Wood warping

[BunnyHopkins]

Dumb question. So y’all don’t start laughing at the same time…

Using a 4 x 8 3/4" plywood sheet but there is a bit of warping in the middle of the sheet. Clamped X axis on both sides solid and 4 corners but can’t figure out how to clamp the Y axis so that the wood doesn’t warp. Suggestions?

Thanks!

[PhilDejarnett]

Can you screw it down? When securing full sheets, I prefer to just screw them right down with short screws. You have to have places outside whatever you are carving that you can be sure the bit won’t hit (usually I just measure out to find spaces).

This is the safest and most secure way to deal with large sheets, IMO.

[SethCNC]

I do as phil suggested and screw it down.

I secure the edges at a safe placement and then ill often incorporate a drill toolpath and run that first, and add screws at those locations before running yhe rest of the carve… even with smaller boards that are prone to breaking. Or of any movements will snap smaller bits… like on this 1/4" walnut.

When you cant screw through then place that side down and maybe add double sided tape… or a vacuum table.

[PhilDejarnett]

I totally forgot to mention the tape trick. For thin boards, I like the painter’s tape + CA glue trick.

• Carefully cover one side of the work piece with painter’s tape, ensuring you don’t create overlaps that affect the thickness. They don’t actually have to cover completely, but it’s easier to glue up if they do.
• Then put some more painter’s tape down right down on the waste board, again trying to ensure a flat surface. These can definitely be a bit looser.
• Apply a small amount of CA glue (super glue) to the tape on the wasteboard. The more coverage the better, as long as it doesn’t seep out and glue the wasteboard to your work piece. Then set your work piece down and weigh it down with something while it cures.
• Once it’s dry, make your cuts.
• After you are done, use a scraper/taping knife to carefully peel off the final work. The tape should come off the wasteboard pretty smoothly.

This works best for thin boards, I doubt it has enough strength to hold down 3/4" plywood. I also like that I can completely cut through the final piece without worrying about tabs, since the tape (if applied correctly) should hold everything in place.

I made a really great looking inlay based on the cutting board design from Inventables for this as a practice, and the finish was excellent. The maple is really thin material

[BunnyHopkins]

Thank you @PhilDejarnett @SethCNC … I didn’t think about just screwing it into the waste board!

@SethCNC I really like the idea of running a drill path, screwing it secure, and then doing the carve. So much still to learn!

[BunnyHopkins]

@PhilDejarnett @SethCNC - Quick question. When I design it in Easel, I would need to have one run with just the drill points, then secure the material with the screws, and then another with the actual carve right?

In other words - there is no way to first drill the holes, make the machine pause while I screw the holes and then do the production run, correct? [without hitting the Pause button]

I have attached my design with the drill holes, so I am wondering whether I need to have one design with just the drill holes and another with the actual production run.

Thanks.

[SethCNC]

@BunnyHopkins

so I am wondering whether I need to have one design with just the drill holes and another with the actual production run.

This, exactly this. Using the bottom panel. You can diplicate the workpiece and then delete the perimiters from one copy and the holes from the other copy, run the holes first, then the perimiter as a 2nd carve.

Make sure steppers are set to hold locked between these csrves though. https://youtu.be/dhj70KKyP5I

[BunnyHopkins]

Thanks @SethCNC . Trying it out today.