I just read your post about wanting a larger printer. I will have to say that it can definitely be done. I have built my own very large printer, 920 mm X 520 mm X 820 mm. If you are wondering, that’s 36 inches x 20 1/2 inches X 32.25 inches of “Z” travel. It was an undertaking to say the least. Still haven’t gotten all the bugs out of it but it does a pretty good job. I have my “U” axis Extruder to mount still but no biggie there. My print bed is a flat top glass stove and my bed heater is the stove itself with a piece of 1/4 inch aluminum plate on it. The stove is wired direct for 110 volts on a really good relay. I don’t recommend this unless you put something in line to protect your bed from getting to hot. About 70 degrees Celsius is all I feel comfortable with, which works out ok with PETG. Not the flattest surface but the Duet WIFI does ok if you do a mesh bed probe first, which takes forever. I would send pictures but it late and the printer is out in the shed. I will send pictures.

I have an X and a U on two different rails. Haven't put the extruder on the U yet but carriage is there and functional. I have been putting it off because I have to redesign my extruder brackets to allow room for the cooling fan between the carriages.

They are both riding on 40/20 extrusions seperately. I have Two Y motors, an X, motor, a U motor, four Z motors pushing 1000 mm Ball screws, and hopefully soon, two extruders. No empty drivers on Duet or Expansion Board. Heat sinks on all drivers witha 24 volt, 90 mm fan blowing across them.

I figured it out. Change the U2 to U1. I feel sheepish now.

I have finally gotten around to installing my second extruder onto the U axis. Both X and U axis can pass by each other freely. I am trying to get both axis to home on the lower end instead of X on low and U on high. I don't see anything in the M574 command to tell it otherwise.

@t3p3tony I was not aware that you could do that. Having two different parts of a print going at the same time seems to be to much going on at one time for me. I might not be coordinated enough to keep all that straight. I have a hard enough time keeping my profiles in Simplify3D with the correct part of the print, I can't imagine having two profiles printing at the same time at different parts of the print.

@3d_low Just for curiosity sake, what are you trying to accomplish with two Y gantries? If its only a weight issue, then use bowden tubes and keep the weight of the extruder motor off the gantry. The only downfall to this is printing with flex. Not saying it's impossible to print flex with a bowden tube either. If you are printing with two extruders, you are either going to park one while the other is printing or you will be doing a ditto or mirror print which you will have to half the bed up anyway. The only reason I have designed mine that way, because I have 36 inches of X travel on the bed and I can mirror or ditto print and I still have 18 inches for each extruder and if I want to print a multi material, I am able to still reach the entire bed with each extruder.
Two Y axis drives would be too much sugar for a dime for me

@mgrimes1907
The Left side is different from the right side. For weight purposes, they will both be the same as left on final build. Single wall extrusion at 60 mm/sec.
It's not a 3DLabPrint design!

@t3p3tony By the way, I was going for functionality not aesthetics. There are a load of wires to deal with and I really need to mount my Duet down to something, but it works day in and day out.

@t3p3tony
One picture didn't show up. Click on the link above the pic to see the overhead shot

@t3p3tony !
I hope you can see this. This photo is from the top right corner of the printer looking down you can see the two extrusions with the drive motors on the other end. There is only one extruder on the left gantry rail but you can see the carriage on the right one. As I said before, it is functional. I need to re-engineer my extruder mounts to squeeze the fans in to pass each other.
Thats a print I did last night. It's 205 mm on the X axis, 23 mm on the Y axis, and 300 mm on the Z axis. Its only half the wing. I would print it in one print but it gets a little wobbly with such a small Y axis footprint. 10 1/2 Hrs. print time.

0_1528729507075_b280a8a0-54fd-4153-8f90-5a773f836a94-image.png

@t3p3tony BTW , I am not quite sure how to post Pictures on this forum as this is the only forum I subscribe to.

@t3p3tony I know but I have had the "Driver 6, 7, 8. 9 Temperature" Warning several times but not since the heat sinks were installed. All Z motors are on 6, 7, 8, & 9. There are 2.8 amp NEMA 23 as well as the 2 Y Motors. Only X, U, and extruder motors are NEMA 17. They are 2.0 amps each. I have the amperage in the config.g set to 80 % of those ratings. Thinking about playing around with the Z motor amperage as they are growling a bit with mesh bed compensation.