This video shows you how to build a CNC vacuum table for less than $25 powered by your shop vac or use at a woodworking station. It can be machined on most CNC's in about 10 to 15 minutes using a 1/4" downcut bit. It can also be made using just a handheld router (or router table) in a little more time.
Materials needed/cost:
I am NOT an affiliate of any of the products/or manufactures below:
Melamine Multipurpose shelf 35.65 in x 15.75in (90.55 cm x 40 cm) at Lowe's cost me $14.43 or if you require something larger -- a piece a 4'x8' Melamine Sheet costs about $44.00 (Note: Most big stores will do a couple of free rough cuts for you if you ask)
Orbit 2" sprinkler head at Lowe's cost me $3.05
Pool Noodle approximately $1.50 (I think I bought it at a Dollar store a couple years ago)
(Shop Vac -- hopefully you already own one of these)
Optional Accessory -- If you want to try a rubber seal for more friction/reduce down grid size then try Orgthin 20FT Backer Rod 1/4 inch, Black Rubber Caulk Saver, Concrete Expansion Joint Filler, Weather Strip Seal for Gaps and Joints about $9 on Amazon (or $12 for 40 ft).
Machining Tips and measurements:
*If you have a dust boot use it (and of course use a dust mask as you don't want to breath in melamine dust)
* Use a 1/4 inch downcut endmill for all machining paths. Group all tool paths together if you have a large CNC bed and cut in 1 job. If you have a smaller CNC bed cut sprinkler hole first with centered rectangular air channel (its length you choose based on how far it is from the machinable area of your CNC to the very edge of your CNC + add 4 to 5 additional inches for extra coupler hookup room). I use a rectangle width of 20 mm (.7874 inches). This works well if you want to seal with packing tape.
* Cut grid grooves 4 mm (.1575 inches) deep using a single continuous polyline vector toolpath. Grid spacing is up to you (I haven't explored the optimal spacing or geometry). However, I spaced my grid lines 1 inch apart and that seemed to work very well. Use a LINE ON PROFILE CUT (I would recommend at least two passes but use whatever is appropriate for your machine) -- If you don't understand how to do a continuous polyline then check out my next video (It's a great trick for faster machining times! The few minutes it will take to watch will save you massive time machining this!)
* Cut Orbit Sprinkler hole 43.75 mm (1.7224 inches) i diameter -- If you want to avoid using tabs then just pocket cut out this entire hole (full depth of melamine). Else for a faster machine paths (and less sawdust) profile INSIDE cut the hole to depth of melamine with multiple shallow passes (Use double stick tape/and or tabs to keep piece from potentially flying out when machining). If you use tabs be sure to clean up carefully afterwards with sand paper.
* Cut rectangular air channel 20 mm wide (.7874 inches) with a length you determine by measuring from the edge of your machining bed area where the grid will be fixed down to your spoilboard -- Be sure to add 4 to 5 inches so there is ample room to slip on the vac hose coupler
* I also recommend you put some indexing holes (so mounted table grid lines are always square to your CNC)
* YOU DO NOT NEED TO USE VCARVE PRO OR ASPIRE TILING FEATURE TO MAKE THIS (EVEN IF YOU HAVE A RELATIVELY SMALL CNC BED AND DON'T HAVE THE ROOM TO CUT THE HOLE, CHANNEL, AND GRID IN ONE MACHINING JOB). JUST CUT SPRINKLER HOLE AND RECTANGULAR CHANNEL FIRST, SHIFT VAC TABLE DOWN AND REMOUNT ON SPOILBOARD (WITH THE CHANNEL/HOLE NOW EXTENDING OFF YOUR CNC), AND THEN MACHINE THE GRID MAKING SURE YOU ZERO YOUR X,Y SO THAT THE FIRST GRID LINE OVERLAPS THE PART OF THE RECTANGULAR AIR CHANNEL STILL BARELY ON MACHINING SURFACE OF YOUR CNC
*Make grid smaller than the work piece you will be holding down
Comments:
* I am very curious as to whether a rectangular grid is optimal pattern for hold down. I suspect that its not and warrants further exploration if someone is interested in pursuing and sharing. I would love to know the results. Maybe a spiral design or overlaping rings (Venn like structure?) or maybe an outward rippling interconnecting ring structure.
Safety:
Always wear safety glasses and dust mask
Cut small air inlet hole (about 1 inch diameter) in sidewall of coupler to allow some air flow to help reduce the chances of your vacuum overheating (see next video). Fein Vacuums are a good choice.
Verify vacuum strength is sufficient to secure wood to vacuum table BEFORE using CNC/power tools (utilize an alternative hold down as a fail safe in case of vacuum failure)
Monitor your shop vac to ensure it is not overheating or it could burn out motor/or even start of fire (stop job immediately if it starts to overheat).
Follow all video's safety guidelines and evaluate all risks yourself before using or machining vac table
Use and/or make the vacuum table at your own risk!
NOTE: Tool path optimization video is coming soon using Vcarve software