I’m in the early planning stages of building a LRv3. I have a Voron v2.4 3d printer that is optimized for printing in ABS. I generally never print in PLA and prefer not to. Has anyone printed the parts in ABS before, and did it work out OK? Would I need to resize the parts slightly to offset the ABS shrinkage?
Are there 2 or 3 interlocking parts that would be a good test bed to print first and try to answer some of these questions myself?
PLA is stiffer, use it. This question comes up every now and then and the answer is always the same. You can try, but it’s not recommended.
You can calibrate ABS to account for shrinkage. Bridges and overhangs are what you’ll need to pay attention to since these are PLA part designs.
You could probably sub materials for PLA but like @Tokoloshe said it’s a deviation from the original design.
I don’t see why the voron couldn’t print pla though.
I used to print mostly in ABS, and have switched out. Now I print primarily in PETg. The only thing that I miss about ABS is vapour smoothing the parts by putting them on a rack in an enclosed space with acetone in the bottom. I don’t miss the shrinkage, or warping, that’s certain.
I am usually more concerned about break strength and temperature resistance in things that I print, and the fact that the PETg that I buy is foodsafe is a bonus too when things I print are going to live in my fridge.
That said, my LR3 is printed from PLA. ABS and PETg both get their strenght from flexing before breaking. PLA is more rigid, so it doesn’t flex as much before breaking, but in general doesn’t flex as much period. Rigidity is one of the big limiting factors for something like a CNC machine, and so in order to get the best rigidity, make it from the most rigid materials available. In this case, it’s PLA.
How much does rigidity count? Well, that will depend on your project. If you are cutting coasters from pine, you’ll never notice. If you are making precision joints in hardwood or aluminum, you might need to get more picky.
Since my usage case was (and remains) a bit uncertain, I opted for the best possible outcome, and printed in PLA, and then went back to PETg for everything else afterwards, with the same settings that I used before.
It certainly could print PLA, but I’d have to remove the enclosure panels (and I still print ABS regularly, so they’ll be on/off a bunch as I work through this build), I haven’t spent any time developing good PLA profiles, and the part cooling is designed around ABS, so it is likely insufficient for fast PLA printing. All obstacles that can be overcome, for sure, but I have a machine that is excellent at printing ABS, which is a material I prefer, so I was hoping it would make sense to stick with that.
However I see the point about rigidity, so if I do go forward with a build, I’ll bite the bullet and make that happen. If nothing else, its a good excuse to burn through some of the PLA that I’ve had on hand for the last several years.
My railcore is enclosed and it prints pla just fine. Worse case if it’s really warm, like if we don’t have the ac on, I might have to open the door and maybe lift the top a bit. That said, I did print my parts in cf-petg. I did add a couple extra shells to the print though.
do they make cf-abs, or gf-abs? I don’t like printing abs, so haven’t looked.
My LowRider V1 was printed with ABS, then each part polished with acetone.
I use 103%-104% resizing to allow for shrinkage in my setup.
Still working fine a year later.
Must get around to upgrading it to V3 sometime this year.
I used ABS faithfully for years. I had waged a war against warpage and in the end, found what kept it from warping. Since discovering PLA+, I haven’t ever looked back. Sometimes I print in PETg, but my LR2 was printed 100% in PETg and I’ve had some serious warping & sagging with those parts over the 4 years it’s been running. In the process of rebuilding it now because of the PETg sagging, and the MDF warping. Sadly I have to finish rebuilding it first, just to cut the parts for my LR3. PLA+ is better than PLA, but only in very few aspects, as temp resistance, and the way it breaks vs the way PLA breaks. I think tensile strength is the word I’m looking for, but it’s not a HUGE difference over regular pla. It just prints so much nicer and easier, without the flex.
Yea, pla+ will have a bit more flex to help with tensile strength.
3DXtech makes a quality ABS-CF and ASA-CF. I’ve used the ASA-CF for Voron parts and it works great. Bought a roll of their ABS-GF on sale but haven’t used it yet. Data sheet says the CF is more rigid than GF tough.
I’ve been reading on this topic Filament stiffness test: PLA vs the world - #26 by jamiek
very interesting, and would love to see abs-cf or abs-gf in the comparison since the proposed alternative to PLA for those of us that need heat resistance is pc-cf blend from prusament which can be made out of unobtainium sometimes.
I’d assume our use case is different but ABS is recomended for vorons and it seems plenty rigid for that use vase. Maybe ABS-CF might be somewhat of an upgrade path?
3DXTech does make CarbonX exPC-CF that is probably comparable to the Prusament. Although you do need a piping hot chamber to print it correctly.
I think a misconception about ABS printer parts is that because these are used in high speed, performance machines it must be a better material overall. However, the plastic parts in these machines are used very sparingly and function mostly to mate purchased, machined parts together. In V1 designs, plastic parts serve a more integral role in the machine and therefore have different material requirements.
Use material data sheets (MDS) to compare a material’s properties to PLA. If it meets or exceeds PLA’s stats you should be OK. If the material doesn’t have a MDS don’t use it.
Also, CF as an additive does reduce layer bonding and that unfortunately is something you won’t often find on an MDS - if ever. Annealing your parts and/or printing in a hot chamber is really the only way to get the layer bonding back to it’s base materials bonding strength.
2 years later with a lot more experience tells me I should also retract this statement -
… until it didn’t. Eventually cracked on any motion parts printed with it. Why? My guess is that I didn’t have the print or chamber temp hot enough. Really should have annealed these parts before use.
Experimenting with new materials has taught me there’s a big difference between nice looking print and a functional part.
Yeah, the problem is I dont have the tools ( or the time really) to go through a bunch of materials and do proper testing as you did.
Then I’d probably stick with PLA and not really bother with any CF material. Unless it’s Nylon, PETG, or PC, I’m not sure it’s worth the hassle.
The problem persists if i stick to pla since the temps in my garage easily reach 40deg celsius in the summer.
I’m looking at buying a pc capable machime (k1, p1s, quidi…) Because i’ve printed some on my old ender and my corexy ant while finnicky i got nice prints from it.
I think it will be fine if i can get the parts printed from pc-cf
You can’t print PC parts that size on those printers. They can’t hold a chamber temp high enough to keep the material from tearing itself apart. I had to modify a V0 just to print functional small parts for my K3. You’re in a whole different machine class if you want to print large, functional PC parts. Sounds like PETG-CF is your best choice. I used it on my LR2 and it worked great.
That’s interesting; afaict the Voron community has settled pretty solidly on ASA as the correct compromise. They seem to prefer this even to Polycarbonate as the parts under load in the hottest area are also (relatively more) likely to come in contact with lubricants, for which ASA/ABS have high resistance but PC is compromised by common ones.
Do I assume correctly that your ASA parts failed on layer lines, not isotropically? If so, that would support your conclusion (print environment/settings) and not (necessarily) contraindicate ASA.
This is all such an interesting problem; we (including myself, one of countless folks involved in the community with an engineering background and plenty of experience in a couple corners of the design universe - but not all, and definitely not polymers) - we are all driving well ahead of our headlights trying to pick the “best” filament …
speaking of which, what was the best filament again?? lol 
What do you consider to be a high enough temp for PC? I have been surprised recently reading the Prusa data sheets that printing in an enclosure is recommended to avoid cooling issues, but no temperature is mentioned, admittedly their PC blend is formulated for a lower temp.
I’ve managed ASA OK at around 42° min, and my dashboard stuff has survived very well, but I haven’t been thrilled with the overall strength of the prints.