[Salty72]

what sort of stuff have Ppl cut (held down) using this method

http://www.dream-models.com/eco/vacuumpump.html

how much leakage do you think you will be able to get away with (what CFM are the pumps)

[abelloise]

Thats what Im looking to do but over my 4'x8 table.
Do you happen to have a dxf file of the cut boards?
What are you using to hook the vacuum up to the table?
got any underneath pics?
Your post is a great help... it seems like the simplest design.
Thanks
Andre

Here are some photos of the table itself. There is nothing really special about it, its just 2 pieces of 3/4" birch plywood bolted together with some vacuum seal between to hold in the vacuum. I modeled it after a few tables I seen on here and my table top on my CNC at work.

[CNCRob]

Thats what Im looking to do but over my 4'x8 table.
Do you happen to have a dxf file of the cut boards?
What are you using to hook the vacuum up to the table?
got any underneath pics?
Your post is a great help... it seems like the simplest design.
Thanks
Andre

Hi Andre,
Sorry for taking so long to answer this question. I didn't even notice it untill now. To hook the vacuum to the table I just used a 90 degree elbow my dad had laying around. I beleive he said it is something used in electrical work. I'll have to ask him to make sure though. I have also included the photos of the bottom. I will look for the dxf drawings I used and post them here when I find them. I hope this helps- Robbie

[petriej]

Hey Guys,
I have already built a vacuum bag for veneering and also fixture construction, but am now looking to build a vacuum table. I have a commercial refrigeration vac pump that is rotary vane type, I am not sure of the cfm, but if necessary I can acquire another to double up - although I don't believe this to be necessary with the right construction. At the moment I only plan to machine hardwoods. If the fixture presents itself as suitable I will possibly use it for metalwork in the future.

My initial brain storm was to cut a platen out of composite (.500 - .750" think) (prob nylon or an acrylic type.) with .250w x .125d slots spaced .500 apart. I think four independantly valved zones would be ideal and then use a sealed spoil board and employ the drilled hole method as mentioned by CNCRob.

Thank you,


J

[Big Daddy]

How come you router guys don’t do this the way the aerospace folks vacuum down a wing section? Just lay down some particle board on your bases (the same size as your base), then deck the surface so it’s nice and flat. Make sure your vacuums on though. Then just place your work piece on the top of the particle board but place thin sheets of sheet metal of some type on the un-used areas of the new table surface to maintain a decent vacuum? And if you still have small voids here and there, lay down some masking tape in the exposed areas. It works pretty darn good holding down metal & aluminum, I don’t see any reason why it wouldn’t hold down a block or piece of wood!

[abelloise]

know nothing about pumps...anyone know what size pump I should get for a 4x8 sized table (im cutting mdf & pvc board).
Also who has the best deal on pumps...and which ones!

Thanks All!
Andre

[abelloise]

Does anyone have a dxf of a vacuum table top that I can modify and cut from mdf?
or does anyone know the best size squares to cut into the board?
Thanks for your help
Andre

[CNCRob]

Does anyone have a dxf of a vacuum table top that I can modify and cut from mdf?
or does anyone know the best size squares to cut into the board?
Thanks for your help
Andre

Here are the dxf's for my vacuum table top the one called vacuum channels is the vacuum channels them self and the one called bolt down fixture holes is for the holes I made so I could bolt down some of my fixtures if I wanted to. Hope they help

[CNCRob]

Here is the dxf for the vacuum channels under the table top that allow the vacuum through all the holes in the top itself. I did make the pocket around the main vacuum entrance (the big hole on the drawing) a little bigger then the one in the dxf

[abelloise]

Thanks for your help.

[Philthy]

I am not sure if this is the right forum for this question.
I bought a couple of V-Clamps for hand routing (sorry not CNC..yet). I moved the rubber to line up with the size piece that I wanted, but one of them works well and the other not at all. They were both working properly when I first got them, but now one does not want to hold.

Any suggestions would be appreciated

[paulC]

I am not sure if this is the right forum for this question.
I bought a couple of V-Clamps for hand routing (sorry not CNC..yet). I moved the rubber to line up with the size piece that I wanted, but one of them works well and the other not at all. They were both working properly when I first got them, but now one does not want to hold.

Any suggestions would be appreciated

Difficult to say without a picture. It doesnt take much to loose a vacume if the pump is small.
Dirt under gasket.
Nick in gasket.
If it is one of those round rubber jobs it can be difficult to get a seal where the end meets the side when it completes the loop. You may be streaching the rubber gasket so it leaves a gap there.
Paul

[Vac-Clamp]

Hello Philthy,
A couple of thing to try.
I am making the assumption that the only thing that has changed is that the seal has been moved or cut to allow you to hold a smaller piece.

First one, which might seem obvious, have you included the vacuum port in the area sealed with the gasket?

You need to make sure that the ends of the seal are touching, and that where they meet the cut is clean. You also need to make sure that you cut the seal to size, and don't try to make the end of the seal butt up to the side of the seal rubber.

Remember the vacuum pump/generator is built into the clamp, so they are not large devices. They will tolerate slightly porous materials but an outright leak will mean the clamps will not function properly.

PaulC's suggestion of a stretched seal may also be worth looking at too.

Errol at V-Clamp

[Philthy]

Thanx for the help. Redid the rubber bit and now all is good.

[Philthy]

I have to pass this on for what it is worth.

I have now got the hang of this little sucker and I have to say I use it more than I thought I would. No need to run it at 80 psi to 120 psi as the manufacturer recommends because 60 psi gives me more than enough hold and uses a lot less air.
I can use a large chamfering bit without any movement, and the best bit is no clamps in the way.

Phil

[ammach]

just caught your article , I have some pics of the one i made up now. In Vacuum Jigs . ( AMMACH ) works great. Cheap

[zoeper]

Just built a vac table for cutting and drilling 6mm Ali parts. All Vac equipment, hoses, presure vessel(vacuum in this case) from trips to the scrapyard. I am mighty impressed with the clamping force to say the least and I am just thinking up more and more uses for vac by the minute.
Good thread guys!

[Pegasus]

I've been wondering about a vac table as well but I don't have a vacuum pump.

What I DO have is a Penn State Industries 1HP DC-1B-XL dust collector that can pull 850cfm at 6.5" of static pressure. I'm wondering if this would be large enough to hold parts down on a 24x60" bed.

In addition, my son gave me a very large used squirrel-cage fan with 1.5hp motor. I'm wondering if I could use it to pull a sufficient vacuum for this size bed... Any thoughts?

Thanks

[LeeWay]

It just won't pull like you need it to. CFM is air movement. You won't be moving any air. It will also be very hard on the motor. Notice how a shop vac sounds when you clog up the end?
Your motor will likely free wheel the same because it can't get any air to move.
Even mild vacuum I tried from an old AC compressor wasn't enough on a small table.
It would hold some, but once a little air loss occurred, it didn't have the strength to pull it back down.

[Salty72]

the squirrel-cage motor might be good enough but the PSI DC will not work, due to the lack of air flow as stated above..

you can get a fridge compressor to work but they need a reservoir to combat the air leaks - these bad boys pull huge vacuum but with low flow pin size holes are a major problem