Prusa v3: extending y-axis

Hello,

i searched thru the forum, but i couldnt find anything on this. i am probably just bad at searching. Has anyone tried extending the y-axis of prusa (v3) ?

By default you can print 200x200x200 ... i would like to extend it to 200x500x200, by using 1m threaded and smooth rod. I am not quite sure about how to extend the heatbed.
I was thinking about just buying another heatbed (lower+uper part) and adding it next to the original one, then create a plastic holder, that will hold them toghether (so the motor on 1st will also move the second one)
Then to connect then i would just use 200x500x200 glass to put on top of the two heatbeds.

Has anyone tried this ? results ? if not, why is this not a good idea ? what will probably go wrong ?

Thanks !

A big heated bed will become much heavier, and only the heaviest from x and y counts. In other words as y bed becomes heavy, it imposes that much restrictions for acceleration and speeds.

The I3 is already weakest in the Y axis. You can easily confirm this by simply picking up the front of one and watching everything move. If you simply extend the Y, you will make that problem worse. I'd plan on making the axis stronger / stiffer if you decide to extend it.

The heated bed chews powere to warm up. Double it's size and you double the power it uses. Right now it's running 12A at 12V on most systems. Normal electronics are not going to be happy at 24A / 12V or at 12A / 24V. Again, you can get around the problem, but it will take some work. I would plan on re-laying out the heated bed PCB so it's all one surface. Otherwise it will be a bit crazy to get it all level / flat / even heat.

A double size carrage will be double weight (as mentioned above). In addition to limiting speed, that will give you more sag on the smooth rods. A bump up of at least a couple mm on the smooth rod diameter sounds like it would be needed.

If you are going to 24V, that opens the door to higher power stepper motors. Higher power means more heat and more fans ....

None of this is a show stopper. You can do this. It's just going to take a bit more work than fitting a new set of rods on what you have now.

Thanks!

Heatbed will not be a problem i think. I am using sanguinololu, which supposedly doesnt handle heatbeds well, so i added a 240V/25A relay in between. sanguinololu drives relay, which gives power to heatbed. I will have to switch relay to lower voltage, (i used 240V becouse thats the only thing i found in the house) and more amps. With diff temp ... if PCBs are bought from same manufacturer and they are made good, it shouldt be a problem. else you would also get diff temperature across one board. In worst case scenario another pwm and thermistor will need to be used to seperatly control the other heatbed to achieve same temp. the biggest problem will probably be leveling it then. even leveling the single one was not enjoyable for me But putting it all in one piece brings much more problems. nobody produces PCB heatbeds of that size. making my own will result in million of problems i guess.

About the weight ... this is what i am worried about. the rods will be more than twice the size (so even with the same weight it might be a problem) ... and the weight will be more than double. i'll see how it will go with M8, rods ... and then try to decide how much fatter i would like them to be.

For the overall stability, i am thinking bout printing the holders (the ones that hold the Y axis frame toghether) with some modifications, so besides holding the axes toghether i can screw them down on the table. so all 4 courners would also be screwed down, which i guess would give some additional stability. maybe i can also add few supporters in the middle of the threaded rod ... but cant do nothing about the smooth one, as bearings are attached to that one.

Are there any other impacts on lowering speed (besides the obvious .. more time to print, more power consumed) ? is there something like "too slow" which will make a drop in quality ?