Vacuum bed for CNC?

[dvddvd]

I'm planning on buying a new cnc and have been looking at vacuum beds. Not sure if they are suitable for what I'd like to use them for?

I normally cut small parts from thin timber, 2mm or 6mm. I normally cut all the way through. Some parts are 50mm x 20mm.
Other parts would be guitar bodies and guitar necks


What i found online is either a grid type or ones with pin holes.

Not sure which sort is the best or most suitable?

I have seen where someone gets a sheet of mdf as a spoilboard and lays that on top and the whole sheep becomes a vacuum with the vacuum pulling through the sheet....would that hold a small 50mm x 18mm part?

Then there is the noise and cost of running a 2.2kw vacuum pump on top of the rest of the cnc machine.

Any help please

 

[Lorenzl]

The grid type may be like the one we used at work; slots all over it with various holes? I cant remember the pump capacity but it wasn't 2.2kw. The benefit of that design was you un plugged the holes you needed and used some soft o ring material around the hole under the part. This meant you were only putting a small area under vacuum. We used to machine metal parts and never had one fly off.

 

[Ollie78]

If you cut all the way through then you will probably want the type with a thin mdf top over the actual vacuum grid. make sure to take 0.5mm off either side of the mdf so it becomes more porus.
There are also smaller vacuum pods. I have seen loads of people make their own vacuum beds from MDF or HDPE using JG speedfit air fittings, you can buy the rubber gasket quite easily.

I would suggest that if it is for a couple of parts then go with the good old tape and super glue method. if its for loads the same then make up fixtures for each.
I have a vacuum pump ready for using on my CNC router but it has been sat waiting for years, I just buy bulk masking tape and super glue. Never got round to needing the vacuum yet.

 

[Lorenzl]

I have just remembered in my first company as a apprentice a guy was flattening aluminium plates with about a 12" fly cutter. He forgot to turn the vacuum chuck on; the plate made a loud bang as it hit some steel filling cabinets.

 

[dvddvd]

So with one of the grid system beds, could you put a mdf spoilboard on it. But don't surface the top and bottom.
Then drill holes where the piece of timber you place on it is going to be and repeatedly do the same size piece of timber again and again. So the full vacuum would pull just under the piece of timber through the holes you have drilled?
I'd use a mdf spoilboard because the part need holes drilling all the way through

 

[Woodypk]

Even without surfacing the top and bottom, you’ll still lose quite a bit through the board including the edges.

50x20mm is a very small part to hold with vacuum alone unless you reduce the vacuum area down to a very small area.

What’s the total area that you’re trying to cover with vacuum?

Have you tried using tabs to keep your parts in place or have you have trouble with this in the past?

 

[dvddvd]

Hi, the vacuum bed I've seem would be 600 x 900mm.

I'd use the size on some jobs but I do lots of smaller repetitive jobs so i was thinking if it was quick and easy as flicking a switch it would be ideal.

I've seen people cutting vinyl and sticking that on top to seal areas and the edges too.

 

[dvddvd]

I've used tabs and blue tape and super glue before. Works fine just thinking if a vacuum bed would be quicker?

 

[Chief Sawdust Maker]

I use a vacuum bed for the majority of my cnc work
I often use specific vacuum plates for components that i run in big batches
Most of my work is British Oak which I profile cut in thicknesses from 25mm down to 5mm
From experience 50mm x 20mm wont hold on a vacuum
We regularly cut 60mm x 42mm and have to reduce feed rate and use a 1/8 bit down cut to be able to do that
Anything under that size then we use ca glue and painters tape
The other issue you may have is holding a vacuum against a 2mm timber, you may also have issues with 6mm depending on what timber or material you are using
I invested a lot of money on a large commercial vacuum pump which is fairly loud and pulls 3kw, the pump was UK sourced but I imported the vacuum chuck and accessories from USA
There is a lot to consider with regards to fixturing gasketing and zoning, I would suggest that it only really become efficient for large runs or items
Happy to help more if required as it was a rabbit hole i disappeared down for a couple of months trying to sort out exactly what i needed however i am now really happy with my set up

 

[dvddvd]

Thanks is there any difference in using a grid type to using a pin hole type? The pin hole ones seen to be more expensive

 

[dvddvd]

The initial piece of wood, would be 100mm x 100mm but it would be cutting multiple 50mm x 20mm parts out of it with holes drilled all the way through and then a profile cut without tabs

 

[Chief Sawdust Maker]

Mine is a grid but using fixture boards you can convert it to pin
Pin is more vacuum efficient mine is 600 x 600 and with various gaskets bungs fixture plates pipes valves gauges and pump I kicked around £1,700 at it but its worth it

 

[dvddvd]

Could I ask where you bought it from? Do you use a mdf spoilboard on top of it?
If so how much pull does it create through a piece of mdf? Is it like a magnetic board? Instant holding?
I watched a scott and sargeant video and they put a piece of mdf on top of theirs. Then placed a 200mm x 300mm piece of timber on top to be held down with the vacuum running, it seemed to move when he knocked it so not to good by the looks.