post-processing printed parts.

I have been working a lot with acrylic resin, Plexiglas or Perspex, and in general no priming is needed, when you use acrylic emulsion paints. Due to their physico-chemical characteristics they stick well to the solid resin, if the surface is carefully degreased. Other, organic solvent-based paints can be problematic, as some of the solvents would be also solvents for the acrylic resin, as you pointed out above. There are datasheets on the compatibility of acrylic resins with different types of organic solvents.

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PostPosted: Mon Jul 24, 2017 5:41 pm 
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The important thing for customers to know is that it is UV light that makes FUD and FXD parts solid, not heat or exposure to a chemical. Ensuring the parts are fully UV-cured is critical to use of enamel paints.

We may be describing the same process, perhaps me poorly. Here's how Shapeways describes their process, slightly differently than how I described it: "This material [FUD/FXD] is printed using the Multijet Modeling (MJM) process. Molten plastic is deposited onto an aluminum build platform in layers using several nozzles, essentially like a large print that sweeps across the build layer. As the heated material jets onto the build plate, it solidifies instantly. After each layer is deposited, it is cured, or polymerized, by a wide area UV lamp. The next layer then applied, and through this repeated process layers of thermoplastic build up into a model. When printing is finished, we remove the models from the tray and put them into an oven that melts away the wax support material. Next, we put the models into an a ultrasonic oil bath to remove any remaining wax residues, and then a ultrasonic water bath to remove any oil on the model. Finally, we inspect the models and dry them by hand."

The wax is needed to act as a "mini-platter", supporting overhanging features until they can be cured by UV light. Here's a drawing showing how the wax (in yellow) supports a model during printing. Note that any area in contact with the wax will have a rougher surface that may require some smoothing by the modeler (an air eraser works well for this, especially for larger surfaces).

Attachment:
fud-support-visualization.jpg
fud-support-visualization.jpg [ 7.49 KiB | Viewed 566 times ]


You can see a cool video of how it is done at the bottom of this page: https://www.shapeways.com/materials/fro ... il-plastic

Great points about using hand-held UV lights and acrylic paints! Thanks!

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Have fun, Monkey around.

-Steve Larsen
Catalog: https://modelmonkey.wixsite.com/modelmonkey

On the ways:
1/350 USS Saratoga CV-3 ('44)
1/350 USS Yorktown CV-10 ('45)
1/192 USS Missouri BB-63 ('45)
1/350 HMS Duke of York ('45)


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PostPosted: Tue Jul 25, 2017 2:45 am 
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OK, they use a different process from what I thought. So their process actually does involve an extruder, but as acrylics are not thermo-setting plastics, they use UV-light to induce polymerisation. This is essentially the same process, albeit at a smaller scale, as the one that is used to produce industrially extruded Plexiglas/Perspex sheets, rods, etc.

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