Finishing 3D Printed Parts with Resin - please add your methods also!

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skahtul

Well-Known Member
RPF PREMIUM MEMBER
Awesome RPF Members, a few people have asked about the processes I use to get rid of 3D print lines left by FDM printers so I thought I would share my processes and hope that others will share theirs so that we can all benefit.

Certainly, one way to finish 3D prints is sanding, lots and lots of sanding. I can't handle tons of sanding, my hands can't take it and when you start printing really complex models there is no real practical way to sand certain small detail areas. What follows is the process I have used ever since I picked up 3D printing earlier this year. It helps both with large flat areas and areas where there is a lot of detail.

Here are the items you need:
  1. Acid Brushes (get them in bulk from Amazon, these have so many uses!)
  2. Wide/Soft-bristled brushes, I also get these in bulk on Amazon.
  3. ZAP Z-Poxy Finishing Resin
  4. Sand Paper (220, 400, 800 grits)

Other resins may work, but I have found this to be my favorite as it has a few properties I really like. It is low cost, it self levels really well, has a 20 minute working time so you have plenty of time to get it down, takes all the primers I have thrown at it, does not smell, and is super easy to clean up. It goes a LONG way, I always mix too much. My very first 2 bottles I bought I used to finish my 1:24 TIE and X-Wing, my USS Sulaco, Rey's blaster, Kylos Saber, Eye of RA, a bunch of testing, and more.


20201121_133251.jpg



Here are some close-ups of the parts I am going to use. These are both failed prints (not oriented correctly) from my 1:24 B-Wing build. Since I am only using these as a tutorial item and then throwing them away, they will not be finished with near the attention to detail I utilize with my actual builds so keep that in mind in case you feel the need to get nit-picky :)

As you can see, the Prusa Mini puts out incredible prints, these were printed at .10. At this point, the only clean up I have done is to get rid of the supports, which consequently is when I realized they were not going to work for my project.

20201121_133140.jpg


20201121_133157.jpg


Here are some of the primers I plan to test, except the AK Fine Resin Primer, I do not like how it goes down. I also saw/received a tip from another member's build about the adhesion promoter so I am taking this opportunity to give it a test.

20201121_134515.jpg


Step 1: Sand with 220 grit sandpaper. This should be a very light sanding, I did not spend any more than about 3 minutes on both wings. I like to use these wipes after I am done sanding to clean everything up.

20201121_141614.jpg


Step 2: Mix the resin 50/50 and stir very well. If the ratios are off it will not cure correctly.

Step 3: Apply the resin. I use the acid brush to get the resin on, you do not have to get crazy with it, you want a very light coat.

20201121_142004.jpg


Step 4: Level the item. This is critical, the resin is self-leveling which means you really need to ensure your part is as level as possible.

20201121_142206.jpg


Step 5: Use the softer brush to smooth everything out. You want to keep an eye out for any areas where it pools. If you have any pooling you simply wipe off the softer brush and go back over the part. As stated earlier, you have a lot of working time so keep an eye on it and go back over any parts that do not look level. You want to use a very soft touch with the finishing brush, you are trying to smooth out all your brush strokes.

Watch for pooling!

20201121_142323.jpg


Step 6:
Enjoy your lack of print lines! You can of course still see them, the resin is clear, but trust me you can not feel them, they are gone. You can stop here and for many of my projects, I do just that. However, if you want to get it perfect then you need to continue on with a bit more work.

20201121_142607.jpg


Below is an example of applying a primer coat at this point with no further work, it's very smooth! The very left part of the wing has been coated with the finishing resin.

20201122_161029.jpg


Step 7: If you are looking to get it even smoother then you are going to need to do a bit of sanding, but not much.

I start with 400 grit and sand the resin part down a bit just to ensure it's all level. The detailed parts have already been filled in so there is no need to give them any further attention.

I will finish both sides the same, one side has resin and the other just gets a light sanding. Make sure you utilize wet sandpaper! Wet sanding is better in every way when compared to normal sandpaper. It does not create any dust, you can rinse the sandpaper so it lasts longer and does not get clogged and it just gives you a MUCH better finish. It's how cars get that mirror-like finish on them.

20201122_084015.jpg


Step 8: Apply your primer of choice, two very light coats.

Step 9: After the primer fully cures, wet sand with 800 grit sandpaper, here you can see the two sides, it pretty easy to pick out the side where the resin was applied. You only need to sand for a few minutes max, it should not take much time at all.

No resin, print lines really stand out after you prime and sand:
20201122_155913.jpg


Resin:
20201122_155930.jpg


Step 10: Apply a final coat of primer.

Final coat, no resin:
20201122_183611.jpg


Final coat with Resin:
20201122_183546.jpg


I will add some final pictures here after the primer has fully cured. I will also post a picture of the side I did with filler primer. I may paint these 'chrome' just to show how smooth the finish is if it turns out good :)

Hope this helps someone out there, and please post your favorite methods for finishing 3D Prints!

- Eric
 
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StevenBills

Sr Member
RPF PREMIUM MEMBER
I love this thread! Some very useful techniques documented here. I wish my printer could print as well as the Prusa printers. My buddy has one and I'm always amazed at how well his prints turn out.

SB
 

Dtrasler

Sr Member
This is a fabulous resource I'll definitely come back to. My 3d printing is very basic at the mo - I'm a real noob, with a Forge Finder and little experience, so I've been using elbow grease and sanding for the few parts I've tried to get smooth. Oh, and bondo.

20201113_095637.jpg

Here's hoping your advice does a better job!
 

Analyzer

Sr Member
This will come in handy for sure. With my resin printer currently this will not of too much use, but I have been looking at FDM printers so I can do some larger scale things as well as more durable parts for simple shapes.

It really seems like you often need a combo of DLP/SLA/RESIN and FDM for best results

In that Making of the Razor Crest video, there was one point where the guy was preparing the surface of the print in a very similar way. I had wondered what that was
 

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skahtul

Well-Known Member
RPF PREMIUM MEMBER
This will come in handy for sure. With my resin printer currently this will not of too much use, but I have been looking at FDM printers so I can do some larger scale things as well as more durable parts for simple shapes.

It really seems like you often need a combo of DLP/SLA/RESIN and FDM for best results

In that Making of the Razor Crest video, there was one point where the guy was preparing the surface of the print in a very similar way. I had wondered what that was

For sure! I have a few parts for two of my current projects that my FDM just will not do, so I am having someone print them in resin for me. I do have a .25 nozzle and the mini 'can' print at .05 so I am going to test that for my B-Wing project if for no other reason than to see if that is really even achievable in a useful way with FDM printers.
 

skahtul

Well-Known Member
RPF PREMIUM MEMBER
This is a fabulous resource I'll definitely come back to. My 3d printing is very basic at the mo - I'm a real noob, with a Forge Finder and little experience, so I've been using elbow grease and sanding for the few parts I've tried to get smooth. Oh, and bondo.

View attachment 1371044

Here's hoping your advice does a better job!

Good luck for sure! I just hate sanding :)
 

skahtul

Well-Known Member
RPF PREMIUM MEMBER
The camera really takes a way a lot of the shine, this looks really good in person. I would not normally pain my model's chrome, but I thought it might be a good way to show off the finished surface. Although now that I see it, it looks pretty awesome. I keep thinking about a black and chrome TIE Interceptor :)

I will post a few more comparisons's between the resin side and the other sides when I finish painting them.

20201125_212653.jpg
 

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Star Lord

Active Member
This is a terrific tutorial! I just purchased my 2nd 3D printer and am still learning how to get the most out of it. But the one aspect of 3D printing that I absolutely HATE is sanding. I understand that Smooth-On is offering a finishing resin designed for 3D prints as well. Thanks again!
 

TazMan2000

Master Member
I don't have a photo to share, but I tried photopolymer resin on a crappy 0.2mm FDM part. It wasn't sanded previously to get rid of high spots and just applied with a paper towel. After curing and sanding, I was amazed at how the resin bonded to the PLA and how it levelled out. Plus the photopolymer resin sands pretty easily and doesn't clog up sandpaper like epoxy does.

I'm thinking with a quick go over another PLA print with sandpaper to knock off the high ridges, the resin will do the rest. Another good thing about using photopolymer resin, is that you aren't limited by the curing time of epoxy, You would just expose to UV whenever you get the object 'painted'. A point of note, though, is that photopolymer resin is toxic, so you have to have care in application.

TazMan2000
 

Albertusfox

New Member
Hi, my first post!

Just a newbie question, I have been looking for a solution for leveling and filling gaps on my scratch built models using Milliput. Would this liquid resin help with this?

I like the finish it gives and will use on 3d printed parts too!
 

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skahtul

Well-Known Member
RPF PREMIUM MEMBER
Hi, my first post!

Just a newbie question, I have been looking for a solution for leveling and filling gaps on my scratch built models using Milliput. Would this liquid resin help with this?

I like the finish it gives and will use on 3d printed parts too!

Awesome, welcome to the forums!

It looks like Milliput is a type of putty from what I saw. If the gaps are tiny, super tiny it could work. But, If you have a small gap and put the resin over that, the gap will be closed but you would still see the divot if that makes sense. Now if you have a large flat surface and you filled the gaps with the putty and then overcoated that maybe... but I really have only used this on my PLA prints so far and I am filling super tiny 'gaps'.

Thanks!
 

Albertusfox

New Member
Thank you for the reply. I think that will work out for me. It is for a large area, which is pain to sand to get the dimples and uneven areas out. It feels like the true definition of insanity- doing the same thing over and over again!

Most appreciated
 

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