Shep
June 29, 2017, 2:38pm
1
I’ve been looking around on this for a while. I’m making a corner-cube retroreflector, but since most people I ask don’t know what that is and don’t fully understand it either, I’ll use a simpler example of a telescope lens. Same printing technique behind both. Just to throw a curveball into the mix, let’s assume we want the lens to be tinted red.
FDM printing does so in layers, in which even the tiniest shift horribly skews results. Plus, without true 100% infill, you get a cloudy lens rather than a crystal clear one. Not many filaments support “true” clear either, nor do they come in colors.
Injection molding would be ideal if the quantity were high enough to justify this. If quantities are kept to a maximum of 4 however, costs are exorbitantly higher than other methods of manufacture, which is problematic.
Given the plethora of 3D printing methodologies, does anyone have insight into a better way of manufacturing the object? Sanding/polishing/etc isn’t a viable option given the very small size of the retroreflectors, it needs to be manufactured to exact specs without any post-processing to make it “clean”.
Depends on your budget. Why don’t you use SLA clear resin with Polyurethane coating (or clear epoxy for a more rigid model), will give you glass looking models with no visible lines.
1 Like
If the requirements are:
-“Exact” dimensions / specifications (even though everything has a tolerance)
-Optically clear
-Absolutely no post-processing
Then there are not going to be any cost effective solutions. With all due respect, the expectations are unreasonable. Formlabs created an article about creating a lens with their clear resin, and the process requires a very high amount of post processing. Post processing will also affect dimensions. You can look into silicone mold making and cast in a clear urethane, but this will also have challenges regarding tolerances, and will still require post processing. Best of luck.
Shep
July 1, 2017, 3:32pm
4
“Cost effective” wasn’t a requirement, nor do I expect it to be. I’ve only invested $300 in this, and was expecting to be in way more by now, but more or less am stuck on the “how” side of things.
Let me ask this: which part of the requirements was unreasonable? If I’m asking for “more than perfection”, let me climb down several rungs and get something that just works first
The “no post-processing” bit was purely because the retroreflectors themselves are tiny faces, on the order of 3mm square. It would be a challenge to sand/polish all these guys up for sure. The outside is nice and smooth, but even Stratasys said the inside was untouchable. Post-processing the rest is fair game however.
Shep
July 1, 2017, 3:34pm
5
Good thinking on the SLA clear resin, I’ll ask around on that one!
More or less wide open budget – I can’t find anyone that can do this for the low quantity period. Injection molding would do this by the thousands, I only need half a dozen tops, and most guys I’m finding are unwilling to offer such a low quantity.
Researching the “how?” more so than the “how much?” if that makes sense
