11-14-2012, 03:38 PM
(11-14-2012, 02:57 PM)TomG Wrote: I'm surprised no one has mentioned that a 400 pound knee is a lot of mass to move when doing rapid moves in Z like peck drilling, even if it's perfectly counterbalanced. It's going to take a pretty healthy stepper or servo to get much acceleration. Why do you want to move the knee instead of the quill?
Tom
Excellent question and I hope the answers are at least reasonable.
The first is based on how the quill is supported on this mill. It is an import and the quill is not supported along 100% of its length. There is a "collar" at the top of the housing and a "collar" near the bottom of the housing with much of the middle removed to allow the rack and pinion mechanism for the quill to fit. Therefore I think locking the quill down and moving the knee will provide a more accurate system.
This is not my mill head but it is an example of what you usually find when you take one apart ...
hm52head.jpg (Size: 38.55 KB / Downloads: 74)
The second ... and probably bigger reason ... is that it is a horizontal\vertical mill and CNC'd knee offers some interesting possibilities. If a chuck is installed in the horizontal spindle then CNC'd lathe possibilities exist. Material in the chuck and the tooling attached to the table. An example of this might be ...
The difference between diagram 2 and diagram 3 would be the difference between his implementation and the implementation that I envision.
Does that seem to make sense or is it still the wrong path to be taking?
Arvid