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SoliForum - 3D Printing Community → 3D Printer Discussion → CoreXY vs Ultimaker-style gantry
I've been Googling gantry designs, and it seems both CoreXY (as well as the related H-Bot, without a belt cross-over) and Ultimaker-style achieve the goal of having both X and Y motors stationary. However, I've been unable to find something discussing pros and cons. Also, if these are superior (in terms of minimizing moving mass), why aren't they more commonly used?
They are more difficult to implement, and less established. I imagine you will see them more frequently if bowden continues to be a desirable setup.
There is a lot of discussion about pros and cons though, if you google it. Especially on the reprap forum, but less often on places like soliforum because that kind of an upgrade is a very intense change in the mechanics.
So I built my H-BOT last month and have been slowly inproving it week after week:
PROs:
Fast
Perfect circles
No moire
X follower sweet (623 bearings instead of delrim blocks)
Single belt tension, very easy
CONS:
Y gantry 'twists' out of square easily (effects to be seen yet)
Bowden takes some tweeking to get right
Frame is not super stable
There are a few more that have nothing to do with gantry system.
My experience so far is that this system has great potential, at the cost of alot of setup. I have doubled the speed of my SD3 on fine printing (0.1mm). But it takes quite alot of work to get it there. HBOT has the nice part about using a single belt which gets rid of X/Y tensioning circle problems. The bad part is the Y gantry can twist. So far, I cannot tell if it is making any problems or not. I still have alot of tweeking in firmware for acceleration and jerk to see if some of the artifacts I am getting are possibly related to the twisting. a COREXY (crossing belts) would eliminate this twisting, but at the cost of having to tension the two belts perfectly to each other. And I have no idea what the comparison to an ultimaker system would be. My best guess is that it would work much the same as a solidoodle, just faster. The only con I would see is putting it together just right to get the quality.
There is a lot of discussion about pros and cons though, if you google it. Especially on the reprap forum, but less often on places like soliforum because that kind of an upgrade is a very intense change in the mechanics.
Yeah, I found a lot of posts about CoreXY vs Hbot (the "twisting" issue due to no belt crossover) or Hbot vs others, or Ultimaker vs others, but no discussion of a direct comparison between Ultimaker-style and CoreXY (which is what I was asking, perhaps not very clearly).
From indirect comparisons of each vs sth else, most pros/cons apply equally to both (except the difference in kinematics and lack of Hbot/CoreXY support in Marlin etal until recently).
Hazer: wow! Sample prints? 
IC... so... a difference in belt tension on Ultimaker-style would have same effects as on SD, whereas on CoreXY it would be... drift (guessing)? Anyway, I'll google that more, thx.
Prints found here:
http://www.soliforum.com/topic/5141/hbo … r-or-yahp/
As for CoreXY and Ultimaker, Ultimaker follows the SD with belt tension. The CoreXY is also two belts that need to be equally tensioned. I believe that the problem with CoreXY not getting tensioned correctly leads to binding.
I think the big problem with the Ultimaker gantry is that it rotates linear bearings. They aren't designed for that so they grind away and the machine needs constant oiling and probably won't live long.
I think the big problem with the Ultimaker gantry is that it rotates linear bearings. They aren't designed for that so they grind away and the machine needs constant oiling and probably won't live long.
I looked into this - the ultimaker uses bronze bushings on the carriages so both linear and rotational movement is ok. You can't 'upgrade' to linear bearings if the shafts have to rotate. There are bearings that are ok with rotation but they're specialised and quite expensive.
My thought for a home-build was to separate the belt drive from the linear motion (e.g. use two shafts, or shafts and makerslide carriages for example). The one thing I'm not convinced by though is the bowden feed - while removing mass is great for speed, it seems like a bit of a step back in achievable print quality compared to a direct feed.
SoliForum - 3D Printing Community → 3D Printer Discussion → CoreXY vs Ultimaker-style gantry
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