How to bolt on a spoil board onto 3XL? HELP ME PLEASE

I’ve been looking high and low for weeks and haven’t found anyone talking about how they mounted their spoil board on top of the stock Shapeoko 3 XL waste board. Not even Winston Moy. Is it a big secret or that logical and I’m making it too complicated?
I bought a 3/4" sheet of MDF, I will have threaded holes about every 3".
And would like to bolt it onto the STOCK MDF waste board, but the three metal supports are in the way. Do most people just screw it down?
It seems Winston bolted his, but he didn’t say how he did it. Must I lift up the whole machine to get under it. Sorry, I’m frustrated.

Please help me.
Thank you,

When I did my XXL spoilboard, I centered it left/right as I saw fit. My first toolpath was 4 mounting holes, 1 in each corner. Once those were cut, I screwed it down to the stock base. Then proceeded to drill the rest of my insert holes. When all was said and done, I removed screws and followed through those Holes with a handheld drill, and then added propel nuts from underneath the machine. Then bolted the new spoilboard down with 1/4-20 hardware.

Since everything was symmetrical on new spoilboard I could easily flip it over and put the bolts into the machined holes.

As far as lifting the machine, I only had to prop it up enough to get the propel nut(with epoxy) into the hole a few inches from the edge of machine.


There was a thread recently about this.

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I used 4 screws in the corners:


Thanks David, nice explanation!
Didn’t the metal supports below the stock waste board get in the way of your bolts? On my XL, the metal supports go out to the very edge of the frame.

i planned out my board, put the holding bolt positions in the corners and spaced along the edge, countersunk them to avoid CNC end Mill crash, then just used these Inserts and away you go quick clean neat ( i think so anyway)

How did you avoid the metal supports under the stock waste board? No one talks about it.
I can’t run a bolt through the two MDF boards without the metal frame plate getting in the way.


The inserts that go into the original spoil board do not go all the way though, from memory the inserts in original are only 10mm so you then it looks a bit like this sorry for rubbish drawingimage

so you can see once you do the math your bolt will not go through the original board based on overall length (minus offsets like countersink etc) thus the frame is not an issue. Does that help - please come back if it is not clear


You are the man, nice diagram! Thanks, appreciate it.
I’m an artist so I’m very visual.
I believe you said you used the S3XL to cut out the holes in the top and bottom pieces?
Did you also attach a 90 deg corner blocks? If so, did you use the S3XL to fine tune it by taking off a hair of material?

The XXL did not have a threaded board, so I used cabinet screws. I recessed my spoilboard (3/4 MDF) so that cabinet screw heads were safely below the MDF surface and made through pilot holes larger than the screw threads (but obviously smaller than the head).

With size of an XXL, the MDF is a substantial chunk of junk…I noticed that the MDF had a little warp and created spring I could see when I pushed it down with my thumb. So, I ended up screwing it down in four corners, 2 intermediates along the edges, and a center spot (Total of 13 screws). I found that that eliminated any spring in the board - but it did create small dips where the screws were pulling down…but after a light surfacing, those dips were gone.


I don’t have corner blocks they are like Marmite - some people love them some not (i am in the not camp) so can answer that question sorry, and as a follow up to why i don’t like the 90Deg corner block, my material size shape and thickness is so different all the time, that it was just annoying in the end, and i created a better workflow measure and set process with a ruler, and doing so as far as i can say has had now negative effects.



I missed that question!

I did bolt a corner block onto my shapeoko. I did this by copying the hole pattern from my spoilboard onto another design and limiting it to an L shaped pattern.
Then I created vertical and horizontal lines on the design at a 90 degree angle and did a cutout Toolpath at no offset. I saved the GCode for the two (Holes and lines) as separate NC files

I clamped an oversized piece of 1/2 ply to the table and ran the gcode to cut the holes. Then I removed the clamps and bolted the board to the table using the holes I just created. Then I ran the lines GCode. This guaranteed that the cutout for the 90 was made by the Shapeoko relative to the bolt holes.

NOTE: If I cut the holes and the 90 degree cuts at the same time, the setup would have relied on my alignment to the spoilboard and might not have actually been aligned to the tram when I bolted the item down. By cutting the holes first, bolting the board through those holes, and THEN cutting the 90, it assured alignment without the need to measure or eyeball precisely.


One thing you need to remember is that your supplementary/sacrificial spoilboard can only be as big as your work surface. With that in mind, my spoilboard is 32”wide 31”deep. My mounting holes are 2” in from each edge on my wasteboard, and this clears the steel braces by about 1”.

Hopefully this offers some insight.

Before you judge my random perimeter spacing, I had a bag of 100 inserts, had to get creative to maintain symmetry!


Thank you for all the good information!
What is the best way to resurface my MDF?
I’m thinking about buying this:
Good choice?
And how should I setup the Carbide 3D file to level my board? Or are there free files files in their library?

Looks good

Using Carbide Create? Just make a rectangle that reaches the extents of your spoilboard. You’re only taking a little bit at a time, so you should be able to go as fast as you’re comfortable at this point.

I used the same tool. Reasonably priced and will stay sharp enough for a couple of flattenings (although MDF does a number on tool sharpness). I just made a box the size of my spoilboard and did a shallow pocket. To determine the depth of the pocket, I attached a gauge to the spindle to measure the variances. Then I set it .001 deeper than the largest dip I could find and zeroed Z at the highest point.

Going faster will give you better results. The first time I did it, it was going TOO slow and burning. Take light passes to get to your depth and go fast.

Nice tips, thx!
To level my board. I’m guessing the CC file should just look like a series of parallel lines?
If the bit is 1" in dia, then perhaps a 1/8" overlap would work?
Or 7/8" center on center.

For your first run don’t worry too much about it, some overlap is good but more overlap means slower run times because you make more traverses. You should be taking a really thin skim off the surface each time anyway.

Run one pass taking off about 0.2mm or something like that, watch it, listen to it, play with the feed rate override and see what the finish looks like. It’s much easier to tune once you’ve got a run done and seen what happens.

And yes, your toolpath will be a bunch of straight lines, here’s one of mine (from Fusion not Carbide Create but you get the idea);

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Ok, thx.
Those lines look pretty close together. What size bit did you use Liam?