Vacuum Hoist Sheet Loader

[fleinbach]

Some of the information here was posted erroneously in some previous topics. So I decided to give it its own thread.


I constructed the gantry mostly out of inch and a half Square tube. The 800lb hoist came from Harbor Freight. The vacuum puck is simply a pot lid from my wife's kitchen.



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Here is a close up of the pot lid vacuum puck. It is 9 inches in diameter, and the only modification I needed to make was to drill a hole for the vacuum line and add a stick on rubber gasket. It actually worked without the rubber gasket except that if the sheet turned sideways It slid across the sheet.


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The gantry allows me to load sheets from my storage rack or the ones I keep under my table. I have loaded 1" 5'X12' sheets and they weight 240lb

[myxpykalix]

A pot lid...now thats what i call RECYCLING!

[gene]

I am sure that beats the 8000. plus i spent on my lift, and probably works just as good. I know that it beats breaking your back to load the machine with that heavy stuff especially after your help has gone for the day

[allegheny]

Here is a shop-built hoisting crane:

http://www.homemetalshopclub.org/projects/crane/crane.html

[nschlee]

Frank,

That's usin' the old noggin'!
What are you using for a vacuum pump?

Neal

[fleinbach]

A Gast vacuum pump. It's not easy to see but it is the black spot with an S shaped hose coming off of it sitting on a shelf over the Shopbot. It pulls 28 inches.

[nschlee]

Thanks, I see it now. I've got 2 Edwards VPumps not being used, I'll have to build something similiar. I also have a venturi VPump, wonder if it would be strong enuf? I'll have to test it.

Neal

[nschlee]

Frank,
How long is the boom? How'd you mount the post?
Thanks,

Neal

[nschlee]

After a closer look, I see how you mounted the boom.

Neal

[fleinbach]

The boom is 8' long and the post is a 4" lolly column holding up my second floor shop. I have picked up 300 lb with it with no problem. A few weeks ago I had a visitor who makes concrete castings. He asked if the puck would pick up concrete so to test it I lowered the cable to the floor and turned on the vacuum. When I powered up the wench it started to pull the boom down so I stopped. I'm sure I had put more weight on the system then the 300 lbs and the puck never released.

[nschlee]

Thanks Frank,

How are you controlling the vacuum? Switch or valve? Is it on the pendant?

Neal

[fleinbach]

At this point I just turn the power off to the vacuum pump. But I can also just release the quick connect at the puck and reattach it if I want to change it's position. But I will be installing a valve eventually

[myxpykalix]

Go to the store and look at the "Foodsaver" vacumn system. Their jars have a small push valve that releases the pressure maybe you can find some type of valve like that made out of something other than plastic. OR if you want to do it on the cheap just install a valve stem from a car rim?

[sawkerf]

Frank, What size pump would I need to make one of your lifts? I got a forklift to make unloading trucks easier, I got a set of pallet racks to make storage easier, now I need a lift to make loading the bot easier. Seems like life should be getting easier, but it ain't. Every time I solve a problem I create a new one. Sound familiar? Thanks, Kip

[fleinbach]

Kip,

The pump I am using is capable of 27 inches with no leaks. The atmoshere is exerting 29.92 inches of mercury at sea level when the temperature is 0 deg C equating to 14.7 lbpsi
so my puck being 12" in diameter should be capable of picking up about 500 lb. I noticed somewhere in the past couple of weeks someone on here made a pump for under $200.00 capable of 22 inches of mercury. I believe it was Robert Ball. According to my calculations with a 12 inch puck you could pick up 404 lb. If you increased the puck size to around 15 inch diameter you could pick up about 505 lb. Just remember all these figures are at sea level and 0 degree celsius they will be less at higher altitudes and temperatures.

[olecrafty]

I use a compressed air vacuum generator on my lift and it works pretty well. It is a Gast VG-260-00-00. Maximum vacuum of 27 and a max open flow of 17 cfm. They are regularly available on ebay.


Kaiwa

[sawkerf]

Here's an idea I just had. What if I tapped into my vacuum table regenerative blower. I could shut off all 4 zones and add one valve for the lift, would I get enough vacuum that way? I figure I could plumb up to the ceiling with a 2" pipe then reduce to a suitable size hose to the puck. I have a 7HP FPZ pump that I bought with my Bot. Kip

[fleinbach]

Kip

My 7.5 vacuum pump from Shopbot draws 14 inches of mercury. I calculate a 12" puck should be able to pick up about 202 pounds. Increasing to an 18" puck looks like it will pick up over 400 pounds. If I get a chance tomorrow I will plug my 12" puck into it and see what it will pick up.

[sawkerf]

Frank

My 7.5 only draws about 8 Inches (Central SC not sure of elevation) How do you get 14 inches?! I was checking out one of those commercial made vac rigs, most of them have multiple, small pucks. How would this compare to one puck like you have? Seems like this may offer more control?
BTW, how do you figure all the math, I'm a math idiot, ok just a plain idiot, but what's the formula? I'm totally excited about this lift thing, it's gonna change my life. I'll never have to lift another sheet of MDF or plywood by my self again! Thanks again for your help. Oh yeah, Your work is truly exceptional! Kip

[fleinbach]

Kip,

Are you sure you are only getting 8 inches. Here is the specs from shopbots site for there 7.5 HP unit 7.5hp Roots PD Blower - 14"HG@145CFM (mailto:HG@145CFM)
I doubt your altitude in central SC is high enough to drop half it's capacity. Even if your altitude was 5,000' above sea level (and you are no where near that in central SC)you would still maintain .83% or 11.62 inches

Are you making that measurement with all your zones closed? I don't drop to 8 inches until I open 20 SF of plenum area.

Conversion Factors
Atmospheres
atmospheres x 29.92 = inches of mercury at 0°C
atmospheres x 1013.25 = millibars
atmospheres x 760 = millimeters of mercury at 0°C
atmospheres x 14.7 = pounds/square inch


At sea level the atmospheric pressure is 29.92 inches when the temperature is 0 degrees celsius. This equates to 14.7 lbs of pressure per square inch. A 12" diameter circle has 37.68 square inches of surface area. So 37.68 X 14.7 = 553.896 pounds of pressure.

[sawkerf]

Frank, my bad, my age is catching up with me. My blower is a 6.2 HP not sold by SB anymore. Kip

[fleinbach]

Kip,


I hooked up my 12" puck to my 7.5 hp pump and picked up the end of a 1" X 61 X 121" sheet. I stood on the sheet with my 170 lbs so I would guess combined with the weight of half the sheet that was at least 250 lbs. It held until I started bouncing up and down on it. This eventually caused it to release.

[sawkerf]

Frank, My lift turned out great! Thanks for the help, it's been an awsome addition to my operation! I do have one problem though, I just got some MDF yesterday and my puck(frying pan) won't hold it. I tested it on some older sheets and it hold fine. I'm pretty sure this new stuff is not LDF. I also lifted a shop cart with me sitting on it, no problem. My question is, have you had a similar experience with your MDF? Are some brand more porous than others? Thanks,Kip

[Gary Campbell]

Hey Guys..
If you are looking to build an inexpensive vac pump, check out eBay. I got this pump for $50 + shipping. Specs are 26"Hg and 4 CFM. Another $100 to Joewoodworker(dot)com for the valve, switch and relay etc. works great. I use it for dedicated vac pucks, vacuum press, but not lifting yet.
Gary

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[fleinbach]

Kip,


I have no problem picking up any type MDF but I use a a high capacity Gast pump for my lift. It draws 28 inches. It can hold far better then my 7.5 HP regenerative I use for hold down. In fact on light weight 1/2 MDF if I place my puck on the stack it will pick up 5 sheets at a time. The lower 2 to 3 sheets can be easily seperated but the one directly below the top needs a good bit of pressue to release it.

Since my sheets are stored in a rack my normal procedure for picking them up is to pull them half way out before applying the puck. That way there is no extra sheet directly under the puck.

If your using the 6.2 hp pump you described above you most likely are losing to much vacuum through the sheet. In that case you should try to find a high capacity pump like the one Gary described above. I picked up my Gast pump at a local flea market for $100.00. A rare find for sure but I believe if you check ebay regularly one will appear for a decent price eventualy.

[sawkerf]

Hi Frank, I put my gauge on the puck and measured several different things. I pulled as much as 24 " on formica, 20" on 3/4 birch plywood, 7" on particle board, 8" on MDF I had prior to this stuff and less than 1" on the new MDF. I don't have a clue what the difference is. Thanks, Kip

[fleinbach]

Sounds like that new stuff would make an excellent spoil board for your vacuum table.

[sawkerf]

That's exactly what I was tinking. I made a set hooks to grab the edges of the porous stuff. They work fine, but a little less cool. Thanks again for your help.