My spoilboard system and how it works

I’ve spent a few months with my new slats and spoilboard and if I had it to do over again I wouldn’t change much, if anything. I think this setup lends itself well to systems like the HDM or any other machine where you want to do both wood and metal, but the ideas it incorporates lends itself to other machines and may give some of you some ideas you may wish to incorporate into your own system. It takes a bit of time to set up, but once you get it going the various elements will last much longer than a conventional spoilboard for reasons I’ll cover.

My HDM started with the standard hybrid table. I replaced all of the original 3/4" MDF slats with 1/2" HDPE. The HDPE supplier in the link cut the HDPE to the exact specifications of the original ones. Since I always use either an mounting plate or MDF spoilboard on top of the hybrid table, there was no need to go with 3/4" thickness for the slats. The HDPE allows me to use liquid cooling without having to remove the MDF slats. If you have no need for liquid cooling, MDF is going to be a cheaper option for the slats.

The slats each have a grid of three columns of 8mm holes(actually 8.05mm to allow clearance for the 8mm stainless dowels). The two outside columns have the holes spaced 50mm apart both horizontally and vertically. There’s also 50mm of spacing to the next set of outside columns for the next slat. All of these holes get a 6mm x 10mm threaded insert installed from underneath. In between the two outside column is one inside column offset by 25mm. These holes do not get threaded inserts. You wind up with a set of 5 holes which repeat along the length of the slat. When installing the slats I use a 8mm collet and 8mm stainless dowel along with the spindle to perfectly align the slats with 50mm spacing horizontally since there’s just a bit of lateral play.

Naturally if you have a differently sized system your spoilboard may be a different size. My MDF spoilboard is 650x650mm with a grid of 25 countersunk holes which are used to mount it to the T-track. I found out the hard way you don’t want to overtighten any of these screws as it will deform your MDF, so better to use more of them and tighten until just snug. After the network of mounting holes were made I installed a 1/4" piece of plywood with the same network of mounting holes between the MDF and hybrid table so I would not cut into my slats for the next operation. The MDF is aligned to the front of the hybrid table.

Next I cut a 8.05mm hole that aligns with the first hole in the 2nd row of slats. Into this hole goes a 8x45mm stainless dowel all the way through to the matching hole in the slat. Next I will cut another hole 550mm to the right of the first and install another dowel for alignment and do the same thing for the rear corners at the extent of my Y to the farthest matching hole in 50mm increments. Once each corner has a dowel installed I can go to down and cut the entire grid of matching holes with my slats. Once I had all of those holes done I moved my entire spoilboard forward, realigned everything with the 8mm dowels in the corners, and drilled the remaining holes that were beyond the extent of my Y axis.

After all the holes were cut I removed the 1/4" spacer and reinstalled the spoilboard using the alignment dowels and surfaced the entire spoilboard as you normally would.

Now my entire spoilboard has 8mm feedthrough holes which I can use to access the threaded inserts or install dowels to align my workpiece. I use a few sets of quickset macros to set my zero point for my most used rows and columns of dowels. I can use the Shapeoko Essential Clamps with the threaded inserts and 6mm x 40mm screws to hold down most workpieces. I much prefer using dowels for alignment rather than the screwed down L brackets more commonly used. The stainless 8mm dowels are more precise, but wooden ones can be used if you want to leave them in and don’t want to worry about cutting through them.

The beauty of this system is when you have used up your spoilboard, you can simply make a new one without losing all your threaded inserts.


I love this - I have one more surfacing pass on my spoil board for my SO3 XXL, then I hit the threaded inserts. I’m going to do a variation of this for the next run. Of course that means all new screws to reach the new depth… :joy:

I have an SO3 XXL and have replaced the spoilboard about 4 times in the last 4 years. The last one was replaced in October 2022. I moved all my threaded inserts over to the new one except for a few that the ears on the tee nuts were bent.

Since October my spoilboard is almost pristine. I started using bottom of the project instead of the top. I rarely get any marks on my spoilboard. I do have an 8" square slight cut into the spoilboard but that was strictly my fault. I had set the material at 1/4" and it was 1/8" and then used the top of the material. When I saw it was cutting into the spoilboard I stopped but it left a battle scar.

I use the center of a project much more than the lower left corner. So when I turn on my machine and am prompted for a bit I put a vee bit in. After initialization I jog over and set the X and Y. Then I move the router off the project to a clear area and use my BitZero to set the spoilboard as Z zero.

The only issue with using the bottom is if you miscalculate the material height you either get the first pass as an air cut or you cut deeper than you expect. You should measure your material accurately but mistakes happen. When I use masking tape and super glue I measure with both the material and super glue and tape and I get the tape cut and not the spoilboard. It does take some getting used to but it works very well for me. Try something new. Just remember that in the rapid positions for the Z+6MM you have to be off the material or you will crash into it.

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My spoilboard slats have all sorts of battle scars. I build my Fusion 360 models in my office, save the code then take my laptop to the garage to run the code on my machine. My mistake is that I assume the stock is always as advertised. Ex 3/4” boards. This is not always the case.

Joe, Make a simple change. Design in your office but after getting your material mounted measure it and then change the dimension in the CC and save and then run it. Accurate measurement and using the bottom saves your spoilboard. The spoilboard is meant to be slowly destroyed but why accelerate that. By simply changing the measurement you do not have to redesign your project.

I always use the “t” as my bottom depth for a cut through. The reason I like that is you can simply change the dimension of the material and save and it is automatically updated. When you use the bottom of the material and not “t” then change the material size it is not automatically updated with the new measurement. You must go into each tool path and edit to get the update. When simply using bottom of material the material thickness is checked and then a calculation is made and is never updated. However if you use “t” then simply saving the file updates the material thickness.

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Reminds me of the line from 2010 movie. It’s full of stars. Replace the word stars with holes.

I am brutal to my waist board and hold down clamps. They do not like me much. I hit them both a lot with my bits. Best to have wooden clamps, easy to make and not as much crying when you hit them.


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