[Kipper]

Nice "KISS" solution :salute: At work we use vacuum priming systems on our pumps 1bar or 29"hg and we have the industrial 2bar flavour rotary vane compressors....You just gave me an idea :beer:

[Vac-Clamp]

Have a look at V-Clamp vacuum hold downs.
They run on compressed air and they work. An inexpensive, and complete, solution for holding you work piece.
CNC application information on this page

[Geof]

Have a look at V-Clamp vacuum hold downs.
They run on compressed air and they work. An inexpensive, and complete, solution for holding you work piece.
CNC application information on this page

Maybe not inexpensive when you take into account the cost of the compressor.

And be careful about just hooking them up to the shop air that supplies all the other machines. They all start flashing red lights when the compressed air vacuum hold down steals all the air and the central compressor cannot keep up.

[Vac-Clamp]

Hi Geof,
It sounds like you are having problems with your Vac-Clamp.

Could you please advise what air pressure you are running them at?
Are you using a VC4 or VC5?
How many are you using at one time?
Lastly what is the size of your compressor?

A VC4 at a supply pressure of 80 psi uses 1cfm. A double sided VC5 uses 2cfm at the same pressure.
We have a display unit that we use at trade shows, that has a total of 4 clamps (3 VC4's and one Double sided VC5) the compressor is a $99.00 (Australian dollars) 2 horsepower item. It keeps up.

[Greolt]

Have a look at V-Clamp vacuum hold downs.

Yeah I think they are fine and probably a good product for bench top use.

But my point is that a lot of users on this forum already have a machine easily capable of

making their own vac hold down device of a very similar type.

Also whatever size they want.

Providing the vacuum to use it is another matter.

My cheap compressor mod is working great so far.

Greg

[Geof]

Hi Geof,
It sounds like you are having problems with your Vac-Clamp.

Sorry I did not realise you were touting your products in a thread.

I read it quickly and thought you were referring to generic compressed air vacuum generators. My experience is that to get any type of decent volume flow to compensate for leakage the compressed air consumption is large. Yor product is designed for non-porous materials which may mean low air consumption but it also means conditions have to be ideal to have a zero leak situation.

[Vac-Clamp]

I put forward the V-Clamps in this discussion because they work, they are cost effective and they are an alternative. They are configurable to a range of applications and machines.

We have more than a few people using our Vacuum hold downs on CNC machinery, with excellent results.

About the only material that we have a problem holding is raw MDF. Coated MDF negates this problem.

Sizing of the pad meant that we could work with low porosity materials as well as non-porous ones as well.
We looked at the flow of low porositiy materials for a given surface area. The surface area of the pad has been matched to the vacuum generator to provide more than useful holding power on materials such as chipboard/ particleboard.

The vacuum generator is built into the pads so you don't have to modifiy your compressor. Indeed you can chain them together to build them to whatever configuration you need.

I simply wanted to make people aware that such an item existed, rather than them "re-inventing the wheel"

If your system works that's great.

Vac-Clamp

[Greolt]

About the only material that we have a problem holding is raw MDF. Coated MDF negates this problem.

Yeah it's unreal how much air raw MDF lets through isn't it.

I put a piece of 18mm MDF on and can feel the air getting sucked through just by putting the flat of my palm on it.

That makes my modified compressor run all the time and not cycle on and off.

Still holds it good though.

Greg

[Greolt]

....................... so you don't have to modifiy your compressor.

.....................rather than them "re-inventing the wheel"

There is no doubt that will appeal to a lot of your users.

However on this forum we are sharing ideas among the type of people many of whom have built their own CNC controlled router.

Taught themselves to use Cad / Cam software and cut all sorts of things on their machines.

These people tend very often to like to make their own devices and have the skills to do it.

I personally wish you every success with your product and have no problem at all with you talking about it on this forum. (especially being an Aussie product )

Greg

[Vac-Clamp]

Hi Greolt,
If you want to get a better hold with MDF us a sanding sealer or watered down PVA adhesive on one side, and allow it to dry. Put this side on your vacuum pucks.
You will find the increase in holding force will give you a better finish on the edge.

I also had a look at the modified compressor that you have used. Nice job.
I assume that the receiver is now the "reservoir". Have you had a chance to put a filter in-line?
BTW, the compressor that you have modified is pretty much identical to the one we have used on the trade display, without the modification of course.

Vac-Clamp

[Greolt]

Vac-Clamp

Do you think I need a filter? I spose long term it might be an issue.

The air comes into the reservoir at a different point to where the copresssor "sucks"

The thing to bear in mind here is that the compressor cost me $50 so unless there is a real cheap way of installing a filter. Who cares.

Greg

[Vac-Clamp]

Greolt,
Might be worth having smaller reservoir before the main reservoir made from pvc pressure pipe fittings. Have the inlet and outlet at the top, and have a screw off fitting at the bottom.
That way when you have some rubbish get into the vacuum line it will fall out in the primary (palstic) reservoir, which can be cleaned out, rather than the steel one that can't.
Your setup might have cost $50.00, but how much to replace.

I built my first CNC machine some six years ago, and faced the same problem as a lot of builders face... how do I hold the workpiece down. The first hold down that I made was "loaned" to a friend. It is still on loan, and is still being used frequently.
This is why I have put in the occaisional posting on this forum.
Vac-Clamp

[Greolt]

Your setup might have cost $50.00, but how much to replace.

Your point is quite valid however I'm not much concerned.

When I bought the compressor I was not at all sure it would work well in the configuration it is now.

My thinking was the reservoir with wheels and all would make an exellent (and cheap) base to mount a proper vac pump.

It would cost me more in materials alone to construct a reservoir out of plumbing fittings etc. JoeWoodworker style.

Over the next few years or whatever that this setup lasts, I will keep my eyes open for a cheap second hand vac pump to mount on top of it.

So money spent on the tank, vac gauge and vac switch will still be good.

The way I look at it the motor/compressor unit on top is just a free bonus.

Greg

[mhasting2004]

Hi Greg

Just reading through your build...nice. Must get off my butt and get mine going.
I'm also one of those lucky ******** that has a nice big Gast pump (along with most of the other pieces to build my gantry router) and would highly recommend you put some filtering in between the hold down and the pump. Its not the dust getting into your tank you need worry about but it going through the pump. It will stuff it up rather quickly I would wager.


Cheers
Mark
Central Coast NSW

[catsam]

wow this looks a good idea i might make one off the for my mill when i finish makeing it do you have any more pics of it

[Greolt]

wow this looks a good idea i might make one off the for my mill when i finish makeing it do you have any more pics of it

There is really not much more to show. Pretty simple really.

But if there is particular detail you're interested in let me know and I'll take a pic.

Greg

[DrewSmith007]

I didn't take the time to read the whole thing, so someone may have already said this, but i read somewhere the other day you can use a refridgerator compressor in reverse, like you did with your compressor, as a vacuum pump. I just don't know how strong they are. You shouldn't have any trouble finding one of those in Austrailia, I would think.

[epineh]

I didn't take the time to read the whole thing, so someone may have already said this, but i read somewhere the other day you can use a refridgerator compressor in reverse, like you did with your compressor, as a vacuum pump. I just don't know how strong they are. You shouldn't have any trouble finding one of those in Austrailia, I would think.

They are all in use... keeping beer cold

[Geof]

They are all in use... keeping beer cold

Go on, since when were Aussies civilized enough to keep their beer cold?

[johnmac]

The compressor in reverse will work better than a refrigerator compressor as it pumps a larger volume of air, thus overcoming small leaks around the work piece. Keep watch on the oil, as some may suck up past the rings.