Brady Vac

[Stagecraft]

Just came in from firing up my just completed Bradyvac system for the very first time...and it really, really works!
After five years since purchasing my first Shopbot, I've finally got a vacuum system.
Presently powered via two lighthouse vacuum motors.
Having never worked with pvc pipe before, the planning and assembly went slowly but its done.
I'll post pics as soon as I get the shop cleaned up.
Thanks Brady for taking the time to design the system and then to share all your hard work with the rest of us! - Boyd

[Brady Watson]

Just came in from firing up my just completed Bradyvac system for the very first time...and it really, really works!...

Well...YEAH! :D



Thanks Brady for taking the time to design the system and then to share all your hard work with the rest of us!

Your welcome. It's nice when a plan comes together and works out. Glad to share it with the group. I'm sure you had a few doubts as to whether the vacuum system would actually work. I thought vac hold down was a complete waste and didn't think it would work...boy was I wrong. :)

-B

[Stagecraft]

So here's some pics...
I went with .75" Sintra as a base material. After roughing one side of the Sintra with my fly cutter I adhered it to the .75' Baltic Birch base with urethane glue.
After the glue had set I planed the top and then cut a plenum design that I had put together in CorelDraw and bored the holes through the Sintra and Birch where the pvc vacuum pipes would enter.
The plenum is divided into four switched zones powered by two Lighthouse vacuum motors that reside in a housing I built from .5" Sintra that resides under the Shopbot.
I used .5" Medite XL as a spoilboard, Trupan would have been my first choice but its near impossible to find in Western Canada.
I removed about .03" off either side of the Medite to "open it up" for airflow.
I cut my first job today using the system and it works extremely well.
My next step will be to seal the Medite to the table around the perimeter and between the zones; I'll be using butyl glazing tape for this.
Butyl becomes quite soft when warmed up so my plan is to lay it on the plenum, lay the Medite on top and then place a radiant heater under the table with the vacuum turned on for a couple of hours.
Hopefully this will result in even more vacuum.
Thanks again Brady!

[Brady Watson]

Looks good, Boyd. I'm not sure I can take any credit for all the hard work you did.

Just for clarity:

BradyVac - A single sheet of Trupan/Ultralight with a grid machined into it, and placed upside down over a 2" hole in your table.

Open Source Vacuum Project - A projected started by me using Lighthouse vacuum motors as a result of research done by Bill Palumbo and myself, on affordable vacuum powerplants - of which has been improved by other folks in this community.

-B

[Stagecraft]

Just the same Brady, it was your concept of using the Trupan as a bleeder board and the fact that you'd done a great job of explaining it all gave me the confidence to build this system in the first place.
My apologies to Bill Palumbo for not acknowledging his input too.
I may have mixed up some of the Brady/Open Source details but in the end it all works!- Boyd :D

[sailfl]

Brady,

Did I read you last post correctly. I thought that most people cut the grid on the top part of a piece of MDF and then place another piece on top of that but you said that you cut the grid into the top piece so that the grid and spoil board are the same piece.

Interesting. Why did you decided to do it that way?

[Brady Watson]

Brady,

Did I read you last post correctly. I thought that most people cut the grid on the top part of a piece of MDF and then place another piece on top of that but you said that you cut the grid into the top piece so that the grid and spoil board are the same piece.

Interesting. Why did you decided to do it that way?

Nils,
In a word - Flexibility.

I cut just about everything in my shop, and I never know what is going to come through the door. By machining about .1875-.25 into the Trupan and flipping it over, it becomes a removable vacuum system. Trupan doesn't really take a screw too well & even if it did, you'd have to counteract the pull of the screw and it's tendency to lift the entire board off the underlying spoilboard. Plus, holes in the plenum/bleeder are not a great idea since they leak.

So...One day you can use the system as is to suck down full sheets (or make smaller ones for smaller material...hint...hint) and the next day, pull it off and screw stuff down to the spoilboard...or use clamps, or adhesive tape etc.

Hold down is practically the ENTIRE JOB of CNC machining...and I've found that a traditional vacuum system just pigeon holes you into relying on the vacuum system only for hold down. I prefer to be able to use the best method of hold down for the task at hand. This isn't always vacuum.

I try to get the idea across that it is more important how you use the vacuum powerplant that you have, than how much vacuum you have. I prefer to direct the vacuum right under the parts without a lot of ambient/wasted space. This means, I have jigs that are setup for 5X96" lumber, 24x32", 48x48" and 48x96" areas. These sizes work for the types of sizes that I often use - and ALL of the vacuum goes to these giant 'pods' of sorts, with minimal leakage and waste of vacuum power. Dedicated systems control vacuum with zones. I control it with the size of each 'pod'. These grid-backed, smooth-faced 'pods' are BradyVac v1, and are considered universal.

BradyVac v2 are specific to a given part or nested group of parts. It starts with a BradyVac v1, and then the perimeter of each part is offset to the inside in software. Then the inside of the part footprint is machined deep enough to puncture the underlying vacuum distribution grid on the back side. This directs vacuum power right to the backside of the part and offers a substantial increase in vacuum performance over the universal BradyVac v1 - at the cost of only being useful for a specific layout of parts. It is perfect for frequently cut parts, re-orders and other things that are done on a regular basis. The customer is charged for a re-usable vacuum jig or that is built into the cost of the job.

Does that make sense?

-B

[knight_toolworks]

what did you use to glue the mdf to the sintra? that's been my debate over using it.

[Stagecraft]

Steve, I glued the Sintra to the birch base with urethane glue.
I roughed the side of the Sintra that would get the glue to give it some tooth, I doubt you'd get much adhesion without that step. I'm sealing the Medite to the Sintra with butyl tape. I've used it extensively on several of my boats to seal windows, stanchions etc. and I'm a big fan of the stuff. - Boyd

[mikenicee]

Nice job on the vacuum table. I had a question regarding the vacuum box. Do you just buy the light house vacuum motors and hard wire it to a plug? Just curious if there is any other circuit board needed. I assume it just mounts to the end of the pvc tubing?

Can you share with me the plans for the box? And which motors you used?

Thanks
Michael