New Vacuum table design, thoughts?

[EricSchimel]

So, I have a PRS 4x8 that came with 4 lighthouse motors just bolted to the bottom of the table. I motor for each of the 4 zones.

My table is in need of replacing and I wanted a better system. I figure since I'm doing it, I should do it once and do it right. To that end I've decided to go from 4 to 8 zones. I cut all kinds of things and I really want the flexibility.

Also, I want to reuse the lighthouse motors now, and later if I get busier get a regen blower. So I've designed a system that houses the 4 lighthouse motors in a baffled box. It feeds into a main 3" PVC pipe and then to 8 valves for each zone. 2" pipes go from each valve to the zones on the tables.

I tried to keep it simple, easy to build, and allow me to swap out the lighthouse motors for the regen. What do you all think? (The drawing is rough, I am just getting layouts at this point)

The pictures are in this link (Posting here isn't working) https://goo.gl/photos/MUq1RJaKRV2xxrFk7

[Simops]

Eric looks OK ..... Having a stationery table (as opposed to the Buddy) makes it much easier to design. I highly recommend a Regan blower.....especially biggest HP you can get. Make sure you seal the plenum zones well as you can get quite a bit of leakage especially with smaller sized pumps. I used 3 coats of Shellac.....worked very well.

Good luck....and let us know how you go...

[Brady Watson]

The shape of the zones is important and should not be arbitrary. You want to tailor the shape of the zones to fit the work you intend to do.

Have a look at my dual input vac system and note how the zones are laid out over a 5x12' area.

-B

[EricSchimel]

Brady, I was having a hard time deciding what kind/size of zones I was going to use. I definitely will cut a fair about of full sheets, and also some smaller stuff. There have been times that I've cut a fair amount of things that are smaller than a 1/4 sheet so that's where I got the idea of the 8 zone. 8 zone also seemed to make sense as I was able to hold a full sheet down in the earlier setup with 1 motor per each of the 4 zones. With this setup, I'll be able to direct more suction to a smaller area if I need it, something I wasn't able to do before.

If I am cutting a really small piece I am fine with screws/clamps because it's likely not something that's going to require production speed.

Simops, I do really want a regen blower and I'll definitely get one in the near future which is why I designed this system the way that I did. So as far as the shape of the zones... I just did all squares because it fit nicely and allows me to have only a few pipe cuts to make. I moved the suction holes off of center of each zone to clear the cross beams on the ShopBot... Do you think that will affect the vacuum performance at all?

[Brady Watson]

Lay out your zones to match your work in sizes that make sense for you.

If I were laying it out, I would make sure my zones allowed for the full 4x8 area, a 4x4, a 2x4 and then break up the last 2x4' zone into an area that matched my smaller work - perhaps 2 @ 12x24.

This would create 5 zones.

3 @ 24x48
2 @ 12x24 (located down near 0,0)

You can turn on zones for:

12x24
24x48
48x48
48x96

Outside of this, you can make custom jigs that you can lay on the table top for smaller work using the same motors, or a small higher pull pump with gasketing. No setup does it all...so you just take your best shot considering the work you plan on doing.

-B

[EricSchimel]

That's pretty close to what I have now. I have 8 24x24 zones so that covers me for just about all sizes that I'd cut. Being able to individually turn each one on and off gives me a lot of control. I figure for anything smaller I'd just keep a 12"x24" peice of MDF around to block off half a zone. I figure if I do that, I should be able to suck down something pretty small... I think....

[Brady Watson]

Leakage is the enemy...Sealing things off should be #1. There is no way to tell what is going on without a gauge plumbed into the system.

You'll find yourself looking at it as the job progresses...which may prompt you to reach for block offs or trash bags...

Thoughtful part programming and nesting can make the difference between holding down a job and failing half way through.

-B

[joe]

I've gotta agree with Brady about leakage.

What's been left out of this discussion has to do with the materials being held down. If and when you have a sheet of slightly warped material like HDU, PVC or glued up wood it will require more hold-down vacuum than a flat sheet of plastic.

Since I've not had much need for thin flimsy stock a vacuum hasn't been used. A few years back I spent a few days and lots of bucks getting one set up. After a few months it was deposited in the Dimsey Dumster. All of my work is dimensional which allows for secure hold downs. Thirty years and still going with no vacuum.

Joe
www.normansignco.com

[EricSchimel]

You know, there's a part of me that thinks I could get away with no vacuum at all... I mean for full sheets where you're panneling them up for cabinetry it makes a lot of sense to me. When I'm making stuff like www.makertable.com where there are lots of detailed parts, tabs seem to work very well. I'm already sanding stuff anyway. Tabs work and they work well.

Still though, for not much money I can get this vacuum system setup so I'm going to go ahead and do it.

[joe]

I've seen some attractive small vac hold downs that are made to be taken on and off the router bed. They are much quieter and efficient than the whole bed method.

Still, when manufacturing dimensional signs like the one below, a vacuum is out of the question. We've debated this topic for years.

Joe
www.normansignco.com