Design Options CoreXY

Hey all,

need some input here.
have these 40 by 40 mm (regular, not V-rails) aluminum extrusions.
length is little over 75cm, but will be cut at 75cm.
The design that is in mind, is the Haeckel edition. Have got more then enough aluminum extrusions for that.
And it can be closed up with plexiglass. Later modification to cnc or laser.
However, when trying to figure out the CoreXYZ. Got some trouble there.
most people and designs so far have been the moving of the heatbed forward/backward, while the extruder has the left/right and up/down movement.
Or heatbed up/down and the extruder with left/right and forward/backwards movement.
However, in the design in mind i wanted to have the heatbed solid state and the extruder moving in the X Y Z directions.
but have a hard time imagening what way it would be most stable.
i like the idea of [www.corexy.com], although that doesn't fix the issue of the Z direction.
Have seen a few video's on youtube.
Have even drawn couple of idea's, however, it would be great to get some input.
Has anyone tried this before?
if you could refere me to some examples, that would be great.

kind regards,
Thierry

Edited 2 time(s). Last edit at 01/25/2015 08:27PM by Lorcan.

I think it's very hard to make that work well, I imagine making a carriage of a reinforced square that moves up/down inside the bounding box of the frame.

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http://www.marinusdebeer.nl/

Why would you lift the carriage with belts, x and y rods and two motors? lowering only the heatbed is much easier.

I had an idea on a way to keep all motors stationary and still have the extruder move in X, Y, and Z. It's not quite the CoreXYZ like in the other post in this section but it's close. I don't know if it has been done before but I think it's definitely doable but probably not practical. What if you had smooth rod shaped like a hex driver (or something along those lines) attached to the X and Y motors that would be mounted on at the bottom or top of the machine? Then your pulleys could have a hex hole in them so they could ride up and down these rods while still being able to be driven. The other idlers could be on just smooth rod. A difficult thing to do would be getting all of these pulleys to go up and down together on their smooth rods along with everything else.

This would cut down on the weight the Z motor would lift if instead of moving the z carriage and two motors you mounted the X and Y motors at the bottom. It seems like a cool design concept but I'm not sure it's worth the trouble just to keep the bed stationary.

Tell me what you think of this idea.

JTT

Edited 1 time(s). Last edit at 01/27/2015 12:51AM by jtoombs.

Well, maybe it make sens to you. To me, it looks like you want to go on too many directions, trying to reinvent the wheel. IMHO, each step you'll go further, you will rencounter problems and go back, to finaly land on an existing principle. Just because existing principles works and each possible problem is solved. Keep in mind each existing designs principles are the most simple way to do, so it's the better, the faster and the cheaper. Most have been said in mecanics since a loooong time. We're just adapting. No Leonardo da Vinci here ? Good !

Haeckel is not a CoreXY printer, it's a carthesian as you noticed. If you want a fixed bed you only have two choices wich are not compatible with CoreXY. First, a regular mobile gantry. Second, the delta shape. A mobile gantry with a plunge Z axis is mostly not in use on 3D printers (with few exceptions in very large printers) because to get enough stiffness ont the Z axis, you can't do lightweight. It's difficult to maintain a reasonable price too. So it will be necessary slow, heavy, and generaly most expensive than other solutions. That's why that design is in use on CNC mills, because you need something very stiff and heavy.

That's why the most interesting way for a 3D printer to deal with a fixed bed is the delta printer. Look at a Rostock or a Kossel, you can't do more simple : 3 identical pods facing together. No need to try to make experimental sliding pulleys works. Anything you can imagine will be more complex, expensive, risky.

CoreXY is a very interessant way too. Because of the stability given to the XY carriage, at high speed, allowing reduced guides size. If you try to install a plunge Z axis on the extruder, you will go against what's make a CoreXY interesting. A plunging bed is not a problem because it haven't to be quick. It's inexpensive to make, and it's independent of the CoreXY mecanism.

You have the choice. My advice : don't try to reinvent the wheel, don't try a mix between two design principle. A good design is done when you have nothing more to remove, not when you have nothing more to add.

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Collective intelligence emerges when a group of people work together effectively. Prusa i3 Folger (A lot of the parts are wrong, boring !)

Yeah... that's pretty much what I thought when I first thought of this idea. There really is no need to make the extruder move in all axes. Just small Z steps of the bed for layers isn't going to effect the print that much. None the less I still think the idea is cool! The difficulties of implementing this concept far outweigh the potential benefits ( if there really are any).

Liked you last sentence of advice, Zavashier. Is that an original quote?
JTT

Well I heard it a lot from a teacher of mine before it starts to make sense to me, I dunno where it comes from

Edited 2 time(s). Last edit at 01/27/2015 11:11AM by Zavashier.

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Collective intelligence emerges when a group of people work together effectively. Prusa i3 Folger (A lot of the parts are wrong, boring !)