Like I mentioned, this is an improvement on my original design which I did on my wood lathe. These were made on my (new to me) metal lathe, and are a significant improvement over the previous incarnation.
In the photo below you can see the relief cut at the end of the arbor that has the threads for the DA disc holder. The previous version of the arbor did not have this recess, and the rivets on the disc holder that I use would hit the arbor before it was fully seated. That is no longer a problem:
Here you can see the disc holder threaded onto the arbor, and seated onto the anti-lock washer at the base of the threads:
And another view:
And here's a shot of the whole deal slid onto the shaft of my sanding motor:
The arbor will accept DA (dual action) disc holders that have the standard 5/16"-24 threads. I get mine at McMaster-Carr, but you can get them damn near anywhere that sandpaper and power tools are sold. I prefer the ones from McMaster-Carr though, because they provide flex and are not too rigid. In this case, the disc holders I use are also hook-and-loop pads so that I can use them with Abralon sanding pads.
The motor end of the arbor is drilled to slide right on to a 5/8" motor shaft, and is secured with #8-32 set screws. Using this setup, even if your motor doesn't have a keyway, the shaft will be held secure. I actually run the set screws right into the keyway on my motor shaft, and that works out very well.
What I do is pre-mount all my sanding discs onto disc holders, then when I want to change grits, I just spin one off, and spin the next one on. It takes me a couple seconds as opposed the several minutes of centering/checking/recentering that I endured before coming up with this idea.
Since I have a few extras, I figured I'd offer them here to the first takers. I'd like to get $39 each, plus shipping via USPS Priority Mail. PayPal, check, money orders all accepted.
Specs:
material: 6061 aluminum alloy
length: 2-1/2"
diameter: 1-1/8"
shaft size: 5/8"
DA threads: 5/16"-24
Includes set screws, but no DA backup pad.
If there's enough interest, I may start another production run. If you have a motor with a 1/2" shaft, and are interested in one of these, send me an email and let me know.
