How clean does the area around the saw have to be and how much dust gets kicked up? You mentioned ~10 PSI for the Boeing thing, what do you run yours at?
The hemorrhoid cushion part was hilarious. Reminded me of a cyclist buddy telling me about shopping for support hose to help with his varicose veins and having the clerk in the lingerie department give him odd looks when he asked for a pair in his size. ;)
R"RicodJour" wrote in message news: snipped-for-privacy@e39g2000hsf.googlegroups.com...
The air pressure that is needed depends on how large the pads are, how heavy the load is, and how smooth the floor is. The floor smoothness and the condition of the pad skirt's bottom surface significantly affects the volume of air that is needed. Of course, some air has to leak out to provide the air bearing function, but the less air escaping from under the pads, the less dust will be blown around. I always sweep my floor before using them, but I don't make it perfectly clean. Sometimes I'll see some dust being blown around on the floor but I never get major dust clouds in the room from them. I guess it really all depends on how good the skirt to floor seal is. They used a vacuum cleaner to inflate the cheaply made pads in the link, which is high air volume and very little pressure, probably only a few psi. I use my shop compressed air system, a 3/8 line to supply line my regulator bank and 1/4 inch lines from the regulators to each pad. My air system has an 80 gal tank and 18 cfm compressor and I've never run out of enough air to run them, but if I was to run a pad over an 1/8 inch crack in the floor, the pad would collapse. I can sometimes crank up the pressure (and thus the volume) to a collapsed pad to get over small defects, but it's best to make sure that the floor doesn't have any significant voids in it where you are going to be using the pads. We used bondo and duct tape as a temporary floor fix to get the pads to work over some bad spots in the floor when I was using the commercial pads to move the robots, but rough floors can be a major problem. Floor defects can easily damage the rubber skirt seals on the pads as well as pose the significant air leak problems. To lift an 800 lb table saw with 3 - 8 inch diameter pads on a tile floor you probably will only need about 2 or 3 psi. I rarely move my tools with my pads any more as my present shop is relatively small and tool locations are stable. Lately, they seem to just get used for moving big clumsy projects where it is very inconvenient to try to move them around with dollys, etc. or sometimes when I'm the only one in the shop and I want to move something myself. Once the pads are in place under a project I usually leave them there until the project is finished, so it can be moved or turned around for the convenience of getting to the other side, etc.
I didn't mention in the previous note that I have been adding a small circle of 1/2" plywood in the center of my pads to take the load off the rubber skirt material when the pads are not inflated. I found that this helps to protect the rubber should a side force (bump) be applied while the pads are deflated. They can easily tear if a load is on the rubber alone and the load is pushed sideways. With the plywood in the center the weight of the load is on it and not on the rubber.
Charley
Thanks.
1/2 sheet 1/2" plywood, 1 2" cutoff 3/8" pipe, hose, clamp, epoxy, 30 seconds labor to drill the hole in the center of the sheet.
If you look closely at the General hoverpad you will find that it's really many small hoverpads on a big sheet. Making one big one will give you stability problems. Multiple small ones like 3 or maybe 4 on one common sheet will give you the stability of the General's version.
Charley
How hard would it be to glue up a manifold from 1/2" PVC?
Actually, my pads have a sort of manifold made into them. I groove one sheet of 3/4 ply and then sandwich/glue it on top of another piece to allow me to have the air inlet enter along the middle of one edge. I epoxy any voids in the plywood groove and also epoxy a quick connect air line fitting into the hole (bored out to fit) in the edge. It's positioned so that nothing interferes with the flat top surface. That way the pad will fit under anything. To be sure of a good glue-up of the two sheet joint and have no leakage I make sure that I run an unbroken bead of glue all the way around the groove area so that it seals real well when put together. Then I hold the sheets together with clamps followed by screws "until the glue dries". Of course, the screws remain when the clamps are removed. If you were making several small pads on a large sheet, manifolding between them this way may not be such a good idea. Maybe you could sandwich a piece of pipe in the groove to minimize the possibility of leakage.
I have never made a multi pad assembly. All my pads have been single and each one has had it's own air line from it's own regulator, so I can feed each one and control it separately. I don't know how they would respond if they were all manifolded together.
Charley
Depends what supplies you have on hand, I guess. I do plumbing, so I have lots of spare 1/2" PVC pipe and fittings laying around the shop.
Good incentive for an inveterate slob like me to change his habits. Cleaning one's work area frequently is a very good practice. Aside from the immediate safety aspect, it is a good excuse to take a break and plan the next operation.
OTOH when turning there is certain charm to standing in the middle of huge pile of chips.
I have yet to hear a blacksmith say that after shoeing a horse.
That particular blacksmith would be a farrier...
Actually, he could belong to any religion.
That's the difference then. For some things I like to build them from scratch like setting up and organizing a workshop, but other things I like them to just be there for use. The HoverPad would fall into that category as far as I'm concerned. I'd just want to use it and not worry about saving a few dollars building one. It's unlikely I'd be saving any time, so building one from scratch is just not a consideration.
:) (Which I also _meant_ to include earlier...)
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