Finishing 3D printed parts

Do be careful with the uncured resin you found. I cure all of my prints in cold water, when you expose the resin to UV light to cure, it will heat up as it hardens which WILL distort your print. Whoever sent that to you did so in a hurry and didn't allow for the part to fully cure with UV light. Wash your hands with soap and water and you should be ok.

As per finishing, yes resin will sand much better than PETG and PLA but you will need fine grit sandpaper and a steady hand to get into some of those places. You can also look into resin smoothing, which involves covering the model in a thin resin coat and then curing the thin coat which should even out a lot of the lines, I've seen it done with FDM prints before so give the ole' youtube a look. I am sure you will find what you need.

Good Luck!

So will the film of resin cure on its own, or will it be stick forever if not exposed to UV light - which I have no source except the sun.

Hey Friend,

It will forever stay uncured w/o a UV light source. The SUN can work but it can also ruin your print if you over do it.

I use my wifes UV NAIL dryer LMAO, it was her idea to buy it not mine

Hope this helps!

Looks like I need to get a cheap UV light and see if I cant stop the sticky.

Thanks

I don't know the source of the print or the actual resin used to print it, but many of the common UV cured resins that are available for hobbyist printing can be cleaned using common isopropyl alcohol.  There are some that can be cleaned with water, but that doesn't seem to be working.  Before trying to cure the excess uncured resin, I would first get some 91% isopropyl and give it a soak with that.  Under normal circumstances, cleaning with alcohol will only take a minute or two (or less) to break down the uncured resin, so don't leave the part to soak for too long.  The alcohol can soften the cured resin as well, leading to damage or deformation from handling.

If that doesn't work to remove the excess resin, then you will need to cure it.  The sun is an option, or you can get a UV "flashlight" to spot cure resin.  One thing to watch for when purchasing the UV light is to get the correct wavelength light.  Again, I don't know the spec on the resin used for your print, but most of the common UV cured hobbyist resins specify 395nm to 405 nm wavelengths for curing.  If you search for "UV light for curing resin", you will see lots of options available.

Hope that helps.
Jim

Without knowing what it was printed with printer or resin; it's hard to tell you what to do.

From the lines in the part, this was likely printed on a low-cost resin printer.

However, there should not be any uncured resin in a part that is shipped for sale. All resin must be fully cured, or you may get a nasty rash by touching uncured resin. Not a good look.

The UV pen light will likely cure the uncured resin, assuming that the wavelength of the light matches closely with the laser or UV light that formed the piece.

There's definitely a print failure of some sort in the top right corner of the nose.  I'd argue that the part should never have been sent out that way.  It also looks like you have some grooves lower on the side of the nose, those will also need filling and sanding to smooth.

As to finishing the rest of the nose, the first thing I would suggest is getting some rattle can primer and shooting some of the underside of the nose print as a test (once you remove or cure the excess resin).  Primer will fill the finest layering grooves to an extent, it may take care of most of them while the larger defects will still need more attention.  If the primer isn't sufficient, then I would suggest some very fine wet/dry sandpaper or sanding sticks, applied with a careful and gentle hand.  There's really not a better way to do it with the various details present.

While resin prints are typically higher resolution than FDM prints, it's a misconception that they will come out of the printer 100% smooth.  Parts can be oriented in the printer in such a way as to optimize the quality of surfaces, but such optimization is really only for surfaces at a very specific angle to the build plate.  All other surfaces by defualt cannot be optimized at the same time.  Curved surfaces are also nearly impossible to optimize by default, so something like the cab roof will likely need some post processing to make totally smooth.

I'm not knocking 3d printed parts by any means.  They are a great way to get things done that might not otherwise be available.  But they will often take some effort to achieve the quality of an injection molded part.  This is particularly acute when printed by a vendor such as Shapeways, where it is difficult or impossible to dictate orientation, or other parameters such as slicing thickness or exposure times.  All of those things play a role in the quality of the printed part.

Jim

Jim is correct; orientation of the part is an art, but easier with better printers.

With my Form Labs 3 printer, I get a smooth result all the time.

That's not a misconception.

Per big train I shot the nose with some Rust Oleum filler primer.  The nose looks better.

Continuing my above post that I accidently hit post.

The nose looks much better after a shot of primer

You can still see some of the "print lines" (whatever you call them).  Once the primer is fully dry I will finish.  My question is will fine polishing Scotchbrite do the job.  Will not eat details like sandpaper.  I can always try, but wondering about experiences.

As to the cab that had the sticky resin still on the inside.  I bought a cheap UV flashlight and it has shined on the resin 24 hrs, much better but still not cured all the way.  I'll let it continue to shine until the batteries run down, hopefully thing will be OK by then.

Gray, ….I know nothing about 3D printing, resins, or whatever …..but I do know body work, and I do know how to prime & fill,…..once you get your resin cured or whatever the case is, …..break out your trusty small sanding block I mentioned in the other body work thread, and wet sand those flat areas. Stay clear away from your fine details, …they look pretty good from the pics,…..block sand those flats with the print lines wet, with 1000 block almost all the way back down to the printed material, then lightly scuff the details with scotchbrite, and hit it with another coat of build primer, …..block that coat down after it dries, and you should be able to do final prep for coloring………just use soapy water as your final prep before spraying ( naturally, let it all dry out )  before mid coat color and top coating.…….

Pat

What Pat sez.....that's pretty much what I would have recommended as well. 

I'm going to reiterate my suggestion to try cleaning the cab part with IPA, or at least try that method if you ever need to fix an uncured resin issue in the future.  I believe it will be the simplest and most effective solution.

Jim

Are you sure the gooey stuff is uncured resin? It may be support material. At work we have an Objet resin printer that uses a sticky wax like material for support. The stuff has to be scraped out and then pressure washed to clean the part.

This stuff is (was) inside the cab roof.  There was no supports inside on that area, it was smooth.  It is hardening slowly with a cheap UV flashlight.

In my quest to finish the parts above, I have used rust oleum filler primer to (attempt) to get rid of the print marks.

Parts have been sanded, print errors fixed.  Now another question on primers as I am ready to prime (before finish) and want a fine coat to cover but not cover up details.

I have three types of primers:

Primer Filler which I don't think is what I want as I would think it would be somewhat heavier.

Primer

and

Sandable Primer

What is the difference between the last two, which is better?

And before color, a scotchbrite scuff?

I would also like to know the difference. I'll bet the Sandable Primer is what you want to go with though.

Not an expert, but I'll take a shot.  I'd say what you use depends on how satisfied you are with the current finish on the parts.  If you have them prepped to a point where you are ready to finish paint, I think you probably want just the regular primer.  If you still have minor scratches or layering to fill, I'd go with the sandable primer. 

In my understanding, sandable primer is still intended in some part to act as a filler for minor defects, falling in between a filler primer and regular primer.

The other thing I would look at is pigment size.  Presuming defects are already addressed, I would use the primer with the finest pigment, and I think that's the regular primer.  The only caveat is I'm presuming the regular primer is also an automotive product, as I think auto products tend to have finer pigments than general use products.

Take it all with a grain of salt, I've done minimal paint work.

Jim

All the products are automotive.  What the problem is with any model is the details, you cant sand perfectly without damaging them.