I had almost all that info scattered throughout the post. It's 6061 Aluminum 3/8" thick in bar stock form. The Depth of Cut was 0.050" and the feedrates were between 2-4 IPM. This was using a straight flute wood bit (3/8"). The Rotozip is rated at 30,000 RPM ... but I slowed it down using a Variac. Since voltage and RPM aren't directly related it's hard to say what the actual RPM was ... I just turned it down as low as possible to achieve good cuts. My guess is that it was running 8,000-10,000 RPM ... slower made cleaner cuts until it started chattering, then a little extra RPM would prevent the chatter (especially on deep cuts.)
The Rotozip bracket is pretty cheesy. Although it has bearings, the plastic body really flexes, so I hope that's were my chattering problems were from. The new router bracket and router is very rigid and has some "Umpff" behind it, so I'm hoping for cleaner cuts. Of course this is also I high-speed motor so I'll need some way of slowing it down while keeping SOME torque. So today I'm pulling an old project out of the closet which did phase controlled speed for large inductive motors ... kinda like what I need here. If that'll work then I'll need an RPM sensor on the router to "close the loop."
I'm interested in the spindle project!
CP  |