How To Flatten Your Wasteboard (And Why It's So Important)

So you just installed a new wasteboard or you need to flatten your current one because its carved into way to much.  In this blog post I'll walk you through just how to do it.
When you first install your new wasteboard its important to flatten it.  While the board my be visually flat, it will probably not be flat relative to the router.  This is important because it will be different heights across the wasteboard.  What could be 1 inch away from the router on the left side of the board could be 1 1/4 inches different on the right side.  This is especially important when engraving or v carving fine details when the depth of cut is only 1/4 or less.  It would end up cutting on one side and completely miss the board on the right.  There are a few factors as to why it wont be perfectly flat to the router.  The wasteboard thickness could be inconsistent from the factory, the machine could not be square, or you could have some sag in the span of the wasteboard.

To correct this we use a large, flat endmill and run a large pocket toolpath across the entire surface of the wasteboard.  This will ensure the wasteboard is consistently flat and equal distance from the router across the entire surface.  That means we will get consistent cuts every time.
First we need to make sure our wasteboard is firmly attached to the machine.  Next, we need a large endmill to do the flattening.  This article and file is written for this specific endmill, Amana Tool RC-2248 Mini Spoilboard Bit. (click here to purchase).  It is possible to use your own bit, but you'll have to edit the file and settings to adjust for it.

Myers Woodshop Spoil Board Flattening File (right click, save as)
OR
Consider purchasing the file from my Etsy site.  It helps me support what I do so I can create more free content.
Myers Woodshop Spoil Board Flattening Etsy File (Help Support Me)
(remember, this is programmed for the above mentioned flattening bit)
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This file is also written for the XXL sized Shapeoko, but it's really easy to change the size down to whatever size your machine is.  I attached pictures above with all the preprogrammed numbers so you'll have a constant reference point.  Its important to fine the center of your wasteboard.  Originally, I thought that the rapid position labelled 'center' would be the center of my wasteboard, i was wrong.  The easiest way to find center is to draw two lines from edge to edge creating and X across the board.  The middle of the X will be the center point.  You'll move the router and zero X and Y off of the center of the X you drew.  Next, you'll lower the flattening bit until you just barely touch the wasteboard.  Since the file will cut 1mm depth, one pass only, its not incredibly important to be exact with this measurement.  Once done, Zero the Z. 
You're ready to run the file.  It will start in the middle and make squares finally reaching the outside.  I have it set for 100ipm.  It could easily go faster, as mdf is super soft and the recommended bit is very large and high quality.  For this sized bit, set the Dewalt spindle speed dial to 1. (the larger the bit, the slower the speed.)  I do not own the Makita version, but I imagine dial setting 1 would be optimal on that as well.  It should take 5 or so minutes to complete as it's only doing one pass.
It's EXTREMELY important to protect your lungs when cutting MDF.  Its dust is extremely fine the eye may not even see them and it's very harmful to your lungs.  Always run dust collection (I highly recommend Suck It Dust Boot) along with a quality vacuum (I use the Fein Turbo 1).  Additionally, a face mask (RZ Mask) and shop air filter (Wen Air Filtration Unit) (A YouTube video I did about it) when cutting MDF.  Don't mess around.
Since I programmed it to only do 1 mm depth per run, it may be necessary to run it a few times.  You'll need to rezero the Z each time, but not the X and Y.  Be very careful not to go too low as it will run across the front of the machine (over hang) and if ran too low it will cut into the metal frame on the front of the machine.  Also, make sure any screws holding the wateboard to the machine are sunk lower than the cutting depth.  Finally, if you have a J-Tech Laser, you'll want to remove the mount.  Since your running the machine to its maximum distance, it may hit or get stuck on the rails/frame.
I hope this helps you flatten your wasteboard and get more quality cuts out of your machine!
Happy cutting!
-Ben