Give me control of the seams!

[yeahtuna]

UPDATED:
Through this thread, I've researched and found solutions to printing extremely high quality enclosure. The key is in the design of the models and not the settings of the printer. The lay you lay things out on the platform will affect where on the part the seams occur. Hope this can be a guide for other makers. -Rob


So I just got my brand new UP Box+ running--doing some test prints. I'm coming from an UP Plus which suffered a burnt out heater element. It has worked very hard for me, so I'm not disappointed--I did buy a replacement part JIC.

I use 3D printing to do low-volume production of enclosures for devices I make and sell online. For me having a pristine finish is key for being able to successfully use 3D printed parts in "commercial" products.

I have been printing 2 enclosures per run on my UP Plus with great results. Now with the extra real-estate afford by the UP Box+, I'm looking to print between 4 and 8 units at a time.

But unfortunately, I'm running into issues with seams. They're all over the place--nasty at times, and in different places for different parts. I need a way to control the seams.

I'm not holding my breath for improvements in the slicing engine and UP Studio (although this can post can serve as my official request). Instead, I would like to hear of anything I can do to trick the slicer into doing what I want it to do.

Some Questions I have Without Answers
Is there any logic to how the slicers decides where to put the seams?
How does placement on the platform affect this?
Does loading multiple STLs versus one STL with many parts in it make a difference?
Is there some sort of structure or feature I could design into my parts that might coax the slicer to put the seam in a specific place?

Some Pics
Here's a run of two that's not too bad. One of them is about as good as I could hope for, but the one the left has a got some stray seams near the top.

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Here's an example of nasty seams. I never want to see things like this. This was also from a run of two. One was perfect, but this one is totally not acceptable.

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[yeahtuna]

I've made some progress by carefully choosing the layout of my parts. I used the assumption that the slicer would try to minimise the travel distance between the various parts. So by keeping the back edges of the enclosures adjacent to each other, all the seams appearing exactly where I want them. I've attached an image of the layout I used below.

Unfortunately, I'm still getting what I would call "nasty" seams, when there are lumps of plastic protruding from the seam, giving the part a bumpy and rough texture. I can only assume that this is the result of filament continuing to extrude from the nozzle while moving from part to part. I'll try playing with the temperature settings, and hopefully that will also be resolved.

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[yeahtuna]

More seam issues with another part. Again, I need to find a way to control where the seams are appearing. Here are pics of the top (visible) side of the enclosure, and the bottom (usually hidden) side of the enclosure. The top side looks nasty, and the bottom is pretty much pristine. I need the opposite. I need the top of the enclosure looking good with seams on the bottom.

Top:

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Bottom:

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[yeahtuna]

Success! I did a few alterations to my part and it printer perfectly! I changed the wall thickness from 1.5mm to 1mm. If you go with 1.5, Up printers will just leave a 0.5mm gap between two 0.5mm walls. In fact, the 1mm wall feels a lot stronger than a 1.5mm wall. Secondly, I add a breakoff support structure to hold up the USB connector cutout. My last design had support structures that came out from the walls at 45 degree angles. An hour ago I was getting ready to sell this printer. Here are pics:

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[yeahtuna]

After a couple of days of research, I've come up with the ultimate solution to controlling the seams on enclosure with 2mm walls. The trick is to design your enclosures as two separate 1mm enclosures that are extremely close together, but not touching (I used a 0.01 gap) Any internal support structures should be attached to the inner enclosure, and the outside enclosure should simply be skin that covers the internal enclosure.

Here are the reasons to do this:

1) Pristine results
2) Stronger Parts
3) Easier on the the printer and your ears; the printer does not need to rapidly oscillate to lay down infill.

Here's a screenshot of one of my models. Notice the built in support structures. DO NOT attach any support structure to the outside skin. I hope this thread helps someone else down the line!

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[JuanCR]

Thanks!