Flattened spoiler

So I got confident enough to try to cut a nine pointed star for my wife today, at close to the maximum size my MPCNC can handle. I’d done some drawings and played with some really small cuts before. I found that my spoiler is pretty far from flat. I’d measured flatness and square on both the machine and the table, but hadn’t checked the spoiler. It’s a 3/4" piece of MDF cut to fit between the two channels I have the clamps in and screwed to the table in a half dozen spots (screws are recessed to keep them away from my bits). When I tried the cut today it was above the surface in some areas and under in others. Maybe as much as 4-5mm off at worst. :frowning:

So, how best to make the darn thing flat? I thought about running a mill bit over the full surface, but my bits are kinda small for that, even the 24"x24" area I’m using for this star would take about a bazillion hours with a 3mm bit. My regular router bits include one for cutting pockets (close to an inch wide in total), but they are 3/8" shank and the DW660 can only do 1/8 and 1/4. Does anyone know of a bit that will flatten a half inch or so with a quarter inch shank? :slight_smile:

I’m guessing I can just draw a box the size of my work area and tell Estlcam to make it a pocket to actually do the job…

Yesterday I was looking for exactly the same bit. I’ll try this one:

6mm x 22mm Router CNC V Groove Bottom Cleaning Bit Milling Cutter


If you use something like that, take really, really light cuts! I tried something similar and it would bog down the 660 at 1mm depth of cut. You also need to find the highest point of your board and set that as your zero. You can use a half or quarter inch 2 flute end mill for the same purpose, just takes longer, but probably safer, and not near as loud. You’re also looking at a really long cut time, even on a smaller footprint machine. I’m going to try again, but with a different cutter. My wife got me one of these for christmas. https://www.amazon.com/dp/B016O7U97G/ref=wl_it_dp_o_pC_nS_ttl?_encoding=UTF8&colid=28LMPZPI61BEQ&coliid=I2HKKVCU7ZGYZV It’s not cheap, but the cutters are replaceable, so unless I do something really stupid, the tool should last forever.

I use a little Bosch bit from Lowes for the occasional board surfacing, I think it’s 3/8", 1/4" shank. It was about $15, spoil board surfacing is the only job it gets used for. Does the job fast enough.

I too have a dip in my table of about 2mm that is really annoying, especially when it comes to engraving small text.
I’m going to be giving this bit a try whenever it shows up from China. For less than $10, I figured why not?

I just use a 1/4" flat bottomed bit. It doesn’t take too long to skim the surface in one light pass. You find out where the low spots are and keep going till the spoil board is flat. I think a larger bit would require some extra tramming.


Martin, I ordered one of these, even cheaper than yours. :slight_smile: I’m also going to try a slightly wider one from Amazon that will arrive a bit sooner. If the wide ones chatter too much I’ll look into one in the 1/2" size range.

Looks good. Please upload a video of your flattening process.