- Sun May 20, 2012 9:24 pm
#144797
No, the MDF vacuum table that's in there now is a single piece of 3/4" and is cross-drilled, 5x in the X, 8x in the Y, not completely hogged out on the inside...which again, would lead me away from the flexing theory. I mean, really?, how can a 3/4" chunk of MDF, that's only cross-drilled, with plenty of internal support structure flex like that? Weirder stuff has happened...but really? And I'm using a 10 gallon shop vac for vacuum. If I was using an industrial strength vacuum setup and drawing the pressure down to .00001 psia, well, maybe I could see something like that happening. But, a shop vac? I haven't put a gauge on it, but I can't imagine I'm pulling more than a handful of in.hg. of vacuum...maybe 15in.hg at the most? Who knows...Maybe I'll make me a manometer while I'm at it...
As far as the bed bending...
When the bed is being milled, I used a 3/4" flat bottomed router bit, multiple overlapping passes, so the same area gets milled at least twice, if not three times, and the bed is NOT under a vacuum.
When I'm etching PCBs, the bed is under a vacuum, the outer edges of the blank PCB get cut deeper than the center-ish of the PCB.
Very odd indeed since I'm using the same process as far as setup and movement (although different bits obviously) to do the flatness-milling and the PCB etching.
I'm going to get a bunch of dowels tomorrow, plug the vacuum holes, and see if I can verify the bending under vacuum.
As far as the bed bending...
When the bed is being milled, I used a 3/4" flat bottomed router bit, multiple overlapping passes, so the same area gets milled at least twice, if not three times, and the bed is NOT under a vacuum.
When I'm etching PCBs, the bed is under a vacuum, the outer edges of the blank PCB get cut deeper than the center-ish of the PCB.
Very odd indeed since I'm using the same process as far as setup and movement (although different bits obviously) to do the flatness-milling and the PCB etching.
I'm going to get a bunch of dowels tomorrow, plug the vacuum holes, and see if I can verify the bending under vacuum.
I ignore "one post wonders".