Need help sorting out my DIY Slab Flattener

[KODAK]

Evening. First things first, not further testing has been done until I finish the cutter head guard.
I hoping to get some direction on how to sort out getting level,flat, and coplanar with my version of a WoodMizer Slab Flattener. Currently I have 1/4" to 3/8" left to right and front to back. Slight hump in the middle of the "bed" but with a long level I have a slight slump in the middle. So I figure before I go chasing my tail some clearer heads can point me in the right direction. All things considered where I'm at isn't terrible and I think can be sorted out to get a fairly dead flat mill. What should my order of operations be to get the desired outcome of a level, coplanar, and flat mill? Take off the gantry, level and flatten the bed, refit the tracks to the flat and planar bed, adjust the gantry to the bed and tracks, and finally sort out the Z-axis? Any help would be appreciated.


 

[Den-Den]

I think there are many paths to your goal.  This could be one of those paths.

Get the tracks level on each side.
Get the side to side travel level.
Tram the cutter head to level.
Mount wood onto the cross-members of the bed with fasteners from below.
Mill that wood down just enough to clean it up.

Start using the machine.

[firefighter ontheside]

You don't really need level.  You need straight and flat.  Are the rails that your gantry travels on straight?
Those need to be perfectly parallel to each other.  Once those are straight and parallel, line up the crossmembers with them.

[Crusarius]

Once you are sure the rails are perfectly parallel to each other and roughly the same height off the bed for the full length.

Bolt some strips of material to the face of your cross members. make sure they stick up at least 1", once that is done run you cutter over all the pieces sticking up to remove about 1/4". then you will have everything aligned to the cutter head.



 
This picture shows my 2x4 cross member on my cnc table with a piece of MDF screwed onto it. this strip of MDF is my spoilboard. It made levelling the table a ton easier and I didn't burn up a set of cutters flattening a 5x12 piece of mdf.



 
and this image shows my custom clamping system that supports the slab from underneath and holds it down. It is super simple and very functional.

[21incher]

If you are starting with rails that are not parallel and straight it will never be right.  I would disassemble it and figure out how to fix that first.  

[KODAK]

Thank you for the feedback guys!

So I think the plan should be,

Remove gantry
Get the bed level and the bed flat. I think I will run strings to make sure the perimeter of the frame is level, the crossmembers at this point may be difficult to get in plane
Get rails parallel 
Make gantry parallel to rails
Make "spindle" level and parallel to rails
Add wood strips per Crusarius 
Make cutting passes over wood strips along crossmembers to make flat to cutterhead

Anyone see any errors in this plan to accomplish my goal?

[firefighter ontheside]

Just to be clear, I would only use a level to set one of the rails.  Make the other one parallel with it.  If you use a plane old level to set both, they could very unparallel when you are done.  

[Crusarius]

make sure to true the spindle before you get to crazy with cutting the strips.

[Erik A]

I would use a water level to check all four corners and the middle of the sides. I would not worry about level, but it seems that may be the easiest way to get it in plane.