CoreXY or Cartesian which is better ?

oliof

@Hiroaki both Cartesian and CoreXY can be made to the same quality as CoreXY is just Cartesian rotated 45 degrees.

If I would guess, I'd assume you are asking about "moving bed" designs or portal style printers versus "raising bed" or box style printers.

Box style printers inherently have more rigidity (if built correctly) because there is more frame. As such they can be better than an open frame portal design. But there are Cartesian Box Style printers (for example the Ender5 with the flying X motor gantry), and Cross-Gantry setups in boxes (Ultimaker, CroXY, ...). And their qualities differ (accuracy, precision, speed, ease of use, ease to build, ...). In the end, as with all engineering projects, it's a matter of trade-offs.

giostark

@hiroaki
CoreXY should be more stiff and accurate (and faster) if build with qualitative parts. Ex here you can assemble a full metal printer with part for hight temp materials , is not cheap but it is really good (CNC milled parts for the most) :
https://hightemp3d.com/products/railcore-ii-300zl-3d-printer-full-kit-1?variant=33213296640086

jens55

Cartesians are ok for small beds but I would say the practical limit is 300 mm square and even then you have some oscillations. I guess it depends on your tolerance for imperfection. Most people would be happy.
I also have a 500 mm cartesian and I have to reduce acceleration and jerk quite a bit and still have a lot of artifacts. OK for large prints where aberrations are drowned out by the size of the print. I guess it all depends on what you print and how fussy you are. For me, I am in the process of building a Jubilee (corexy)

fcwilt

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

Cartesians are ok for small beds but I would say the practical limit is 300 mm square and even then you have some oscillations.

Because of the weight of the X axis stepper motor in motion?

jens55

@fcwilt, because of the weight of the bed moving around. The stepper motor is stationary so it doesn't make a difference. I am talking about a CR10 style printer where the bed is actually the Y axis but it doesn't matter which axis it is, either x or y, the bed just as too much mass to be 'slinging' it about (which is why these kinds of printers are often called bed slingers)

I guess when it comes down to it, as long as the bed is Z and only moves slow, it doesn't matter what the rest of the motion system looks like.

fcwilt

@hiroaki

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