Designing cuts in pre-painted stock

[dwhiddon (Douglas H. Whiddon)]

Is there a process that makes designing on pre-painted stock feasible? For example, I have this pre-painted stock (flag) and want to cut the union and stripes. It has been nearly impossible for me to get the cuts to align. Thought maybe one of you super users might have some suggestions. Any help is much appreciated. I attached a photo of the pre-painted flag.

Thanks,

Doug

[SDGuy (Anthony)]

Doug,
I make flags on my SO5 Pro.
Here is my process.

Step 1 Design the flag in CC/Vectric.
Step 2. Load the wood onto my CNC machine.
Step 3. Put Oramask on the Whole Flag.
Step 4. Cut the Black Areas of My Design. I put a black line where the Union meets the Red.

Step 5. Spray Paint the Black Areas. Let dry for 3-4 hours.
Step 6. Remove the Oramask on the Stars and the Stripes. I leave it on the Design.
Step 7. Stain the Red Areas, Stain the Blue Areas. I remove the Oramask from each colored area as I stain it.
Step 7. Carve the Stars, then Carve the Stripes.
Step 8. Apply your favorite finish.
SYF 30.5 x 15.75 (longer stripes).c2d (616 KB)

Please do not use my file for commercial use.

American Flag made on Shapeoko Pro 4x4

[Tod1d (Tod (with 1 'd'))]

Couple of things to consider. How accurately are you aligning the part on the machine?
And how accurate is the machine? (Has it been calibrated?)

Use the machine to align your part. Pick up a point on an edge you want to align. Move the X or Y axis a distance and align the edge to the same X or Y value.

Pick up a point on the corner of your union. Zero X&Y. Move to the opposite corner. Does readout jive with your measured dimensions? (If not, calibrate GRBL by setting the steps per mm parameter.)

Another option is to measure the Union with the machine, then scale your design accordingly.

[cryptoSquid (Andy)]

As SDGuy stated above, I do something similar but a little simpler I believe. I oversize my blank by an inch (1/2" on each size).

1. I put the blank on the machine, McFly it to make sure it’s level and smooth.
2. I make a 45˚ scoring cut to separate the blue from the red.
3. I take it off the machine and using painter’s tape, stain the blue and then the red.
4. Put back on the machine and complete the cuts, recutting the 45˙ line deeper to match the depth of the pockets. This has the added feature of cleaning up the area in case some of the stain bleeds into the area.