[castinite]

That is correct, you cannot really compare the properties of epoxy and polyester. It is more like comparing stain to paint. Two different products for two different uses. It does depend on the application, but I would never try to use a polyester for any machine base, if you want it to be stable and useful for more than a month.

Terry C

[bugattibuilder]

To the Croatian guy: You are certainly looking in the wrong places. If you need help finding a suitable supplier for your epoxy needs, contact me and I can direct you to some suppliers in your area.

[probinson]

Woo - If sbr20 rails are sturdy enough for your machine then polyester resin is a good match, just be sure your mounting points are adequate. You wouldn't want to just embed a coupling nut as a mounting point, for example, but you could weld one to a rectangular plate or a couple inches of rod to have a nice sturdy "T" shape embedded.

[woo]

i will try some mold.i put some fine quartz sand, alot of metal saw dust for strenght(i have it alof from lathe and mill on my workplace) and connet all that with poly resin. for rail fixture i have in my mind steel bars 80 x 20 mm

[jestah]

Hi guys,

I have worked a lot with epoxy but mostly mixed with carbon, glass and wrapped around foam/balsa or other light weight cores. Never mixed it with rocks and sand!

I am keen to work my way into this new building style and think that small steps will be the best way to give it a go. I started with skimming over 100 or so pages (from page 70 or so) before getting to the point of feeling a sick of reading to find a decent tested recipe that I can start with.

I hope this is not seen as lazy but I would like to ask if someone could point me in the right direction or maybe starting a second sticky with the most current tested recipe help others like me who are keen to give it a go, have the required tools and materials but a little short on time to dig into the 4000+ posts AND have time left over to actually build something!

Getting back to the small steps I think I should start by first filling the voids in the base of my mill drill table (soon to be converted to cnc) to get a feel of working with rock and glue and then once this is up and running I am very keen to join in on trying to build a full EG mill.

I have found a few recipes (walters post #1753 ) but they require a brand of aggregate that I can not find in New Zealand so could some one help me work out the size and ratios I should be on the hunt for? Is this the most current tested mix or should I be using something different? I have also found a local counter top maker who is willing to rent time on one of his vibration tables to help me compact and deair my mill drill pour and will even let me put it into his oven for post curing!

Thanks in advance
Jestah

[ckelloug]

Hi Jestah,

Sorry the last 3000 or so posts haven't been more practical in nature.

The most current formula I have posted is in http://www.cnczone.com/forums/898373-post2.html

I also recently did a model run for nivea http://www.cnczone.com/forums/907633-post4394.html

The formula used by Walter in post 1753 isn't too bad either. You could also quickly knock out an approximate formula by using Fuller's formula by googling or asking brunog for his spreadsheet.

Given no models, equal parts by volume of all sizes is a good starting formula and is in fact what my implementation of the compressible packing model uses to initialize itself. The optimal formula typically has about 20% more of the smallest and largest sizes. For each middle size, you typically want slightly less than the percentage of the next largest component.

According to the models, the optimal formula for a given set of aggregate is dependent on the exact characteristics of the aggregate used. If you have sources for aggregate, I'd normally offer to run the models and give my opinion but travel and hardware failure have rendered me more useless than usual

I cannot be of much help until May however as I am on extended travel and the computer with all of my models and data suffered a motherboard crash a little over two weeks ago. I switched to my spare laptop but it promptly suffered an LCD backlight failure the next day. I am currently working from a tiny netbook without access to any of my resources. Fortunately, the data is not lost, I just can't access it until I get back to my office and a new computer arrives onto which to load the contents of the old hard disk.

The oven and vibration table will make things a lot easier for you. The exact utility and settings for the oven will be a function of the epoxy and hardener chosen.

Sorry I cannot be of much more help right now.

Regards all,
Cameron

[tronger]

hello everybody!
I have one question need help everyone
epoxy granite have properties of compressive, tensile, flexural strength weaker than steel and Iron cast several times. So based on what criteria it can still be used as the base machine

[ckelloug]

hello everybody!
I have one question need help everyone
epoxy granite have properties of compressive, tensile, flexural strength weaker than steel and Iron cast several times. So based on what criteria it can still be used as the base machine

Because the base of a machine is designed primarily on the basis of displacement under the design loads, the strength differences and modulus differences aren't major problems in an actual machine. They do require careful design however in order not to use the materials in a way that exceeds their specifications.

As a rule of thumb, a part that is deigned heavily enough to have displacements that would make it precise enough for precision machine tool use, very likely has the strength required to do the job.

Regards all,

Cameron

[bagherdn]

the key features of EG are it's rigidity,damping, stability
i've found it can take much $ for a big machine (1 kg costs about 2-3 $ for me )
so what about combination it with a steel truss structure ? it can be strong and stable enough and has good damping properties. i have used it in my machine u can see :
http://www.cnczone.com/forums/diy-cn...00*1100mm.html

[tronger]

Because the base of a machine is designed primarily on the basis of displacement under the design loads, the strength differences and modulus differences aren't major problems in an actual machine. They do require careful design however in order not to use the materials in a way that exceeds their specifications.

As a rule of thumb, a part that is deigned heavily enough to have displacements that would make it precise enough for precision machine tool use, very likely has the strength required to do the job.

you are say too general.
the material released by the company to achieve the lowest compressive strength is 100Mpa, flexural strength is 28Mpa, tensile strength is 15Mpa ( Reference link: [URL="http://www.schneeberger.com/products/mineral-casting/technology/material-characteristics/"]

I want to ask is how to calculate it can be concluded this material to qualify as durable machine bed?

[Kevin_Johnson]

Because the base of a machine is designed primarily on the basis of displacement under the design loads, the strength differences and modulus differences aren't major problems in an actual machine. They do require careful design however in order not to use the materials in a way that exceeds their specifications.

As a rule of thumb, a part that is deigned heavily enough to have displacements that would make it precise enough for precision machine tool use, very likely has the strength required to do the job.

you are say too general.
the material released by the company to achieve the lowest compressive strength is 100Mpa, flexural strength is 28Mpa, tensile strength is 15Mpa ( Reference link: [URL="http://www.schneeberger.com/products/mineral-casting/technology/material-characteristics/"]

I want to ask is how to calculate it can be concluded this material to qualify as durable machine bed?

That would be determined empirically. Examine the issue: You have a material that is already empirically known to qualify as a durable machine bed using design considerations that you understand (from your comment), therefore if you propose a new material or formula you must measure its properties and compare them to an accepted product.

It is a good idea to carefully read through patent literature because many issues with alternate materials are addressed in the discussions of prior art.

[Kevin_Johnson]

I am sure it has been mentioned before but probably bears mentioning again.

If you use different materials with varying coefficients of expansion to create a precision base then it is presumed that the machine will be maintained (transported, stored, housed, used) at an ambient temperature close to that of its construction.

Spikes outside this range should be considered hazardous to the machine. Think about, say, all the research done to improve pavement exposed to extreme swings in temperature.

[castinite]

I started the first independant polymer concrete casting company in the US, so I can help anyone interested in this technology. I have made more PC machine castings than any US company.

Although the title of the thread is "epoxy granite", granite is not used. When Studer licensed companies in the US, they had them use granite. I proved that quartz is a much better filler. I also developed the epoxy system used by all US machine base manufacturers.

Let me know how I can help.

[Kevin_Johnson]

I started the first independant polymer concrete casting company in the US, so I can help anyone interested in this technology. I have made more PC machine castings than any US company.

Although the title of the thread is "epoxy granite", granite is not used. When Studer licensed companies in the US, they had them use granite. I proved that quartz is a much better filler. I also developed the epoxy system used by all US machine base manufacturers.

Let me know how I can help.

http://www.cnczone.com/forums/epoxy_...tml#post277305

Comments?

Also, have you ever looked into using very small particles like Zeospheres and does shape matter at this size level?

[castinite]

Yes, we have looked into using spheres and other fillers, but have not changed to them. We are always seeking new fillers. The most common fine fillers are silica flour or calcium carbonate.

[Herbertkabi]

hi,
I have not read this thread few months, sorry,
perhaps you have seen this,
CR-900 High Strength Casting Resin, 26 fl. oz.
what is your opinion?
cheers,
herbert

[brunog]

Herbertkabi,
I believe this product is urethane.

I like the product's viscosity

Best regards

Bruno

[lgalla]

Here is another source for inexpensive epoxy and mold materials.
Thin Epoxy Resin- Fast (5 Gallon, 2 1/2 Gallon Hardener) [EPXTHNFST500] - $269.00

[JohnMcNamara]

Hi All

The semantics of commerce…. or they keep moving the cheese.

Research keywords:

Polymer concrete
Epoxy concrete
Epoxy granite

Maybe the above are becoming outdated.

“Mineral Casting” may be where industry is moving?

Try the following search for "Mineral Casting"
Google

Also here for a large number of pictures of actual examples
mineral casting - Google Search

Cheers

John McNamara

[greybeard]

"A rose by any other name would smell as sweet"

These old eyes read no fundamental development in the change of name from Epoxy/whatever to Mineral Casting

John