[ckelloug]

Howdy to all of those patient enough to stick with this thread through 3000 posts! I promised some data a long time ago but it took a lot of work to get there.

I have performed ASTM D790 flexural tests on 15 samples from jhudler (5 each of 3 different formulas) and the results are as follows:

Sample Type 2

Formulation: 1/6 of each of the aggregate types as discussed before.

Mean Flexural Modulus 2140ksi
Standard Deviation 169ksi

Mean Flexural Strength 6339psi
Standard Deviation 229 psi

n=4 specimens (5th was broken due to operator error with no data)

Notes: No additives. The specimens in this sample had no visible bubbles at the point of breakage.

Sample type 3

Formulation: 1/6 of the various aggregate types as discussed before with some portion replaced with barium sulphate of unknown size.

Mean Flexural Modulus 1350ksi
Standard Deviation 148ksi

Mean Flexural Strength 4947psi
Standard Deviation 281psi

n=5 specimens
Notes: Buff colored Sample, all specimens significantly less strong the the other formulas.

Sample type 6

Formulation: 1/6 of the various aggregate types as discussed before with BYK A525 deairing and BYK 969 wetting agent.

Mean Flexural Modulus 1870ksi
Standard Deviation 251 ksi

Mean Flexural Strength 5588psi
Standard Deviation 345psi

n=5 specimens

Notes: Air bubbles were present in this sample due to incomplete deairing and so this result it potentially unreliable. Whether this is due to the additives or a placing procedure problem has not been determined. Walter indicated a long time ago that wetting agents can reduce strength if overdosed.

I have also constructed a mold out of UHMW to facilitate production of sample blocks. Such blocks hopefully can be cut using a diamond saw rather than having to cast the samples exactly to size.

So, if anyone wants to join the new sport of making samples and testing them to see if you can beat me and jhudler on modulus and strength, the starting pistol has sounded.

Regards all,

Cameron

[roach]

bet you i can beat you lol :P
we take and make a test peice with every casting

[ckelloug]

So roach,

If it isn't proprietary, do you have the numbers for us to beat?

Regards all,
Cameron

[jhudler]

Thought I would followup with the specifics of each sample:


The 1/6 formula is 1/6 or 1 part by volume each of the following:

• #6 Agsco Aluminum Oxide
• #4 Quartz
• #2 Quartz
• #2/0 Quartz
• G-200 Zeeospheres
• G-800 Zeeospheres

Sample 2:

1/6 formula
10% epoxy by volume
24 hour cure
2 hours @ 100C post cure
vibrated for 15 minutes
no vacuum de-airing

Sample 3:

Formula: (essentially the 1/6 formula where Zeeospheres are replaced by Barium Sulfate

• 1 part #6 Agsco Aluminum Oxide
• 1 part #4 Quartz
• 1 part #2 Quartz
• 1 part #2/0 Quartz
• 2 part Barium Sulfate

15% epoxy by volume
24 hour cure
2 hours @ 100C post cure
vibrated for 15 minutes
vacuum de-airing

Sample 6:

1/6 formula
10% epoxy by volume
BYK 525
BYK 969
24 hour cure
2 hours @ 100C post cure
vibrated for 15 minutes
no vacuum de-airing

[romihs]

Ckelloug,

Good things come to those who wait... :-)
Thanks for all your effort!
I'm really sorry for not contributing much lately. (I'm sposl if you you guys haven't figured it out yet)

Jack,

I don't have the same experience with epoxy as you do, but doesn't epoxy require a longer post cure; ~8 hours?
I am just wondering how much of a difference the duration of the post makes on the final properties....

Just my 2c's worth.... again...

Regards

Sandi

[lgalla]

On the testing;
Would testing a block of solid epoxy and a block of solid granite be a good starting point for reference?
Larry

[ckelloug]

Larry,

Funny you should ask that. I'm heading for my lab to pour a block of solid epoxy into the shiny new mold. I suppose I can run wire for the oven while it is drying. I don't know whether I have enough oomph in the test machine for a block of solid granite but I guess I'll see eventually. I just need to talk somebody into grinding me a block of scrap granite down to 7.5x0.5x.375. Granite is supposed to be miserable in tension so it will probably work.

romihs/sposl/Sandi why did you change names on us? I was getting exciting that there were two guys in Slovenia as crazy as we are! Don't worry about not contributing much lately, there is only so much we can all do. Don't forget: I'm single and obsessed with E/G.

The reichhold data sheet suggests 24 hours at room temp and 2 hours at 121C.

Regards all,

Cameron

[jhudler]

It was 2 hours... the post cure stuff is in my head as 1 hour @ 50C... I just have to remember it's times two... 2 hours @ 100C... yet another asperger moment!

[lgalla]

The starting pistol has sounded.Their off.
IN the lead, we have Jack at 2to one with Roach wiping the rear at 50 to one.Jack has the advantage at 10% epoxy by volume and 1/6 mix,lighter weight.Roach has not Placed,WIN,or showin values,so the odds are still 50to one.
Approaching the first furlong,Jack is clearly in the lead.Folks this is a really exciting race.If Roach can come up with some #'s it should be a neck to neck finish.Stay tuned for the results.

[jhudler]

120C/250F! Damn I'm still wrong!
Wonder were I read 100C!

[ckelloug]

So Far So Bad. . .

Well, I botched 2 batches of epoxy last night. The first botch happened when the scale went overrange while adding hardener. I eyeballed the hardener for 2:1 and set the batch aside. Of course, this one set up hard.

In the second batch, in my hurry, I seem to have put in a smaller weight of epoxy than I should have. Of course I poured this one in the mold which is now filled with sticky not-quite set epoxy. I'm heat lamping this now in hopes of getting it out of the mold in one piece to throw away.

Sometimes you win, sometimes not. Coming around the back stretch, Jack is in the lead and I'm 100:1. I'm supposed to be 2.35:1 but I don't seem to be able to get mix ratios right. . .

Regards all,

Cameron

[veteq]

Hello people,

Nice info and knowledge on this webside.
After reading a few years and 2 attempts to finish a engineering bachler degree ( automotive and machine building ) my cnc mill is completed in a few weeks. Think i learned a lot in the last 5 years, this is the result off hobby and education. When reading a lot off good books on the basics and specified subjects off engineering, after 1 year already the things become to fall into place.
I think engineering is more logic than most people think, but all is based on facts.

On school here you are allowed to follow every class on the hole education traject off 4 years, so i did. I made my own path to succes off the bigger goal. (NO not finisching the STUDY, Making my own HQ cnc mill)
With that in mind i focust on Basic engineering, manufacturing/production methods CAD/CAM and off course the hole proces from idea to end product.
The inside knowledge on specific subjects you can`t learn on school, it is found when entering a company after study and after 30 years you mUst know a lot. HERE PEOPLE GIVE THAT ALL AWAY FOR FREE, AIN`T IT NICE.

So did i lost the time and study money???
i will have plenty off time to think about when entering my third study in a few months. LOL

Look bellow for a few samples off the end-products after this short story.
My actual machine that i`m am building isn`t there. (sorry)
When Benchmarking let`s say Minitech i see they must make uge proffits, maybe i will start a company 2 !?!?


By the way: ARE THERE REALLY NASA ENGINEERS HERE, THEY MUST BE REALLY SMART. have some questions for one.

Regards Roy
the Netherlands

[greybeard]

........
So did i lost the time and study money???

Hello Roy, and welcome.
I will only answer this question, because I have no formal engineering education, but a wide practical experience of many different areas of technology.
I think you have not wasted any time or money if you follow a formal course of study.
Every experience afterwards will expand that, and you will be adding knowledge that the underlying logic will enable you to test as you develop your own skills and interests.
It's a regret of mine that my own background doesn't contain such training, but I try to make up for that by extensive reading and keeping the brain active !

Tot sien,
John

[jhudler]

Mix more than you need, then add it to the aggregate by weight.

I usually throw whatever rock is handy in the leftovers just to have a paper weight or get lucky an discover something.

[ckelloug]

I'll echo greybeard that formal training is never a waste. It is also true that lack of formal training does not make one any less knowledgeable: only less marketable. greybeard has probably contributed as much technical insight to the theory of how E/G should be made as anybody here. He has asked brilliant and insightful questions that led to many advances in my understanding and everyone else's. He's probably the leader in posting useful references on the theory.

As far as I know, greybeard's lying about being untrained anyway I thought he once told me he was trained as a chemist.

I on the other hand have a Bachelor of Science in General Engineering from Harvey Mudd College. Though I did study paint removal in my senior clinic project, nothing I ever studied in school trained me specifically in E/G but because I had a firm grasp of the foundations of materials science, I was able to figure out which information I needed and I was able to write software to help get it. (I believe it was a link to a reference that greybeard provided that got me working hard on this). My work on this E/G thread allowed me to talk my way into an assignment writing software in support of some elite research scientists who study fracture mechanics.

What I can tell you is that school, if you are lucky, will teach you to read that math which is the currency of engineering knowledge. I was once told by one of my college's dropouts who worked at Los Alamos National Laboratory that the importance of school is to learn how to learn and after you have done that, you can take charge of your own destiny. This guy dropped out of my college because he said he had learned how to learn and that was what he needed.

The bottom line here is that we're all here to learn and I know I've learned more from the questions I've received here than I did in many of my engineering classes.

Regards all,
Shiva, Destroyer of Samples/Mixer of Mismeasured Epoxy
aka Cameron

P.S. I'm sure there is someone with better NASA credentials to answer Roy's questions but I did work for a year as a contractor in a Software Human Interfaces Lab at the Marshal Space Flight Center.

[veteq]

Jolly good John,

by the way. E/G is going to be the base off my machine, in the research on E/G or "mineralguss" i`ve been reading Peters "cncecke.com" for a long time.
Very nice forum, nice concept off machine designs, a lot DIY real cnc machines (Cast iron / Lineair bearings etc.) Also a lot on E/G, alot off threads.
German Engineering.

Two years ago i had a long conversation with ITW polymer technologies, the 2 Engineers i spoke were very open and we talked about a concept off one off my designs. The Zanite expert said his product would be great for a benchtop mill (ferro maching also) but to expensive, he had an idea and put me through to one off his colleagues. His option was Chockfast red.
http://www.chockfastgrout.com/itw_techmsdsCF.html

easy to pour and designed for permanend aligment with dynamic load on it.
thermic stable, nice
comes in bags off 200 pound complete mix for i believe 650 dollar.

That is the easy route every design needs different specific parameters, but all need a good E/G mix. Think that chockfast red provides a stable base.
The hardest part is to get every thing in proportion.
Remember most off us are designing HQ but still a hobby mill.
http://www.chockfastgrout.com/CF/video/CFredPour1.mov

regards,

Roy.

[greybeard]

Polymer chemistry, yes - engineering, no.

"Learning how to learn" sums it up pretty well.

John

[veteq]

Nice to see that the worldwide communication is going flawless.
Internet provides a nice base to talk and focus only on facts.

Quote:
I'll echo greybeard that formal training is never a waste. It is also true that lack of formal training does not make one any less knowledgeable: only less marketable

A good design is in my opinion always more powerfull than a Diploma,
You only get good designs with commitment.

How more you educate yourself, the more you see the thruth.
We live in a Powerfull world.

[Gizmot]

getting my mech E degree in 4 days

[veteq]

John and Cameron,

send you the messages?!

Kind regards.