Vacuum table

[balsaman]

Well,

A lot of people ask about vacuum tables. I had some ideas, but never really tried. I kind of retrofitted my first table with one, but never completed it.

So here I am trying again.

I first built a shallow box to be mounted under my existing table. It's made from 3/8" MDF, and the walls are 3/8" deep. Like I said, it's shallow. I added some supports in the center too so it won't collapse.

Here it is mounted under the table (table is flipped over).

Stay tuned...will it work? Not sure.

[Darren_T]

Hmmm... interesting idea. I know you are building it slim for obvious reasons but I believe an efficient vacuum table requires a larger volume chamber for static pressure. I wonder if it would benefit you to create a couple down tubes which hook to a larger chamber. I'm thinking on a larger scale though... I have a 1200cfm cyclone collection system I use.

Please let me know how your system works out. I'd be interested in the slim design if it has good holding power.

Darren

[balsaman]

I flipped it over, bolted it down and drilled the top 1.25" for the vacuum cleaner hose (at the back, where the gantry rolls over the unreachable part of the table.

It's working great! It has good holding power to hold light sheets provided you block the unused holes with sheet paper. I made it to hold 3 mm depron (foam sheet). I cant move it at all, unless I pick up a corner to release the vacuum first. I will cut the sheet today sometime and see what it's like once the cuts cause some leaking.

E

[kong]

Balsaman, sounds good so far. Check out the Trend MiniMach vacuum table kit. I was thinking about the rubber gasket. If you had this between your holes, the vacuum would not release as much through cutting. I don't know if you have anything similar in your part of the world?

[buscht]

Here's the USA distributor for the Mini Mach
http://www.eagle-america.com/html/ca....asp?id=334361

[balsaman]

Thanks for the links guys.

I cut this 24"x36" sheet of foam out and it worked great!

Eric

[CNCadmin]

Originally posted by balsaman
Thanks for the links guys.

I cut this 24"x36" sheet of foam out and it worked great!

Eric

MAN I wish I never sold my CNC router, I'm hot on making those fommie plane myself. I had to cut my YAK out by hand.

[samualt]

If you have a the space under your table then it pays to have bigger chambers, not smaller ones. It just collects more vacuum and means you have some in reserve.
Think about it like an air compressor. The bigger your air tank the more reserve you have.
I know it's kinda hard to think about collecting/reserving a vacuum, but that is what you are doing in effect. The trick is to make sure it doesn't leak, and make it where you can plug-up those holes not used.

Here is some Vacuum motors (Don't ever get the "Flow-through" type):
Surplus Center - Vacuum Motors

[Carver]

Hey, Balsaman, Looks good to me.

I use similar set ups in a commercial production shop daily.

If you are using a shop vac for the suction, you are depending on flow rather than pressure ( vacuum ) for effect. Your slim box should work fine for that as it will have a quicker recovery time.

I used MDF for an embarrasingly long time before I finally started sealing it with shellac and making sure all surfaces ( including back and edges ) not under my product were sealed or taped. My table is 5x10 feet with no resivoir at all. The table is piped with 4" pvc for flow, not volume or pressure. A regular shop vac will hold down parts to about 2 ft. square and I am putting considerable side force with 5/8 roughing bits cutting 3/4 mdf in one pass. I cut at 150+ IPM. I couldn't do this until I started sealing my MDF.

I have a heavy Seimens pump that I use if I leave it un-attended running overnight carving. Some of the cuts take 20+ hours.

I guess I keep going back to my roots, the shop vac works so well, I just tend to turn it on first.

Also, it is hard to find, but if you can get a source on LDF ( low density fiberboard ) It bleeds so much, that you won't need to make any holes or tape your parts. Just lay thin sheetgoods over the areas you want to block off. I use scrap formica for that.

Good job, I bet you'll love it.

Phill Pittman
digicarve@verizon.net
www.masterwerkes.com

[steveald]

Hi

Here is my idea for a vacuum table, the perforated square tube is 6" x 2" x 0.125" wall architectural aluminum, the pieces between are staple-frame awning extrusion 1" x 2" that have a slot to allow for clamping as well. The ends of the tubes will be sealed with removable sintra plugs so I can clean out debris when required. The rest is just your standard ABS plumbing stuff and ball valves available at Home Depot. I will use 1.5" so they don't restrict flow, and connect it all to a 1HP regenerative blower. The holes will be made by the router itself, 1/4" dia, then a sacrificial piece of sintra will be taped to each tube, and the hole drilling program run again with a 1/8" bit, through the sintra, and again with a 1/2" bit to create a shallow pocket around each hole to provide more surface area. Each tube can be on or off, and the excess holes behind the material to be cut will be covered with a piece of 1/16" lexan to prevent leakage. The drawing is the design for my 2x2 table, I don't know if I will ever get around to adding it to that table, but I am going to scale it up for my 4x8.

Eric, the shallow vacuum bed should work fine provided your vacuum has enough CFM. Usually vacuum pumps are high vac/low CFM or vice versa. I have found that you don't need high vacuum, as long as you can maintain a decent vacuum in spite of leakage which requires more CFM. Regenerative blowers are the way to go in my opinion, but they don't like to run in a closed system, a little leakage or a relief valve is required so you don't overwork the motor. Shop vacs might be more than enough vacuum for most applications, I would try one for a while before investing in a regenerative blower. One drawback is the vacuum table can be as loud or louder than the router unless you can install the pump or shop vac remotely.

Steve
Steve

[balsaman]

Mine is quiet becaue I am using the house central vac right now... It's in the basement, so I can't hear it.

The above plane took 10 mins 39 seconds to cut.

Eric

[Mr.Chips]

Phill,
Does the pores in the LDF eventually fill up, and become non functional? If they don't this sounds like a good material.
Hager
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Quote:
Also, it is hard to find, but if you can get a source on LDF ( low density fiberboard ) It bleeds so much, that you won't need to make any holes or tape your parts. Just lay thin sheetgoods over the areas you want to block off. I use scrap formica for that.
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