Gotta home made system?

 

Pretty cool challenge!

 

One day too I would like to see the machine that originally did those.  Gotta wonder about the size of it.

They make a jig for this, I’d just like to make my own.

I wasn't aware of the jig.  I mostly just run routers for profile work and pattern work.

 

On original pieces it must have been a ganged set of hole saw looking things for the one side and a ganged set of half round cutters for the other.  That second one is easy enough, something like a large horizontal mill (for metal machining) would do it.

Look up the Isolock templates for the Leigh DT jig. Jack's version did a really nice job.

40 minutes ago, Fred W. Hargis Jr said:

Look up the Isolock templates for the Leigh DT jig. Jack's version did a really nice job.

 

None of those are Knapp joints though.  Jack's version is a lot closer.

It's an interesting joint, I think if I was doing factory stuff I would prefer something like the Knapp over machine dovetails.  In reality though, I'm going to stick to my saw and chisel

Briefly met a doctor who did them by hand but didn't have time to get the full details. 

 

His looked more like this-

 

 

Not sure if you can see this article

https://www.finewoodworking.com/2018/09/26/how-to-make-the-cove-and-pin-joint?srsltid=AfmBOors3hcEF9wNTBK4tiEffR2rc5YQ3ziPtVoosTKROCB_XJIYJPiw

 

 

http://www.vintagemachinery.org/mfgindex/detail.aspx?id=502

1 hour ago, Fred W. Hargis Jr said:

Look up the Isolock templates for the Leigh DT jig. Jack's version did a really nice job.

I’m familiar with the  Leigh jig, wanna make these with a homemade jig..

 

When I brought this up on the  other  forums, nobody really wanted these and Go for the dovetail. 
 

It’s a lost joint..
 

 

56 minutes ago, lew said:

Briefly met a doctor who did them by hand but didn't have time to get the full details. 

 

His looked more like this-

 

 

Not sure if you can see this article

https://www.finewoodworking.com/2018/09/26/how-to-make-the-cove-and-pin-joint?srsltid=AfmBOors3hcEF9wNTBK4tiEffR2rc5YQ3ziPtVoosTKROCB_XJIYJPiw

 

 

 

I've seen those done.  They called 'em "love tails".

 

On the specific Knapp joint, a person could most easily to do with a slot mortiser with an annular cutter instead of a solid bit.  Hard part would be indexing each cut to keep the spacing consistent.  Could also be done on a drill press with the table tilted to the vertical, and rig up a fence & clamps etc.

 

The drawer side would be easy enough with a half round molding head cutter in a tablesaw, using the pin holes as the index, like is done to cut a box joint.

 

It's a lost joint alright - fair amount of specialized machinery to do an exact copy, or less specialization and more fuss & hassle.  A routed version with the bit between the coves curved instead of square is probably about the best version can readily be done.

Fine Woodworking

I may pick it back up as the temperatures break. i’m like a pit bull on some things, I’ll bite till I’m exhausted..

 

Edited February 19, 20251 yr by BillyJack

38 minutes ago, BillyJack said:

I may pick it back up as the temperatures break. i’m like a pit bull on some things, I’ll bite till I’m exhausted..

 

 

I had a terrier mutt like that when I was a kid

Here is a historical perspective as well as pics of machine. Joint was only used for about 30 years.

The Knapp Joint Explained

I guess Woodworkers Supply use to sell something affiliated with the Knapp joint, but that link is gone. I guess I starter a post in 2020 about this joint trying to find some info on a jig, but nothing. 
 

My brain has been tossing this joint around and I’m coming to the conclusion I will need to router table setups. I believe the  bits needed are there , I just need to combine them...