[brunog]

I
There's this pneumatic rotary ball vibrator (vibrates in all directions), the puts out 689 lbs of force at 200Hz and costs $99.78 (5807K73). Draws 15CFM @ 60psi which my compressor can handle. I thinking about bolting this to a table for making my own vibrating table. Then strap down a pressure pot (vacuum chamber) to the table.

Zumba,
Vertical vibration is what you should be looking for, the ball vibrator should do the work as long as you fix it on a leg limited to vertical motions

Best regards

Bruno

[walter]

Much ado about degassing, but why? Is it to create a precision surface? The only precision surfaces discussed in any detail were the "surface plate" floors. There's no vacuum bagging or vibration being used there. How did they get it to work?

From one of the links on page 21:

"The Epoxy Surface Plate eliminates any and all guess work by providing a perfectly level and perfectly flat floor surface. We are talking 'Dead Level', not just close. With the Floor Plate Epoxies FP-85 and FP-80, simply pour into a framed out area of any size to produce an exactly level floor surface.
The Epoxy Surface Plate has superior flatness and cosmetics for a fraction of the cost over steel plates..."



1. Mount to 2 inch 'L' angle aluminum using to form the retaining walls of the surface plate.

2. Using standard 2 inch duct tape, tape a waterproofing seal around the inside perimeter of the aluminum and floor. Area must be water tight to contain the fluid self leveling epoxy.

3. Two component, self leveling, pigmented 100% solids epoxy system is mixed and poured to a depth of 1/4 inch at a rate of 6.4 square feet per gallon to create the structural body coat of the surface plate. This coat will establish the level plane of the surface plate in relation to your concrete floor.

4. Spread epoxy with squeegee or trowel to aid leveling if needed.

5. While the epoxy is leveling and starting its curing cycle, you must assist with air release because of surface tension. Air bubbles come from several sources and need to be minimized as much as possible; when measuring and pouring epoxy components into containers, when stirring components and when pouring mixed epoxy into surface plate area. During the 1st pour, air is also released from the concrete as the epoxy penetrates in. The amount of this air source is determined by the concrete's degree of porosity. This factor alone makes one pour application impractical as air is still releasing as the epoxy cures. To release air, take a propane torch and wave the blue flame over the surface like a wand. The epoxy is not flammable; however, should you dip the flame into the epoxy, it could leave a charred or burnt looking spot which should be dipped out before continuing, especially on the next two coats.

6. (second day) The epoxy is mixed and poured to a depth of 3/16 inch at a rate of 8.5 square feet per gallon to create the cosmetic color coat of the surface plate.

7. Spread epoxy with squeegee or trowel to aid leveling if needed.

8. Area is then torched to release air. Air bubbles will be at a minimum with the first pour sealing off the concrete.

9. (third day) The 2-component, self leveling, clear 100% solids epoxy system is mixed and poured to a depth of 3/16 inch at a rate of 8.5 square feet per gallon to create the perfectly level, perfectly flat surface plate.

10. Spread epoxy with squeegee or trowel to aid leveling as needed.

11. Area is then torched to release air.

http://www.precisionepoxy.com/PlateInfopg4.htm

************************************************** *****************

EDIT: To recap (and new info for those just joining us):

Article in post #541 (page 46)
E/G Tips&Tricks in post #364 (page 31)
Useful links in post #241 (page 21)

[davo727]

There is a pipe embedded in the EC that the 1.25in bolt goes through. The machine column that bolts here will have the bottom 5 or 6 in filled with EC with another pipe insert . A plate on top of the EC and crank down the nut should give some huge clamping force to hold the base and column together. I had to grind down this upper surface to allow the column to sit flat as it ended up about 1/32 to 1/16 higher than needed. I used a 4.5 in grinder with a masonary wheel on it. I would reccomend avoiding that deal, no fun to grind this stuff . PS... My mix looks to me like Epoxy concrete, dont know if theres any granite or quartz in it Dave

[speed33317]

Hi,

Results of my 10% epoxy by volume mix experiment.

I have actually impressed myself. Might have gotten lucky and got it
right the first time.

The filter sand mix is super strong, I only had one spot of epoxy pooling
but I figure this is caused by incomplete mixing. Also has a nice surface
finish. I used Glad plastic containers. And they break out of the molds nicely.
I havent been able to break it by hand.

The dirty mix, just as strong. Same finish result.

I really don't think you can mess this up.

Just get your epoxy ratio right and your set.

Too dry and you have loose sand, too wet and your wasting epoxy.

I know there has been ratio of epoxy by weight, I think you will
be using alot of epoxy this way.

Oh and these little blocks are pretty heavy. The dirty mix is heavier.

Vibration dampening, you tap them with a hammer and other than
the pressure of the hit you don't feel the resonance.

As soon as I get a little more $$ saved up and do the math for the amounts
I will be needing I will be casting my lathe.

This may be a useless post :-) But these are my results.

[martinw]

I actually have no problem with the repeat posts. As time passes, we look back at what we said earlier and may have a different take on things.

Anyway, let's discuss vibration. I thinking about bolting this to a table for making my own vibrating table.

Dear Zumba,

I mentioned RC countertops in post #587, and a book on the subject by
Fu-Tung Cheng. The author said that bolting serious vibrators to the outside of the formwork might destroy the whole shebang unless the form-work was pretty strong. My guess, and it may well be entirely wrong, is that powerful external vibration may create much greater forces on the formwork than the forces needed to contain a static mix.

I have only done a few pours with RC, used hand-held sanders to the outside of the mould, poked wooden sticks to begin with, banged the outside of the mould with a rubber-headed mallet, and put a sander in a plastic bag on top of the mix (messy). I have also applied vacuum, but not with the purpose of drawing off excess liquid .

IMHO, powerful external vibration will do a good job, together with internal vibration....but watch out for the dynamic forces on the formwork.

These were points made by the author, a better man than me.

Best wishes

Martin

[martinw]

From one of the links on page 21:

[I][SIZE=2]"The Epoxy Surface Plate eliminates any and all guess work by providing a perfectly level and perfectly flat floor surface. We are talking 'Dead Level', not just close. [I]

Dear Walter,

Any chance of the tolerences that these people claim?

My best guess for flatness is 1/4 inch over 20 feet.

It's a garage.

Best wishes

Martin

[walter]

My best guess for flatness is 1/4 inch over 20 feet.

1/4 inch?

You mean like one point of the floor at zero and other 1/4" higher? Why? Does gravity pull in different direction there?

[Geof]

1/4 inch?

You mean like one point of the floor at zero and other 1/4" higher? Why? Does gravity pull in different direction there?

If you want to get really, really, really picky.....yes. Gravity pulls along a line passing directly through the center of the Earth so it is in a different direction in different locations. Well, theoretically that is the case and it would be true if the Earth was a perfect homogeneous sphere; Google 'Geoid' or pick up a recent copy of "Discover" that has an article about the GRACE satellite data.

But I don't think gravitational anomalies would show up it the poured floors. More likely uneveness arising from air currents but I have no idea how large these could be.

1/4" sounds like quite a lot but over 20 feet that is one part in a thousand. Considering the picture seemed to show an auto body shop I would say that qualifies as 'perfect' in their terms.

[martinw]

1/4 inch?

You mean like one point of the floor at zero and other 1/4" higher? Why? Does gravity pull in different direction there?

Dear Walter,

I think we may be talking at cross purposes.

"Dead flat" for a garage is not quite the same for "dead flat" for others.

That was the only point I wanted to make.

If I wished to grind telescope optics, I would not use a garage floor as a reference table.


Best wishes

Martin

[lgalla]

Hi,my name is Galellio.I know I may be found guilty of blasphemy by the church,but epoxy surface plates are flat and the earth is round.
Thankyou
Galo
Apprentice

[walter]

"Dead flat" for a garage is not quite the same for "dead flat" for others.

I have to disagree. Epoxy performance has to be tha same. The garage has a weaker base (of course)- I'm just assuming it's stable enough to do the measurements.

Optics grinding facility has 5ft of granite on pneumatics (on 20 tons of concrete). So what.. Their epoxy "pour" should look the same.

EDIT: Hi Galo, welcome to the thread!
...

[Geof]

Hi,my name is Galellio.I know I may be found guilty of blasphemy by the church,but epoxy surface plates are flat and the earth is round.
Thankyou
Galo
Apprentice

Epoxy poured out and allowed to flow level solely under the influence of gravity is just as flat, or round, as the earth; it doesn't have any choice.

[lgalla]

Right on Galo.
Epoxy surface plates,orESP's are truly flat.That garage floor is an F1 race car plate to adjust suspentions etc.The US space program uses ESP'sfor spacecraft servicing, robotics labs and docking tests.Their ESP floor is 16X14ft,accurate end to end .003!!!
I took the figures from a pdf which is very long.I will link it for those interested enough to read it.
[The granite table
was replaced by a 16 foot by 14 foot epoxy floor leveled within 0.003 inches end-to-end.
An “Indoor Global Positioning System (GPS)” system was added to provide absolute
positioning up to one millimeter accuracy within the laboratory environment. This
chapter will cover the details of these two new facilities.]
Larry

[Zumba]

The main problem I had when pouring in cups was that the top surface was flat out FUGLY. Vacuum got rid of the foam but it was still rough. You could easily see and feel the sand particles protruding from the surface. The bottom and perimeter were silky smooth.

So your castings should be done upside down.

[lgalla]

your castings should be done upside down.
Or ESP'd?
An air hammer at max pressure is 4500BPM which I think is 700cps variable by air pressure.May this be useful as a vibratory instrument?Air hammers are the cheapest air tool.
Larry

[martinw]

Epoxy poured out and allowed to flow level solely under the influence of gravity is just as flat, or round, as the earth; it doesn't have any choice.

Geof,

The problem is that it does not have that wonderful luxury.

Alas, we live in an imperfect world. Stuff gets in the way of it.


Best wishes

Martin

[Zumba]

"Alas, we live in an imperfect world. Stuff gets in the way of it."

Yep, like the aggregate!

Tension/cohesion also makes it climb up the sides of the form.

[lgalla]

Math is a bad subject for me.If epoxy leveled to gravity and the curvature of the earth how accurate would it be?
Curvature of the earth is 8"/mile or 8"/63360" On a 10ft table what would this be?
Larry

[walter]

Spacecraft docking and satellite servicing have been key areas of interest since the beginning of the space program. They combine aspects from Guidance, Navigation, and Control (GNC) research with robotics applications. These concepts were first experimented on-orbit in the 1960s during early manned space missions of the Gemini program. They were later expanded to such missions as the Hubble Space Telescope repair mission and the Space Station Remote Manipulator System, to name a few[...]

Twenty-first century space programs have developed a need to further expand their docking and servicing capabilities for interplanetary travel and spacecraft servicing[...]

To further the technologies that will enable autonomous spacecraft docking to
take place, several laboratories have developed on-the-ground experimental test-beds.

The Spacecraft Robotics Laboratory (SRL) is a research laboratory of the Naval Postgraduate School, founded in February 2004, and is still under development. Beginning in July 2004, the laboratory testbed consisted of an eight foot by six foot granite table, a single vehicle that operated on the table, and a remote computer with which to build and transmit software to the vehicle.

The granite table was replaced by a 16 foot by 14 foot epoxy floor leveled within 0.003 inches end-to-end. An “Indoor Global Positioning System (GPS)” system was added to provide absolute positioning up to one millimeter accuracy within the laboratory environment.

To correct for the granite floor’s deficiencies, research was conducted in finding a larger, more reliably flat surface. A solution presented itself in the form of epoxy surfaces. Epoxy surfaces begin in the form of a liquid and are mixed together with a resin hardener. These materials, when used properly, will form into a hard surface that lays level within 3 thousandths of an inch over the surface of the floor[...]

http://www.precisionepoxy.com/NPS%20plate.htm

[lgalla]

Walter WOW who could argue ESP's are not accurate. Thanks for the post.
Larry galo