Auto zoning vacuum bed router ( how to do it )

Hello

I have retrofit a CNC router RYE-MG2420 with linuxcnc and mesa 5i20 7i33 card
it is a 5x8 table with closed loop servo.
My next step is the vacuum hold down system.
I already have a 60m3/h becker vacuum pump ( pallet ) which is to small for the whole table.







I found this very interesting video on the net




I would like to know how linuxcnc can open an closed multiple vacuum valve by following the the tool-path.
Wich strategy should i follow except the solenoid


It could be a very interesting methods to save money from a smaller pump and less electrical power use.




Thank you for helping me .

Papaours

I would not recommend what you are planning. The biggest problem I see is that you would probably need more CFMs to switch zones than to try to draw down the whole thing. The problem being every time you open a new zone you have to draw down the whole area area of the new zone and its plumbing from 0 inHg to what every your pump can maintain. Not to mention problems with the work piece maybe not laying flat and getting a good seal when the new zone switches on. I would suggest just adding multiple pumps and or a bigger one.

We do a lot of nested milling of 5ft X 10ft MDF (have 4 machines cutting 24hr 5 days/week.). To cut nested stuff 3/4" thick down to about 1sqr foot in size with a half inch compression end mill (single pass) requires maintaining at least 15 inHg vacuum. We have found this takes about a 20-25 Hp pump per 5x10 machine. There are tricks to cutting out smaller parts without them moving. The best we've found is to use a 1/4inch down spiral to pack all the dust into the tool path to help hold every thing down (plus the down force of the down spiral helps to). We don't use up-spirals for hardly anything. Most of our cut outs would fly off the table if we used up-spirals. Another trick to get better hold down with marginal vacuum, is to not mill on a porous fall board, use gasket material around each piece your cutting, and drill holes to pass the vacuum to each piece you are holding. We used to cut this way with as little as a 3hp pump on a 4x4 sheet. But storing and maintaining the jig boards can be a pain.

If you have multiple machines needing vacuum, I think it helps to tie multiple pumps into a centralized system. We have 2 5x10 machines and a 4x8 connected to 4 Becker VTLF250 pumps (8hp each) and a VTLF400 (18hp). This seems to keep up about the same as our two single 25hp pump/machine combinations we also have.

Thank you for sharing your experience


I will keep my small 3hp vac pump for gasget hold down, and pod aplication.
I have found a 15kw 500m3/h Reitschle dry vane pump ( second hand )
I should have enought for nest 4x8 kitchen melamine parts and birch plywood.

About the 1/4 negative bit, tow weeks ago i rent my shop to a wood worker in trouble of machine.
He came whith 10 board of MDF 18mm paint finish to nest kitchen carcass, he normaly cut whith a multicam 1000.
We route all the parts at 24000 rpm feed at 5 m/mn whith a 5mm negative single flute, and i have push it to 7.5 m/mn at the end.
We lost one piece on the job....'.... The finish on the bottom was acceptable and we trim the seen edge parts.

The dust was hardly compact between the parts, and until you keep some material on the four side of the main sheet, nothing can moove, like a puzzle.

The work shop in question use to make green furniture, and by shuting down his vac pump, he reduce the co2 bill and his electrical bill by the way.

I join a picture of the job we cut without vacuum pump.

Possibly a better way to get a little more efficiency, would be to use multiple smaller pumps on a common plenum with a series of vacuum sensors to turn off/on unneeded pumps so you are only running as many pumps as are needed to achieve your desired vacuum level. Also I believe that different types of pumps are more efficient than others (I think that rotary screw pumps are about the most efficient, but i only have indirect anecdotal evidence to support this)