Vacuum table Setup Advice

[andy_con]

been trying to do a vacuum table setup but an failing badly.

I purchased this -

http://www.ebay.co.uk/itm/CNC-Vacuum...item487aa50799

and today I got the uni-jet 75

http://www.cattaniesam.co.uk/suction...ry/uni-jet-75/

the guy from ebay recommends 3cfm, if I worked it out correctly the uni-jet does 1250L/min which is 44cfm. so in theory plenty of suck.

got a 32mm pipe coming out of the vacuum pump, then just before the table reduced down to 10mm as that's what you need to plug into the vacuum table. length of pipe maybe 2 metres

when on and you try to move the work piece with your hand, you can but its bloody hard, its stuck down pretty dam well. you have to really really force it to get it to move with your hand. but when trying to machine it, it seems to move so easily.
I'm using a 6mm cutter, with a z depth of -0.5mm with a feed rate of 300mm/min

anyone got any advice?

[Boyan Silyavski]

UNI-JET 75

Max. vacuum level: 140mbar (continuous service)

Are you sure you have got the right pump?

you need ~25 Inches Hg which is around 850mbar vacuum

My air compressor at home pulls on the inlet 0.94 bar =~ 940 mbar =705.05993009406 mmHg

Your pump is way off, it seems.


Who told you to look for CFM? you dont have 4x8 machine where you need 20HP pump with CFM rating.


Unscrew your air compressor/ what ever size, 1-2hp is ok/ inlet filter and connect the vacuum table and check what i am talking about. Dont worry about the continuous use, nothing will burn. In fact it runs cooler. Temperature rises from compression, not suction. If your compressor is newish it will make damned good vacuum.

[andy_con]

Ok, so I have the wrong pump?

Not sure what you mean by


you need ~25 Inches Hg which is around 850mbar vacuum

What's an air compressor got to do with a vacuum table

Sorry I don't fully get your reply

[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.