6.2 HP FPZ Vacuum users - looking for feedback

[mbarinholtz@chdc.org]

Well, this forum is really great. We've been recieve a lot of helpful suggestions from ShopBotters recel=ntly, and I was looking for some feedback from individuals who have a 6.2 HP FPZ Vacuum system on their 'bot.

Our 'bot is being used in a basic training environment for homeless youth, who are making a transition into housing and employment here in Washington D.C. About two weeks after Brian and Zach came down and put together our machine and vacuum system, we had the blower motor overheat and scream to a halt. ShopBot was very kind in replacing the blower (not an inexpensive gesture, I add...no questions asked. They responded to my frantic phone call with a calm,cool "let's get this taken care of" and got me in touch with the Dave at FPZ in Grafton, WI. That was a Friday. On Monday morning, there was our new motor.) and later on, an in-line filter for the relief valve.

We have been using the 'bot more and more, and have had to make some changes to the arrangement we originally recieved. The gauge has given up, (and we have a replacement on the way this weekend), and are moving it to just before the inlet on the blower. The relief valve needed to be relocated to tie into a "T" just between the gauge and the in-line filter cannister. With those changes, we hope to get a true reading on the actual load on the system. We have a few questions.

- Heating. I remember well that Brian said, after setting up the system, "That baby is going to heat up - don't freak out." Dave from FPZ said the housing is rated to reach a maximum of 120 degrees F. over ambient temperature. We are wondering if anyone has experienced any unusual sounds or smells that actually have ended up to be usual. It's hard to describe what's happening, but I am afraid to burn up another motor. We get a hot wiring smell after a few minutes of running the vacuum. I have run it for up to an hour at a time with no problems, but the smell is surely there. Is this just the smell of air being pulled though MDF and passing through a really hot vacuum pump? or is this a much more obvious "you better turn the darn thing off, buddy" issue?

We had the Z take a couple of nosedives (it lost steps, we are sure - no operator error around here...) with a big (1.25") ball nose bit in it, and one actually pierced the spoiler down to the plenum, about 6" away from the inlet of our zone A (near our 0,0 corner) Luckily, the in-line filter caught any **** that may have found it's way downwind. Our solution, until we reskin the 'bot, is to keep that hole covered (duh) when the vacuum is on. Is this causing limited pressure? Is there a way to check up the line if something is clogging a channel in the plenum? Would some little crappy chunks caught in one zone really cause -3 inches of pressure lost?

The relief valve is supposed to open when pressures reach about -9 inches of mercury. I have never been able to get our system to draw more than - 5.5 to 6, but that's not with the entire spoiler board covered. I am more interested in having a full draw with three zones closed off, and one zone really cranking. What's happening?

We made a big investment in this system, and would like some advice from anyone who cares to share their knowledge with us. Especially about smells and sounds.

Thanks!

Matt Barinholtz, Covenant House Washington, D.C.

P.S. - The kids really thought Brian and Zach were cool. That's saying a lot, coming from the youth that we work with. They;re great teachers, have fun doing their work, and can successfully navigate the highways of NE and SE D.C. without fear. It was a pleasure to spend time with them!
I've got some photos of them in the shop teaching our guys and gals how to cut a sign using Part wizard, and it was as if they were witnessing dogs playing poker - they were truly mesmerized and interested. We need to get more Shop Bots into the inner cities!

[bjwat@comcast.net]

Matt,
One thing to keep in mind when trying to reach maximum pressure on your vacuum setup is your spoilboard material. The vacuum will actually bleed through the MDF since it is not a 'vacuum proof' material. I have heard of guys using LDF specifically for vacuum setups with no holes in it to hold parts! If you can afford it, I would look into using UHMW plastic for the spoilboard or something that is closed celled.

Just my $.02...I've been researching vacuum setups all week...

-Brady

[elcruisr]

I've got a 5x12 table covered by 3/8" "Trupan" MDF with 6 zones. I bought the same pump as you as per Shopbots reccomendation. I've never made more than 7.5" with only one zone open and a large part on the table. Quite frankly while the pump has been working OK it is just not big enough for the job on a table this large. We routinely cover up unused sections of open zones with scraps of plywood or HPL to help maintain adequite vacuum. We are hoping to be able to upgrade to a much larger pump in the future. In your case you need to make very sure you have no unwanted vacuum leaks. We siliconed all connections that were not glued. Sealed the plenum and all the edges of the table. We also siliconed the edge of the spoil board to the plenum and between the zones. All of this helped to at least make it workable for now. We've never had any over heating troubles and some days it's run 8 hours with few breaks. It gets pretty warm to borderline hot but never smelled like something was burning. The trick is to make sure you can hold your parts and if I can hold 5 I can usually hold most parts and if they are small I use bridges. Hope this helps.

BTW Covenant house is a great program, let me know if we can ever help.

Eric Lamoray

[steve]

Eric what do you consider to be a small part and what are bridges? I ask because I have just got hold of a vacuum pump for my prt96 but have not yet set it up.

Steve Benjamin

[elcruisr]

If my parts are smaller than about 2 square feet of surface then I usually find it beneficial to hold it to the larger panel with bridges or some call them tabs. You can program the cut file to leave small pieces of material at the bottom of the cut. I often use a piece .15" thick by .35" long. Four or more depending on the part keeps it locked in place with the larger panel. After all the parts are cut in the panel we use a 1/4" laminate trimmer to trim off the tabs. It's also good for preventing a small cut out from comming loose and bouncing around the cutout and deflecting the bit into the cut. A typical project we just did involved rectangular pieces 10" x 46" with 54 small circular cutouts in each out of 4'x8', 3/4" Birch ply. The larger pieces were bridged together and the cutouts bridged to the pieces. Nothing came loose, no deflected bit gouges and the vacuum held it all down. Five minutes work cleaned everthing up with the trimmer.

Eric Lamoray

[rgbrown@itexas.net]

I regularly hold down parts in the ~20 Square inch range with gaskets and a $15 vacuum motor. The motors are available surplus and have external fans. For low produciton items inexpensive gasket amterial is available at the local "home improvement" store.

Ron

[geobre@aol.com]

Where do you get these motors? I know you have mentioned them earlier in another section of the forum. Do they have a website?

Thank You
George

[rgbrown@itexas.net]

George,

My source is surplus center - 1-800-488-3407. The specific part is a item #16-1193-E "Bypass Design" AC Vacuum Motor Blower. To get the high vacuum holding on small parts one needs to have a gasket and a good seal.

There are a lot of other simple and good techniques to seal tables and get a better 'hold-down' with inexpensive materials. For "production methods", it is hard to beat a large vacuum motor and inefficiency. For those of us who do not run our machines 30-40 hours a week and do many varied parts, the inexpensive way may be better.

Don't think you are going to take a $15 vacuum motor and do the work of a 6 1/2 hp specialty tool. But, some of us don't know we are limited by our inexpensive ways.

Ron

[rgbrown@itexas.net]

I forgot to mention they do not have a website I know about.

Ron

[rgbrown@itexas.net]

In my mailbox this morning was a catalog from surplus center. They now have a website (makes me a liar). Here is the "URL" for vacuum motor:

http://surpluscenter.com/item.asp?UI...item=16-1193-e

HTH,
Ron