[ckelloug]

hey guys, I'm back from the grave.
Instead of wasting my own time to do research on the topic I'm now paid to do it

Anyway, I now work as a metrology engineer and I'm trying to acquire a 4x10 inspection surface plate. I just got a quote for a Starret granite and total is close to 20k, which is a good enough excuse to look at other solutions.
I'm trying to find out :
-what is epoxy wear resistance.
-what is the cost of creating a granite epoxy base
-what is the typical precision of countertop granite.

I'm open to all solution, including casting a large base out of concrete and having a precision floating top, buying a countertop granite plate.

Gizmodo,

Despite your new paid position, I see you are still here looking for advice

First of all, look for a used surface plate. I have a 4x5 and it only cost $900 including the $300 minimum for my local riggers to forklift it onto my loading doc. With industry rolling up the sidewalks, there ought to be a plate from a closing metrology lab out there at a place like HGR industrial surplus or a local used machine tool place in your area.

Raw epoxy is not wear resistant at all. You'll have to add something to it like the surface treated titanium carbide particles that Tony suggested a ways back. Nobody here has tested and posted about how flat a surface you can actually get with a poured epoxy or poured epoxy with small particles. Physics says it should be good to the curve of earth's equipotential suface which is .0002/foot but I think a good large surface plate is flatter than that.

Epoxy and hardener probably runs $60/gallon. Aggregate is generally between $.025 and $2.00 a pound. Big surface plates are very thick so they don't sag under their own weight and the weight of the parts to be placed on them. For cost purposes, you can assume 80% aggregate.

As far as I know, Countertop granite usually has a very high smoothness but a flatness that is unsuitable for precision work. Some folks over on Homeshop Machinist suggest float glass but if you are doing metrology and need a plate that big, I suspect float glass won't do it for you either.

If Starrett is too expensive, try Rock of Ages surface plate division and see if they do any better. (The other division makes tombstones).

I'm on my way out to the shop later to finish up the rest of the piston assembly for my particle packing density instrument.

--Cameron

[Gizmot]

Gizmodo,

Despite your new paid position, I see you are still here looking for advice

First of all, look for a used surface plate. I have a 4x5 and it only cost $900 including the $300 minimum for my local riggers to forklift it onto my loading doc. With industry rolling up the sidewalks, there ought to be a plate from a closing metrology lab out there at a place like HGR industrial surplus or a local used machine tool place in your area.

Raw epoxy is not wear resistant at all. You'll have to add something to it like the surface treated titanium carbide particles that Tony suggested a ways back. Nobody here has tested and posted about how flat a surface you can actually get with a poured epoxy or poured epoxy with small particles. Physics says it should be good to the curve of earth's equipotential suface which is .0002/foot but I think a good large surface plate is flatter than that.

Epoxy and hardener probably runs $60/gallon. Aggregate is generally between $.025 and $2.00 a pound. Big surface plates are very thick so they don't sag under their own weight and the weight of the parts to be placed on them. For cost purposes, you can assume 80% aggregate.

As far as I know, Countertop granite usually has a very high smoothness but a flatness that is unsuitable for precision work. Some folks over on Homeshop Machinist suggest float glass but if you are doing metrology and need a plate that big, I suspect float glass won't do it for you either.

If Starrett is too expensive, try Rock of Ages surface plate division and see if they do any better. (The other division makes tombstones).

I'm on my way out to the shop later to finish up the rest of the piston assembly for my particle packing density instrument.

--Cameron

thanks for the advice. Thing is I never found out any data concernig self leveling epoxy with carbide particles. I used that before, worked nicely, but not in self leveling application. Countertop I assume was going to be so so for flatness, but thats where my metrology gear comes into play. I'm also trying to find a used table. Bloody hard as hell to find over 8' long. And when you find something around 8-12', its almost the price of new. Anything around 4' is almost free today.

[lgalla]

http://cgi.ebay.com/ws/eBayISAPI.dll...BSI%26otn%3D12

[dimitar]

visit:

http://www.partenovcfd.com

[compositepro]

i didnt read the entire thread but as a composites engineering blokey im wondering why no one has mentioned adding some fibres in there?

[greybeard]

i didnt read the entire thread .....

Therein lies a common problem.

There have been some suggestions on fibres, and a search might answer your question specifically.

John

[lgalla]

Dear Compositepro,
Fiberous reinforcements are a great addition increasing modulus,but pardon my english they suckup too much resin and the magical 10% resin is not obtainable.Perhaps some fiber and higher resin ratios would be the cats meow.A Japanese Company made machines totaly of composites,no granite.Sure it worked and surpassed all E/G parameters,BUTT, THE BIG BUTT,who could afford a glass or carbon laminate inches thick?Extreme accuracy is not my cup of tea as I only machine wood.
Cameron has the machinery to test samples.Perhaps someone will send some samples with some fiberous enhancements to put to the test.A good starting point would be some 1/32 milled glass fiber.Very short to expect much increase in strength, but will increase the bond strength between the granite or whatever aggregates.
Larry

[altaic]

Hi all,
The way I look at composites is this: if each component has some good property, the engineering task is to figure out the balance of properties for the desired use.

For instance, fibrous materials have excellent tensile strength in the direction of the fibers. This may equate to good flexural strength since half of flexural strength is tensile and half is compressive. The catch is that you don't get close packing unless the fibers are going all the same direction, which means that the gaps filled with epoxy are much larger. As I understand it, epoxy is much stronger as a binder than a bulk material, so the closer the packing the better (I suspect exponentially so, however I have nothing to back that up). The maximum strength fiber composites I've seen have all been layers of uni or wound tow, cured while compressing/compacting the fibers; a very time intensive layup requiring special equipment.

Now, aggregate has the ability to be close packed in a mold without being constrained to 1.5 dimensions (fibers running one direction, plus the ability to be wound). Many aggregates (quartz, alumina, titanium carbide, cubic boron nitride, diamond) are also very hard compared to fibers (and epoxy). This leads to two properties: good surface wear, and good vibration damping (due to high contrast grain boundaries and the variety of particle sizes as I understand it; I like Cameron's explanation above). Adding fibers to the aggregate may not greatly affect the ability to be close packed, but the main benefit of fibers (directional strength) also is a detriment to one of the main properties of aggregate (vibration damping); the fibers provide long grains to transmit vibration. As I see it, the more fibers, the more strength, the less vibration damping, until there are so many fibers and so little aggregate that they cannot be close packed with aggregate and strength decreases (before this point the fibers should be woven, not randomly packed). But it seems silly to begin this engineering phase, modifying E/G with the intention of augmentation for a specific purpose, before we know what kind of strength it can provide without giving up other beneficial properties...

Cheers,
Will

[ckelloug]

It's not much but I have taken the data to get the Beta packing coefficients for all the materials in the sample formula I last posted courtesy of the samples Walter mailed me before he disappeared. I sure do miss that guy. I haven't cranked much of the data yet
but it appears that the theoretical maximum packing density for agsco #4 aluminum oxide is 0.64. The rest require harder calculations since they are size mixtures.

The packing achieved in my test without corrections was 0.54. Multiplying the correction for the packing process gave .61 and correcting for the size of the packing apparatus gave .64. This assumes that my packing process is similar to de larrard's which isn't strictly true because the vibrator is smaller and the mass of the piston assembly was larger.

Regards all,

Cameron

[LXH]

That is perfect~!
I use 3days to read this,the polymer base is quite nice though.
I'm try to build a X3,the polymer base may be a good idea.

[Quad2T]

ITW sold the polymer casting business to competitor Cleveland Polymer Technologies. The doors close March 31st. So if you want any information from them...you better hurry up and contact them now.

[dfro]

Cameron,

I have all the aggregates and finally the time/space to start making test EG castings. But, I do not quite understand your explanation a few pages back on how to measure the aggregates based on your latest ratios. You wrote:

The original mixture was an 85% mixture designed for the sake of simplicity. A mixture with about 89% density using the minimum segregation criteria is suggested by the model as:

0.18744 Agsco #6 Brown Aluminum Oxide
0.38420 Agsco #4 Quartz
0.12950 Agsco #2 Quartz
0.11514 Agsco #2/0 Quartz
0.11352 3M G800 Zeeospheres
0.07020 3M G200 Zeeospheres

These percentages are in intrinsic volume of particles (not bulk volume from like that from measuring the aggregate in a beaker). So, multiply each fraction by it's density to get the mass required when doing the calculation. Also note, I left more significant figures than reasonable to show that it adds up to 1.0.

Firstly, I do not understand what 'intrinsic volume' means. I tried to search the net a little to get a definition with no luck.

I researched the density of the various aggregates and got:

G200 Zeeospheres 2.5 gm/cc
G800 Zeeospheres 2.2 gm/cc
Quartz 2.65 gm/cc
Brown Aluminum Oxide 3.97 gm/cc

Could you show me an example or two of the math to measure out a batch of eg?

Thanks,
dfro

[dfro]

I think I get what Cameron was trying to say. You do not want to measure the volume of each material in a container with volume measurement lines on the side, because there are millions of air gaps between the particles. Cameron's ratios are to calculate the volume of each material as if it was a solid block. To get the final volume you want when all of the aggregates are combined, you will need to calculate the mass of each material. The simple underlying formula is:

Volume * Density = Mass

cc * g/cc = g

(cc means cubic centimeters. g means grams.)


If for example I want 100cc of EG, I will calculate as follows. Lets say I want to have 10% epoxy by volume:

10% epoxy, so 100cc * .1 = 10 cc
90% aggregate, so 100cc * .9 = 90 cc

I calculate the volume of each material as if it was a solid block using the ratio numbers provided by Cameron:

#6 Agsco Brown Aluminum Oxide = 90 cc * .18744 = 16.8696 cc
#4 Agsco Quartz = 90 cc * .38420 = 34.578 cc
#2 Agsco Quartz = 90 cc * .12950 = 11.655 cc
#2/0 Agsco Quartz = 90 cc * .11514 = 10.3626 cc
3M G800 Zeeospheres = 90 cc * .11352 = 10.2168 cc
3M G200 Zeeospheres = 90 cc * .07020 = 6.318 cc

(My calculator is removing a decimal place on all of the ratios that end in 0.)

Now for the mass (in grams) to measure of each material:

Volume * Density = Mass

Material Densities:

Brown Aluminum Oxide 3.97 gm/cc
Quartz 2.65 gm/cc
G800 Zeeospheres 2.2 gm/cc
G200 Zeeospheres 2.5 gm/cc

Calculations:

#6 Agsco Brown Aluminum Oxide = 16.8696 cc * 3.97 g/cc = 66.972 g
#4 Agsco Quartz = 34.578 cc * 2.65 g/cc = 86.332 g
#2 Agsco Quartz = 11.655 cc * 2.65 g/cc = 30.886 g
#2/0 Agsco Quartz = 10.3626 cc * 2.65 g/cc = 27.461 g
3M G800 Zeeospheres = 10.2168 cc * 2.2 g/cc = 22.477 g
3M G200 Zeeospheres = 6.318 cc * 2.5 g/cc = 15.795 g

If I measure the mass (in grams) of all the separate materials and then mix them together, I should get 90 cc's of aggregate to add to 10 cc's of epoxy to get my 100 cc's of epoxy-granite to fill the mold.

Correct? Please, let me know if I have this wrong.

[ckelloug]

Dave,

Sorry I didn't get back to you sooner. I think you are thinking the same thing I was as far as getting the volume percentage mixture by mass using the densities. I got that technique out of the Book <u>Concrete Mixture Proportioning: a Scientific Approach</u>

I may make some minor corrections to the last published mixture as I get more measured packing coefficients in the next few weeks. I don't know whether it will make a significant difference or not.

So much to do in life . So little time to do all of it.

Regards all,
Cameron

P.S. Kudos to greybeard John for making me understand how these percentage numbers were actually supposed to be interpreted a while back. He asked a bunch of clever questions that forced me to reread a lot of book sections on this last year.

[brunog]

dfro,
your logic is Ok except for epoxy calculations.

Because the epoxy density is 1.25g/cc 10% epoxy by weight will give you twice the % in volume in comparaison to most of the aggregates, unless you really want to go with 10% in volume which is rather low for E/G.

Best regards,

Bruno

[dfro]

Thanks Cameron for the reply. I will try mixing and casting a batch of e/g in the next week. I am just about finished with my DIY table vibrator. I will post some pics of it.

Bruno,
I wasn't very clear, but I left the mixing of the epoxy as a separate operation that did not involve calculating mass. In the example, I wanted 10cc's of epoxy no matter how I calculated the measuring and mixing of it.

Usually, I mix epoxy by volume. I will check the epoxy that I got from US Composits to see what the best method of measurement is. Making some test batches will help me decide how low in % of epoxy I am able to go and still get it to flow.

Thanks,
dfro

[ckelloug]

Dave,

I predict that aggregate mixture will need 12% epoxy by volume rather than 10% but I don't have the measurements to back up what the actual number is right now. I've got to go do some more lab work later in the week.

Bruno,

How much epoxy is really in E/G seems to depend on who you ask as roach seemed to think it was fairly low whereas others have said higher. I suppose it depends on what a given mixture was trying to achieve when it was designed.

My prediction is that for epoxy of the strength we have and the aggregate reasonably obtainable that the answer has to lie between 12% and 10% to make the performance numbers Accures and Zanite are publishing.

Regards all,
Cameron

[brunog]

Cameron,
10 to 12% epoxy by volume is very low, I understand that 90% packing density is the goal.

However keep in mind that 16 to 24% (8 to 12% by weight) is what has been achieve by other DYI (including Thomasz).

But we'll never know until it's tried and tested!

Best regards

Bruno

[ckelloug]

Hi greybeard John,

In regard to your particle separation wind tunnel experiment oh so many posts back: I don't think it actually failed. In one of the books on plastics fillers that I was reading, there was a comment that much natural sand has a very very narrow size distribution i.e. sand produced by the same geological process is mostly the same size.

I haven't gotten much done lately but in addition to data reduction on particle packing density measurements, I'd also like to measure the compacted density of the mixture I keep proposing.

I'll post when I get something. Good luck to Will when he gets his tests done.

--Cameron

[greybeard]

Hi Cameron. Yes, I think I posted something to that effect, but again I might have only thought I had
After some discussion with a local tame geologist, he suggested that all the local deposits would be windblown sorted sands, hence when I got to using a set of sieves, the narrow distribution I found was understandable.
He also pointed me to a site where I might find a broader mix, but I haven't got to it yet to test his idea.
This weekend my nephew, who is a geologist/hydrologist, is stopping over, so I'll pin his ears back for his thoughts on sourcing a broader range of sizes. We don't seem to have the plentiful sources of pure quartz sands that you have on that side of the pond, nor the grading companies that go with them.
No doubt someone in UK will put me right if I've got it wrong

John