Which Material for CoreXY parts

Hey there,

I own an FLsun Cube which has a very large build platform (300*300) but I dont like it's kinematics because it has to move the x motor.

So i want to build a CoreXY (design from Zelogik/jand) out of it which does not need so much parts and seems very feasable for me.
So i used to print everything out of PLA and got good parameters for that. But i wanted to make the parts for the CoreXY out of PETG for some reason.

Now after I printed 2 bigger parts out of PETG I noticed that they are not as rigid as PLA but more flexible, which I think is not what you want for a (fast moving) CoreXY.

So my simple question is: Should I print the parts for the CoreXY in PLA or PETG and what would be the benefits of each?

PLA is more rigid, and more brittle, main issue is low melting point, can start to deform at 60c, so warm stepper and hot extruders can be a issue.

Edited 1 time(s). Last edit at 08/27/2017 09:05AM by Dust.

Melting temperature notwithstanding - if deflection is an issue - use thicker models or lighter components.

AFAIK CoreXY you're trying to print was originally designed for aluminum. If you want similar performance you'll have to thicken the parts for sure - especially motor mounts. Have you considered Hypercube design? That one was modeled with PETG in mind and people seem to have a good results.

Edited 1 time(s). Last edit at 08/27/2017 10:02AM by newbob.

I've rebuilt my (now heavily customised) smartrapcorealu corexy with petg parts and whilst they might not technically be as rigid as PLA their survival long term is practically guaranteed. It previously had PLA parts which cracked.

If you can make everything out of metal do so, it will make a difference.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

I do not own or have access to a cnc so making the parts out of alu would cost more than the printer.
The design of zelogik was originally designed for metal but jand adapted it for printed parts. There are some people using this design with printed parts. And it also looks very stable (but also more bulky than hypercube).
I ve heard a lot good things about petg and was just wondering wheather the flexibility would be a problem but it does not seem so.
Thank you all

PETG is only really flexible in thin sections, thicker printed parts do not exhibit gross flexibility. Its very strong, but its impact resistance is far less than for ABS/PLA and it shatters if dropped onto a concrete floor. But I happily print most functional parts in PETG. It taps nicely for addition of hardware.

---

Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

How about eSun ePC? It has worked well for me for some structural parts. Not cheap, but very strong and durable.

PC produced some very tough and durable parts for me, i like the material though i seldomly need something as tough. Usually ABS does the trick for me. Since ABS is a lot easier to machine i prefer it over PC

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[www.bonkers.de]
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Quote
Schild0r
I do not own or have access to a cnc so making the parts out of alu would cost more than the printer.
The design of zelogik was originally designed for metal but jand adapted it for printed parts. There are some people using this design with printed parts. And it also looks very stable (but also more bulky than hypercube).
I ve heard a lot good things about petg and was just wondering wheather the flexibility would be a problem but it does not seem so.
Thank you all

Each plastic has different qualities so unless jand adopted the coreXY for parts made of flexible filament printed parts may not be strong enough - depending on plastic used and type of forces (compression, elongation, sheering). If PLA is exposed to heat PLA looses to just about any other plastic but has very good properties otherwise.

There are many strength testing videos on youtube. Here's one: [youtu.be]

The zelogik design has already been translated into plastic - the G&C printer

More info here: [forums.reprap.org]

This is what I've built, with only a few modifications. It's currently sitting about 100mm from my left elbow as I type, as I've been printing some parts today! The designer has also published a more sturdy version using linear slides, but that's a lot more expensive to build.

Edited 2 time(s). Last edit at 08/28/2017 11:20AM by David J.

Before rebuilding your printer, you might want to look at how much moving mass reduction you will actually achieve as compared to the increase in belt length. Generally, you want to reduce the moving mass to reduce ringing from the springiness of the belts. If you cut your moving mass in half but end up doubling the belt length (thus halving the belt stiffness), then you haven't really achieved anything. Unless, of course, you are doing it for fun.