Holding Panels For Surfacing

My wasteboard is the combo of threaded inserts and ttrack. When I have cnc project that requires a glued-up panel too large for my jointer (6 inch) and planer (13 inch), I flatten and thickness it on the OneF. Can’t use regular clamps of course because an uneven panel will just spring back once the clamps are loosened. I have been using a combination of shims and wood-blocks-on-painters’-tape-with-superglue, and while that works, man is it time consuming! Are there any other gizmos out there that are specifically for this application??

Have you tried cam clamps with the threaded inserts? I just use shim wedges with crowding blocks that are screwed into the waste board. My next iteration of waste board will have both t-track and threaded inserts for the same purpose though.

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Not sure I understand. I have cam clamps, but they only provide side pressure, they wouldn’t keep a bowed panel from moving up and down?

Hey John, I do the same thing you’re doing, shim it like crazy, then flip it. If it’s a big job I use a hot glue gun and glue the shims in place so that they don’t shift around. I never considered there might be a better way to do it. I’ll throw it in the back of my brain and see if anything comes up.

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Would clamps such as these Tiger Claw that clamp down on a slight angle towards the waste board work?

Possibly, but again any force downward on the panel is likely to induce springback when released. I’m going to play with some push clamps, perhaps with a serrated face, and see what I can come up with.

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Perhaps any potential spring back could be avoided or limited by the use of shim material that will not give under the downward force of the ‘claw’.

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The Raptor Polymer Composite finish nails used by boat builders and restorers are also used by woodworkers for holding work during glue-ups. They are non-rusting, sandable, and saw blades and router bits apparently slice right through them without damaging the cutter. They are left in the wood and are stained or painted over. AvidCNC sells the nails and the Omer nail guns optimized for them for such use in cnc workholding. The nails swell somewhat from the friction heat of insertion, so they have high holding strength, but they also can be sheared with a lateral blow to release the work. Some have used PorterCable nail guns, but jams apparently are common unless using one of the specialized Omer nail guns. If you can live with the occasional jams or can justify the expense of another nail gun, the Raptor composite nails apparently work quite well for router cnc workholding, although I have no experience with them myself.


I’ve used 2"x4"x3/4" plywood scraps screwed to the waste board with a pocket screw slot cut in the top to put a screw into the side of the workpiece for work holding during facing operations.

Derek, that is a good idea - the other suggestions here do not address the need to keep from deforming an uneven surface while getting one surface flat relative to the CNC axis. I am headed to Lowes tomorrow and will get some smallish threaded inserts and relatively long screws…the thought is to sharpen the end of the screw, have the threaded insert mounted on an adjustable base, and then I can pierce the side of the panel from multiple points, pinning it in place. We’ll see how it goes…

All I do is side pressure from all 4 sides not the top, the bit pushes the wood down, so it shouldn’t come up. Then use a shim under the elevated part to hold it up. Flatten the top then flip and flatten the other side. A year plus and neeeeever had a problem.

If it’s a thin’ish sheet, look into vacuum holding.

My 1f isn’t going to be here until Tuesday but what I have done with a router sled is use a cheap handheld planer to rough one surface flat enough so it doesn’t rock. I’ll still do it this way even with the 1F simply because I have to believe it’s a lot faster. I got a cheap $50 Porter Cable one from the big box store.


That is a good thought. I find myself tempted to do everything with the one tool and spend more time trying to get that one tool to work.

Woodpeckers has some Slab Clamping Dogs (4-pack) [SKU: SLBFLT-CD4] That might work. I bought a four pack but haven tried them on my cnc yet.

Woodpeckers Slab Flattening Mill Pro (Scroll all the way to the bottom)

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