Matt finish for better post processing?  

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Lize
 Lize
(@lize)
Trusted Member

I'm planning a project which will involve printing circa 8K of lego style pieces.  Once completed these will form a picture and only the top of the pieces will be visible.

I'm just been doing some test prints trying to get a compromise between speed and quality and looks like it'll work out but may take about 1 month to print them  😆 .

They don't need to be strong and will be used indoors so I'm thinking of PLA for ease of printing, cheapness and colour range.

I'm also thinking if necessary I can perhaps lightly block sand the whole lot once assembled just to improve the round tops a little rather than doing any prep on individual bricks.  I don't want to create a difference in surface shine though so I'm thinking a matt finish might be advantageous.

So should I look at matt finish filaments or turn the temp down on a regular PLA?

I'm also wondering if I should use the same filament brand so some don't look slightly glossier/silkier than others?

It'll be quite a big project so any suggestions or advices gratefully received, thanks.

Posted : 14/12/2020 5:58 pm
Baklin
(@baklin)
Estimable Member

That is a huge project. with 1x1 lego and 8000 pieces it will be a square of around 90x90 pieces or 70x70 cm.

Just trying to picture that and thinking how that would look from what distance. Would the surface finish really be that important? I would think you will look at it from a distance anyway.

 

Getting that many pieces look the same with different colors will be very hard. You idea of sanding that all together sounds like a good idea to me. But be careful with sanding as it is very easy to overheat PLA that way. 

 

Just thinking out loud here. Lets see what others thing.

But would love to see the finished project.

Posted : 14/12/2020 6:33 pm
Lize
 Lize
(@lize)
Trusted Member

Yes, pretty big at around 70x75 😀

I had wondered whether to reduce the number of bricks and colours but I don't think it'd look good.  I think it might be quite challenging and if it works out I'll definitely share a photo.

Looking at what I'm testing now I'm tending to think that 0.2 height with concentric top layer won't need any post processing.  I'm used to printing small things which are examined closely but with this one as long as the bricks aren't terrible I think it'll be OK.  I'll print a larger number of bricks and decide from there as well as exploring the matt option too.

Posted : 14/12/2020 6:54 pm
Baklin
(@baklin)
Estimable Member

Prusa Slicer has the variable layer height option that could be useful for this as you will only see the tops of the bricks. That could speed things up.

Posted : 14/12/2020 7:46 pm
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bobstro
(@bobstro)
Illustrious Member

If I'm understanding correctly, you want to print a large piece that looks like it was made from lego bricks. Only the tops will be visible. If this is the case, why not just print thin tops and save a LOT of filament? Have you considered just printing panels of brick tops at the maximum size that will fit on your printer bed, then just painting the tops? If you use a thick paint, they should all look somewhat like the original plastic (ABS IIRC) and have a uniform finish.

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 14/12/2020 7:51 pm
Lize
 Lize
(@lize)
Trusted Member

Thanks, different layer height is a good idea, I've made the bricks a low height but it would still save a fair chunk of time.

 

Individual bricks of 1x1 size (8mm square with 1 round top) in different colours which are snapped onto a board in a single layer to form a picture.  I could print smooth tiles but it won't look the same without the lego shape.

I was hoping to avoid painting as that will be very time consuming, if I did that then I could make a board with tall dots and space around them to make spraying easier.

Posted : 14/12/2020 8:02 pm
DarcShadow
(@darcshadow)
Trusted Member

I was hoping to avoid painting as that will be very time consuming, if I did that then I could make a board with tall dots and space around them to make spraying easier.

More time consuming than printing in different colors? For the time and money you're going to spend I'd find a lego store and just buy what I need. Have the whole project done in a weekend.

Posted : 14/12/2020 8:16 pm
bobstro
(@bobstro)
Illustrious Member
Posted by: @lize

[...] Individual bricks of 1x1 size (8mm square with 1 round top) in different colours which are snapped onto a board in a single layer to form a picture.  I could print smooth tiles but it won't look the same without the lego shape.

Sounds like you want to do something like Lego pixel art but on a larger scale. If most of the background is one color, you can print larger plates in that color, then just do the individual colored "pixel" pieces in other colors. I'd be inclined to cheat and print larger pieces in the needed patterns and fit them together rather than build it from that many 1x1 blocks. In the example below, print the green sections as 2 large parts. Unless, of course, this is just something you enjoy doing like a jigsaw puzzle.

 

This post was modified 2 months ago by bobstro
My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 14/12/2020 8:37 pm
Lize liked
Lize
 Lize
(@lize)
Trusted Member

I understand what you're saying. I'm not in the habit of printing things for the sake of it and will opt to buy something if its cheaper/readily available but I thought it'd be a fun project and be satisfying.

Lego store bricks = over £500 + base boards

Rolls of PLA in colours I don't have would be about £150 or less if I bought smaller rolls of the shorter volume colours and still quite lot of left over for other things.

Think I'll give it a go and report back.

Posted : 14/12/2020 9:24 pm
Lize
 Lize
(@lize)
Trusted Member

@bobstro

Yes, I wondered about printing larger parts but then thought you might see theres no gaps.  I'll have a try at that as well and see what I think, it'll take some time to sort out the colours for various sizes.  Would be even more like a jigsaw, just a bit quicker on assembly.

Did you print those, they look very smooth or are they bought ones?

Posted : 14/12/2020 9:29 pm
bobstro
(@bobstro)
Illustrious Member
Posted by: @lize

[...] Did you print those, they look very smooth or are they bought ones?

Oh, sorry for the confusion. That's just an example of "Lego Pixel Art" I found on the Internet. I wanted to make sure that's the sort of thing you wanted to print.

You could try printing larger parts with groves between the Lego parts, then dip just the bottom-most layers in a thinned wash of dark paint to enhance the appearance of separate pieces.

 

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 14/12/2020 10:09 pm
Lize liked
Swiss_Cheese
(@swiss_cheese)
Reputable Member

Perhaps printing with a Hilbert Curve and a single perimeter will give you the look you want? without having to post process.

 

Posted : 15/12/2020 1:19 am
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