Vacuum Hold Down Table 

Thank you Frank! My dad and I have been working on a cnc table design and one thing that we've been dancing around is a vacuum hold down surface. Thank you for showing how easy it can be!

I've messed around with vacuum tables quite a lot, and what I found to work best is just sucking the air through the MDF. You have to machine off about 1/16" from both surfaces to get rid of the hard outside layer, but the core of the MDF is porous enough for the air to pass through. Some guests in the shop have been really surprised to see how well it holds when there is seemingly nowhere for the vacuum to get at the workpiece! I also found that if you have the entire surface covered it takes very little airflow to keep up, so you need surprisingly little space inside for the air to flow. My most successful vacuum table was simply one piece of 3/4" MDF with a tree-like pattern of 5/16" channels CNC cut into the bottom, with a piece of 1/4" MDF glued to the bottom of that. The bottom and edges were sealed with varnish to prevent any leaks. All of my vacuum table experiments were using a central vac motor (similar to a shopvac in performance) providing about 60 inches of water.

I used to do a lot of screen printing and the table we used had this vacuum system. We just used sheets of paper to block the other holes. We also had an upright copy camera that used similar system to hold down the film and it used an empty canister between the vacuum and the area to be held by vacuum, it was about the volume or a little less of a 4 litre paint can. I think its purpose was to give you instant vacuum after throwing a lever or switch as the canister would be in vacuum and as soon as you threw the lever the work was held instantly and you didn't have to wait for vacuum build up. Hope this vaguely remembered stuff helps in some way.

Paint the sides to help. MDF and particleboard allow air to flow through. At the maker space I go to the have MDF on their CNC to clamp plywood sheets down.

Even if you're not totally pleased with it as a vacuum hold-down, you've made yourself a darned nice downdraft table. Perfect for sanding on to keep dust to a minimum. We've got a couple of these in our shop for this.

What you need is an actuating part that blocks the holes not in use for your run. This may be a manual switch that you have to actuate from the sides or top or bottom of the table. Ideally your CNC program would run the actuation automatically when you located your part and hit the "go" button...but that's a different set of circumstances. Good stuff, as alway, Frank. Thanks for doing what you do.

I used to work on a 4x8 cnc that had a built in vacuum table. There were a bunch of grooves in the table and we inserted rubber gaskets in a rectangular shape the size of the piece we were working on (this would localize the suction just to our work piece). Also, we would sometimes just install a piece of MDF large enough for our work surface - it's porous enough that the vacuum would pull right through it, especially for cuts on large sheets. Maybe try some 1/2" or 1/4" MDF on top of your setup and see if that gives you enough suction when you put pieces on top of that.

Wow. That fade into the outro is genius

I used to work as a CNC operator at a local shop, I recommend routing a small groove midway between all the holes both X and Y directions and using a closed cell foam tube gasket/foam backer rod to seal the area below your work piece (If you plan to continue using boards to cover the "extra/ unused" holes then you would need to put the gasket in the groves around the edges of these pieces as well) This will allow the vacuum to pull the piece down onto the table and create an air tight seal. Also you may want to consider routing a ledge around each hole and creating "mushroom top" pegs that you can drop into unused holes so you dont need all the extra wood on the table. This will allow you to cut irregular shaped stock (we had rubber pegs that we placed into the unused holes but I'm sure you could make something out of wood). Good luck with you CNC machine! Love the videos.

Great video. Thanks. MDF is porous anyway, so it may not be necessary to drill all those holes (if you have enough vacuum). If you cut 1/8" / 3mm from each face of the MDF sheet it removes the most dense part of the MDF and makes the vacuum significantly more efficient. I use scraps of plastic sheet to cover the remaining area when I need more vacuum on the job piece. A vacuum cleaner is not designed to be dead ended as the air going through it is intended to cool the motor. Using it for a vacuum table may not allow it to have a long and happy life!

Super interesting stuff, Frank. The test piece at the end was very cool to see emerging! Thanks for makin' !

Hey Frank. Heres an idea. cover the table with rosin paper then poke holes where you need suction. Simple and cheap.

Great build. A couple of things, One: paint any MDF to seal it from air leakage. MDF is basically a sponge with micro-channels all the way through it. Either latex paint or similar, or just PVA glue diluted half glue half water should do the trick. I heard the glue trick to seal the edges of MDF to keep it absorbing to much moisture even in storage or when 'fresh cut' parts coming off CNC machines. Second: Zone the hold down. If you are having a permanent vacuum hold down, make it into zones, say divided in thirds along the sides, and in half down the center length wise, making 6 segments that could be turned on or off individually with a simple 3" PVC manifold and ball valves.

Mr. Howarth, appreciate all your videos, very impressive skills!

Awesome Frank! I use a biesse cnc at work that uses vacuum as the hold down. Not sure how powerful your vacuum is, but I use 3/4 mdf as a spoil board. The holes are all under that, the way I get it to suck down parts is to plane both sides of the mdf. You be surprised at how porous mdf is after removing the protective layer.

Frank your vacuum working table is fantastic.

That is the coolest large setup have ever seen, so jealous!

Looks like it does the job well Frank, and nicely made as always. The only suggestion I can think of (and it is only a suggestion which may well prove impractical) would be to make some sort of sliding boards within the table itself. Sliding them back and forth would close and open the holes withing the struts, rather than you having to use boards on top. I don't think it would work any better than the system you've already devised but the idea may prove to be food for thought :-)

Hey Frank - Cool Idea & great video! Perhaps instead of the 'wood dams' that you made, you could use a heavy/cardboard paper. The vacuum should hold it down just fine, and you could cut out the paper where the work piece is allowing you to do virtually any shape/size that fits on the table.

Hey Frank, great build, what i use on my vac table is a plastic bag and just lay it over the open areas, not as sexy for sure but gets the holes covered!!

always entertaining Frank, always!

That "peg board" making part was cool to watch!!! Great project!

I really like your videos. I have built a number of vacuum tables before. The only recommendation that I will make is smaller holes. Like 1/16 to 1/8 in size. The vacuum hold down for this size is much stronger then the 3/8 inch holes that you used. They would be closer together and you don't need as large of vacuum. For the tables that I build I use dowels instead of raceways. I have found using raceways over time you get scalloping of the surface where it is not supported underneath. I also use a much smaller chamber size. No more then an inch between the sandwich. The smaller the area of volume produces more suction.

Frank, love your work, always a good watch. I have a suggestion if you remake your table. Rather than making a torsion box, if you simply laminate together 2 sheets of ply or MDF you can route a deep criss-cross pattern into the surface to act as air flow channels. Then a third lamination with holes through it to act as the surface, where the through holes meet the channels below. This would be just as heavy as the torsion box, and easier to make and maintain the vacuum.

Where I used to work, we had a 4' x 8' CNC router and we laid 1" x 4' x 8' sheets of foam as the sacrificial layer. It breathes amazingly well, so the vacuum still holds powerfully. You then cover up the 'non work' areas with some cheap plastic sheet (Coroplast, etc). After a while, you flip the foam sheet and use the other side. Once both sides are too marked up, you replace the sheet. Cheap and easy.

Now hook a leaf blower up to it instead of a vacuum and you got yourself an air hockey table

Very nicely done! Not sure why this video didn't come up when I was researching my own vac table. Enjoyed the video - thanks for posting!

I was very skeptical about a shop-vac being able to hold a board down, but you've proved me wrong! Kudos! :)

I was kicking around making something but I was no where close to this idea. Gonna give it a try for my small ShopBot. Thanks Frank.

To get better suction you want to make a larger number of smaller holes. Big holes like what you have or pegboard for example don't make very good tops for suction tables. I'd suggest looking at some videos related to making vacuum forming or vacuform tables - they're extremely similar in build and are used for holding down forms to molded, while a hot pliable plastic is placed over top that then gets sucked tightly over the form to make a mold of it.

I worked a huge flat bed beam saw once that had the opposite the bed had ball bearing vents that when pushed down blow air up and lifted the board which meant one could move a 9x8 board with one finger. I wonder if you could use the same principle in reverse so to localise the vacuum to the work area? Love your videos thanks for sharing your time and adventures.

Hi Frank. Very nice video and work you did there again. A small hint for the next top surface. Normally the holes in a vacuum table are made in two steps. Larger diameter pockets in the top that doesn't go through. In these pockets there are smaller diameter holes drilled (1/16" or smaller), this time through the top. That way you have a large area for hold down force but only a small hole to limit the airflow. In case there are some leaks you don't lose your vacuum at once. Thanks for sharing your work with us. I'll keep following your channel. Greetings from Belgium. Julien

Hi Frank just a few pointer I used to program CNC machines.the Matrix machine works better if you seal the sides of the mdf your vacuum with increase, you will have air leakage at the side until it's sealed, you could put a sacrificial board on top so you can cut right through I set the cutter depth to -.2mm we put 25mm mdf on top of our plenum which we would skim every day until its about 6mm we skim both sides so we get airflow and seal the edges. we do exactly what you are doing by covering the unused bed with melamine covered 6mm ply we tried various method but for speed we found this to be the best way but mostly we used 8x4f sheets. Great build of the CNC liked the way you overcame all the problems.

Very cool I just ordered a 4x8 router and was thinking about a full size vacuum table as well but I like this idea much more!

NICE ! And as a professional photographer, it reminds me of the smaller, peg board topped vacuum box I made "back in the FILM day" - to hold down sheets of 16x20 photographic paper below my enlarger. That way I could expose the entire sheet to easily create a borderless image... ( it worked great.)

awesome job frank

in our shop we just used two pieces of mdf and routed a center groove that branched out on top and bottom pieces and glued them together so they made an air channel and had holes on the top piece. when you wand to use a small section we just put a peg in one of the center holes and it stops the air from going to the other branches. works pretty well

Hey Frank, not sure on the vacuum required but some of the CNC router companies I've come across draw vacuum directly through the MDF w/out the peg board design needed. You can isolate this surface area with thin plastic sheet i.e. trash bags. Love your videos.

Great video, as always. Thanks! Love the dynamic cover boards idea...

very cool. your cnc seems to be the best one I've seen yet. at least that is home work shop size.

I used to run a graphic arts camera that had a vacuum film back. To allow different sizes of sheet film there was a sliding valve that would close off the area around the edge allowing smaller and smaller sizes of vacuum area. The sizes were marked off in red so you could align the film where the vacuum was, worked quite nicely and I'm sure you could do the same thing and not even need those pieces for blocking off the air flow but the pieces for alignment might be nice.

Frank, could you make some type of manifold system that allows you to shut off certain sections of the table instead of plugging them from the top?

Nice build Frank!

A commercial vacuum table I saw years ago had several dozen ball bearing valves with a grid of rubber/foam gaskets; just slap a workpiece anywhere on the table and it stuck. The springs holding each ball bearing in place were just strong enough to resist a shop vac, but any weight on top would break the seal and start the vacuum effect. I thought it was pretty neat, but always thought that a huge workbench sized version would be more awesome.

You could use a sheet of plastic to cover the holes when you have an odd or round shape. Just cover the table with the plastic, then cut and remove the plastic from the hole that you need to hold the work in place.

Every time you said struts I took a shot and now I’m hammered hahaha!!

For an example of vacuum fictures in use on cncs on another scale I come to think of John Grimsmos channel (metal/knifes cnc). His setup was consisting of multiple fixtures stacked with one having groves cut around a central air vent which would be sealed with an rubber string to form the perimeter of the vacuum to form. maybe easier to setup than the holes and chamber even if the vacuum might take longer to form. The tricky part would be to get the ratio of rubber compression, deformation and groove dimentions just right so that you get an air tight seal and have the workpiece rest on the ridges instead of the rubber.

As always, super idea.. well done frank

What i would suggest (when you make a lot of pieces which don't take a lot of time to cut) that you build a foot pedal to switch the vacuum on and off! I also would find another solution fpr covering the holes cause that looks not good and is inefficient. I work as a carpenter and at work we have a big CNC and we also use suction to hold it. For that we have a few rails where you can put some rubbes "boxes" on which have a few holes in it and every time we step on the foot pedal, the "boxes" get the suction to hold the piece somehow through the rails. Maybe membranes are used . Maybe you thought about the same thing with the suctionboxes. Respect and love 4 wood from Germany

Awesome vid Mr. Howarth, and as always, tnx for sharing it with us!!! 🙂

how about covering the whole table, workpiece included, into a disposable sheet of plastic, the kind of plastic garbage bags are made from. the cnc should easily cut the workpiece trough the sheet.

Looks nice! I always thought about using little spring-loaded ball bearings in the bottom of each hole to act as automatic valves. You just toss your workpiece on indiscriminately, and every hole that it doesn't cover will shut itself as the ball gets pulled downward. (Unfortunately, the holes probably would get full of sawdust in a hurry...)

I'm hardly qualified to make a suggestion, but I can think of a couple of things. 1. Actually just use perf-board. 2. Make an external PVC manifold to go between chambers, rather than the holes in the supports. By doing this, you only draw vacuum on the chambers you need. 3. A thin film of plastic would work as well as plywood to block the holes you aren't using. Just suggestions. You are waaaaaay better at this than I could ever be. Love the channel.

A friend has a vacuum table for all his CNC, he doesn't have holes in his vacuum table only a piece of MDF with a 64th trimmed off each side to open up the pores. This does a great job doesn't have the loss issue that you're trying to deal with by putting boards over the unused holes

Small note if you make another. Your inner baffles are perfect, what I've see in other is having a second mirror piece then you slide them shut to block of sections of the holes so it's just a little easier.

I run a vacuum bed at cnc at my work. I would recommend sealing the sides to restrict air flow through them. I was wondering, does the end furthest from the side with the vacuum port have enough suction to hold strong?

you can use rubber mats. like the ones you make gasget out off to cover up the holes not in use.

Another gem Frank Cheers Mike

I think the outlines of a lot of past projects in the CNC table at 0:52 would make cool artwork.

thank you Frank wonderful as normal . question if you dont mind could you not use some sheet plastic and just cut out to size the part size ?

As always great videos entertaining & professional Nice work Frank!!!

Pretty cool, loved it.

Hey Frank I put a 1/4" piece of mdf on top of the holes and your vacuum will suck through the mdf and hold your piece down (depending on how strong your vacuum is) then put trash bags on the part of the mdf that's not been used to direct the suction to the work piece. You might try that and see if it would work for you.

Hi frank, make sure you have enough air flow to allow the shop vac to stay cool. They rely on air flow to cool the bearings and motor. I've seen people use motors from ducted vacuum systems and drill a small hole in the hose so it leaks just enough to keep the motor cool. Love your work

I own/run a commercial CNC in a millwork shop. Not sure how well the information would transfer to a smaller CNC, but here are a few ideas: Our CNC has an aluminum table with holes for vacuum. Instead of having so many holes (ours are about 4" apart), our machine has channels around each hole to spread the vacuum of each hole. Would reduce cutting time, and allows for realistic plugging of individual holes. Ontop of that we put a "spoilboard" solid 4x8 sheet of 3/4" MDF (no holes). We prep the sheet by running all edges through the edge bander. This stops air from leaking out the sides. Once that is done, I use a 3" cutter to mill off about .2mm from one side of the sheet. No only makes it very flat, but the surface is now much more "open" for airflow. Flip the sheet, and repeat. The sheet is now perfectly paralel to your gantry and open for airflow. I'm not sure if a vacuum should have enough power to do the same (pulling through MDF) on your scale. Our pump is 10hp, but it is capable of 5x12 cutting area (usually setup for 4x8). I can cut a 24" x 24" piece of MDF sitting in a corner of the sheet without blocking the rest of the sheet off.

That's a lot different than the conventional grid plenum with MDF spoilboard top, cool concept!. You may find you have better performance with the tried and true with the addition of a few whole house vacs. There is a lot of good information on making these in shopbots forums. If you are interested I have some of these vacs and a homemade manifold that I could send some pics of. Trupan MDF is ideal for your spoilboard. I run an 8hp vac on my CNC and I think the whole house vacs are nearly as effective.

I remember a magazine article from way back in the day where they used a roll-up window blind to cover part of a down draft sanding table. As someone else suggested, a roll of craft paper would work and you could cut the opening you needed.

We had a thermwood in high school with a built in vacuum table and what we did is cut custom waste boards for each project. We'd cut a 1/4" groove was offset to the inside of the outline of the piece (if that makes sense). And a grid pattern of the same size/depth cut inside that outline along with small holes drilled periodically to allow the air flow. Then we'd fill the the outline with a 1/4" rubber strip. Once the piece was in place and the vacuum turned on, the suction would fill that grid pattern and apply even pressure across the entire piece. This was especially effective pieces that needed to be mass produced but even for small one-off projects it was fine because the work bed 8'x8' so you could simply grab an old waste board with some room on it and use that. I hope at some least of that was coherent. It's early and I haven't finished my coffee lol

Well, if the test piece at the end is surrounded by other boards it surely helps keeping it in place... not sure you proved this is working as intended.

You shouldn't have drilled the second sacrificial board. The best way, is to get an MDF product called Trupan (it's from Chile, but quite a few lumber importers carry it) but it's technically LDF, and you skim off 1/32" on both sides. That is your work surface. Place anything on that it will create enough vacuum pressure without all the holes nonsense. Plus, you need to paint or coat all the other wood. As it breathes quite remarkably under vacuum. The bottom box would have been better if it had been made out of melamine.

I have been wondering if after years of use this will clog up internally somewhere due to ineviteably sucked in debris and dust

in between the two top layers you can glue a "rail" system in which 2 wood stripes for each row would be inserted from two opposing sides meeting in the middle. do that for every row and u have a convenient way to activated each hole individually by pulling out the stripes sometimes more sometimes less. or one side more than the other.

Great idea! A sub vacuum table. I think that's the way I'll go at first. Although I am quite happy with my downdraft table.

Good job man! I am right there with mine.

so we have a very expensie cnc mill at school that uses a vacuum table but instead of relying on holes in the mdf the vacuum is strong enough to actually penetrate the mdf without any holes which means that there isnt that much loss of suction of parts of the vacuum table arent covered of course the larger the area of the piece the better it will be held down but it does a pretty good job and if the piece is small we sometimes just hot glue it down the the mdf which really holds it well

I just literally ordered my 3mt by 2mt cnc router this week... Been watching your video's for years. I love the way you work and edit them, but this could be the most useful yet!!! 1 question, what software do you use? Like vector to G code?

What if each hole had some kind of floating valve? The weight of the workpiece would open only the holes needed.

Hi, Frank! Better is to not drill the holes right though the MDF, and then drill with 1mm right though, else wise your vacuum will not be able to build up because the sum of hole size will be bigger than the air being able to be pulled out. Also you will have to cover up the unused holes very carefully as to much air will be lost. Adding to the problem is that MDF lets though a lot of air even without holes - I've used 3mm MDF without holes on my vac table as jigs at time, so use a good layer of I.e poly on both side before drilling the small holes...

You could create slides that slide along the venting on the inside to make your work area larger and smaller depending on need.

I do commercial large format printing on an Océ Arizona which features a 3050x2500mm vacuum table separated into multiple zones. If you made some of the baffles solid, then split your vac run with valves, you can turn on/off the individual zones and lessen the need to cover the unused areas. Also the space inside need not be so cavernous, its just a pathway from the vac hose to the holes in the top. You could make it much lower profile by using a thick sheet of polycarbonate/aluminium/sealed MDF and route a series of channels only 3-5mm deep, then add your spoil board with the holes directly sandwiched on top. Our table is 2 sheets of aluminium with only a 3mm space between them. Also the holes are barely 2mm in diameter at 30mm centres. You'd be surprised at the hold down force it can generate. Your table does what you need it to do, so I don't imagine we'll be seeing Mk II anytime soon. But I just thought I'd share incase anyone else can benefit.

1/4" holes are sufficient for the vac hold down. If in your software you have a feature called Convert circles to drill points then it will do a straight plunge instead of walking around. When I have to drill mine it's about 5500 holes and takes about five hours. I just turn off the lights and go do something else for a while.

Great video Frank. Was wondering why you didn't cut the whole thing out on the CNC? Would have been less work than dragging things over to the table saw etc.

One suggestion. On the supports inside put slides with pulls on the outside to close off areas that are not used. Then use the boards on top to cover what is left of the open areas. Make sure the slides are on the opposite side of where the vacuum is so they are pulled in to help seal.

I am thinking have pieces that have matching holes that is under the top. if your want to seal an area you could slide the lower piece half an inch so the holes no longer line up.

i have some videos of a similar inc with a 5'x12' bed we used a large vacuum and a sealed table with mdf on top the pdf was ports enough to allow very good suction. it helps to cover the unused space with rubber mats to increase suction where you want it

Frank, may I say you are an inspiration and ambitious. Your vacuum table. My experience is that you’re never the right size and cover pieces. Rather than trying to make one big one, make many small one’s. A round piece of wood say 3” and 2” thick with an O ring grove cut into top and bottom with a hole through the side. Make several with a ball valve on each. Small flexible hose to each all piped individually back to the vacuum pump. Place them under your work piece, open valves only to the ones you going to use. Switch on vacuum pump. Suction cups fix to bottom and work piece at the same time. Job done. Many thanks for your entertaining videos. Johnathan

great video and idea! is the shop vac prepare for this? I mean, it is running on vacuum so there's no cooling for the shop vac right? maybe I missed something.

The cutter table at work has small spring loaded ball bearings that drop down when something is placed on them allowing air to come up around them giving it a cushion. Perhaps you can do something similar.

Great work as usual, but why not make all the drilling with the sacrificial board from the start?

Using the box you've made, you could use a thick plastic sheeting/film to block the unused holes. A different design would be to build a box with the vacuum hose connected to the center of the bottom piece, and one side left open. The top should be made of thick HDF or ply (or HDF sandwiched between ply), because the box has no built in support members (other than the three outer walls). To limit the top holes exposed to vacuum, you would make various diameter shallow cylinders to insert into the box, the height of the inside of the box, and 2 long pieces of ply the width of the inner height of the box, along with various sized pairs of shorter pieces of ply to also use to sequester work under vacuum.

I suppose you can add in some adjustable sliders, or pluggable tubes, to create multiple zones to vacuum. For example, you could create a box with 2 full depth dividers inside it to create a box with 3 zones, then drill 3 holes in the sides and externally have some sort of elbow mechanism as needed, or have one vacuum hole, then additional holes to connect the side to the center. Or have some more elaborate dividers that slide internally with offset holes so that if you move them a few inches, the holes are aligned to combine the 3 zones into one, and a few inches the other way closes the holes.

Can you make a video on how you program your cnc machine.

what if you cut out a larger recess at each hole then dropped a washer blank or some other stamped disc in it? quick and easy to pull out with a small magnet.

Great idea... But how strong it is... Did you make some tests? For example How many force you need to move a piece of wood, or how is the seal... The air that flows between the fixtures and the machined piece... I really like your videos.. But I think is missing something tests sometimes... :/ Anyway! You are great, Frank! :)

Not sure if this is a factor or not but your registration pins on the blocker boards might be preventing it from sitting flush and blocking all the hole underneath. Might want to go with a slightly smaller pin? I'm not sure. Great stuff as always!

That could be handy for something that can't be clamped with classic clamps. But otherwise, the classic clamps you might use more often than that table, classic clamps are faster and easier for parts that have plenty of clamping room. I forgot what you call them, but little connection points in your work piece so the part you cut out don't move, then you just use utility knife to snip the tiny tabs, no need to mess with a vacuum clamp. you might find it more convenient, but from here it looks like traditional clamps have it beat. Nice experiment, thanks for the share.

MDF is porous and doesnt need holes drilled for air to pass through. On CNCs we use in the millwork and cabinet industry we have vacuum tables built in and we use MDF spoilboards and the parts are held down to the mdf with suction. sometimes you can tape the edges of the mdf to improve the suction and also put laminate or another non porous material around the parts similar to what you are doing. Also just using a 3/8" bit and drilling with your CNC. instead of routing a circle for every hole would speed up your running time significantly.

Hi mate. What do you think about just using some plastic sheeting, bags or tarps to shield off the area that you're not using? You can just cut a hole where you put the workpiece. You might even be able to use some butcher's paper.

hi frank I live in England and where i work we have a CNC ( Multicam 3000 series ) we use a vacuum table and we use stock MDF no holes the air can get thot the MDF just fine but we do have a big vacuum pump so may be somtink worth looking in to and just google the CNC ( multicam 3000 ) your find videos on how there table are set up .

Frank, this is really clever! At the end of the video though I couldn't help but wonder - is the vacuum really doing much of the "holding?" Or is it the boards with pegs covering up the remaining holes. I'd be curious if you did an identical piece to your test piece with the vacuum turned off if it wouldn't have the same result. My guess would be that the pegs on those boards are more than strong enough to hold the piece in place themselves without the vacuum even on. What do you think?