PDA

View Full Version : Small vacuum table project



browne92
07-11-2014, 10:26 AM
I want to fit my cheap chinese cnc router with a small vacuum table to make setup easier. I look on ebay for aluminum drops, and I see "aluminum plate" (extruded?) and "cast aluminum tooling plate". Table size is 14 X 21, using it to cut parts out of 1/8" to 1/4" acrylic with a 1/16" 90 degree drill point mill. The original table is in 3 sections, I'll remove the middle section to make way for the "plumbing" and clamp my new table on top of what's left. I'm looking at either 1/4" or 3/8" on the thickness. Any reason in this situation to choose one over the other?

Thanks.

Old Hat
07-11-2014, 11:54 AM
"Cast aluminum tooling plate". is manufactured to be flat and intended for uses
like yours. The other not so much. 1/4" plate isn't going to take much loading though.
I can picture vacume over much area distorting it.

Toolguy
07-11-2014, 12:18 PM
Contrary to popular belief, cast tooling plate is not guaranteed to be flat. Ask the provider for a flatness guarantee. There isn't any. There is the assumption of flatness because it's called Tooling Plate and looks kind of like it's been Blanchard ground.

I have seen as much as a 1/16" low or high spots on a 2 x 2 foot plate. Also, being cast, threaded holes break out easily. I will take rolled or extruded plate every time over cast. It is usually flatter and stronger. I've made a lot of jigs and fixtures with an alum. base up to 4 feet x 8 feet in size. The wrought plate is a lot more predictable than the cast.

Rich Carlstedt
07-11-2014, 12:49 PM
I respectfully disagree with the above post
I also have machined hundreds of Aluminum Rings from 6061 Plate and Mic-6 Tooling Plate
We made threaded rings up to 60 inches in diameter and cast Tooling plate will not warp, while Rolled Plate when machined, looks like a pretzel.
Cast Plate has very large crystal structure that make it weak for tensile, but virtually warp resistant.
I agree that CTP flatness can be a problem due to suppliers, but on the whole it is still better than rolled plate.


Rich

PS If you use CTP, be sure to watch your threaded holes, they are weaker than regular Aluminum and can pull easier