Mid-build with questions I should have asked before I started

[iquant]

hello,
First I think it's amazing what the HevORT project is doing to push boundaries. I hope eventually I can contribute in some way to further additive manufacturing.

I have a few questions. I am mid-build of a corexy machine that I started without an exact BOM. The base or core of the machine is mostly parts that I already had so I just dove in and started building. Now I am currently at a point where I need to make some decisions, finalize some of the frame/enclosure details and make a big decision about the printer-head (idex vs. toolchange vs. dual extruder). My frame approach is a little different: You don't see many 3d printers being tig welded and fabricated out of mild steel square tubing.

I only have one non-negotiable: It must print PVA & HIPS as support materials. (and for ABS & Nylon the second big item is heated enclosure) I have a cube with a rough interior volume of 500x500xTBD. I'm thinking about a 350x350x??? build volume. The cube is made with 3/4" (19mm) square tube. The cube will be boxed/walled on both sides of the 3/4" square and the cube's floor, ceiling and walls will be filled with kaowool insulation.

Questions:
Why don't you guys (and girls) hang your stepper motors and lead screws upside down?
Meaning let the build plate hang down from the screws vs. have the screws potentially deflect, vibrate, wobble, etc. while attempting to support the weight of the part and build plate. Is there a reason that I am not aware of? Is there a reason why I should not build my printer that way?

Why don't I ever see people using chains or gears?
I want to keep as much as possible outside of the heated chamber and I'm brainstorming about the best way to pass the drive motion through the side and rear insulated walls.

What do I want for XY stepper motors?
I haven't figured things out to the point that I have a weight of my carriage/XY gantry so I'm not really sure what I need in terms of specs (torque, step degrees, voltage, amps, etc. I bought a Duet3D 6hc board. I am not married to the duet board (can use for other project) and I'm also not married to 120VAC. I would rather power this thing with 240VAC mains and run 24/48vdc systems.

Is there a good brand and size nema 17 or nema 23 stepper motor I should start with?

IDEX vs. Toolchange:
The reason I am building this machine is to print with PVA+PLA and HIPS+ABS. The way I see it is with IDEX it won't be anything all that fast/special. It will do one thing and do it well. Almost like a dedicated machine. On the other hand, toolchange will leave future doors open for expansion, other processes, experimentation, etc. while at the same time has the possibility of being an absolute cluster-f, over-complicated disaster that I regret.

Any IDEX vs. Toolchange ideas, suggestions or words of wisdom?


Thanks for reading all that. I am hoping to have it assembled and moving (with spare XY steppers) by this weekend.

[RedFlash]

Hi, welcome to that nice small community.

I can‘t contribute much to your build, but it sounds very interesting.
There is much more activity on discord, the forum is mainly used to document the progress.

What i can recommend is the LDO-57STH41-2804MAC(HEV). Its a 0.9 Nema23 stepper. I use four of them with an BTT Octopus pro and hv driver for the XY axis.

Im looking forward to see the progress with some pictures. May you post one of the frame?


Discord invitation:
https://discord.gg/sfUTyYJh4S