Welcome to the SeeMeCNC Community

Hello.

After assembling my Rostock and making the calibration, I tought it must possible to make with the the parts of the Rostock a bigger Rostock.
I know that several parts should be new to fit the new dimensions , but this would only the chassie parts , the towers, the hot bed , maybe the PSU, and the arms, but thats all. Calibration should be possible via reptier.
What do you think, is the effort to much?

LOL - "chassie parts , the towers, the hot bed , maybe the PSU, and the arms" isn't that almost the entire printer?

What do you want bigger? Z axis movement? If so, that's easy, install longer towers. There is no real limit to this except for structural rigidity. I think the new Max V2 design is more "solid" with its 2 plate top but no reason you can't extend Z on a V1.

If you want bigger X-Y (print radius) then that is going to require almost a completely new mechanical/chassis for both the base and top plate to mount the towers further apart. A larger X-Y is going to require a much larger heated bed if you intend to use that and that is going to be a custom fabricated part AND require lots of power. Another option is to use smaller commercial heaters (the silicone pads would be interesting here) and create several zones. Then you will have to calculate the optimal arm length - and there are spreadsheets on the web to help with this.

All in all, Z is easy, X-Y extension is probably best done by building a new printer.

Just my .02!

cheers,
Michael