[walter]

Lol.. Larry. Your new avatar totally made my day!

I really needed that :cheers:

[lgalla]

Walter,actually the picture is a poor likeness of me.You know bad lighting,one mega pixel camera etc.In reality 30 years of polyesters and polyurethanes and you to can look like this at 30 years old.Epoxy is much safer.Just Punning as usual.

[walter]

I dug out your old recommendation READE Advanced Materials. Turns out they also sell nanoparticles and nanoadditives.
I should give them a call.

And I found someone who sells decent quartz gravel. Out of Ohio, I think.

We'll see if they sell me a bag.
_

[ImanCarrot]

My machine has a granite polymer base and housing to stop vibration, I've tried to find out how they make it but only got as far as a commercial name for a polymer granite/ concrete... perhaps others can find out more.. it's called Harcrete.

In fact, I searched these forums and Harcrete is already mentioned elsewhere

[ckelloug]

Walter, Sorry about that last post. I had the impression you had a series of tests planned this week from one of your other posts. There are a lot of choices in aggregate design theories. I agree most with the one from greybeard's niss report.

Having scoured the internet with #80 steel wool, I think I have an out of the bag product that is close to the niss standard mix and not totally unlike what was recommended by reichhold for polymer concrete! Take a look at this dupont starblast ultra blasting compound:

http://www.titanium.dupont.com/TTPOR..._H_52218_2.pdf

It has to be the ultra grade though. The regular grade has a differnt mix.

Compare this with the ratios computed by brunog with fuller's rule and the reichhold formulation here http://www.cnczone.com/forums/showpo...postcount=1210

One can also compare this with the pdf graph I posted of the niss paper's theory in http://www.cnczone.com/forums/showpo...postcount=1199 however this graph is relative with the largest aggregate size being normalized to 0.1. I concluded from the niss paper that you want a largest aggregate 3% of aggregate mass, and then a uniformly distributed mass of smaller aggregates being sure that there is less than 1% of aggregate sized near the first one. Using the niss formulation, there is 30% epoxy by volume.

I also believe we might be better off with abrasives than sand because abrasives are normally rigidly graded and widely distributed in that fashion.

I also think that it might be better to mix up the batch with vastly more epoxy than it needs and take a page from whoever posted it a while back to do vacuum bag compression of the mold such that excess epoxy is squeezed out. Not my idea. Wouldn't have thought of it. Just mentioning it again cause it seems useful.

Finally, I was going to call http://www.agsco.com/ and see if they could mix us an aggregate with the right distribution once we decide on one or if it is not outrageously expensive if they could mix up bruno's formula, the reichold polymer concrete formula and the niss formula and see which one is better.

Unfortunately, I am in the middle of digging up the yard with a tractor to facilitate construction of my shop and appeasing the neighbors by the installation of nicer front yard grass. As a result, I won't get much done this week.

[walter]

Ok, I found it...

I found the endless source of super clean quartz in every size and shape imaginable! With small min orders and rock bottom prices.

I wasted 4 weeks because I didn't know where to look.. How stupid of me.

THE FILTRATION SUPPLIERS! (chair)

High purity quartz sand and gravel in every size! Just a phone call away..

One guy quoted me $7 on a 50lb bag of 0.25" gravel.

Looks like I'm back in the game! lol

[walter]

Cameron,

Thank you for all the info. I'm not sure about abrasives, didn't someone say something about impurities? I have to look into that.

And don't worry about the next 2 weeks- take care of your business.

Testing is on hold until I get some decent quartz.

I'm moving onto the mold. My gantry will be poured in one go so I have to come up with something funky..

Cheers!

[brunog]

walter,
feel free to post your design

Best regards

Bruno

[ckelloug]

Used abrasives=bad. Brand new shiny fresh from the bag probably good. I like the starblast ultra because the particle distribution happens to be what we want and all of the minerals in it are really really hard.

I just talked to Harvey at Agsco Illinois www.agsco.com and it looks like it would be a several hundred dollars to have them mix up 50 or a hundred pounds of a test mix for us if we can get our specifications written in such a way that they are comprehended by sand guys. While this may be more expensive initially, it saves having 50 pound bags of 10 kinds of sand shipped to us. It also means that they can tell us exactly what we got and if it works, we can all get the same thing.

<B>If anybody has time, it would be a good idea to check out the Unified Abrasive manufacturers association and figure out how to write a spec for sand. I'm probably making this more complicated than it is. Then, if somebody could write up the proposed specs and call agsco for budgetary pricing, that person would probably have made everyone's life easier.</B>

http://www.uama.org/

[ckelloug]

In responding to acomment in a PM for everyone to see, For those not used to procuring industrial materials, two places to look for suppliers are www.thomasregister.com and www.globalspec.com. Thomas register used to be a 30 or so volume green book that usually required a trip to the library while globalspec is new to the internet. The search on either of these is much more likely to yield results than a general purpose search. Do note that clicking on a company from a global spec search often will get you either a call from the company or a catalog in the mail.

I hope that this help in minimizing time wasted looking for materials.

Regards,

Cameron

[martinw]

I also think that it might be better to mix up the batch with vastly more epoxy than it needs and take a page from whoever posted it a while back to do vacuum bag compression of the mold such that excess epoxy is squeezed out. Not my idea. Wouldn't have thought of it. Just mentioning it again cause it seems useful.

.

Dear Cameron,

It was Stepper Monkey, post#791, who introduced the concept of using excess epoxy, and then removing it when everything is nicely wetted out.

It sounds like a winner to me.

Best wishes


Martin

[harryn]

I am not sure if this is helpful or not, but I have used fiber reinforced concrete at home for its improved toughness. (I was not concerned with deflection at that time)

Here is an example link of a data sheet from an example supplier found with a common search engine.

http://www.na.graceconstruction.com/...ta%20Sheet.pdf

It seems like it would help with toughness and strength, but perhaps not with deflection, which is really our goal I guess.

In any event, if we are serious about consistent results, esp. for any real volume, we are going to need some kind of mechanized concrete mixer. There are some manual 1 cu ft ones with baffles out there that work, but for anything more, it takes a real mechanical mixer. It is not that easy to uniformly and quickly mix even 50 Kg of material manually. If you are in doubt, just try mixing a few bags of sand and water into a relatively dry mix using a hoe and wheel barrow.

[Udayan Patel]

Hi !! Folks,

I have just joined as a member yesterday and have read couple of pages and exchanges between people having interest in E/G or Polymer Concrete. I have yet to go throgh all the pages and digest the subject.

All I have to say at this moment is it is highly interesting and I am getting lots of new information throgh this thread. I would rather say thread after interlocking have became a big Canvas and gradually picture is evolving for all to view.

Some time two years back I was interested in this subject and visted Google and found that ITW Polymer Castings are producing Zanite in US and in UK there is another company called Granitek , In france also there is Brand name CELITH which you can see on website of Microplan Group. Oh Yes Anoroad is also using similar material and so are Studer Grinding Machines built on Granitan 100.

I was told that Harding Machine Tools also uses E/G

That shows a day is not far when Metal Cutting Machine Tools would also be built on this so to say Exotic material due to its excellant Vibration damping properties.

Can Granite aggregate bbe obtained from near Granite Quarry ? When they Saw Granite Blocks enfd pieces are useless for them and does not fatch any value to processors of Granite Blocks-- Infact it is a problem for them to dispose off. Can these End Pieces be cushed and used ? I am sue cost of E/G can be brought down if wastage of Processorsof Raw Blocks can be used.

As an Engineer I would like to explore carrying out some expriments after picking clues from this thread. Can anyone suggest type & grades of Epoxy for this aplication ? I am totally a novice in subject of Epoxies and adhesives. When I see manufacturers Catalog there are hundreads of varieties to choose from and I get lost due to my inadequate knowlege.

Shall catch up with you all soon once I have gone through all the pages amd it takes preety long to go through so much of inputs from you all guys.

Udayan
[email protected]
India

[greybeard]

Let me be the first to welcome you Udayan, both to the zone and to this particular thread.

Re epoxies, I'm only repeating what Larry has posted several times, but what you should be lookig for is low viscosity, for ease of mixing and loss of air from the mix.
However, the low viscosity must NOT have come from the addition of solvents, as apart from the personal hazard that they usually present, when the epoxy cures they lead to post cure shrinkage - not good.


Regards
John

[ImanCarrot]

Welcome Udayan!

This is about the most useful forum I have ever come across, hope you enjoy your stay here- these guys really know their stuff and are incredibly friendly too

[walter]

Iman,

great to have you on board! I know you have that incredible E/G machine base- how cool is that!

I would pay a lot of money just to be able to break one and see what's inside...


Udayan,

Welcome, Join in the fun!

The answers are in the thread, I just want to touch on crushed granite.

The newest generation of product seems to use carefully sized Quartz (exclusively). Crushed granite was used in older systems.

Now keep in mind that this crushed granite has to be precisely sized, I don't think you can do it "at home". The whole idea is based on "compaction", where you fill ALL the space with carefully sized material and follow a mathematical formula.

Dig into the thread to find out more.

Cheers!

[uhrgerat]

Re epoxies, I'm only repeating what Larry has posted several times, but what you should be lookig for is low viscosity, for ease of mixing and loss of air from the mix.
However, the low viscosity must NOT have come from the addition of solvents, as apart from the personal hazard that they usually present, when the epoxy cures they lead to post cure shrinkage - not good.

Regards
John

Hi John,
I was wondering about this. I ran across a patent (#5,393,807) for low resin polymer concrete. A diluent is added to the resin and filler, it's all mixed and then the diluent is "educted" in an "eduction chamber" (vacuum chamber?) before the resin/filler mix is then molded. The patent mentions several non-reactive solvents, furfurol alcohol sticks in my mind. The health hazard is still there, but would this reduce the shrinkage problem?
I'm still not up to speed on this thread, but it's certainly fascinating!
Regards
Jim

[walter]

Looks like HSM guys are on our side

"Cast iron or polymer concrete; which material is better for HSM-centers and why?

Answer: Polymer concrete is practicaly an inert material, manufactered out of compact packed rocks in various sizes, fillers and a low percentage of epoxy binder. It is resistant against oil, coolants and many chemicals.

The extraordinary temperature stability and damping characteristics of polymer concrete are about 6 times higher than those of cast iron.

Particularly with regard to HSM, polymer concrete has become state of the art for all non moving components of the machine structure, such like beds, bridges and columns. All moving components are usually especially strong and heavy in order to optimize damping and stiffness of the structure. For all moving components a minimum weight concurrent to a maximized stiffness is desired to ensure optimum dynamics. Only this kind of weight distribution and selection of materials allow to design a machine tool suitable for HSM."

(Mikron AC ,Switzerland)
www.mikron-ac.com

[greybeard]

Hi John,
I was wondering about this. I ran across a patent (#5,393,807) for low resin polymer concrete. A diluent is added to the resin and filler, it's all mixed and then the diluent is "educted" in an "eduction chamber" (vacuum chamber?) before the resin/filler mix is then molded. The patent mentions several non-reactive solvents, furfurol alcohol sticks in my mind. The health hazard is still there, but would this reduce the shrinkage problem?
I'm still not up to speed on this thread, but it's certainly fascinating!
Regards
Jim

Hi Jim.
If my reading of the word "educted" is correct this is suggesting that the diluent(present to reduce the viscosity and therefore make impregnation easier) is very volatile. Thus when you reduce the pressure above the mix it effectively boils off.
This would seem to fit the bill very well. If it's not present during the curing process you've removed the post cure contraction.
Brilliant.
Don't remember any chemistry of furforol, but that can be checked out.
The key thing for this to work is that all the diluent does actually boil off.
As it starts to come off, fine, but as it does so the epoxy is getting more viscous, and it's becoming more difficult for the rest to escape.
Eventually there will be some left, still trapped.
This is he problem. How to remove the last traces if they produce contraction problems.
Regards
John

[greybeard]

.......
Now keep in mind that this crushed granite has to be precisely sized, I don't think you can do it "at home". The whole idea is based on "compaction", where you fill ALL the space with carefully sized material and follow a mathematical formula. .......

Cheers!

Walter, I'm gettimg a bit concerned about this "mathematical" formula.

I'm trying to get my head round spherical packing and the effect on the packing of the fact that none of the agregates are anyting like spherical.
This leads me towards the idea that this fact, combined with the mixing methods suggested, will drive the mix towards "random packing" with a much lower fill.

Hope to post an idea of a way round this soon.

Regards
John