@Helensdad said in Core XY firmware.:
My D Bot is bog standard apart from using the 300mm square bed as opposed to the 300 x 220 version.
Take a look at the Z-bot in my signature. It's also a Dbot with 300x300 bed. I had to make a few modifications to the Z axis and bed frame to be able to handle the larger bed size. Mainly switching from 2 lead screws on either side to 3 lead screws in a triangular pattern. The cantilevered bed design of the stock build works ok with 2 lead screws because you can find the balance point fairly easily since it's weighted towards the wheel guides. But when the bed size increases it becomes much less stable, the balance point gets harder to find, and binding and bouncing is likely to occur.
In my case I added a front cross member to the bed frame to make it more rigid, added the 3rd leadscrew, and used a single motor and belt arrangement to keep the lead screws synced. Another popular way to go is to use 3 independent motors one for each lead screw and then use the automatic bed leveling to resync them and level the bed. This requires a Duex expansion board for the extra driver though. The issue with this approach is that the dbot bed frame and wheel sleds weren't designed to allow for the flex inherent in adjusting 3 separate points of the bed frame.
Just something to be aware of as you dive into it.