[pecamuzicar]

Hi to all!

Do you anyone know about using Thixotropic epoxide resin for Epoxy-Granite?

Some of characteristics of my resin:

- bending resistance 16,5MPa,
- pressure resistance 70Mpa,
- adhesion to the substrate 4MPa .

I would use mixture of iron (steel) aggregates (0,3mm about 60-70%, 5-6mm about 25-30%) + glass wool (10-15%). Agregates-Epoxy about 10-11/1.

Then I would fulfill space between two steel square tube one in the second (120x120mm and 60x60mm) to make 1m long metal lathe bed. Please give me also your opinions about such design.

Thanks in advance! :-)

Peter

[veteq]

@Terry,

May i ask you when this mill was made..?
Is the Horzizontal part that holds the spindle made of full EG? No steel inserts for reinforcement?
I was wondering how long this mill was used, where there no creep or fatique issues in the horizontal head part.

Been searching the web for cree and fatique data on EG, but thats very hard to find if it even is there..


Kind regards,

Roy

[danielpublic]

where do you get thins stuff.I am in the USA

Apparently on eBay e. g, I guess its "same same" (?).

Anyhow, this plasticizer & superplasticizer-stuff seems really interesting even if it doesn't suite any application/half-god-holygrail-performance-machine in any random basement/commandcentral. However in the beginning of the last century concrete-lathes was pretty common. If one does not exclude the other, it might bring down costs if nothing else.

I guess one can mix that to/with any concrete?
I mean... look at that flow.

[johnohara]

Slashdot posted an interesting story today about a breakthrough in nanoscale 3D printing at the Vienna University of Technology.

In addition to the impressive results, the last picture on the page shows the device they used.

Here's a link to it.

~John

[lgalla]

Hi to all!

Do you anyone know about using Thixotropic epoxide resin for Epoxy-Granite?

Some of characteristics of my resin:

- bending resistance 16,5MPa,
- pressure resistance 70Mpa,
- adhesion to the substrate 4MPa .

I would use mixture of iron (steel) aggregates (0,3mm about 60-70%, 5-6mm about 25-30%) + glass wool (10-15%). Agregates-Epoxy about 10-11/1.

Then I would fulfill space between two steel square tube one in the second (120x120mm and 60x60mm) to make 1m long metal lathe bed. Please give me also your opinions about such design.

Thanks in advance! :-)

Peter

Peter you can not use a thixotropic Epoxy as it will not be able to wetout the fillers.You need a very thin epoxy similar to laminating epoxy at 600CPS
Thick epoxy is 20,000Cps
Larry

[cjtoombs]

Hi Lgalla

From your post:
"water absorption in weight 1 - 2 [Mass %]"

I can only assume it expands.
It is a pity they do not quote a figure.

Without an accurate number it is a No Go zone.

Cheers
John

The assumption is not neccecarily valid. Mass conserves, volume does not. If the water molecules fit in between the other molecules there would be no exansion. The easy way to solve any volume effects would be to condition the parts at high humidity and saturate them prior to final machining/assembly. I live in the desert and relative humitity here rarely drops below 20%, so in all likelyhood the water once absorbed will stay in the part for life, allowing for the dimensional stability desired.

[pecamuzicar]

Thanks lgalla,

Peter you can not use a thixotropic Epoxy as it will not be able to wetout the fillers.You need a very thin epoxy similar to laminating epoxy at 600CPS
Thick epoxy is 20,000Cps
Larry

Yes, it was logical and expected, but still somehow I got ordinary epoxy from same producer with same characteristics, looks nice. What is CPS?

But I like to build shorter lathe bed with it, about 1m or something longer with steel tubes like I mentioned, or maybe better without like on the sketch. I would apply there ways with simple square edges, but for this size I have not idea for shape and thickness of EG bed to get also other adequate properties like strength, or there are need some reinforcement ...

All of you are machinists and some of you are EG experts like you, so give me some opinions and advices here. Otherwise, this idea with superplastics is not bad for building Romig style lathe http://www.vintageprojects.com/machi...urretLathe.pdf

Cheers,

Peter

[lgalla]

Peter CPS is viskoznost.The glass fiber would also cause very high viscosity
I am no machinist but if I built a machine I would build a steel structure and fill in the tubes and spaces with E/G.The steel frame work would be the strength.The E/G the damping of vibration and will add to the overall strength and stiffness.
laku noc

[pecamuzicar]

Oh, dobar dan Mr lgalla, :-))

It is nice to met you and speak something on domestic language. If you are not machinist, how you are longer interested in such "new" EG technology? From the beginning I had idea to using EG fulfilled steel tubes and i would agree with you 100%. But recently, after few private messages with John McNamara where he expressed doubt about damping characteristic of this construction because of big stiffness of cold or hot rolled steel tubes, I changed my mind something (something).

For good dampening he recommended me rather to use Bamberg's design construction "Concrete Core Cast with Reinforcement" if I would like to use steel tubes. Do you maybe know it is already discussed here, and it is not problem to speak about that here? It looks pretty reliable and affordable. But however, only thin (0,4mm) damping sheets ISODAMP C 1002 looks hard available and expensive even more than epoxy. I would substitute it, but ... ? I did not see that before and I will maybe ask Aearo Company to send me some small sample, or ... Romig bed style is checked. But just I am not sure, but I would.

But at least for headstock and other parts I have some ideas to apply EG, and I would to use my epoxy I bought. So, you and other EG machinists guys, please stay with me here to discuss and conclude something about that.

Pozdrav (Cheers),

Peter

[lgalla]

TAMO METEP XENO
please excuse my Serbian,I do not speak the language.To make new members feel at home I just look up a few words.
E/G is not new to me after 25 years of use.It was used to backup fiberglass molds subject to high pressures And used to dampen vibrations.When you take different materials to gether they tend to cancel each others natural resonate frequency.E/G works as it contains many different materials and sizes which all resonate tending to cancel vibrations.
Again I say I do not agree with a total fabrication of E/G as it would require a precision mold which would cost more than the part.If big production fine.My english spelling is getting bad.Too many UNBO:cheers:
NappN
http://www.cnccookbook.com/CCMillEpoxyFill.htm

[pecamuzicar]

Thanks Larry,

In that my first idea I though mostly about strength. EG mixture I found here with iron aggregates was described like machinable, but very strong because of glass fiber (and some additives not so much available). It seems because of very stiff steel tubes, there I not need to care so much about strength like about dampening.

For pure EG construction mold I would not care - it is wooden - simple and no problem I think (?), because still I am interested how it should be for such narrow and long lathe structural base. On e. - it can be in some standard lathe bed shape (?), probably with some reinforcements (?).

Cheers, :cheers:

Peter

[janaf]

Here is my first part, fresh, from oven (1hour at ~80C)
First made epoxy-granite part . - YouTube

epoxy 20% by volume. (hardener is 1:10)

Hi, is that the spindle house?

20% by volume is lower than the numbers I have seen elsewhere, typically 12-14% by weight.

[alex_ku]

Hi, is that the spindle house?

20% by volume is lower than the numbers I have seen elsewhere, typically 12-14% by weight.

Yes, it's spindle house. Lucky that this part is not so loaded and filled mostly for weight/rigidity.

BTW, I found why my mix was so dry.
I'd made a mistake during mixing and put twice less epoxy
So it was ~10% by volume. But! The "snowball test" was ok. It holds form with no problem that why i decide that all is fine. Later i filled the part with extra epoxy using small syringe. Now its looks and feels like rock.

So guys, look sharp during calculating/measurement of mixtures

[rocketflier]

Searching epoxy concrete images came up with a couple links I hadn't seen before

http://www.cnczone.com/forums/mechan...ests_pics.html

fabrication d'une fraiseuse CN 3d granite époxy : Projets de fraiseuse et portique d'usinage CNC

[mchabot]

I have already post the thread of this mill.

I have made a small trip to see it. Lucien (the builder) is a former owner of a metalworking company so he knows his trade. He decided to build this mill only with homeshop machine: BF20 and 9x20 class lathe (since he get back his previously owned deckel FP3).
The only part non-home made is the steel plate used as table, it was ordered milled/rectified from factory (bosh rexroth).
The result is very nice, robust and clean.

[ckelloug]

Hi E/G'ers,

I wish I had more time to spend on this thread. I've been busy with some commercial work on something else and I hope I can tell the story about it here some day. I've been thinking a lot and I hope this year I have time to finish making and testing the E/G recipe I was working on.

While rechecking a calculation I had originally published on this thread, I found that I was missing a set of parentheses in my implementation of the Isahi-Cohen model of the lower bound on E/G modulus which I used to produce the graph that shows E/G modulus vs. percentage of quartz.

The correction raises the predicted modulus for E/G at 88% quartz by volume and 400,000 psi epoxy to about 4.6 million psi from about 4.2 million psi with the broken equation. To me, the corrected question suggests that commercial E/G probably has a filler percentage of about 88%. I have believed this for a long time but now that the model result matches the published modulus value for commercial E/G, I now believe it more strongly.

Anyway, for what it's worth, I've attached the corrected modulus graph for quartz.

Regards All,
Cameron

[johnohara]

Hi Cameron~

Hope all is well.

Is the 88% by weight or volume?

Regards as well,
~john

[ckelloug]

Hi John,

That's on a volume basis as that's what the Isahi-Cohen equation uses. Epoxy is very close to 1 gram per cc and quartz 2.6 g/cc therefor the mass of 1 gram of the mixture is .88*2.6 +.12*1.0. For a single cc that makes for 2.288g quartz and .12 g epoxy for 2.408g/cc.

2.288/2.408 is 95% by weight.

Regards all,

Cameron

[svenakela]

Hi John,

That's on a volume basis as that's what the Isahi-Cohen equation uses. Epoxy is very close to 1 gram per cc and quartz 2.6 g/cc therefor the mass of 1 gram of the mixture is .88*2.6 +.12*1.0. For a single cc that makes for 2.288g quartz and .12 g epoxy for 2.408g/cc.

2.288/2.408 is 95% by weight.

Regards all,

Cameron

That really depends on the epoxy. I sell epoxy, and I have a range between 0.75 to 1.45 g/cc in my catalog.

[RomanLini]

Good info thanks! And the specs for the most common types? I use a few types of epoxy and polurethane in my work and all of them are within the 1.10 to 1.15 g/cc range.