[CNCRob]

Here are a few pics of what I was talking about above. I have included a few differen't angles to try to show it better. It was kinda hard to take pics of something that small without it blurring.

[lgalla]

Large commercial routers,5x10 require 15 to 20Hp vacuum pumps.Is it possible to make say 4 zones and the software could sense where the router is and turn on a relay to a valve switching the vacuum to the area the spindle is cutting?You could get away with less Hp.
Larry

[CNCRob]

Large commercial routers,5x10 require 15 to 20Hp vacuum pumps.Is it possible to make say 4 zones and the software could sense where the router is and turn on a relay to a valve switching the vacuum to the area the spindle is cutting?You could get away with less Hp.
Larry

I have read of routers that have air clamps that hold the part inplace on all four sides. When the router gets close to a clamp on one side, the control will automaticly raise the clamp on that side untill the cutter passes. Then after it passes the clamp will lower itself again. In theory, it don't seem like changing vacuum zones would be much different. One thing that might prevent it from working would be to get dust and chips under one of the zones that wasn't sucked down then when it came time for it to change to that zone it may cause problems. Maybe someone else can answer this a little better then me.

[Geof]

... When the router gets close to a clamp on one side, the control will automaticly raise the clamp on that side untill the cutter passes. Then after it passes the clamp will lower itself again.....

Or if the clamp does not do its thing, actually it was a stop that did not lower on my friends machine, all hell breaks loose.

On some machine using pucks the zone activation is used, mostly to allow for reloading the machine in one zone while it is working in the other. But they still have a big pump because pucks need a good vacuum.

[Beezer]

Well it's been awhile since I posted on the Zone but the house has been keeping me busy and haven't had much free time. Haven't even been doing any work with the CNC router, but I finally got some time to finish my vacuum pump stand. Thanks again Robbie for the Cad files of you stand.




I picked up some 3/4" thick HDPE sheet which I will use to make a removable vacuum table for the cnc router. Hopefully I will find some more projects to do with the router especially with winter coming. Yes I said the "W" word. HEHE


Hey Robbie. You mentioned earlier you were thinking about using a foot pedal to switch your vacuum clamp on and off. Did you see the one they sell now at joewoodworker.com? Not a bad little unit but I think for the price the lever valves work just fine.



Carl

[CNCRob]

WOW! Your stand turned out great Carl. Maybe I should have painted mine a solid color, that looks awesome. Again great work on the stand! - Robbie

[Beezer]

Thanks Robbie.

I used particle board for my stand because it was much cheaper then a good quality plywood such as Russian ply but in hindsight I probably should have used the plywood since particle board is not the strongest stuff and breaks easy. When I was tightening the pipe straps to secure the pvc tanks some cracks developed in the particle board and particle board doesn't give the nicest finish when painting. A learning experience but it's done now and I am quite happy with it. I was quite pleased that I didn't have one leak to fix the first time around. I was surprised at how low the vacuum force actually felt like when I put my finger tip at the end of the hose. I thought it would be so strong that you couldn't remove your finger but it wasn't that way at all even at 21"hg. I guess it is different when the vacuum is spread over a larger area?

Carl

[Colin Ellis]

I've been vacuum clamping for about 15 years on a manual overhead router using a small 3 to 4 cubic mtr per hour rotary vane vac pump. I always use close grained hardwood for the base (most mdf leaks too much) the smallest item I can hold safely is about 4 inch diameter. Neopreen round strip let into groove is the best sealing stuff I have found but flat self adhesive is good too. you can easily tell when the piece to be machined is ready, which is almost instantly you turn on the vacuum and you just leave the vacuum running whilst you machine. they are designed for this, shop vacs and hoovers arn't they will ovrheat.
I have also just had the good fortune to buy a virtually brand new vac blower off ebay worth about £1500 gb pounds new for £80 which I am going to use on my cnc. I have been doing some tests and the smallest area this can hold is about 8 x 8 inches but it will hold a lot of this size from the one pump and small leaks are not a problem.
Hope this helps a bit feel free to ask

Cheers
Colin

[CNCRob]

Thanks Robbie.

I used particle board for my stand because it was much cheaper then a good quality plywood such as Russian ply but in hindsight I probably should have used the plywood since particle board is not the strongest stuff and breaks easy. When I was tightening the pipe straps to secure the pvc tanks some cracks developed in the particle board and particle board doesn't give the nicest finish when painting. A learning experience but it's done now and I am quite happy with it. I was quite pleased that I didn't have one leak to fix the first time around. I was surprised at how low the vacuum force actually felt like when I put my finger tip at the end of the hose. I thought it would be so strong that you couldn't remove your finger but it wasn't that way at all even at 21"hg. I guess it is different when the vacuum is spread over a larger area?

Carl

Wow no leaks on your tanks the first time around, I wish I could have said that. I had to use that calking ideal on the plans with mine. The key to making it work properly is to have as few leaks as possible. Thats what caused me all the pains in the beginning. I thought my plywood was dense enough. I thought I would be able to hold a good vacuum without having to seal it. I was planning on sealing it eventually anyway, just not for a while. I tried my vacuum out and it wasn't holding hardly any vacuum. I didn't think it was leaking straight through the plywood. Any how I sealed all the edges on the plywood table and it made all the difference in the world. It also made the table look better and made it more durible. I don't think you will have too much to worry about using the HDPE sheet for your table. It should seal pretty well. Your right about it having more vacuum over a larger area. Here are a few pictures of things I have cut using nothing but the vacuum to hold it down.



























That's just the tip of the ice burg of the things I have used the vacuum table to hold while machining. Keep in mind the signs are 3/4" mdf. Which leaks vacuum straight through the work. It still held in place great. I have been using the same vacuum fixture for most of the work I have been doing lately, Its about worn out but keeps on going.



That pic was taking a while back. It looks even worse now( I will try to get a recent photo of it). It still works though

And heres one last photo of a sign being machined.





After using my vacuum table for the past while, It makes me wonder how I ever lived with out it.

[Beezer]

I finally got some time to make my first vacuum jig and I'm amazed how strong the vacuum really is. I used 3/4" HDPE sheet and cut all the grooves on the cnc router. Already got a second jig drawn out and I just need to get some time to cut it. It's going to have two zones that will be controlled seperately. Still working on the design for the main vacuum table which will also be made from HDPE. Just need to figure out how many zones I will have in it and how to best cut them. I was thinking of how you did your table Robbie and I might cut the bottom of the HDPE with the vacuum channels and bolt the whole sheet to a piece of aluminum plate or more HDPE sheet to seal it.

[Vac-Clamp]

I have just posted a video on our website www.vac-clamp.com showing a sign being machined using our vacuum hold downs, and face plugs.

The video quite large (2Mb), but I would like to know if it makes sense to everyone, or should I reshoot the thing.

Look in the Video Gallery drop down menu or Click Here for the link to the CNC application page
Errol

[mugim0e]

I machine only plastic components in work, and we use a lot of vacuum fixtures when we are not able to use a vice.

Beezer, i would use a different material to HDPE as its quite soft and isnt as stable. We use Delrin and Cast Nylon as they are pretty solid and relatively inexpensive.

We also have a CNC router, which has a wooden bed with a grid of slots in. On top of this we use MDF for fixtures with a neoprene/rubber vac seal between the mdf sheet and bed and then around the area of the part to be machined. A few grooves/slots about 0.5 - 1 mm deep are machined to help suck part down to fixture.With a normal pistol drill we drill a few holes through the MDF.

[cl707programer]

I've been working on a fixture out of aluminum. It uses a .025 thick gas permeable paper between it and the parts to be cut. The problem I'm having is the paper I have is 2'x3' and my fixture is 4'x4'. I found the paper at Datron and can't seem to find anything else like it anywhere.

The fixture is 4 24"x24" parts mounted in a square. Right now each square has 2400 3/32" holes in it. I may have to enlarge the holes to get better flow thru though. I was pulling 3psi of vacuum with no parts or paper on the prototype 12"x12" I made.

If anyone has any suggestions for some permeable paper I would appreciate it. I will post some pics of it when it's finally built. I have to wait to use our VF5 to make the fixtures.

[Vac-Clamp]

Hi cl707programer
You might want to have a look at what is being used in the Nested Based CNC area. They use MDF as a spoil-board, and draw a vacuum through that.
Make sure you seal the edges of the spoil-board and make sure that you have a powerful vacuum pump.
Vac-Clamp

[Salty72]

creating a vacuum thru a sheet of MDF is the best method, but it does take a RAELLY BIG Vac pump, and most of these motors as I have fond out are 3Ph especially if the MDF sheet is to be used as a spoilboard (10-20mm thick)

one thing I tried was 2mm sheet of MDF sanded both sides with 60grit paper -this removes the gloss coating and allows better suction.
I then painting the edges of the MDF with a PVA glue and used plastercene (like playdough) to form the seal around the edge of the material to be cut.

This worked really well untill the tool cut into the PVA glue and I lost VACUUM, - guess this goes back to you need a REALLY BIG Vac Pump so it can overcome losses

Has anyone tried to modify a dust extractor to creat a rotory vain vac pump, - Reason I think this might work is that if you aren't goining to "suck" any particular matter up, you should be able to place the vains very close to the wall of the housing to increase it efficiency, and over a 12"x12" area even a partial vacuum of 7psi is a huge amount of pressure

[Geof]

Go to your local car wrecker and pick up an old carburetted V6 or V8 engine; you need one that has a separate intake manifold to each cylinder bank. Or has a manifold that can be blanked off to isolate half the cylinders.

Run the engine on one cylinder bank and just attach your vacuum tube to the other unused manifold feeding the other cylinder bank.

A carburetted engine can easily pull a manifold vacuum down in the 20 inches of mercury region and if you getting a honking great V8 it will pull a lot of volume.

And you don't need three phase electricity to run it.

[Salty72]

What about using a turbine to generate the high flow High Pressure required to suck thru MDF ???

[joeski]

Hi All,
Did anyone answer the thread of using the intake of an air compressor pump? Or would this screw things up?
Joeski

[Geof]

Hi All,
Did anyone answer the thread of using the intake of an air compressor pump? Or would this screw things up?
Joeski

I think it was greolt has a thread 'An Aussie Adventure in Vacuum Pumps' or a name like that and he describes converting a compressor to a vacuum pump.

[Salty72]

here is the link

http://www.cnczone.com/forums/showth...ssie+Adventure