CoreXY or Cartesian which is better ?

fcwilt

I currently have three printers:

The first is a "classic" Cartesian, an FT5, with a remote drive extruder, a Nimble

The second is a design of my own based on the MarkForged style but with two Y steppers, also with a Nimble. I recently modified it to use a belt driven Z axis with three steppers to support auto bed leveling.

The third is a modified Chinese kit based on the Ultimaker style (cross gantry) also with a Nimble.

They all print just fine but I don't try to print at high speeds - I stick to 60 to 90 mm/s.

I tried a CoreXY but did not care for the long belt paths which led to the design of my second printer.

The kinematics of the third printer strikes me as rather elegant but it is a small unit with a 200x200 bed and perhaps that avoids any problems that the cross-gantry approach might have.

I've seen lots of CoreXY designs but not many MarkForged or Ultimaker designs but I have no idea why.

Given my success with my current printers I don't see me trying a CoreXY again.

jens55

@fcwilt, that list puts you well above my level of experience. I just know that throwing a large bed (or really any substantial mass) in x/y is a mistake. I currently use the same speed range that you describe but speed really isn't the issue but rather acceleration or change in speed per given time unit. I can s l o w way down and all of a sudden there is no issue with moving a heavy bed.
I am sure that my understanding of 'cartesian' motion system is not complete either so if there is a 'cartesian' setup that doesn't move the bed in x/y, my comments don't hold water (or filament)

Michael Hathaway

@hiroaki The less you move the bed, the better. Linear rails is a plus. My new printers have lifting/flying gantry with a solid non-moving bed. I have all screw drive with no belts which I think is better, but that is debatable.

Hiroaki

@hiroaki said in CoreXY or Cartesian which is better ?:

Hello there.
I have made some CoreXY printers and one Cartesian (which moves heating bed for X axis) but I am wondering if Cartesian which moves the nozzle X and Y axis is better than CoreXY to make the machine more accurate.
If there is anyone who has made both CoreXY and Cartesian which moves the Nozzle for both axis, please give me your idea.
Regards

Everybody Thank you.
Please take a look at the photo.
My question is whether COREXY or cartesian has better position accuracy, assuming a printer like this one. 　Sorry for confusing...

fcwilt

@jens55 said in CoreXY or Cartesian which is better ?:

I am sure that my understanding of 'cartesian' motion system is not complete either so if there is a 'cartesian' setup that doesn't move the bed in x/y, my comments don't hold water (or filament)

A bed slinger always struck be as a less than good idea and I never considered having one of those.

My first non-delta printer was the FT5 which moves the bed on the Z axis.

Two steppers move the X gantry along the Y axis.

One stepper, mounted ON the X gantry moves, the extruder assembly along the X axis.

This to me was the "classical" Cartesian printer but perhaps a bed slinger is a Cartesian as well.

As I understand it one of the goals of the CoreXY design (and perhaps others) was to get the X axis stepper OFF of the moving bits thus reducing the mass of the moving bits - in theory.

Phaedrux

CoreXY is a lot easier to build than an ultimaker style cross gantry. I'd say it's hard to beat in general for a good all around printer.

fcwilt

@tinken said in CoreXY or Cartesian which is better ?:

@hiroaki The less you move the bed, the better. Linear rails is a plus. My new printers have lifting/flying gantry with a solid non-moving bed. I have all screw drive with no belts which I think is better, but that is debatable.

Ya gotta love it.

My current favorite printer has all belt drive.

I guess these differences are what keep life interesting.

fcwilt

@phaedrux said in CoreXY or Cartesian which is better ?:

CoreXY is a lot easier to build than an ultimaker style cross gantry. I'd say it's hard to beat in general for a good all around printer.

I can see that it is easier to build - with the cross gantry system getting everything lined up just right so there was no binding took a bit of fussing and cussing.

Now I'm no expert and I have seen the math on the different kinematics but I let my eyes glaze over and move on to something else.

My "MarkForged" style printer with the two Y steppers seems to avoid the racking issues folks talk about. What I like is that the belt paths are are shorter even though it takes three belts instead of two as in a CoreXY.

I've got a couple of Chinese CoreXY kits that have been sitting in boxes for a year or more - perhaps I will decide to re-visit the design.

Hiroaki

@fcwilt I agree! Thanks

Hiroaki

@fcwilt I have thought about to make one with lead screws(or ball screws) . But when I calculate the travel speed between belt drive and screw drive, and also wear out of the screws, I gave up making one. What is the lead of screws of yours? I feel that with the belt drive, it goes too much and with leadscrews it goes too small....

o_lampe

@hiroaki
There are leadscrews with 8mm lead. They'd be faster, but IMHO also wear out faster and need stronger motors (higher risk of loosing steps).
I went for ballscrews right away, but not for XY axes. They run easier and don't wear out fast.

oliof

@phaedrux CoreXY may be easier to build, but it's ultimately (pun intended) harder to square. An ultimaker style sheet-based box printer is more or less self-squaring ...

o_lampe

@oliof said in CoreXY or Cartesian which is better ?:

CoreXY may be easier to build, but it's ultimately (pun intended) harder to square.

Do you talk about belt tensioning?
TBH, I made up an easy to implement "belt tension-equalizator". But never felt the urge to implement it.
Lazyness: 1
Difficult to square: 0

oliof

@o_lampe no, I mean getting the frame square, especially when using aluminum extrusions. Belt tension is another issue, looking forward to see your fix (-:

fcwilt

@hiroaki said in CoreXY or Cartesian which is better ?:

@fcwilt What is the lead of screws of yours?

I don't understand the question. The one printer I mentioned, in response to your post about having all screw drive, has all belt drives.

Frederick

fcwilt

@oliof said in CoreXY or Cartesian which is better ?:

@o_lampe no, I mean getting the frame square, especially when using aluminum extrusions. Belt tension is another issue, looking forward to see your fix (-:

What do you think about the E3D motion system in that regards?

Thanks.

Frederick

fcwilt

@oliof said in CoreXY or Cartesian which is better ?:

@phaedrux CoreXY may be easier to build, but it's ultimately (pun intended) harder to square. An ultimaker style sheet-based box printer is more or less self-squaring ...

Can you provide a link to a design like that?

Thanks.

Frederick

mrehorstdmd

You don't "tune" belt tension in a corexy printer. The exact and even the relative tensions of the belts isn't important (of course, you don't want them flopping around and you don't want them so tight that they destroy the motor bearings). All that matters is that the x and y axes are square when you're finished. That's easily verified in different ways depending on how your machine is built. The way most corexy mechanisms are laid out, the belts will be about the same tension when the axes are square.

It can be pretty easy to align the linear guides in a corexy printer if you build the xy mechanism on a flat plate. That's probably true of any other xy motion system, too.

You can design any printer to be easy to align or alignment can be an afterthought, and then you suffer the consequences.

Hiroaki

@mrehorstdmd I understand! Thank you!

Michael Hathaway

@hiroaki I don't use T8 lead screw (too slow), I use Igus high helix lead screws. I will never be as fast as the corexy guys, but I have no belts.

https://youtu.be/I-3kKkkonrs