Cutting preview

LowRider CNC Advice
1

Hi,

I’m having a lot of trouble securing my plywood sheets to my sacrificial plate. I often notice that the sheet is warped in certain areas, and as a result, even though the machine is fairly precise in the Z-axis, I end up with inconsistent engraving depths.

It seems to me that the simplest solution is to secure the sheet with a few screws.
The problem is placing the screws in the middle of the sheet.

What do you think of the following idea? Maybe one of you has already tried it and has some feedback on the subject?

  1. Attach a pen at coordinates X, Y, and O relative to the router bit
  2. Set up a virtual cut with a single pass, router turned off, without actually cutting—using maximum feed rate and a depth of 0.5 mm, for example
  3. The probe is performed with the bit, and a macro allows you to offset the starting point by -X -Y
  4. The machine traces the contours of the parts, making it easy to secure screws in the uncut sections

The ultimate setup would be to have a projector suspended above the machine, but that would be quite expensive and difficult to adjust (scale)

2

Strong double-sided tape, or the blue-tape-plus-CA-glue method, may be strong enough to overcome some warp, depending on the thickness of the plywood.

3

I’ve been using this for years with my pattern routing. Used it to flatten a board with my LR4 last weekend and it didn’t move until I pried under it a bit. Just the right amount of hold without tearing wood fibers, and not thick like some others.

And much better and cost effective than the blue tape trick.

4

I just used screws, but in very deep countersunk holes.

5

Thanks to both of you for the tip about the double-sided tape. It does seem pretty simple that way. I’ll give it a try.

1 Like
6

Yes, but even when milling fairly deep, if the screw is in the cutter’s path during the cut (i.e., if it goes all the way through the plate), things could go wrong.

7

I use screws for my cnc jobs. I make a separate gcode with the drawing that’s just for poking 2mm deep holes where I want the screws to end up. I put 1-2 screws in at very safe areas, then setup the workspace coordinates, and run the poke gcode. Then I go back with my drill and driver to put the screws in the right place. Then I run the main gcode.

2 Likes
8

What an elegant solution! I really think it’s very clever. Unfortunately, I use ESTLCam and I don’t think I can add a drill hole to my drawing at a later stage…
I use a nesting tool to position my parts and then create cutting paths in ESTLCam. I’m just missing the step of positioning the screw holes…

9

Sure? Just select any tool and the drill option and click anywhere… :smiley:

1 Like
10

That is a really great idea!!