Shaper Origin: Undercut

Published 2023-10-25

Performing an undercut with Shaper Origin. It looks like a pocket, because it is, but what makes it an "undercut" is that we are using a 3|4" diameter router bit with only 1/8" cutting height. Using the clearance between the disc-like cutter head and the collet, we can "cut under" ("undercut") adjacent material as long as we don't crash the shank into said adjacent cliff. It's like dangling a cutter over the ledge of a cliff, cutting into the face below, but not too far because the reach is limited. How limited you ask? Well, one half the diameter of the bit minus one half the diameter of the shank. In this case, it's a Whiteside 3/4" × 1/8" CH with 1/4" shank, so we have 3/8" - 1/8" clearance, or 1/4" clearance that we can undercut. For this application, I know that I have limited the size of my pocket (using -1/6 × bit-dia. as offset to pocket all the way to the line) so that I cannot crash the shank. Secondly, I have defined an offset (-3/8", or -1/2 × bit-dia.) guide in the center of the pocket to indicate where it is safe to plunge/ retract. I move the cursor to the "safe zone" for both plunge and retract (because plunging or retracting outside of that safe zone will cause the bit to cut when/where we do not want to cut). Last but not least, the depths applied are 11/16", then 0.65", then 0.725", then 5/8", then 3/4". By changing the depths in this way (in between plunge, pocket, retract), we sneak-up on a 1/4" diameter undercut pocket groove to capture 1/4" brass rod. That is what you see me doing at the end; testing a short length (1-1/4") of 1/4" diameter brass rod in the slot (key way). There is a small burr on one end of the short length of brass rod that acts as a no-go pin gauge while the other side is clean with no burr, acting as a go pin-gauge. I am testing to make sure that the go side indeed goes while the no-go side indeed does not go. All the tests passed and I am (as usual, since the Shaper Origin is amazing) pleased. This setup is now complete and I can move on to the remaining 5 setups for this unit.