Thread: Vacuum and Clamping

I posted a question on Sunday re the above.

Through a little more investigation I have solved the supply source question.
SMC at Castle Hill in Sydney can supply the stops I am after.

PEN

For anyone who uses a refrigerator type pump with an oil 'bath' thingy. Do you have any problems with the pump sucking in debris?

I was looking at the US based veneer man's website ... http://www.veneersupplies.com/produc...oducts_id=1100 ...and he has a special filter for vacuum pumps which stops any junk getting back into the pump. It wasn't very expensive USD$16.00, but the postage was horific ... USD$39.00, Does anyone know of a local supplier?

Cheers,

Alan

Alan

Did you ask about using USPS? I would be interested in getting one too so maybe we could share postage.

Greg

Check as he is probably using a standard rate box so filling it up will not cost any more.

Allan when you do the fridge pump see if you can't use the exaust as a blower at the spindle - dual use.

Greg,
His postage is using USPS Priority Mail International and as Rod suggested it must be a standard box rate of some sort. I recalculated my shopping cart for 2 filters and it was the same rate of $39.00 (2.5lb) ... change to 3 filters and it goes up to $43.85 (3.5lb) ... 4 filters is then $48 (4.5lb). If I could remember any algebra from high school I should be able to devise an equation to work out the weight of each unit ... but I could send them an email and ask!
Greg, if you think that this is the right filter for the job, would be happy to share postage with you.

Rod,
Am not sure about using the exhaust for the air jet onto the cutting tool as my pump seems to have a slight oily haze in the exhaust ... is this normal?

Cheers,

Alan

Hi Allan,
Yes this is an issue with fridge and aircon pumps - forgot about that. Would not be a good thing for wood.
You will have to top up the oil every so often as you don't want it to run dry. No big issue so don't let it stop you from continuing. Perhaps exaust it into a tin or something so you don't breath it in all day.
I know a fellow that is using one of these as a compressor for his metal machining shop and it has been running a couple of years. Very quiet and he has it running through a modifed gas cylinder for a reservoir. Glad I wasn't around when he welded the fittings to the gas cylinder.

I went into Clark Rubber the other day and found some 5mm round rubber.
I want to make a vacuum table using this stuff and remembered Greg made his table using similar stuff.

Does anyone (specifically greg) have the dimesions used to make their table?
ie: what cut should i make for my 5mm rubber so it allows clamping of an object flat to the table? Any specific square size I should use?

/Michael

Mike

I use 1/4" dia rubber, sponge I think they call it.

Don't remember the size of my groove. What I did was machine a lot of different sizes in a bit of scrap till I got the right size groove.

It wants to squash the rubber just enough to seal but not hold the material up.

You want the material to sit tight against the plennum so that it is perfectly flat.

And enough pressure on the rubber to seal against leaking.

Here is an old thread about it. "http://www.cnczone.com/forums/showthread.php?t=34537"

Greg

Thanks Greg, read through all 12 pages. Got a little political and something about selling used cars!

/M

You read the whole thing !!!!!

Mike
I copied a photo of greg's vacuum table and ended up using 6mm sponge rubber from Clark Rubber, and machined the grooves 3mm deep using a 4mm ball-end.
Works terrific.
by the way, my plenum has grooves spaced at 30mm square and I find that this gives a lot of adjustment for different size projects.
Cheers
Noel

Thanks Noel for the dimensional information. I'll try to interpolate and see what ball-end units i can get for the 5mm rubber I have.

Maybe 4mm ball-end, just cut it at 3.5mm to start with and see how it all fits.

/M

Mike
That's how I worked out the depth for my rubber - the good old try and fail method.
Starting at 3mm might be better if your rubber is only 5mm, as you need a bit of compression to hold it in the grooves.
have attached a couple of photos of my two plenums.
Cheers
Noel

Just for your info, I use 6mm dia sponge rubber,

Groove 5.5mm wide and 4.5mm deep.

Greg