My vac table with alignment pins

[sbd1]

After what seems like an eternity, I finally have a fully-functioning vac table of my very own! Thanks go out to all of you on this great forum that contribute your ideas & thoughts, especially Gary Campbell & David Buchsbaum for their personal help.

Base & plenum: 3/4" moisture resistant MDF
Spoilboard: 3/4" ultralight MDF glued onto plenum
Vac Grid: 6 zones
T-slots: 3 facing up in Y axis direction between vac zones cut into solid hard maple strips embedded in the plenum, 1 cut into maple end block facing out at the far end of the X axis for vertical part clamping
Machinable hold downs: 5/16" nylon threaded rod fixed into flat metal T-slot nuts (below plenum surface) & nylon nuts or threaded wooden knobs (on top of spoilboard)

In conjunction with the maple T-slots I don't have to worry about cutting into anything metal. The maple also allows me to resurface the spoilboard down to nothing (just resurface off the old glue on top of the spoilboard along with the maple T-slots a little & glue on another spoilboard).

Ironically, I picked up some free oil based paint to seal the plenum grid & outside edges from the local recycling center & it turned out to be an exact match to ShopBot's blue.

[sbd1]

A few more pics of the underside of the table showing the boxes I built around the air cylinders to protect them from getting hit when storing items beneath the table. They also show the push rod supports for the vac zone valves.

[beacon14]

Great job!

[sbd1]

Thanks David. I couldn't have done it without your help. Here are a couple more pics of the T-slots & finished table (with matching blue edges!).

[blackhawk]

The table looks great. I noticed that you vac holes are not centered in your zones. Is there an advantage to that?

[sbd1]

Brad, you are correct about the hole spacing. I'm don't know whether that is an advantage or disadvantage. The holes are spaced wider apart (from the X axis center line) as the go further down the table to allow the valve pushrods to have a direct route to the end of the table. You can see this better in my SketchUp model (2nd picture in the 1st post).

[dlcw]

When I built my new 7 zone table (PRSAlpha 96x60), I positioned the vacuum holes where it was convenient in regards to the gates to open and close the zone. If your zones are sealed well from one another, I don't think it would make much difference where the hole is located.

Each of my zones has its own piece of 3/4" Trupan. The edges are sealed with plastic edge banding and stuck to the table with caulk using the vacuum system as the 'clamps'. So the zones are WELL isolated from each other. At 2500' altitude, I pulling 7.5" of vacuum, which from what I've heard, is pretty darn good.

[sbd1]

Don: That's an interesting idea with the separate pieces of Trupan for each zone. I never thought that perhaps some of my vacuum is leaking through my spoilboard 'sideways' between zones.

Todd: Thanks.
1. I'll have to check the hg number more accurately when I'm at the shop next & get back to you, but I believe with the 2 motors & all valves closed I'm getting around 8" also. Although I'm getting good hold down so I didn't think that was too bad.

2. I'm not sure what you mean by "unsealed plywood". My table is made up of 2 sheets of moisture-resistant 3/4" MDF and 1 sheet of ultralight MDF 3/4 (spoilboard) with painted edges (and painted vac grooves in the plenum). I do get a little vac leak through the painted edges though so I'm going to apply a second coat. Unless you mean my vac box, which is made from unsealed plywood, in which case I don't know if it's leaking. I'd have to finish it & compared the results. Good question.

Cheers,
Daren


Todd wrote:
Darren

I really like your vac box you did a very nice job. I have a few questions for you if you wouldn't mind answering.

1. How much vac do you get when all your ports are closed and you measure it near the box? With my system I am only getting 8" hg so I think my box has leaks.

2. Do you get vac loss through the unsealed plywood?

Thanks for the help

[sbd1]

Here's a picture of my vac gauge with 2 motors running & all valves closed (10" hg).

I also just installed the second pair of motors in my vac box & the gauge reads the same, but the table now has even more hold-down.

[dlcw]

Makes me sometimes wish I lived at a lower altitude... :D

My max is 7.5 with a plastic bag placed on the spoil board covering just 1 of 7 zones and only that zones gates open. Good air flow though, so that's a good thing.

[TravisH]

Hi Darren,

Where did you buy you gates from? I have been searching, but no luck yet.

[curtiss]

Very nice work

Of course you now have to rig up a way to turn the zones on and off from your keyboard.....

[sbd1]

Where did you buy you gates from? I have been searching, but no luck yet.

Travis, sorry for the delay. I've attached an image showing the valves I used.

Curtiss, good idea. Too much work for me though. I believe that others (ie: David Buchsbaum) have already done this with air cylinders.

Cheers,
Daren

[Ken Sully]

Daren

What vacuum motors did you use. Are they very loud?
Very nice system! I am in the early stages of planning a vacuum system.
Noise from a vacuum could cause neighbor issues.

[sbd1]

You can find the info on the vac motors I used in this thread Ken: http://www.talkshopbot.com/forum/showthread.php?t=11813

They are loud (you can find actual DB ratings from others in this forum, but I don't recall what they are), but they are not as loud as my PC router when it's running. I also work in a garage with neighbors and I'm glad it has 6" thick insulated walls.

Cheers

[Howley]

What kind of vacuums are you using?