Wood CNC Boards

can be bought in many colors, dyed, so no sanding away the evidence…

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Unfortunately. community spoil boards don’t seem to be a feasible option. Each user needs to provide their own board. Please keep in mind that the user can gang multiple boards if they need to cut a larger item. The uncomfortable truth is why respect smaller DMS provided boards when larger, more expensive boards are destroyed?

2’x4’ MDF boards are readily available from Home Depot. The real question might be how thick they are required to be. 1/2" is probalby too thin to serve as an adequate safety margin. 3/4" is probably the best solution.

This rule is expected to emerge from the new rules when they are codified and posted. Another expected requirement will be for the users to provided their own router bits. This should cut down on people being so careless since they now have a little skin in the game.


Not sure what difference it really makes. If you are going 1/2in below the bottom of your piece it is so far off that why wouldn’t you be going 3/4in. I am just concerned that the thicker the board the worse the vacuum will work

That is a great question. The MDF should be held by the vacuum the same whether it is 1/4", 1/2", 3/4", or 1" thick. Consider the thickness of the puck. Is it thicker than 3/4"? How thick would it need to be in order to protect the machine’s table if someone were to forget to zero out the bit? The thicker the better, over 3/4" it begins to become a bit heavy to move. Historically, most spoil board cuts have been within 3/4". With this arrangement you get the benefit of attaching your work to your spoil board in any manner desired. Tape, screws, brads, tape, whatever. When the dogs are added to the solution you gain the ability to create jigs that register job after job. Since you are a thinking person, test some 1/2" and 3/4" MDF and drawn your own conclusions. BTW, the last accident an extreme anomaly, it would have happened even with 1" MDF.

Spotted this in the manual for the CNC I just bought. Passing along since it seems pertinent to the discussion of collets & cover nuts:

“Collets are good for 4-500 hours maximum of use if they are kept clean and no “event” occurs such as a broken bit inside the collet or a plunge that bottoms out on the collet.”

DMS is not an “event” free zone … so it might be worthwhile to purchase new collets on a schedule … especially the 1/8 and 1/4 sizes that get the most use.


The point Hanna was making is that the table’s vacuum will still suck down your workpiece through a 1/2” spoilboard. A thicker board and the vacuum won’t work as well. In either case auxiliary work holding, at least in the form of blocks or clamps to prevent lateral movement, are advised. Downward clamping advised for use with an upcut bit. I use a 23 gauge pin nailer to fix my work to my spoilboard in strategic places.


I have had an issue with even a very large piece walking during a cut with tabs. That’s why I switched to just going directly onto the vacuum board which solved that problem but obviously that wasn’t a great solution for the above reasons, and I understand that not being allowed anymore. I don’t really see a great solution other than trying to tack down the whole thing with double side tape.

Two or sometimes four 23 gauge micro pins will attach your MDF spoilboard to the vacuum boards well enough that it won’t walk. They pull right out with pliers and don’t leave a visible hole in the vacuum boards.

I have the issue of the piece walking, not the spoilboard.

Same solution. 23 gauge pins either through the piece or through blocks placed against the sides of the piece.

Problem is that the piece gets cut. Like obviously it’s secure before cutting but even with tabs I’ve had it walk when doing the final cutout

More tabs, or thicker tabs. The whole purpose of this change is to save the very expensive, time and treasure, community spoil board. I doubt you will destroy the spoil board, but I have (I purchased the current can of wood putty due to a screw up), anyway advanced users have to follow the same rules that we expect the once in a blue moon users to follow.
At times I have even used the router chips to help hold things in place via wedging. What is worse, spending a little effort to become a more creative in your work holding, or arriving at the space to find the machine unserviceable? BTW, Matt’s 18ga pinner solution works great, if 23ga isn’t strong enough for the feed rate you are running, move to 18ga, then try #8 construction screws. After all, you will own both the spoil board and the router bit. If you cut into your jig and destroy the bit, the next user isn’t paying the price. View this as defensive measure to ensure that the machine is ready when you are.

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Oh, I agree with the measure 100%! I am just trying to figure out the best way to do what I need to do. Very frustrating to ruin an expensive piece that took 20ish minutes to cut. Haven’t had enough practice to really get it nailed down yet. Any help with jig/hold down design is appreciated as well. Perhaps if I just put a bunch of holes through my spoil board the vacuum will hold better to the middle pieces.

Hanna, CNC holddown is an art and a science. It would help to know what your project looks like.

Holes in your personal spoilboard are probably not going to make things better, but could make it worse. No matter what else you do with mechanical options (pin nails, screws, clamps, double sided tape, etc.) when a project has small parts, you need to maximize whatever vacuum capability exists. Leakage is your enemy. Starting with the table, make sure you turn off any unneeded zones. Then cover with non-porous freezer paper, plastic, etc. any areas of used zones that are not under your personal spoilboard. Then make sure the edges of the personal board are sealed because they represent a big leak (aluminum tape is my edge sealer of choice because it is not porous and is very sticky.) Now cover any part of your personal board that is not under your project. Finally, your part needs to have a flat bottom that will mate with the spoilboard. All of these things together concentrate whatever vacuum force you have on the entire bottom of your part.

If your loose parts are small, they still may not hold. Tabs will help but you may need more than you think. You can improve the odds by reducing the violence of the final pass. This includes: leaving an onion skin to clean up manually with a palm router, knife or sandpaper, making the next to last pass so that only a thin layer remains and then switch to a smaller bit for the final pass (but using same toolpath) so you make the final thru cut inside the previous kerf so the bit won’t be rubbing the part. Oh, and use downcut bits. Upcut with a regenerative blower vacuum system is a problem just waiting to happen.

A word about a “flat bottom” … if you have a warped or bowed board that will pull down flat with the vacuum, you still need to be careful. During the cutting, you may end up losing the ability to hold it flat and all kinds of fun things can happen once that begins … almost none are good things. Two layers of masking tape with super glue between them can be a day saver when working with hard to keep flat materials.

Anyway, my two cents from the peanut gallery.


The times I’ve used the Multicam, I’ve wished for more knowledge about ways to hold my workpieces. I knew how to set up tabs, but I didn’t really know the strategy of where to put them. The class covers the basics but I think the users could benefit from some kind of resource - a link list, some youtube channels to look at, even a book full of laminated printed-off pics. I get Facebook ads for CNC machines and I’ll watch (yes, I know, SUCKER!!!) and still get surprised by some of the work-holding strategies.


I am currently compiling a list of videos that have this kind of information for a CNC course.

If this is something you’d like, could you do some exploration on YouTube and find video(s) that you think are helpful and send them my way? I will include them in the course.


2 posts were merged into an existing topic: Woodshop Training Requests Q2 2021

Here’s a few links. None are particularly ground breaking but they could help spark an idea.