Design Choices - Vertical or Horizontal Printing?

I just can't decide what to do.

I want to 3d print objects about 7" x 30" x 5" although I'd also like to print some things around 12" cubed but that isn't my main reason for building this . I was also thinking about using some Nylon X or similar nylon & carbon fiber filament. I have decided to go with an IDEX style dual print head.

Do I want to print the parts horizontally or do I want to print the parts vertically?

The vertical system will be far easier to build. I will only need one Z axis and the build plate will be much smaller, perhaps 12.5" x 15" based on some of the linear rails that I have and using IDEX dual extrusion.

The horizontal system would have a build plate of about 14" x 36" (with about 30" usable) and require two shorter Z axis and be more work to build and take up a much larger footprint.

I will be using good square type linear rails for the whole project.

I am concerned that printing the parts vertically will lead to less strong parts, although I think there may be ways to fix that and reinforce the parts afterwards.

I am concerned that printing the parts horizontally might lead to increased chances of peeling from the bed and other problems?

If it turns out that I don't need the soluble support material, the IDEX configuration will allow me to print two parts at once in either configuration.

Any advice is appreciated. I just can't decide what to do.

well the first thing has nothing to do with the printer design.
Nylon ? really ?
Didn't peg you as a masochist :-)

So the most important thing you'll need is a good actively heated print enclosure.
It's probably the hardest filament to use I've come across.

You can use MyMatt nylon - non warp doesn't need enclosure - not sure if it's available in the states: http://mymatstore.com/epages/ec7809....oft%20Nylon%22
Amazing stuff - no warp !
I guess the money you save on enclosure could go towards the p&p from spain :-)

As for vertical versus horizontal - it's entirely down to the materials you'll be using and what direction any stress will be applied to the parts.
Nylon and flexibles tend to have much better layer adhesion than the harder plastics.
Get pet-g right and it's also got excellent layer bonding.
Get it a tad not perfect and it's absolute crap :-)
I've just switched the brackets ona slinging target from pet-g to cheap flexible pla on the gorunds the pet-g broke when hit with a large hammer and the flex-pla didn't :-)

If these are structural parts and take either a tension force either parallel to the long axis, or a shear along the short axis, printing them vertically makes no sense. Yes you can reinforce them later but then the 'reinforcing' will be taking all of the load and the 3d print will be purely cosmetic. I don't care what anyone says about the layer bonding of nylon it's still FDM and the layer lines are considerably weaker. Besides, that's a really long part and nylon is a floppy noodle compared to most other 3d printing plastics, what exactly is this part going to do?

Printing them horizontally is going to have more risk of warping, but makes more sense structurally. Could you draw a quick diagram of the part (a rectangle will do) and the forces you're expecting it to take? That'll help decide which orientation to print in. For some cases it might even be beneficial to print them vertically.

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Originally Posted by curious aardvark

well the first thing has nothing to do with the printer design.
Nylon ? really ?
Didn't peg you as a masochist :-)

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I've been accused of a few things, but never a masochist. Wait, is a masochist someone who makes their own life difficult and tortures them self because of dumb decisions or for no good reason? Mind blown. I might actually be one. Is there a self help book for this kinda thing?

Quote:

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Originally Posted by curious aardvark

So the most important thing you'll need is a good actively heated print enclosure.
It's probably the hardest filament to use I've come across.

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So some of the issues that I am thinking about..........I found these videos on YouTube, I am not affiliated with any of the makers of these videos, I am simply using them to facilitate discussion, so if one of these videos belongs to anyone here, thank you for sharing it!

Some discussion on unheated surfaces for printing Nylon:

phenolic
https://www.youtube.com/watch?v=TgkFS2MeQFI

garolite
https://www.youtube.com/watch?v=WcYnSTZscGc

Interesting in the above video at 9:52 he mentions that the mark forged printers do not have a heated bed. From this it looks like Nylon is easier than ABS is you get the right bed material and make certain your rolls are dry?

Looking at the strength of Nylon:

https://www.youtube.com/watch?v=48NC0KDmcBo

If you look at 7:15 in the above he mentions that the strength of his tests was actually lower when printing horizontally, which I find to be surprising.

Nylon on it's own is too flexible for my application, which is why I have been contemplating a Nylon Carbon fiber mix. I have also been contemplating trying to use continuous strand carbon fiber embedded in the prints. I think I could modify a colour mixing nozzle to do this. If I go with the vertical build, I can't do this anymore as the orientation will be in the wrong direction. But perhaps this would be a waste of time to pursue, given some other simpler options, at this point, I don't know.

Quote:

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Originally Posted by curious aardvark

You can use MyMatt nylon - non warp doesn't need enclosure - not sure if it's available in the states: http://mymatstore.com/epages/ec7809....oft%20Nylon%22
Amazing stuff - no warp !
I guess the money you save on enclosure could go towards the p&p from spain :-)

As for vertical versus horizontal - it's entirely down to the materials you'll be using and what direction any stress will be applied to the parts.
Nylon and flexibles tend to have much better layer adhesion than the harder plastics.
Get pet-g right and it's also got excellent layer bonding.
Get it a tad not perfect and it's absolute crap :-)
I've just switched the brackets ona slinging target from pet-g to cheap flexible pla on the gorunds the pet-g broke when hit with a large hammer and the flex-pla didn't :-)

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Thanks for that info. If the layer adhesion for Nylon is better, perhaps this isn't an issue and I should do whatever is simplest to do? Even though Nylon isn't stiff, but can be made stiff with CF, my understanding is that it has good impact resistance and is hard to actually break, so that's a big reason why I'm considering it.

Some more thoughts that I've had:

Looking at bed lifting on larger parts:

https://www.youtube.com/watch?v=X6_i6DHRLhA

I've been watching a bunch of this gentleman's videos, perhaps he is a member here? Looks like he is using ABS, which I am not planning on at this point, but it seems to me that the larger the print surface in contact with the bed, the more the chance of it delaminating from the bed while printing? Or perhaps this is just an ABS phenomenon?

Lastly, I will be using the Z axis of this printer as a top down DLP printer also. As this kind of printer only has one moving axis, it seems obvious to me to simply incorporate it into the design, mount the projector on the side of the FDM machine frame, have a piece that connects to the printer's z axis from the other side, and bob's your uncle, you could use it for either purpose. The longer Z axis would give me the option of DLP printing longer parts. Although if it turns out that horizontal printing is better for FDM, I could simply make a separate printer with a single axis for DLP.

@ Trakyan, I can't really say what the forces will be, it's more of a thing where if it were made from 3/8" hardwood and hollow in the middle, that would be sufficiently strong. I am more concerned with delamination between layers and stiffness (hence carbon fiber). Impact resistance is also important. Also these parts are much longer than any I have seen in any Youtube vids being printed vertically so issues of Z banding perhaps and print quality, I don't know if they would be an issue, but I would be using much better linear components than you typically find in 3d printers so this should make a huge difference.

Also I should mention, thank you gentlemen for the replies so far, and I still don't know which path I will take so any further input is appreciated.

You'll run into a few issues with continuous fiber. First of all, there isn't really a 'finished' design out there you can borrow or use. Markforged are closed source and have a patent on their system. Second, you cant use regular carbon fiber strand, the stuff they use is sort of 'soaked' in nylon so it adheres/fuses to the print when heated. Lastly, it's a whole lotta hassle and I can't think of any slicers or firmware you could use, unless you fancy writing it yourself. Personally, writing a slicer is above my pay grade.

Since strength doesn't seem to be an issue, why are you using nylon and trying to make it stiff? Why not just use a stiffer material to begin with? PET/PET-G seem like they'd suit your application. Side note, nylon being as absorbent as it is isn't a good choice for things that are likely to get handled often-ish. It absorbs oils and dirt from the skin and ends up looking a nasty yellow.