finishing abs model from .stl file

[Guest B.A.F]

Hey all,

 

ive just received my 3d model printed out. It is a rapid prototype in abs plastic, and the surface is quite rough and porous.

 

Does anybody have experience in finishing these types of models: so I mean spraypainting and using lacker on this type of material. I guess sanding is necessary, should a chemical primer be used of somekind??

 

thanks already

[Guest Bizzo]

hi there...

 

well i was disappointed with the quality of the print from our machine at school as a finishable piece. i sanded it. it got worse. once you sand down the ridges you are met with more ridges underneath. i then used a filler like bondo and spot putty. all this basically did was lose the shape i had underneath. i sanded that off and tried using a filler primer to fill the gaps.. by this time small fibers from the plastic were sticking up all over the model like little hairs. sanded on that for a bit and gave up and reprinted it... i ended up just spraying it primer grey and calling it a volume model.

 

this material was also abs plastic...

 

your machine may be of a higher quality than the one we have, so get a test piece and see what it does.

 

good luck to and your model

 

bizzo

[Guest kenne]

hmm, my school did some RP out of SLA and the final product is also sort of a porous material, but what we do is put on a thin layer of putty(polyfill) on it and sand it down and the final coating is spray paint. it turn out quite fine. All the beat for your proj.

[Guest B.A.F]

hmm I dont really think that my model is of very high quality, because the structure of the surface is coarse: the lines from how it is built up, are very clearly visible.

 

I have two models, so I have two chances..

[Guest RFA01]

Hi all

 

I used to work in a prototyping centre which had an FDM machine which created ABS models.

 

We used to treat the models with Tolulene. This used to gradually dissolve the surface and left a glassy smooth finish. Main problems being Tolulene is not a particularly nice chemical and secondly if you put too much on it would disolve more of the model than you'd really want.

 

Another option is to cover with a car body filler and sand it back; this may change the accuracy by quite a lot if not done carefully.

[Guest 3dman]

Your best bet in preparing this surface is slowly apling layers of bondo to fillup the ridges. These rigdes are going to be a problem no matter how far you sand down .If your skilled, you should be able to just fill up all the ridges with bondo, and lightly sand it down. And after that, do some skilled body work untill that surface is perfect. This is the best way I found to do it. Although, I did have a bad prototype machine experience. But I always remember back to when I had to start from scratch, and it alway makes me feel better. For the guy that talked about the hairs sticking up, that is just a horrible machine that did your prototype. It should not do that. So get your money back, or find a better machine. To be honest I tried drywall compound on my last model and that worked great. Just have a blow dryer near by so that you can work fast. The stuff just falls off on a light sand and it doesnt afect your 3d cad shape. Thats about it. Any more questions I'd be glad to answer if I can. So to all of you shape builders, good luck. Take care..... 3Dman

[Guest B.A.F]

Im gonna start this week.

 

Here a few images of my model, as you can see, the surface quality isnt that high...

 

[Guest keffmalone]

I spent a fourteen month industry placement at Unilever producing, sanding and spraying these little beasties. The technique we used was as follows:

1: sand with 240 grade wet & dry sand/glass paper (should be a grey colour with waxy paper backing.) Whatever you do DO NOT use normal sandpaper, it gives a bad finish as described by Bizzo

2:Sand again using 600 grade wet & dry sand/glass paper (These steps take time but are worth it. Be patient)

3: Spray the whole model using filler primer - normally a yellow/orange colour.

4: Sand the model AGAIN using 1000/1200 grade wet & dry.

5:Spray model using required colour standard primer (i.e white or grey etc).

6: Spray an undercoat on the model.

7: Spray a topcoat on the model (x2)

8: Spray a laquer if needed.

 

Between these coats of spraypaint quickly and lightly rub down the model using 1000/1200 grade wet & dry just to take off any dust or rough bits that show up. This will give a very good, smooth finish. Don't forget that each coat of paint should be fairly thin. If it's too thick it will run and not look good.

 

We never used metallic paint, so the painting process may be different, I'm not sure. I've said it before but this process takes time and it's not worth rushing it. Byall means sand as quickly as your arm can manage, but don't try and sand the paint before it has fully dried, it just take you longer to repair the damage.

 

I hope this helps you, and good luck I look forward to seeing imaged of the final model.

[Renzsu 4]

keffmalone, great tips!

 

Were you using the same model materials?

[Guest MrG]

All of the above are great help...The key is take your time!!!! You have to plan out all ur steps. Another thing you must to consider is making your model in sections. This will enable you to have greater control over part lines etc..The outer sections which protrude need to be separate as well as the buttons. Thi swill enable you to have a much esier job bondo/sanding etc.. and it will be a doodle when you come to paint them.. good luck

 

Happy sanding!!!!!

 

Mr G

[Guest R_ADesigns]

light sanding, and an acetone bath will smooth it right up, but don't leave it in the acetone for too long. just in, wait a few seconds, and take it out. next time, set the file to high-res (high quality depending on sofware used) before exporting it into an .stl file, and it will print alot smoother.

[Guest keffmalone]

Renzsu, we had three different machines for rapid prototyping using three different materials:

SLA Resin (a slightly transparent yellowy liquid that hardens when laser is fired at it), SLS powder (a white/metallic powder tht again hardens when a laser is fired at it) and extruded ABS.

 

The SLA resin gave a good smooth finish very quickly and when we first started using SLS we worried that we couldn't get as good a finish, because as you sand it it appears to be quite fluffy and soft to the touch.

 

Looking at these photos it appears to be the same material as our SLS models (the banding looks identical and a much more detailed model than the extruded ABS machine we used. It also has a slight sheen to the surface that is the same as we had. Finally, there do not appear to be any rough areas where the supports would be - a strong hint that it is made using a powder based process.)

 

B.A.F. Do not worry if you have the same problem with the fluffiness. As soon as you spray it goes. Thats why we used the filler primer in a yellow colour because we could then sand it back down and see where we reached the original white model. The filler primer is just to remove any fluffiness/deeper lines in the model. (These machines aren't perfect unfortunately.)

 

Good luck.

[Guest Moonman]

I would only use ABS if I needed the properties that ABS provides. I think you might have chosen the wrong material. A standard SLA is great for models. Just give it a coat of primer and sand down the build ridges, apply more primer. Done. Another thing I notice in your model is that you have too much detail. I would have made the basic model, finished it, and then added buttons and stuff later. Why? Quicker to clean and much easier to detail with paint.

[Guest B.A.F]

ok I started working on my model. Turns out that my model is from polyamide, better known as Nylon 9.

 

Ive been sanding quite a lot now and lost some detail in my model. I have used "surfacer" or spot primer to fill in the ridges, and than sanded it off again. Rpeated these steps a few times, and now I am quite happy with the surface quaility.

 

Only one thing went wrong uptil now: that is that I havent built my model from different pieces. I cant spraypaint every part seperately, and have to finish by hand (brush) and the detail is not that good, I will put up the photos later on.

 

For now these results:

 

[Guest B.A.F]

here are some pictures of the final models:

 

These are pictures taken from my desk, the display images are not in high res yet, and the polycarbonate displays are not yet attached correctly.