Zman
(MICHAEL ZEMANEK)
August 6, 2022, 5:05am
1
Was at a fellow CNC’rs place. He showed how he made this joint. “OMG Becky look at her xxxx.” (you got to be old to get it).
He made this small piece and joined it. I was so amazed. No glue
Being that it was pine, I thought it would snap as he was cutting it or when he tapped it together. WOW
He was using an Avid machine and ASPIRE
2 Likes
WillAdams
(William Adams (Carbide 3D))
August 6, 2022, 11:24am
2
This is known as a Knapp joint (for the inventor) or a “pin and cove” (descriptive name).
Has anyone ever tried to create Knapp joints with their CNC? It looks like a very good candidate for CNC joinery.
It’s a distinctive appearance, and has the advantage of not requiring special tooling, but it does require a vertical fixture such as:
and then at minimum 3 operations:
cut parts to length/size and machine interior features (rabbet for a bottom/lid, &c.)
mount all four boards on the machine and cut the joint for two corners
repeat for the other corner
If you don’t set up the file for cutting two corners at a time, it’s 5 operations.
An alternative is to use joinery designs which allow cutting the parts flat on the table — for the photo for the box below, no glue was used:
See:
Building from a couple of different ideas[1][2], and giving up on the perfection of void-free, and limiting tools to a reasonable number (2), I have arrived at:
https://www.blockscad3d.com/community/projects/1270618
which allows one to cut out a box in 2, 3 or 4 operations:
bottom (cut to size)
top (cut to size) — possibly combined w/ the bottom
front/back and one or both sides (repeat once for 2 operations if need be) — this will cut the joinery blind box joints and miter as well as feature…
and
I’m working on a simpler version which will allow test fitting first, and won’t require the narrow V endmill:
3 Likes
Zman
(MICHAEL ZEMANEK)
August 6, 2022, 5:51pm
3
Thank you Sir !!!
I looked through the forum last night, finding out it was a Knapp Joint, not getting much farther. The info you provided looks great.