[mdaweb]

Walter thanks for showing some interest.Also check www.moglice.com.Interesting stuff.
Why epoxy granite?It takes 4 to 6 months to develop a machine tool of traditional cast iron.After casting,it has to age for 4 months to releive stress before being surfaced and then get heat stress relief.Cast epoxy/granite can be ready in one week with coolant lines and other inserts or ways moulded in.As I stated before Epoxy/granite is super $$$$,But a machine tool manfacturer can save tons of money from the time saving and have better properties than cast iron.As stated in geoligy reports granite was stress releived billions of years ago.
Also companys are filling weldments or machines made of steel tube to eleminate resonance.Since epoxy has 0 VOC or solvents,when filled it has ZERO shrinkage.If you poured raw epoxy on the floor it will self level to .005 or better.What a way to get an accurate table surface to measure and build your machine on.
I am in the composites business,Know little of CNC stuff,but have knowledge of fillers and micro packing.
BTW in my business polymer concrete is out of date Polyester resin mixed with rocks for garbage cans and parking lot thingies.
Never Never get the idea I'LL use polyester or fiberglass resin as a bonding agent.It just shrinks too much and is extremely brittle.
Walter thanks for expressing interest,all the research time seems worth it.
I am not discounting the hobbyist use of the materials as they cost so much,but will not recommend usage until I am sure of performance.
Wow thought this would be short as I am swamped with orders righ now And
don't have much time.I am guilty of going on and on.I have tons more info on the subject if you want to hear more.Let me know if your intrest is still there and I will try to post something {short}daily.Questions are welcomed,Hope I can answer.
Larry

HomeMade Moglie, in Portuguese Brasil.

Moglice - revestimento deslizante

MDAWEB!

[johnohara]

I think mdaweb was trying to post this Moglice formula:

(Translated from Portuguese)

The formula was (by weight):

260GY Resin:           40% 
Ren 943 Hardener:       8% 
Graphite Powder:       15% 
Aluminum Powder:        8% 
Bronze Chips (TM23):   27% 
Colloidal silica:       2% 
Colloidal silica (1kg bag has this, it seems artificial snow).

I think "colloidal silica" means silica powder <320 grit. That's why it's referred to as "artificial snow."

The images didn't work for me. I think you have to be logged in to view them -- meaning a one-off registration. Not going to happen today.

Thank you for the formula mdaweb.

[mdaweb]

I think mdaweb was trying to post this Moglice formula:

(Translated from Portuguese)

The formula was (by weight):

260GY Resin:           40% 
Ren 943 Hardener:       8% 
Graphite Powder:       15% 
Aluminum Powder:        8% 
Bronze Chips (TM23):   27% 
Colloidal silica:       2% 
Colloidal silica (1kg bag has this, it seems artificial snow).

I think "colloidal silica" means silica powder <320 grit. That's why it's referred to as "artificial snow."

The images didn't work for me. I think you have to be logged in to view them -- meaning a one-off registration. Not going to happen today.

Thank you for the formula mdaweb.

Colloidal silica = magnesium silicate

Recommend 380 grit.

sorry, my English sucks, I use the translator of Google.

[]'

Mauro.

[yancho]

All are buried in bills and ideas.Raise your head and experience of engineering.[ame=http://www.youtube.com/watch?v=H5ZDFBBiiSE]Prototipo a cinematismi paralleli - SPIDER - WWW.GRUPPOPARPAS.COM - YouTube[/ame] [ame=http://www.youtube.com/watch?v=a8wkTL3MOHI&feature=related]Tricept T805 aluminum block machining - YouTube[/ame]
With the greatest respect for all.Yan

[veteq]

Pretty old machine...is it made from epoxy granite..?
Dont think so, do i like it.

[yancho]

Hello Thomas. I looked in detail your project. The design is very cool and Technology. I think it is difficult to invent new things, but can be improved old ideas. I hope that you will not mind if I use your idea for my machine. If you do not mind going to start work on the project. Of course all the problems encountered will solve them alone. This will not happen tomorrow, of course, I would need a lot of time (working alone). Thanks in advance for your understanding. I do not want to copy machine and use the idea. But they will look like. If you have any objections, I will consider another concept. Thanks Yan

[yancho]

Is not new but is interesting as a solution. I think that the first no concrete, but the second is likely to have such a frame.Yan

[thomasz]

Yan, it's no problem - I look forward for your machine.

Thomas

[yancho]

Hello Thomas. Thanks very much. Yan

[RomanLini]

In the "open source designs" section of the woodworking machines area of this forum someone has started a build thread using EpoxyGranite;
http://www.cnczone.com/forums/open_s...ld_using.html?

There's some interesting photos. It looks more like a metalworking 4th axis to me than a woodworking one, ie it's going to be pretty solid!

[yancho]

When wood cutting forces are not at all small. Stability is always welcome, it will increase tool life and improved surface processing. Very practical and cheap solution. Congratulations Yan

[Steven.ji]

The base is for laser cutting machine

[rocketflier]

The base is for laser cutting machine

You're not using Popsicle sticks to mix epoxy in Tupperware containers,.. are you?

[johnohara]

Steven.ji~

Why does a laser-cutting machine need a base (or gantry) that heavy?

~john

[rocketflier]

I can't believe I've gone through the thread again....

Round page 330 discussions on mixing came up, and I started mulling it about.

I was thinking of the time we were fiberglassing bodytubes for a 17' tomahawk and the cup I was mixing epoxy in kicked in the 110* heat. We were just mixing in plastic 'party' drinking cups and mixing with craft sticks. Managed to heat the cup to the point I couldn't hold it and it went downhill from there.

That started me thinking about pouring out some of the mixed epoxy, then a layer of aggregate, more epoxy, aggregate,... perhaps folding the mix in on the next layer pressing the newly added aggregate into the mix.

I kept thinking about mechanical ways to do this when it hit me,.. muller. Normally used for mixing casting sand. Wheels press the sand down, while a plow scrapes the side and another sort of turns over the sand and places in the path of the wheels.



[ame=http://www.youtube.com/watch?v=tU7zJJ_DCTo]Sand Muller - YouTube[/ame]

I wonder if that wouldn't allow a 'dryer' mix. There would of course be the issue of air, but I think that would have to be vacuumed out after or during the mold vibration to pack the mix in there.

Course, the thoughts didn't stop there. When mixing APCP (rocket propellant) they use a KitchenAid mixer with a dough hook. The chemicals form a doughy, sticky mixture that is usually rolled into little logs and packed into the casing.

[ame=http://www.youtube.com/watch?v=XuSM2BY84As]Mixing and Casting DD Motor part1 - YouTube[/ame]

The second video has more of the thick mixing:

[ame=http://www.youtube.com/watch?v=0Abd7WcTKrk&feature=related]DD part 2 - YouTube[/ame]

Which made me think of a suggestion I made a while ago (before I realized how thick APCP was prior to 'pouring') on another forum. IceCream maker.



Which is pretty darn close to that mixer in Scott Bader's video. These can be had for pretty cheap from a thrift store and might be useful for small batches. The mixture in that video appeared closer to pancake batter than icecream,..

[ckelloug]

Hi Rocketflier,

Interesting suggestions on the mixing methods, especially the ice cream maker. E/G is very abrasive and is certain to erode mixing paddles although I can't say I'm sure whether plastic or metal would fare better. I've seen a fair amount of erosion on the metal agitator of the tiny lab mixer that I use for my samples. A Kitchenaid mixer would also be good as most of the commercial mixers are just more advanced versions of a Kitchenaid mixer anyway.

I haven't gotten a lot of E/G research done for the last several months. I've been traveling a lot and my scant available lab time is being taken up by another related project..

The last thing I learned in the lab was that there is a serious square-cube law effect using small particles to make E/G. For spherical particles, the volume of each particle is (4/3)*pi*r^3 while the area is 4*pi*r^2. Thus as the particles get smaller, the ratio between specific surface area (surface area per unit mass of particles) and specific volume (volume per unit mass of particles) increases dramatically. The behavior of small particles in epoxy becomes increasingly dominated by a combination of capillary forces and Van der Walls forces. These forces are attractive between the particles and overcoming them to get a well mixed material requires high shear mixing.

In this bad circumstance of Van der Waals attraction and capillary attraction, jamming also occurs since an E/G particle size distribution is designed to pack the particles together as densely as possible. The capillary forces and Van der Waals forces increase the difficulty of forcing the particles apart via the action of the mixer. My text on Surface and Intermolecular forces suggests that jamming occurs for spherical particles when the volume packing density is above 55% which definitely is true for the E/G mixes I have worked with having packing densities above 80%. All these effects mean that it is difficult to remove the air from a high density mixture containing small particles, even with vacuum, as the capillary forces are very strong.

After a couple of experiments with high packing density mixtures using my small lab mixer, I developed a criterion for mixture design based on dividing the epoxy volume in the mixture by the estimated specific surface area of the particles to get a theoretical coating thickness for each particle in a mixture at the edge of mixability. I then programmed my packing model to optimize the packing density with a penalty clause that requires enough epoxy to be added not only to fill the volume between the particles but enough to cover each particle with an epoxy layer equal in thickness to the barely mixable test mixture. This thickness was a few micrometers but the exact number is in a lab notebook I don't have with me right now. With the penalty clause in place forcing coating all the particles with a thin layer of epoxy, the model suggests that a higher packing density can be obtained without using the zeeospheres. I believe that adding enough epoxy to coat each particle with a thin layer prevents the mixer from having to separate capillary bridges every time an incompletely coated particle moves. The few percent extra epoxy added to coat particles also ensures that the particles are reliably glued together.

I also saw some anomalous results when measuring the flexural modulus of my high packing density silicon carbide mixtures. The flexural modulus was extremely non-linear such that the material moved many thousandths of an inch with virtually no resistance before it became much stiffer as the displacements got larger. The modulus near failure was one of the highest I've measured (4.8e6 psi) but the modulus at the beginning of the test was almost zero. I don't understand what happened in this test but such non-linear behavior isn't what we would want in a precision machine: materials with a linear behavior are preferable. The only explanation I could think of for the anomaly was that the hollow zeeoshperes deformed much more easily than the other solid aggregate.

Odd test results aside, my current thinking is that zeeospheres and other particles in this size range probably should not be included in a practical general purpose E/G mixture due to the increased epoxy demand that they cause. Based on the material samples from Agsco that Walter sent me so long ago, I believe that a practical mixture will probably use Agsco #10 and #5 quartz which aren't shown on Agsco's web site. I haven't tracked down the actual particle sizes for #10 and #5 quartz to rerun the model so I don't have a new mixture design yet but I believe that the components of the final mixture I would recommend will be:

Agsco #10 Quartz
Agsco #5 Quartz
Agsco #4 Quartz
Agsco #2 Quartz
Agsco #2/0 Quartz

The aluminum oxide I included in my original formulas probably over-complicates things and is more expensive than quartz. Thus, going up in size on the quartz makes more sense than adding one aluminum oxide fraction as I had done before.

Congratulations to everybody who's built something lately!:cheers:

Regards all,

Cameron

[alex_ku]

Hi Cameron!

Thanks for info :cheers:

I'd like to ask you about this mixtures:


Is it usable to make polymer granite mill ?
It's a silica sands.

Local supplier already have it, so maybe one trouble is gone...

[RomanLini]

I found this somewhere else on the forum, it's a small 6 axis precsion CNC machine with an interesting epoxy granite frame. Price about $120,000 I believe!



Cybaman Technologies

[ckelloug]

Hi alex_ku,

My suggestion would be to see if that supplier has any material with a larger maximum size. You can probably make a usable mixture with any of these but it will tend to have a higher epoxy content and less stiffness than a mixture with a wider size range. I'd suggest going to 6 or 8 mm as the maximum size. In the distributions that my model recommends, a large portion of the material is normally the largest aggregate.

Regards All,

Cameron

[ihavenofish]

I found this somewhere else on the forum, it's a small 6 axis precsion CNC machine with an interesting epoxy granite frame. Price about $120,000 I believe!



Cybaman Technologies

i had thought that one was natural granite. its a neat machine.