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Smart math peeps get in there! Fab table sinking in asphalt calc.

[memphis]

Web wheeler
Joined
Jun 6, 2020
Member Number
1867
Messages
719
I found a great deal on a piece of 10x4 .50" plate and want to turn it into a frame table. I'm ghetto building in a tent on an ashalt driveway
I plan to trim the sheet to 3x8 which puts the top weighing in at 490lbs. For science lets assume the remaining framework and legs weigh + the top weigh 750lbs

If I make my foot pads 12"x12" out of the scrap cut offs will it provide enough floation so that the table won't sink into the driveway?
My redneck logic is as follows:

Previously had a 5600lbs truck parked where I am building. It had 265/70/17s on it... but I'm going to assume that was less than 10"x10" and I never noticed any significant sinking...

If possible, can I get away with smaller feet? Or is beef better in this case?
 
Filthy McChevy said:
Throw a sheet of 1/2 inch plywood under it.
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Not a bad idea, and I am doing that presently but the driveway slopes toward the backyard and all of the rain water travels that way (backyard catch basin) so I will likely be putting horse stall rubber or something similar to keep the water at bay. The wood that is on the ground isn't going to last much longer, and I've been changing over to plastic skids which has helped a lot
 
Four 12x12" feet? That's 576 square inches...less than 2 PSI of pressure based on your estimated weight....surface is probably uneven and will concentrate the weight on the high points until they smooth out....perfectly fine.
 
Your at ~190lbs per leg at 750lbs, that's less ground pressure than you standing out there. If you really don't want it to sink then the rubber mat under the pads would be great.
 
TheFlyingDildocupine said:
How hot does it get there?
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In the summer time it gets up into the 90F range. I would argue the tent acts like a greenhouse and can be 20F warmer. I had a 3B roller frame on small caster dollys in there this summer and they sank... the 4 wheels per dolly are only 1" wide so I'm not surprised but I want to minimize that from happening. That's zipped up, if I open the front flap it will cool down pretty quick. Put it this way... I can't work in there with the door down it's hotter than Africa
 
In that case some 6"x6" feet should be more than plenty. You could always go partial retard and make skids between the feet to really prevent sinking.
 
Thefishguy77 said:
Only real solution is to build a shop with a 6” concrete slab and 2 different lifts. Otherwise your just sinking in the asphalt, so to speak. :flipoff2::flipoff2:
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I don't have the 40-50K to do it properly. Can't put a monolithic slab because of the elevation change. Sure I could bring in dirt but that will drastically change the grading and everyones backyard drains into mine because I have the catch basin. Need to put a foundation in and can only build about 18ft wide x 40ft deep
 
add adjusters to the plates so you can relevel the table if it does sink.
 
It will sink and there is nothing you can do to stop it. Over time, asphalt will "creep". I left a 50 lb floor jack sitting on my driveway for 6 months and it sank.
 
Eric said:
It will sink and there is nothing you can do to stop it. Over time, asphalt will "creep". I left a 50 lb floor jack sitting on my driveway for 6 months and it sank.
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See ya !! :lmao::lmao::lmao:

Roadways are constructed of asphalt over crush rock and road base just like your driveway. Think about it. :idea:
 
Splib said:
Roadways are constructed of asphalt over crush rock and road base just like your driveway. Think about it. :idea:
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Exactly. I'm sure you've got 12" or more of stone that was proof rolled and certified before they put down 8" or more of asphalt. Asphalt is asphalt, right? :rolleyes:

12"x12' feet should be plenty, and non-OP's idea of making them adjustable is a good one. Some scaffold feet should do the trick and not break the bank.
 
Splib said:
See ya !! :lmao::lmao::lmao:

Roadways are constructed of asphalt over crush rock and road base just like your driveway. Think about it. :idea:
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Totally different scenario. Unless you know of a roadway where something just sits in one place for months on end.
 
Splib said:
See ya !! :lmao::lmao::lmao:

Roadways are constructed of asphalt over crush rock and road base just like your driveway. Think about it. :idea:
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Holy retarded statement.

You think a road and a driveway are constructed to the same standards?

"Think about it".
 
HillbillyDeluxe said:
Holy retarded statement.

You think a road and a driveway are constructed to the same standards?

"Think about it".
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I worked for the Highway department engineering for 20 years. Not the same standards but a properly designed and well constructed driveway, not some clown contractor dump on uncompacted earth and run, is built with similar methods and performance. Not retarded really.
 
I cringed when you said "cut it down to 3x8". Anyone EVER complain that their table is too big?

Surely you've got a steel suplier that sells cutoffs? Little chunks are easier to come by than full sheets.

I'm ghetto enough I'd use treated 2x6 wood as pads under the feet. Cheap, and spread the load even further.
 
Rolls eyes at people comparing static loads to dynamic loads. :lmao:

Your proposed pads and load sound reasonable to me. It will still sink eventually though. Asphalt is has some elasticity to it and a constant load will eventually wear out that into an impression of some sort.
 
junkytj said:
Rolls eyes at people comparing static loads to dynamic loads. :lmao:

Your proposed pads and load sound reasonable to me. It will still sink eventually though. Asphalt is has some elasticity to it and a constant load will eventually wear out that into an impression of some sort.
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Exactly, asphalt is not a "solid" in the strictest sense of the word, it's like glass, which is also not a solid, over many years glass settles towards the bottom of the window pane, at least that's what I learned in high school science class. I know I have to put shit under the kickstand on my motorcycle on a hot day or i'll come back and it's sunk an inch in to the asphalt.
 
Drummer79 said:
Exactly, asphalt is not a "solid" in the strictest sense of the word, it's like glass, which is also not a solid, over many years glass settles towards the bottom of the window pane, at least that's what I learned in high school science class. I know I have to put shit under the kickstand on my motorcycle on a hot day or i'll come back and it's sunk an inch in to the asphalt.
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So it's like tar? Or maybe bitumen?
 
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