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TL;DR

Is ABS a better material to use for structural parts of a 3D printer, as opposed to PLA?


I have been looking at various suppliers of printed parts for a Wilson II, on eBay.

One supplier supplies all of the parts printed in ABS, whereas another supplier provides the structural parts, which form part of the frame, in PLA, and the remaining (non-structural) parts in ABS. The second supplier states the following:

This kit is printed in two materials, the structural parts are printed on high-quality PLA to provide the necessary rigidity, and the others in premium ABS.

MJRice, who developed the printer, also supplies the printed parts, which are made of PLA.

Is PLA really a better choice for structural components? A quick google lead me to ABS or PLA: Which 3D printing filament should you use?

ABS is going to give your projects better structural integrity and will be more suited to mechanical use given the material can better withstand the elements, but it will also require specific types of printers and printing surfaces. On the flip side, PLA will give you more precise prints and better aesthetic quality, as well as more flexibility with printing conditions if you can do without the strength and resilience of ABS.

Another link, What's stronger? PLA or ABS?, also implies that ABS is stronger than PLA:

The strongest ABS is stronger than the strongest PLA

and

ABS is much less brittle than PLA

although warpage could be an issue...

I choose ABS for it's strength over PLA. I would love to avoid the warpage/shrinkage problems of ABS.

Heat seems to affect PLA more than ABS (obviously, due to the lower melting point),

FWIW, I know a guy who had a reprap using PLA-printed parts. He was taking his machine around to do demos and he left it in the car mid-day once. It melted the parts enough that prints were coming out very poorly even after his best effort at recalibrating the machine.

and as I am in Thailand, my room gets up to 50°C some days (it is unbearable), I wonder if that would be cause for concern?

So, from the above nuggets of information, wouldn't ABS be a better choice? I am surely missing something, as both the second supplier, and MJRice, use PLA.

1 Answer 1

50°C is hot for you. PLA's glass transition temperature is 65°C. A car in the mid-day sun can get very hot indeed.

As to the question of "stronger" - if the part is designed to be strong enough for its use in PLA, it will be no better in "stronger" ABS. If the PLA part will be "more precise" and "less warped" - that may well make it better for its use. Other than a widespread community dedication to self-replication, (or mostly self-replicating with some metal parts) there's plenty of arguments for making most printer parts out of machined metal, for that matter - much stronger than ABS or PLA.

Brittleness likewise might matter if you were planning to drop the printer; but should not matter in use if the part is designed for the forces it will see in the material it's designed for. Looking at older technology, many machine tools are made of cast iron, which is quite brittle, rather than steel, which can be less brittle depending on how it's processed. If the part is designed for the job and used/handled in a reasonable way, "brittle" is not an inherently bad thing, and a thin steel part that flexes is a worse thing than a thick cast iron part that flexes less.

As for

withstand the elements

that appears to be a reference to outdoor use where PLA will break down - but if you are not leaving your printer out in the rain (which will be bad for many other parts unless you do a lot of engineering to protect them) that should be of little concern.