Hi,
Looking for information on whether anyone has used PolyMide PA6-CF before to print the parts for the MPCNC? Ive just seen that it looks like there’ll be an upgrade soon, so will probably wait for that to print the parts, but what are your thoughts on the material?
Thanks,
Zac
Wow that stuff is expensive!
If anyone has ever used it for the mpcnc, they haven’t mentioned it on the forums.
I personally feel that nylons elasticity makes it not an ideal material for this application when compared to PLA, but i’ve been wrong before.
My printer
The question is: why do you feel like you need such an exotic filament for the MPCNC? There are many filaments that are better than PLA, but they are all overkill for the MPCNC. PLA works great. If it ever doesn’t then I would consider reprinting the specific parts that you have trouble with.
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Nylon is generally softer but they are claiming it is much stiffer on account of the carbon fiber reinforcement.
Another potential disadvantage besides cost is the parts are designed to flex somewhat to accommodate the tolerances of the tubing and other things. A build that is quite a lot stiffer could suffer by being too stiff. You could end up with very different clamping force on the tubes and different behavior of the tension bolts. That’s speaking of Burly. I can’t say if Primo will have parts that can be made extremely stiff without downsides.
Same issues.
I’ve read the page about dimensions of the MPCNC, and the contributing factor for it being defined to certain working perimeters is because the larger it is the less rigid it is. I was wondering whether the PA6-CF could overcome these rigidity issues
The rigidity limits are an outcome of the flex inherent in (and thereby contingent upon) the length of the conduit rails, not the plastic components that connect them together.
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For X and Y size, the deflection of the tubes and stretching of the belts is a bigger factor than deflection of the plastic parts. For larger Z stickout, maybe, but stiffer plastic may or may not be the best workaround compared to drop tables or even crazy less common approaches. The general attitude is that the bit length limits Z anyway, so just build it short and that should accommodate almost all the use cases.
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What length and width do most people build these to? In metric if possible
What I was trying to do was increase the build space by upping the strength of the overall build - stainless steel tubing, stronger printed parts with extra feet for more stability along the tubing, and stronger connections. Otherwise maybe I’m better of building the LowRider v2? I’m wanting to cut aluminium and other soft metals, and just wanted to do everything I could to get the best of both worlds
Aluminum works better with smaller builds, roughly 60cm square. If you already have the filament, go for it, but know that it’s pretty much two kilos of plastic to print, plus whatever midspan supports will use. I’m interested in how it turns out.
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I’ve printed that filament for structural parts that need high impact resistance and flex. It prints much more easily (oozily?) than some other straight nylons without much warp at all- but, as others have pointed out, it’s probably unnecessary and expensive for an mpcnc build where PLA will do 
I’m new around here, planning an MPCNC build for the stuff I can’t print or laser. I’m aiming for 2x3’, a little larger than recommended for a first build, but the project that started me down this road needs some parts that are about 400mm long. I don’t see any reason not to add mid-span supports to the 3’ axis, so I’ll likely do that.
Since this seems to be the “what filament?” thread, what about PETG? Everyone around here seems to just recommend PLA, but as my machine is likely to need to be able to run outside, I’m a little concerned about things softening in the sun. There’s one reference in the build guide to PETG, but I’m wondering about the pros and cons. I haven’t really dialed in PETG on this printer, but I have ABS printing quite well, so it should be doable. HTPLA is an option, but expensive, and the heat-treating has dimensional stability challenges.
For that matter, is ABS not mentioned because of warping, or some other reason?
Any advice is appreciated, I’m reading all I can, dragging my feet a bit to see if the new design is ready before I get to this project.
Thanks! -Zandr
PETG can work, but it isn’t as rigid as PLA. So add another 1-2 perimeters. ABS is similar, but why mess with that nasty stuff?
PLA deforms at about 60C? The motors generate some heat, but unless it is in a greenhouse or a car, I would expect it to be ok. I would keep it in the shade as much as possible. I don’t thin UV is very good on any plastics.
The plan isn’t for it to live outside, but my back yard is on the south side of the house, so there isn’t a ton of shade. I’m in Norcal, so it’s not that hot most of the time, but it is sunny. Space in the garage is at a premium, and I’m planning a portable build so it can store vertically.
Yeah, Tg is about 60C for most PLA. I was actually thinking about the fiber-reinforced HTPLA before I found this thread, but it sounds like the fiber stuff might be too rigid.
The good news is that I can always re-print if there’s a problem, so I guess I’ll just get some cheap-and-cheerful PLA (in white to minimize heating in the sun) and try it.
Thanks for the quick reply!
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I am getting ready for Primo and (reasonably priced) PLA is sold out in most places. The PLA rolls I have…are not colors I would want to make the MPCNC. However I can find PETG fairly easily; on top of that my MPCNC sits in a shed outside that can get pretty hot. I thought that I might print the next one in PETG. I always print anything structural with 4 perimeters, is there anyone that you know with experience using PETG for the MPCNC?
My center part is made from good quality PETG. It looks and feels great, but when I try to twist/bend it, it seems way too flexible, compared to the PLA. There’s too much flexibility in the center part now. I will for sure use PLA for the Primo, but not a brittle type, since the brittleness is detrimental to the bolts and heads. I used very brittle PLA for the feet, and they cracked quite easily.
My “trucks” are PETg, as are the feet, with 6 perimeters. The main center assembly is PLA, though (and I was afraid I wouldn’t be able to get it square; it was stiff!) I haven’t cut anything significant yet – mostly still carving high density foam while I get my feet wet / figure out what I’m doing – but it’s working quite well. Given their size, infill, and perimeters, my PETg pieces don’t bend or flex at all. (Well, except where they’re supposed to, e.g. the feet clamping to the legs.)
I wonder if PLA+ would provide a better (or worse) build.
I have heard that PLA+ has lower stiffness than regular PLA. This was a shock to me and troubling since I normally print with PLA+. I’m not sure if “PLA+” is well defined or if it is just “with additives” but regardless, I bought some straight-up PLA for when Primo comes out.
I’ll try to find the thread where they talked about PLA+ vs. PLA. It wasn’t that long ago.
Edit: from another thread eSun filament data sheet: https://www.matterhackers.com/r/oqRtJt
But not all PLA+ is necessarily the same.