Vacuum Table on a budget... seriously

[harryball]

OK, don't laugh. I'll post pictures tomorrow. I've just finished making a vac table using 4 shop vacs... well just the heads anyway :-)

I had 2 Shop Vac Pro Hangup units
see http://www.acehardware.com/product/index.jsp?productId=1289191&cp=1254944.1259528&par entPage=family&searchId=1259528

Our local ACE had them on sale for $59.99 each so I picked up 2 more. Now... looking inside the unit with the head removed I noticed the intake looked a whole lot like a 2" PVC fitting... turns out a 2" PVC pipe fits right in with just a little trimming of the plastic insde the tube.

So, off came the filter posts and ball. In goes a PVC pipe and I now have 4 shop vac heads mounted upside down under my table. It's actually a pretty good setup. I'm going to build some sound cabinets around them to help with the noise. I tried some cardboard boxes and the sound was cut about 1/2 so I know a decent wood enclosure vented through baffles will work well.

It works better than I expected too. I can lay a piece MDF of material down that covers about 1/2 the vacuum area and my wife can not remove it. I can not push the part sideways but with hard prying I can lift it from the table.

A whole sheet won't budget sideways. What surprised me though was a part as small is 3" x 4" stuck to the table with the entire table being open. I could lift it off and I could push it around with some effort... but it stuck.

I think for what I do it's going to be perfect.

Robert

[harryball]

I finally got around to taking some pictures. I have been running the vacs without the doors on the bottoms as the heat builds up pretty fast. I don't know if it'd be a problem or not but I didn't want to take a chance. Eventually I plan to add a small ventilator fan. All and all, works well and was cheap enough.


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Robert

[richards]

I've seen non-Fein vacuums with a small 'bleeder' hose connected to the suction side. Its purpose is to let a very small smount of air get sucked into the vacuum for cooling. The Fein and some other vacuums have a separate cooling fan. Most of the shopvac type vacuums expect to have unrestricted air flow so that the suction also supplies air for cooling.

[harryball]

Even when sealed off there is some air flowing through the heads. The way I mounted them I drilled small holes and added screws to the base to prevent the unit falling off. Those screws allow a very small amount of air through. So long as the cabinet is open the heat just comes out in the room, nice this time of the year.

My biggest gripe is noise. I've heard some other vac pumps, the large 3 phase ones, and they are loud too. I'm getting used to my headphones with radio. I just can't communicate well in the shop, have to yell over it when it's running.

Robert

[baltic_birch]

Can that hold down a full sheet of 3/4 baltic birch?

My alpha will be here in a few weeks, still deciding on vacuum system, but yours looks great.

May smallest cut part will be 8x11". Will use router, 1/4 inch bit, 1/4 step down passes.
All cab/panel work only.
I'm planning on leaving a thin skin also.


Just wondering if your vac set up would suit me.

Thanks

[harryball]

I've been cutting 3/4" cabinet grade plywood with a down spiral bit. I use down spirals most of the time not as much because of lift for the up spiral but because I get nice clean edges on top.

I also cut 1/2" exterior plywood in a single pass with a down spiral, that is the majority of what I cut. I plan my path carefully to tab parts smaller than about 12 x 12 and cut from small parts up to large parts.

The 1/2" sheets are BC, the same stuff you get from home depot. It is not normally flat, it generally stands off the table an inch or two which I try to keep in the middle. When I start the vacs nothing happens... until I press the board down then FWMMMPP! it sucks to the table and holds well. You can hear the pitch of the motors change when it seals.

I've been running these more than a month now, the heads are still sucking strong and seem OK. They generate heat so I keep the cabinets open just being cautious. I'd like to seal them up with a vent fan like from a bathroom and have the option to exhaust outside vs. inside if I need the heat. I figured I'd see how they run a month or two before I put anymore effort into the design.

BTW, I notice significant holding power on a small 8" x 8" square with a smooth side. I have cut parts that are 4" x 20" long without tabbing. I just "feel better" tabbing anything smaller than 12" x 12".

Robert

[harryball]

Thought I would provide an update...

I've been running 4 vac heads, 3 of old design and one of the new updated design. The old design has a switch facing front that slides up and down, the new design has a small switch more on top that rocks like a seesaw. You MUST seek out and use the old design if you want to do this.

The newer updated design is lighter weight and does not strip down to the motor only. The decorative housing is actually part of the structure and is of much thinner plastic than the old model. I've had 2 so far and both failed in about 10 hours. My other 3 vac heads (1 about 4 years old and 2 purchased new) are doing well.

The heads must be stripped clean and have air that can circulate around them. I also added a small 1/16" hole on the intake side to allow some air leakage when the zone is fully covered. I don't know how much good it actually does but it makes me feel a better knowing some air is still going through the head.

Holding power is very good through a bleeder board. This would not be a good setup to run with open vac zones (no bleeder).

I have run these for more than 8 hours with only brief pauses to change sheets about every 50 minutes.

That said, before you go buy and mangle a bunch of these, try one first to see if it works ok for you. For myself, I'm happy with the performance and expense so far considering what they've accomplished.

My current plan is to continue to seek another vac head of old design and replace that failed unit. If I start having problems with the other vac heads I may reconsider and go with twin feins or something, but right now things look good.

The primary vac head on the 0,0 quadrant is at least 4 years old and runs the most. It has well over 100 hours on it just from the shopbot usage.

Robert

[steve4460]

Hi Rob

Just call the manufacturer and have them sell you just a replacement motor for the one that you like , with out all the other stuff on it they will be cheaper and it will save you the time to take them apart.

Bot on

[harryball]

I tried that, they no longer mfg the older design nor sell parts for it, all they will do is sell me the new head design. I found these two older models new on the shelf, I've been keeping my eyes open. So far as saving money, they want more for the head direct than I could pick them up at Ace for complete.

Robert

[steve4460]

Well Thats not nice .

[danhamm]

Robert thanks for the pics, looking at your motor
from underneath, there is and obvious impeller..
So I took the old shopvac from the garage to the shop and dis-asembled it and like yours it has a separate fan for the motor..so I ran it upside down with the ball check in the 2in suction line and it got very hot very fast..not the motor but the vacuum impeller, unable to dissapate the heat its all plastic except for the impeller..I drilled a series of holes around the shroud of the impeller to change the air flow..put the ball back in the 2in suction fitting and ran it for 10 min..it got warm but not hot enough to start and distortion..this idea of your s has possibilities...cheers Dan

[steve4460]

Hi Dan

If you run this umit upside down with the ball in there then you will not have any suck going in toyour plennum . The way I see this you have to take that out when you conect it to the table . that ball is only for when you normaly oerate the vac to suck up water so that when the tank gets full that you dont suck water out of the tank and in to the motor .
Just my tow cents I hope I didn't miss anything here.
Bot on

[danhamm]

No...I did this to see how hot it would get with no air movement on the vacuum impeller..the unit was totally disassembled...cheers...Dan