3D Printed SJA Emblem

[Bob's your Uncle]

Hi Everyone,

I just want to show-off the newest accessory for my TARDIS. http://tardisbuilders.com/index.php?topic=6434.0

A 3D printed St. John Ambulance sign.

 

 

A friend from work bought a 3D Printer a few months ago and has been creating some very cool stuff, so I begged him for a SJA sign.
The first attempt turned out to be a little too small. I told him that my friends on tardisbuilders.com would notice if he didn't fix it, so he made a new one, full size.
I just need to trim off the square part.

As a bonus, he also printed this small TARDIS mug using food-safe plastic.

 

But, back to the SJA sign.
I don't know very much about 3D printing, so I'm hoping some of you can help answer some questions.

At first my plan was going to be to fill the recessed areas with white paint. I figure that I can easily do this by slopping paint in the low spots, then after it dries, lightly sand the high spots to remove any remaining paint. I will definitely practice on the small one first.

Now, I do know that 3D plastic will not hold up very well on an outdoor TARDIS. So I started thinking that maybe I could use this 3D printed version as a mold to make a copy (or multiple copies) out of something more durable, similar to what Matt Sanders did with the Crich Police Box windows.

So, my questions are....
Will either of these plans work?
What kind of paint works best?
What mold materials would work with this type of plastic?
What should the finished sign be made out of?
Should I abandon plastic all together and save up for a metal etched sign? (This one only cost me a Starbucks gift certificate).

Any advice and opinions will be welcomed.
Thanks.
Greg.

[galacticprobe]

Well, making a mould would be a good idea anyway so you can cast replacements as needed. I don't know that 3D plastics aren't great for outdoor things, but I would think if you coated it quite well in a clear varnish (non-yellowing kind), and then gave it a light rub with something like Rain-X or a car wax, the weather would just bead up and run off.

For making the mould, silicone is the material of choice among most model-builders. It's flexible so it makes it easier to remove the master plug, or any castings. It's also somewhat self-releasing because it's a slippery thing. That said, most model-builders I know still give their moulds a quick shot of cooking spray (it works just as well as the expensive "Mould Release" some stores sell). Also, I would put a clear coat on the 3D printed one you've got before pouring silicone over it. You'll want to seal that porous material beforehand to avoid the silicone seeping into the pores and making it impossible to get off cleanly, which would ruin the mould as well as your master "plug".

Casting material? Resin, obviously, and it does come in different colors. You could cast it in white and then paint the tops of the letters black. Or cast it in black and fill the hollows with white paint. If you want to really authentic (and hb88banzai can correct me if I'm wrong... even though we are talking about a resin casting rather than the actual ceramic and metal used on the early originals), you could cast it in black resin, and once that cures you could very carefully pour white resin into the hollows. Then sand the surface to remove any white overspill from the black areas and then put on the clear coating to protect and seal everything since resin is porous. Since you've 3D printed one of the early versions of the St. John Logo that would be the way to make it look real... until someone touched it. (If not for the exploded cross on the bottom, you would have a Cushing TARDIS logo. That one had just a round dot at the bottom as was the most common on actual Met Boxes.)

I'm sure others will have better ideas since I've never painted anything 3D printed yet, but I sort of like the idea of making a mould of your master, and then casting one in black and filling in the hollows with white resin.

I hope some of this was helpful.

Dino.

[karsthotep]

or you could jump on etsy and buy this metal one for 9 bucks

https://www.etsy.com/listing/520349858/tardis-sign-for-st-john-ambulance-metal?ga_order=most_relevant&ga_search_type=all&ga_view_type=gallery&ga_search_query=st.%20john%20ambulance&ref=sc_gallery-1-1&plkey=fa8a805ddf86724d7cc0278ab536a6023b5faa9e:520349858

[Davros Skaro]

If you want to make a revers stamp for printing SJA's, you could just ask your friend to 3D print you a negative of the sign & use that to print/stamp out signs! Be easier than trying to make a cast of this one & the casting material getting caught on it & destroying such a lovely piece of work.
Just a thought!

Oh & that mug looks great too! Very nice job!

Chris.

[rob49152]

A few years ago I did a whole post on 3D printing and making rubber mold for resin casting. I'll answer any questions I can.
http://tardisbuilders.com/index.php?topic=5977.msg71952#msg71952

As for the plastic being outdoors, it depends on the plastic. The most common filament used in 3D printing is PLA. It's made with corn and a few other biodegradable materials. So it would warp and start to break down after a few years.

If it's made with PET, PETG and PETT or ABS, Nylon it should be fine for outdoors. But it's much harder to print as the temps have to be quite high.
http://3dprintingfromscratch.com/common/3d-printer-filament-types-overview/

[Bob's your Uncle]

or you could jump on etsy and buy this metal one for 9 bucks

https://www.etsy.com/listing/520349858/tardis-sign-for-st-john-ambulance-metal?ga_order=most_relevant&ga_search_type=all&ga_view_type=gallery&ga_search_query=st.%20john%20ambulance&ref=sc_gallery-1-1&plkey=fa8a805ddf86724d7cc0278ab536a6023b5faa9e:520349858

I never even thought about buying one.  
As much as I like making things myself, this would be the most economical.  

I'm still going to investigate the molding options that have been suggested, just because it looks like fun.

Thanks for the ideas.
Greg.

[galacticprobe]

or you could jump on etsy and buy this metal one for 9 bucks

The description for that one says it's 3 inches in diameter. That's small. You'd need a 5-inch for a TV TARDIS (New Series; 4.5-inch for Hartnell's TARDIS), or a 6-inch for a Met Box/Cushing box. So you'd need to contact the seller about having it custom-made (as it says in the listing).

That said, the latest review (2 days ago) wasn't the best, so I would approach that listing with Caveat Emptor.

Dino.

[karsthotep]

Good catch Dino