Vacuum table Setup Advice

[Boyan Silyavski]

i am saying that the job could be done by any 1-2hp air compressor with or without additional expansion chamber. which cost for 2hp ~70 euro at any home depot.

so you can hook the compressor and check if you have all right, cause with the compressor should work Ok without any problem.

what i am saying is that a typical air compressor pulls 6x more the vacuum compared to the pump you have bought

[Boyan Silyavski]

please read that thread http://www.mycncuk.com/threads/8294-DIY-Vacuum-Fixtures

[andy_con]

I don't understand how you can use a compressor, but will take a look at that other thread at lunch.

A compressor blows air, not sucks air

I only have a small compressor

BB24D:


http://www.bambi-air.co.uk/uploads/f...dget-Range.pdf

[GEOFFREY]

For a compressor to compress air it must first suck the air in through the inlet filter. If the inlet is blocked or choked it will pull a vacuum. Boyan has suggested trying to use that vacuum to operate your vac hold down. that would be a very simple and cheap (free) way to check if the system works. Good luck. G.

[andy_con]

Ah now that makes perfect sense thanks.

When you say the system works, I know the table and bits work as work peice does get held down just not strong enough.

I'm assuming you wpuld only use a compressor to test not as a final solution as the compressor would need to be running for an hour straight to draw a vacuum whilst you do the machining?

[Boyan Silyavski]

Ah now that makes perfect sense thanks.

When you say the system works, I know the table and bits work as work peice does get held down just not strong enough.

I'm assuming you wpuld only use a compressor to test not as a final solution as the compressor would need to be running for an hour straight to draw a vacuum whilst you do the machining?

depends on your priorities. yes, i suggested to test it using the compressor which makes perfect hold down.

having in mind a compressor on a boot sale is 20-30euro or brand new is 70-80euro, who cares if it will last an year or 2. electricity price and noise are the only real life concerns. people have reported compressors running like that more than an year without any problem. as i said before this is much more easy for the compressor than to compress.

[andy_con]

ok ill give it ago, thanks

ive never in my life seen a compressor that cheap. mine is a silent one and new its about £400-500

just about to read that other thread you linked to.

with the current uni-jet vacuum pump i purchased, how important is size of pipe? should i be aiming for big or small piping to the vacuum table?

[JAZZCNC]

The other option if you have a good compressor is to use a Vacuum generator and pull a vacuum into a cyclinder.
This way your not stressing the compressor motor or if usiing the Compressor tank has the vacuum reservoir risking the chance of Compressor tank imploding because it's not designed for vacuum.

Also you don't say how small the part is your trying to hold.? Small parts are difficult to hold due to less surface area so you may need a dedicated Jig with better Vacuum seal to maximise the pull down.

[andy_con]

My compressor in very big so probably couldn't do that

Work peice was 100 by 120 mm

[JAZZCNC]

My compressor in very big so probably couldn't do that

Work peice was 100 by 120 mm

Couldn't do what.? Was you referring to my suggestion because Big is good when it comes to a vacuum generator.
The cyclinder doesn't need to be massive just strong to handle the vacuum. Your only creating a reservoir of vacuum to help with the intial suck down and to save the compressor or vacuum pump from running all the time.

Like a Compressor has Preassure switch you can get a Vacuum switch that does the reverse and switches on when vacuum drops below set amount.

For small parts like this you don't need high volume but do need High vacuum pressure so a small tank pulled down to high vacuum will work. With small part like this you will be better with sealed around the part setup rather than pulling a whole area of a plate which will waste some vacuum.
That Vacuum fixture plates is ok for wood and larger pieces that fill most of the area but for best hold down you'll be better with grid system and seal just the area your using.