Welcome to the SeeMeCNC Community

I've built a Metal Max Delta printer, with the same frame that trick laser sells, and most other parts came from either them or SeeMeCNC.
I'm using Marlin firmware 1.1.0 RC6. I'm using an Atmega 2650 and a Ramps 1.4 board. I've got all the motors adjusted and everything works well and homes at the top. I'm ready to start calibration. The problem I have is that the numbering for the Z axis is backwards. When I being Z down to the bed it's at 271 not 0. X and Y go down to the bed with Z and they stay at 0. All the calibration advice has the Z axis at the bed at 0. How do I flip that around? Any help would really be appreciated. Thanks, Jerry

You probably need to tell your firmware and host program that G28 takes your machine to X0 Y0 and Zmax, not min.

But how do I do that? That's the part I don't know.

There is going to be almost no one on here running Marlin, so you will probably have a difficult time finding an answer here, I haven't run it in 4 years.
You might want to try the Delta Printer Google Group https://groups.google.com/forum/#!forum/deltabot or possibly the RepRap Forum.
The RostockMax ships with Repetier firmware and has for 3+ years.

How is it done in Repetier? I posted on RepRap but sometimes it takes weeks before you get an answer there, I'll try the Google forum, but I'm curios how Repetier does it. Thanks for the advice.

You can look at SeeMeCNC's configuration file here
https://github.com/seemecnc/Repetier-09 ... guration.h

Basically it's function of getting the Axis movement directions correct and setting the XYZ endstop positions, though I think it only uses the Z one on a Delta.