Hi Guys

I am wanting to build either one of these printers , at least I would like to build a CoreXY printer. ( Build volume X400 Y 300 Z 400 ) with 30x30MM aluminium extrusions.
Which out of the two do you prefer and reasons ?

The other question is , do you think its important to have the bed supported on both sides ( two or one Z Stepper motor ). I see some have only on the one side.

Wondering if the bed vibrates because the opposite end has no support.

I would appreciate your comments and ideas ,
Thanks
Vaughan

Just my $0.02, I wouldn't attempt a cantilevered bed at that size. The need to ensure no tilt on that size would be easier to engineer as a dual support scenario instead of over-engineering the one sided design. The frame will need to be a bit larger for dual support but at the size you're planning that wouldn't seem to be an issue.

Also, at that size bed you'll likely want a MIC-6 or ATP-5 bed to ensure flatness, which will add a decent amount of additional weight needing to be supported.

My 300x300x300 dual support HyperCube can be seen at [www.thingiverse.com]

My Folger FT-5 has worked far better than my first Kossel Mini, but is has it's share of issues. You will likely want to mod it a fair bit. You could do far worse, but I don't recommend it for a first time builder.

If I knew then what I know now, I probably would have used the FT-5 design as a basic template, but bought all the parts myself, from higher quality suppliers. I have really replaced that much.

For that build volume 30x30 or 30x40 extrusions may not be rigid enough. I recently built a 300x300x700 machine using 40x40 extrusion and it's barely adequate. The problem is the tall vertical distance and the moving mass (mostly when the Y axis moves) up at the top of the frame. I'm going to be adding some corner braces to the sides of that printer to try to stiffen it up. If you're planning to add rigid side panels, securely attached to the frame, 30x30 will probably be OK even for that size.

Cantilevered beds are difficult to do right. It generally requires a LOT more material and size ( translates to expense, too) than most are willing to throw at it. It's easier to get good performance from a 2 or 3 screw (or belt) set-up that supports the edges of the bed on opposite or three sides. I would not recommend multiple motors - there are too many problems with keeping them synchronized. Use a single motor and a looped belt to drive all lifting screws or belts.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Personally I would go with single motor/dual screw z-axis for bed this large.

Hi

Thanks guys I really appreciate your comments and advice.
I thinking maybe reduce the height to 300mm and increase the frame from 30x30mm to something like 40x40mm extrusions.
After reading a couple of threads , I am not sure which way to go on the style of printer ( CoreXY) . I have build two printers from scratch ( Mendel90 & Prusa i3 ) .
I am not too concerned about speed of printing, rather have accuracy and a good finish to the print.

Thanks again for the good advice guys.