Adding a spoil board after build completed?

Mostly Printed CNC - MPCNC Advice
#1

I’d like to add some minor spoil board conveniences but I made a mistake when I built my table and didn’t cut out a large section in between legs that would allow me to easily replace the board. Once the build is completed I don’t see an easy way to cut this middle part out. I went with the recommended height so if I put a 3/4" MDF sheet on top of my base it will drastically cut into my cutting depths.

I was thinking I can loosen each leg and lift the whole thing off in one piece. Cut out the middle and reattach, then put everything back into the legs and tighten them down.

But maybe if I’m going through that much trouble, I should just add some height to the legs (+.75"-1") and then I can add a sheet of MDB on top of my base and not worry about losing any the height. If I only change the leg size and not the Z-axis, I think it means that I’ll never be able to mill down to the original base which doesn’t seem horrible.

Any advice on an option that isn’t a major rebuild but still gives good flexibility for spoilboards?

#2

Cut a couple strips of whatever you’re using for spoil board and put them under the feet. That will rase it up without lengthening the feet. Then you can mount the spoil board between them.

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#3

I purposely made my spoilboard match my cutting area. If it is larger, you create a pit when you surface your spoil board, which makes it difficult to mill pieces that hang off the edge of your cutting area. My recommendation is to put blocks under all four of your legs, and then size and position your spoilboard to match your cutting area. Strips like Barry suggests could work the same way.

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#4

Since I’ll be re-attaching the feet won’t this mean that the system will almost certainly be out of square and will need to readjust a bunch of things?

#5

No, you can unscrew all four feet and put them on the strips at the same time. You’ll need to check square, but it shouldn’t screw it up that much. My spoil board was also the same size as my cutting area like Robert mentioned.

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#6

I’m not sure what the rest of your build looks like, but can you use the router to cut out a piece from the table? Lord knows I’ve cut into mine plenty. Maybe even pocket it out?

Then you can throw a new spoilboard in there amd fix it down however you like. Shim it up with some 1/8 or 1/4 mdf underneath so you can surface the top. Or if you’re pocketing just don’t pocket all the way.

On second thought, that’s stupid. Just lift the legs up like the other guys said, lol.

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#7

My legs were longer, but this is what my spoil board looked like. I can cut anywhere on the board.

20200512_191751
20200512_1917514032×1960 1.38 MB

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#8

If you use slightly thinner stock (e.g. 1/2" ply) for the “leg lifts” than your planned spoilboard (e.g. 3/4" MDF) you’ll automatically get the lifted cutting area recommended below. I did angled cuts on the edges of my lifts and spoilboard, and my board is basically a giant sliding dovetail.

image
image3024×4032 3.26 MB

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#9

Neat! I liked having my spoil board only in my cutting area though. Lets you skim off the chowdered top every now and then. Have done it that way since the second version of the mpcnc.

#10

That’s a pretty simple and elegant way to approach this.

I agree with the ideas that you should just use the cnc to cut the pocket. Stealing Tom’s idea you could make a final pass around the pocket with a chamfer bit and create your own sliding dovetail if you liberate one end with a careful bit of hand sawing too.

#11

I built my mpcnc on top of an old dining room table which was solid wood. I didn’t want to cut it and lose any rigidity. The 3/4" spoilboard was added on top. All I did was added an extra 3/4" to the legs to compensate. Works beautifully.

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#12

It can’t be too stupid. That was my first thought too. Bonus that your spoil board is exactly the size of your cut capacity.

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#13

I mean, even a broken clock can be right twice a day, i guess…
But generally when people agree with me they end up reevaluating their life choices.

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#14

I actually pitted my spoilboard to match the maximum reaches of my machine. For my use, it makes squaring up the workpiece as easy as dropping it into the pit. Of course, if I decided to machine something larger, which would have to be done in separate steps because of the machine size, it would have to rest on top of the pit which might prove unstable. But I have never needed anything larger than my pit size. It works perfect for me but other people might find it unsuitable for their needs or purposes. I think this community has a lot of people doing lots of different things with their MPCNCs. That is the real beauty of this design, you can make it your own, fit your space or your needs.

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#15

Cool idea. And if you planned ahead, you could pocket it out so that the machine’s (0,0) was the corner when using the fence. It is not unusual for me to have stock sticking out beyond my cutting area. The reason is kind of stupid…I hate “wasting” stock. If I leave the stock intact when doing irregular cuts, I can have islands of usable material that would have been lost if I cut the stock to the size of my finished piece.

#16

I’ve seen some examples of creating an L fence at 0,0. If I understand it, you basically attach (in a removable way) an oversized “L” piece of MDF that you then machine out so that it’s perfectly square to the machine. Depending on the size, you control how far it extends on the X and Y axis. I believe this is similar benefits to what’s described above.

I’m way down this rabbit hole and constantly reminding myself that I’m still a super noob and don’t need the world’s most advanced spoilboard :joy:

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#17

That is exactly what I did. To start a project, I just drop the work piece in my pocket, clamp it down, home the machine, and off I go. I know the work piece is always square, and home is always the same place on all work pieces. I suppose I just went for the lazy simple way, but hey, I am a simple guy. Not lazy, but I do like to simplify things like repeatability.