To CoreXY or not to CoreXY

[Rubyfox]

This is true path and good upgrade

[tpalagyi]

Hi,

Just do it!

If you build it nicely it will print perfect. The big advantage can be that the motors can be outside of the print chamber so the chamber can be heated up to print big ABS parts without cracks and wrap. Also the build plate moving down so its tend not to have that ghosting effects on the prints witch all the prusa printers suffer.

I think a maximum of 250mmx250mm XY motion should be good with COREXY mechanics after this the X carrige weight is increased so much that its doesn’t count a lot if the X motor is on the carriage or not.

Do not bother with crossing belt COREXY mechanincs just shift the 2 belts in height (look for a Craftbot printer for an example).

If possible use GT2 10mm wide steel reinforced belts as one side will almost require 2m of belt and cheap gt2 6mm with glass reinforced ones cannot perform good in such a length.

Br.,

Tamas

[nmaggioni]

I second this question.

I own a Kossel myself, and find the CoreXY mechanics rather interesting - I’d build one just for the fun of it, but the BOM and the useless-ness (I already have the delta) of the idea hold me back.

[Mirth]

Oh yes, definitely! I’m currently printing the parts for my machine. It uses V-slot and so can be scaled in size, including size of bed. I’m also experimenting with coupling wire to belt. CoreXY is the next logical step after a desktop printer.

[tpalagyi]

(have an original Rostock and also a Kossel delta

If you need bigger XY motion than go for it, also the option to use a direct driver extruder can be benefit compared to a Delta(lower retraction amounts and to print flex materials).

A good corexy printer can handle almost the same acceleration settings that a delta printer so they can be as fast, but without the pain of calibration and their print resolution is the same across the whole build plate.

If you have a nicely calibrated Delta the print quality of the COREXY will not be better.

[Flatox]

Hi ! I am interested to learn more about this subject too. I have a “Voron CoreXY” in my mind, but not ready to jump on the coreXY train yet.

[Mirth]

Really depends on the design of the printer. I’m currently making my own design and the BOM is pretty short, even with a few luxuries thrown in.

[Mirth]

In my design I’m using V-slot so my bed chassis rides up and down that on all four corners using elongated runners and has a leadscrew halfway along the left and right sides. I feel it’ll be rather stable.

[John_CORExy]

I built a C-Bot as my very first printer with a 300mmx300mmx500mm build envelope. It uses V-Slot. The build thread can be found on openbuilds under Carl Feniak’s design It prints exceedingly well and my benchmark prints come out much better than most I see online.

[tpalagyi]

I have linked this many times but who is willing to understand the different belt designs please read and understand this blog entry:

http://blog.fabtotum.com/blog/2014/04/04/belts-and-stuff-experiences-to-share/

It has all the information and calculations.

It will make clear how the XY motion is handled.

The only thing you have to design is the Z axis and this where a lot of printers are suffer. It has to be as stable as possible, if you grab the front of the table and move it up and down or right to left it should not flex/move at all. As any possible play of the table will catch up resonance of the XY motion during print and will show up in the print.

If you want to build a stable buildplate use 2 lead screws on the sides of the table and 2 or 4 linear rails(for bigger tables) to support it.

[zx81]

For me the cost is only for the v-slot, the smooth rods, pullys etc. I’ll rob the motors and electronics from my very first printer.

[zx81]

I was thinking of building a 500x500x500mm cube, obviously the print dimensions will be smaller probably in the region of 350x350x300mm by the time space is taken up for electronics and the actual motion gantry… 10mm GT2 belts are a sound idea.

[Mirth]

Mine is a 500mm³. Here’s the V-slot I’m planning on buying: Linear Rail - V-Slot® Linear Rail - OpenBuilds Part Store

I think you’ll find the price is quite reasonable.

[zx81]

That was a very useful link thanks If I do build it I will probably use 4x 10mm smooth rod pillars to support the z axis motion probably also 2 trapezoidal / ball screw rods.

[zx81]

Thanks for the link, I’m going to use a uk supplier (ooznest.co.uk) there prices are quite good and they will also precision cut it for me.

[zx81]

I just started ordering some parts for this printer build, I’ve ordered just enough V-Slot to make the outer frame … so I can get a feel for the V-slot and dimensions.

The V-Slot is actually fairly cheap however the Fixtures sure add up!! I’m going to have to have a good think about this … the way I was planning on doing it would require 7 Gantry Plates (the wheeled type) there £24 each… I think I’m going to have to design some Plastic parts to keep the Costs Down.

[Mirth]

Ok, small tip, don’t bother with the special slot nuts, just use M5 square nuts. I don’t know about the plates but wanting more control over the process I’ve just finished printing all the fixtures. The D-Bot and C-Bot do this. I use 1.5mm walls, tops and bottoms and 40% infill. Go for the smaller V-slot wheels too, no point the extra bulk

[KDan]

I found the square nuts recommended in the D-Bot BOM to be a PITA. They often stick when tightened down and you have to push the screws back in to break them loose. They are also marring the insides of the extrusions. I much prefer hammer T-nuts for ease of assembly and adjustment. Bangood sells the M5 Hammer Tnuts for $6.49/100 with free shipping. Not much more that the crappy square nuts.

100pcs M5 Hammer Nut Nickel Plated Carbon Steel Aluminum Connector T Fastener...

The problem with most T-nuts, both twist lock and pre-assembly types is that they can bottom out on the raised channels in the D-Bot 3D printed parts before the part is securely fastened sometimes.

I’ve fixed that problem by remodeling all of the D-Bot parts to allow clearance for the T-nuts.

[zx81]

That’s handy to know I did buy a small qauntity of the proper drop in T nuts, they are actually pretty good. I also bought some square nuts there ok they do the job. I just ordered a load of gt2 pulleys from banggood never even thought to look for the nuts on there.

[Jerry_Naidoo]

Link no longer active.