OK folks, I got the Dugong drive and ran the 4th axis up to full speed with a 4" chuck and a hunk of cast iron in the chuck. I also changed from 3:1 to 2:1 ratio for the first time . . zoom! Max accell/decell it would handle. Shaking my whole workbench! I'd call it a success. The thing is scary . .LOL!
I'll make another video when I get a chance.
There is a lot of interest in 4th axis and I am considering making a limited production run of these machines, possibly for the European market, where most of the interest comes from. I am in the process of redesigning for production. The drive belt mechanism works fine, but is too complicated (read expensive) for the target market. Conventional trapezoid tooth profiles are also too noisy at full speed. I'll be going with the newer GT2 belt system and no idler. I'll be looking for a vendor to produce the spindles, preferably in Europe, so anyone interested in that can send me a PM.
The current iteration was intended as final so it is nicely finished and has the index photosensor on it and is ready for prime time. The only part used from an off-the-shelf indexer is the spindle and I already bought a Phase2 indexer quite a while back when they were on sale, so I have another spindle. I have to make everything else over again except the frame, so before I take the current 4th axis apart and trash all of the pieces, I thought I'd offer it up for sale if anyone is interested. I'd take a reasonable offer and just start over from scratch. It seems shame to waste a working prototype. Better someone using it than just having huge custom made timing gears and belts sitting on a shelf.
In any case, keep watching for more refinements and higher speeds. My new drive design is finished and I ordered the new belts, pulleys and aluminum stock today. If I have time, I'll design and build a prototype spindle; longer and with a threaded nose to accept a conventional chuck, but with my schedule that is unlikely this time around.