[Matty Zee]

Hi,

Not having worked with a CNC router before, i'm curious to the actual operation when it comes to the base board or table. Is it sacrificial? does it get all cut up when cutting through the work piece?

I would imagine to get a get edge cut you would want to go a fraction deeper than the work piece, but then your cutting into your base. This seems fine if using a sacrificial board but what about if you have a vacuum table?? You wouldn't want to be cutting into to vacuum table and replacing that. Especially some of the aluminium ones i've seem here...

If anyone can shed any light on this it would be greatly appreciated.
Thanks

Matt

[Madclicker]

The vacuum table I made uses an LDF bleeder/sacrficial board.

[tajord]

From my experience with CNC, well actually with a Thermwood Router, the vacuum table has two layers of wood, MDF mostly, one is the initial base board about 16mm or so suspended on little what appeared to be nylon pegs spaced evenly apart for leveling consistency, then there's a "spoil board" about 5mm or so place on top of that, this is what takes those fractional cut through marks, the vacuum we used was so strong that it pulled "through" the surface of those two sheets, then your sheet to be cut is then placed on top of those and held down, i was amazed when i first saw this, couldn't believe that you could suck through a whole sheet of MDF like that and how it held in place, no need at all for any clamps, but bare in mind that using this method the edges of the 16mm MDF had to be sealed so the vacuum wouldn't leak through the edges, thus reducing vacuum pressure.

[Jojje Bergan]

Put this, or simular, on top.

http://cnc-plus.de/index.php?cat=c76...rough-mat.html

[Matty Zee]

Thanks guys. Vacuum through the MDF with a thin sacrificial board sounds good. Couple of questions though...
How do you connect the vacuum to the under side of the baseboard? How big an area can you use a vacuum through the MDF? I'm going to have a large cutting area (1400mm x 700mm). I'm guessing you need more than a domestic vacuum or shop vac....

[Jojje Bergan]

http://www.amanatool.com/bits-fv/rc-2257.html

[ger21]

http://www.vortextool.com/standard/p...fm?groupID=305

[CNCRob]

Here is a couple more for the list.
http://www.onsrud.com/pdf/Spoilboard-4.pdf
http://www.whitesiderouterbits.com/catalog.html -on this one just scroll down to the link that says "CNC Spoilboard Surfacing"