# 3D Printing > General 3D Printing Discussion >  3D Printing Car Body Panels, a few questions from printing-n00b lol

## don.binary

So this whole post may seem a little stupid to some people on here but oh well, you don't learn if you don't ask right?

Basically for the last few months I have been teaching myself 3D design and in my opinions i'm getting pretty damn good! Lol...

I understand quite a bit about aerodynamics and things, and my favourite thing to model is cars. Modelling a car from scratch, customising real-world cars, you name it I love it lol... 

A few of my friends have seen my designs and have liked them that much that I've been asked about designing custom body kits and things like that. Now smaller pieces like dash trims and door handles I could obviously print at home if I had a 3D printer, but was stumped when it came to large objects such as bumpers or spoilers.

So my first question is:
Does the strength of the composite plastic that printers use vary? As in can you get stronger/weaker plastics or is it all pretty much the same stuff...

Second question:
Following the first question (thinking purely in terms of strength of material, excluding fitting issues and smoothing errors in design process) would it be better to treat the printed design only as a mould or in theory would the material be suitable for things like car bumpers?

Third question:
Would there be businesses capable of printing large items such as bumpers, or would larger items have to be printed in sections? (I live in the UK so if people can recommend business that could I would be extremely appreciative, but any advice would be appreciated)

I will leave it there for now, I'm sure I will have a few more questions but these are the main issues that I can think of right now  :Smile: 

Thanks in advance  :Smile:

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## 3dkarma

1. Strength does vary quite considerably, as does things like resistance to heat and UV, which are important for things you'd stick to a car.  PLA is pretty much out of the question, as the temperature at which it becomes soft is too low when you consider it will be attached to hot metal in the summertime.  ABS is better and is less "brittle" than PLA, so is probably a better choice.  Nylon is another alternative, is UV-resistant and better at higher temperatures, but is more expensive.  Painting the ABS would deal with the UV issue, though.

2. A car body has already been printed - http://en.wikipedia.org/wiki/Strati_%28automobile%29, but I would question how well it would last long-term.  If you look close-up, the finish of the body is extremely rough.  This is a direct consequence of printing large things in a (relatively) small amount of time.  It takes time to 3D-print - the larger the print, the more time it takes.  You can reduce the time by reducing the quality (or layer height) of the print, but your finish will not be as good.  You also need to consider the weight of what you're printing.  To get any strength from the finished article, your bodykit panels will be significantly thicker than their fiberglass equivalent.  For that reason, you would be better off printing the panel, filling and smoothing it, creating a mold from the positive then using that mold to create your panels from something stronger, cheaper and more lightweight (also much faster to produce one your molds are done).

3. Can't help you here.  I'm not aware of any service in the UK that can print parts to the size you're after.  A word of warning, though: anyone you find that can print something that bid is going to charge you in the order of thousands of pounds for a single panel.

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## don.binary

Oh yes that does look a little rough doesn't it lol... I never really considered just how rough it would be, I didn't expect it to be perfectly smooth but that's an easy problem to resolve. Don't know why I didn't consider weight though. Thanks for your reply, it's given me quite a bit to think about. 

I'm thinking my best bet is probably to buy a reasonable size printer, then print larger panels off in small sections, then make a mould from it. It definitely would be ideal having a mould after the panels are created. I'm quite a way off that all yet, just wanted to build an idea of how I would actually go about doing it, having a company I could send designs to in order to get printed would have been easier but would probably get better results cheaper this way, and having a mould I could always recreate panels easily with fibreglass  :Smile: 

Thanks again for your help.

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## rikky

As a brief reply:

3D Printing of pieces as big as bumpers, dashboards, car doors, ... in a single go is possible. Materialise (manufacturing site in Belgium) has SLA printers which can print (roughly) up to 2 x 1 x 0.5 m. The resin can be polished by hand after printing, so even high gloss paint jobs are possible.

In terms of strength: most SLA parts would suffer from high temperatures (summer sun) and/or big forces (wind friction at high speed, for longer durations). The printed parts (based on the original CAD files) would probably be strong enough for display purposes, but not for actual driving. Reinforcing the inside of the part with glass fiber would make the part stronger and possibly usable to test drive a car (this has actually already been done by manufacturers to support their design phases). Using the SLA-printed part as model for (silicone) moulds would also be possible, but I'd doubt you'd be able to properly fill the mould...

Last comment: if you're thinking of actually printing a bumper -> expect a quote between 10.000-15.000 Euro (+ shipping)... You'll need to make very exclusive items to make it interesting to potential buyers :-)

Best regards,
Rikky

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## 3dkarma

I really must remember how to spell mould and mold correctly.  Printing in smaller parts is a good idea.  Take a look at this 3D-printed kayak for ideas on how to put it together: http://www.dailymail.co.uk/news/arti...ching-too.html.

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## awerby

I suppose you could print small panels and glue them together, but it would look more like a tile floor than a car body. If you want to make big, strong, smooth contoured panels like most car bodies require, use a CNC router to machine urethane foam into the shapes required, then coat them, sand them out, apply mold release, and lay up the panels in fiberglass and resin, or a similar composite system like epoxy and kevlar. This will be stronger, cheaper, and better-looking than the method you're proposing. 

Andrew Werby
www.computersculpture.com

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## rikky

Printing through SLA-technique (in stead of FDM) would result in a very smooth surface. SLA pieces can always be sanded down if required, so even high gloss finish is achievable. Unfortunately, for these types of applications, SLA parts (certainly if based on normal CAD drawings as used in car design) would be too weak to support the pressure (air friction) on the parts while driving. And any parts with manually increased thickness would become impossible to print (and too expensive anyway). They could also easily distort overtime when exposed to higher temperatures.
The solution to all of these issues is to reinforce the SLA parts with fiberglass to make them much stronger. It's been done before, even on whole cars (during design phase)!

Unfortunately, there's not that many service providers who have large SLA printers where you could order these as a whole. There's one though in Belgium who can print volumes up to 2 x 1 x 0.5 meter (and has a whole series of these machines), but you'll need to be prepared to pay 10.000-15.000 Euro for such a part (bumper, dashboard, set of 2 doors, ...). You'll probably need quite some very high end cars / tuning lined up to make this kind of investment worthwhile...

You could also use the SLA part to make silicone moulds. I'd doubt though that you would be able to decently fill the mould and get usable parts out of it...

Most small series bumpers are produced with RIM (reaction injection moulding resin, poured into milled moulds). So milling is probably a good first step to investigate... (but it won't be cheap either)

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## raysspl

The Local Motors 3D printed car may be a rough example but it's a great start.

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## Sebastian Finke

> ... For that reason, you would be better off printing the panel, filling and smoothing it, creating a mold from the positive then using that mold to create your panels from something stronger, cheaper and more lightweight (also much faster to produce one your molds are done).


^^ This.

If you're serious about manufacturing your designs then ditch the 3D printing idea. Then rather have a master part machined out of some epoxy board like WB-0691, use that to create a mould out of a resin and then mass produce. 

Perhaps invest in an autoclave and vacuum station....

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