Rotary Spindle Adapter Plate Album
I love my Avid Rotary Kit. I use it as much as any other aspect of my Avid setup. It’s been very dependable and has really expanded the scope of what I’m able to do. I’ve done conventional woodturning for over a decade and still do quite a bit on my Robust American Beauty lathe.
The chuck of the Avid Rotary kit has been problematic for me. Mechanically it’s sound, but it has a lot of drawbacks that are evident to woodturners. I’ve tried to work around the drawbacks, but all the solutions have been kludges. I was talking to Jim Neeb about this, and we kicked around potential permanent solutions. Jim felt the best solution would be to put a ‘lathe spindle’ where the chuck is which would allow us to use all of our lathe accessories as we do on our conventional lathes. Brilliant!
Some designs were made, followed by some prototypes that Jim and I tested on our own lathes. We’ve come up with a rotary spindle adapter plate (RSAP) that you see pictured above. I’ve also created a Google Album that shows the RSAP closer, along with different use videos. Various measurements have been taken to give an idea of performance characteristics. In short, you give up a little precision and get a lot of versatility, particularly if you are already a wood turner.
Basically, what you do with this piece is remove the Avid chuck (three bolts) and the chuck adapter plate underneath it (seven 6mm bolts). The RSAP mounts to the planetary gear box (Avid calls this the reducer) with those same 6mm bolts and its alignment pin. The RSAP provides a standard 1 1/4 x 8 TPI spindle thread.
For reference, runout on my Robust American Beauty lathe spindle collar is about 1 thousandth. When I mount a Beall collet holder on it with a 1/4 inch rod, runout is about 1 thou.
The runout on the Avid reducer collar is about 2 thou.
Mounting the RSAP on the reducer gives RSAP collar runout of 2.5 thou. Measuring runout with the Beall collet holder gives runout of 8.5 thou (see video). So, on the one hand, runout is quite a bit higher than my lathe, but overall that kind of runout for rotary CNC work is quite okay with me.
The versatility gives the ability to use a collet chuck, all my other lathe chucks, and spindle plates (videos are also in the album). I can now safely machine right up to the edge of my work. Fixturing to round parts is much more secure with a lathe chuck, particularly in expansion mode. The other nice thing about this is that you can take the piece from the CNC and put it right on the lathe for other work (like hollowing out a bowl). Just unscrew the chucked piece from the RSAP and mount it on your lathe spindle.
If there is any interest among Avid users, please let me know. We can explore having a batch of these made which brings done the individual part cost substantially. I’m also happy to provide .STEP and Fusion 360 files to individuals on request.
Scott