Datsun Roadster Forum-311s.org

Hey everyone.
I have the potential to have runs of letters 3d printed on a commercial machine. Obviously this wouldn't be a free venture for me, but would people be interested in purchasing a set of 3d printed hood letters?
I have a set of plastic ones on my 70 that would be used for the design. They would not initially be as smooth as the injection molded originals, but could be cleaned up with some minor sanding by the purchaser. I spoke with the CAD designer yesterday and showed him one of the letters, and it's quite feasible. What price would be fair for a set of letters that need some finish work, but fit as factory?

Sounds great. Some clean up on the letters would not be a problem for me. Even if the letters were bare plastic and you had to spray them, if there was info on what product to use it would be easy. I know there is spray paint designed for plastic.

Linda

Pricing would completely depend on the quality - if it looks poor, or is difficult to clean up, then less value. If they look good and are easy to clean up then probably pretty decent money. These would be in a plastic coated chrome, what will the final look be? Great project and I wish you the best of luck with a great reproduction part!

Not being privy to the whole thing, but if one has to clean up plastic/chrome - could be a pain.

I know that 3D prints aren’t exactly the strongest parts. Just curious what process is being used. If fdm (fuse deposition modeling), aka 3D printing, is being used they can break along the layers and aren’t very durable if used for the hood letters; orientation is important here. If sls (Selective laser sintering) is used the letters would be more durable but pricey. If sla (stereo lithography Apparatus) would produce the highest quality/detail parts but also pricey.

And then the chroming on plastic process is difficult to do correctly and also pricey if done right.

Not trying to shoot you down. But the cost seems like it would be prohibitive.

Almost seems better to Cnc them out of aluminum or even stainless and polish the snot out of them.

Cheers Matthew

No Matt, you're right. These are all the same concerns that I had. I've made 3D printed parts before (FDM), but they were large, and took a lot of work to make them look good. SLS letters would look great in aluminum. A website called Shapeways could make them for about $2-300 as a best guess. Even if just the front was sanded and polished (with textured edges) I bet they'd look great.

These are center caps that I printed for my 521 aftermarket wheels. It took a lot of acetone, sanding, and painting to get them to look good.

charlee0620 wrote: Wed Feb 12, 2020 2:46 pm I know that 3D prints aren’t exactly the strongest parts.

That's not true. Yes if you printed in PLA, it will not be strong or last. There are many other plastics that are much stronger than the original plastics letters.
My issue is that there is no chrome type plastics, the best you could do is silver and getting an acceptable finish on a set would not be easy.
Maybe I will make a simple " T " and see how it comes out.

Greg it’s not the material that is the weak link in this process, it’s the process itself. In fdm, which I suspect is the process utilized here as it is the most common now a days, is inherently flawed because of the layering. It’s like a very precise hot glue gun squirting layer after layer. Not all the layers will bond correctly, even on high end machines, and a split between layers will occur. This is why this process is mainly use for prototyping. Sla will produce the most viable part be cause it can produce pretty smooth surfaces, but again pricey and the parts are extremely UV sensitive so they would have the be coated. My experience with all this stems from working at the Rapid Prototyping Center at The Milwaukee School of Engineering while in school.

As for the chrome, there are not really any decent “chrome” plastics out there. Instead the parts would have to be chromed, which can be done. But even the budget versions of this process are stupid pricey and are meh in quality. If good models are out there of the letters I would again suggest producing them in aluminum polished with a clear of some sort on it. I’m actually thinking of trying it in the future, but my CNC mill is still under construction.

Matthew

I create structural parts from time to time by melting the outer layers together either with acetone or MEK. It works pretty well, and creates a solid exterior shell that prevents delaminating in the layers.

I met with a guy last night that does injection molding and 3d printing. He said he can help me get some low-run molds made fairly inexpensively. I am going to take my letters to him in the next week or so and see how feasible this is. I might not be able to get them in a chrome finish, but I should be able to get them as strong and durable as the originals. He seems to know quite a bit about material strength and finish capabilities.

I'd say injection molding is far more promising. That way you can get the finish quality required for chrome. I can't imagine any finish other than chrome is going to be very desirable-other than maybe SS. (Anything else won't look right) Clear coated AL will look worse than original when (not if) the clear fails.

JT68 wrote: Fri Feb 14, 2020 7:59 pm I'd say injection molding is far more promising. That way you can get the finish quality required for chrome. I can't imagine any finish other than chrome is going to be very desirable-other than maybe SS. (Anything else won't look right) Clear coated AL will look worse than original when (not if) the clear fails.

You can use vapor deposition to make plastic look like chrome but it really depends on the smoothness of the sub-strata, as the "chrome" deposit is like .005" thick. The 3D printed stuff we use for rapid prototyping or for rapid casting all have a rough surface that looks to my eye to be around 400 RMS -ish. How would you get rid of those layer benches to be able to get a nice finish once coated. Acetone? Tumbling? buffing?

I've handed off my letter 'D' to a friend who is going to make a sample in the next few days. I should have more technical info shortly as well.

So my friend got laid off, and there's a vendor doing letters for 99$, so I'm going to shelve this project.