Venturi pump

[magic]

What choices are there for Venturi pumps that can be attached to a 100v air compressor rated at 100 psi"

And who has the best price?

[Gary Campbell]

magic...
look at the cfm on the compressor. Then check the venturi pump for the cfm used. That should set you straight. Make sure that the compressor number is equal or larger than the venturi pump. Also make sure that the ratings are at the same pressure.
Gary

[navigator7]

This is a math problem.
What is needed is to know what work you require of the vacuum.

[magic]

I want to hold down wood and/or pvc while I work on it. Possibly cutting out a part, on the bot, from leftover scraps.

I also want to make a straight-edge for cutting veneers AND for running a router (or the bot) so as to make a straight edge on an irregular board- instead of using my jointer.

I also want to make some 90 degree jigs to hold two pieces.

I also want to attack a few pods to the side of the table so the Bot can drill holes in the side of the board.

And finally a double sided pod to hold large pieces to the table.... instead of me screwing things down.

(This is in addition to me making my table a vacuum table - eventually)

[butch]

magic
I bought two V-Clamp pods from Rockler. I have a 3hp 80 gallon compressor, and I turned it up to 65 lb. for the pod. I tried to cut boards with it, but couldn't hold the board solid to the pod and had a few of the boards release and go flying across the table. I use mostly oak, and it appears that the oak let too much air through to keep it held solid. I did try cherry and walnut with better results, but had to back off on the speed and depth of cut to get it to hold solid enough.
I finally gave up trying to use these. May give it a try later and see if I can't figure it out.
Errol was very good and tried his best to find a solution. There are companies over in Australia that use them to hold down wood similar to oak with great results.
Might be one option, but I couldn't get it to work.
Butch

[pfulghum]

To hold down porous stuff, volume is your friend. In Idaho, I draw 5" vaccuum with a fein and can hold most things > 40 sq in.

To hold smaller stuff you need more vaccuum.

-- pat

[navigator7]

@ Magic,
I think I see where you are going with the Venturi vacuum pumps.
As Pat above said: "Volume is your friend!"
So is area!
I've done slabjacking with concrete and 2-6 pounds of pressure will jack the world. (It won't do nothing in 6" of area) 2 pounds of vacuum will implode a house.
I've got no experience machining while using vacuum as a hold down but have used small venturi vacuums (powered by shop style compressors) for many other things including, pulling 8' of water up an 18" pipe, pulling pigs and removing air from mixes for potting submarine cable splices.

Where the venturi comes into its own is pulling down something that is already airtight. Plastic bags, containers, sealed units...etc. There is no real volume involved like that found in a vacuum system, vacuum cleaner or regen unit.

I'm not even sure you could pull a vacuum on a 2' x 2' board with a venturi pump and still be able to supply the air required to maintain vacuum. Plus you risk losing your part when your tool penetrates your work dumping what little volume already exists......ultimately producing scrap.

It makes damn good Seal-a-Meal ......or a method to press two halves together during gluing festivale. First, you suck all the air out with a vacuum cleaner and attach the venturi for the final suck down.

I think a venturi pump is ideal for some of Smooth-On's plastic products. Some require a really good vacuum before pouring into a mold to eliminate bubbles and produce advertised strength or consistency.

There's an idea!: Shopbot yourself some fixture molds and patterns of cams, wedges, steps and custom handled hold-downs and what-nots. Then, pour your own fixtures! They are even sacrificial for when the board is too close to call.

8173

You have got to view this website:
http://www.smooth-on.com/Industrial/c1275/index.html

If you are creating component parts....ShopBot is essentially a 3D machine when you have to use parting line principles and draft angles to extract parts from a mold.

As someone who has slung my fair share of scrap across the shop I've found that: " Fixture Happiness is But a Tear Drop and a Proper Hold Down Away!"

8174

[magic]

SO

Would it just be better to get a Fein and make reduction fittings?

[navigator7]

IMO Yes.
Don't forget about volume and area.
Reduction fittings can restrict the volume.....negating the intended affect.

Use the force, Luke!

[magic]

OK then

Where is the best price fir the Fein's

Thanks

[pappybaynes]

Magic,
I bought a reconditioned Fein...cheaper with the same guarantee. Try Amazon.

[joe]

I like screws.

[beacon14]

Joe, you're just - different.

[magic]

I've been screwing things since i got the machine and now it's time for a change.

[myxpykalix]

Joe..we know you like screws...since we all know you have a few loose ones lol!

[joe]

Thank you Jack.

My point being, too much time and money spent on the subject.

For those of you who don't have a vacuum, let me state, you aren't dis-advantaged. There's plenty of good cheap and superior, ways to get the work done.

Joe Crumley
www.normnansignco.com (http://www.normnansignco.com)

Aaron Siskind, my gruduate lead at the Art Instutue, suggested if Horwitz, had 106 piano keys rather than the paultry 88, he'd not improved his skill or the results.

[Gary Campbell]

Joe...
I am sure that you apply the same principal to your other tools. Cheapie .99 brushes from the home depot. Maybe not, I bet Dr. Crumley has some fine scalpels!

Gary