Jacobs 14N Super Chuck Gridfinity Holders

This is the drill chuck that came with my Bridgeport when I bought it as surplus.  I hadn't expected it to come with a chuck, so it was a nice surprise that its prior owner left a pretty decent one installed in the spindle, and nobody decided to pocket it before it made it to me.  I don't use this one all the time (I usually use a keyless chuck).  One thing that I didn't like, was it was on a 3/4" straight arbor in a 3/4" R8 collet.  I opted to switch it over to a dedicated R8 arbor.

Since I had both arbors, I made versions of this Gridfinity holder to fit both of them.  The R8 arbor I bought is just an imported Meda brand, so nothing special there.  I am including the stepfiles of both holders, so that you can modify it to fit your specific arbor if necessary.  The key recesses are for the current production of the official Jacobs brand K3 key.  They're different between the two holders, because I was able to fit the straight 3/4" arbor version of it into 2x4 squares, so I had to put the key at an angle to fit that holder.  I had to go to 2x5 squares for the R8 unit, so there was room for it to lay flat.

There's apparently two different versions of the 14N out there.  Mine is the older USA made unit that takes the 30345 rebuild kit (good luck finding one of those at a price that doesn't exceed the value of the chuck).  The newer version (which I think is manufactured offshore) may or may not fit this.

Like my other Gridfinity models, the bases are altered to accept 6x3 magnets as a press fit, with the upper surface of the magnet holes modified to make the slicer bridge across correctly for a clean result.  Due to the size of these models, I have included sacrificial “mouse ears” in the CAD to give the ends more surface area to help prevent them warping off the bed.  These will need to be removed after printing.

The R8 unit pictured was printed out of Overture PLA on my Bear upgraded Mk3S+, using a 0.6mm nozzle, at 0.3mm layer height, and the other one is Polymaker PLA.