[DAK3333]

Hello, All
I have finally read all posts. Whew!!

Now for a couple of points.

1. Load cell
Think automotive- rear drum brake wheel cylinders = small hydraulics
and a gauge, add an oil pressure sending unit and you have an analogue
signal for data recording and analysis. Our hobby cousins in amateur
rocketry use this to measure motor impulse.

2. Vacuum
I have worked on research into energy absorbing “green” materials, including epoxies reinforced with natural plant fibers and fumed silica. A good mix was achieved by simply “folding the material in” like egg whites. However pulling a vacuum on the batch with fumed silica and epoxy was a must, before the addition of the larger aggregate, in this case natural fibers. Vacuum is again pulled on the batch before molding. Vacuum was applied in a vac oven. The increased temp. decreased viscosity and aided in air removal. No vibration or compaction was needed.

3. Silating agents
Bad mojo in general. But spray on refractory repair material is available for industrial ovens. Check out some of the backyard metal casters, they are using it. In general silating agents help eliminate moisture and allow better adhesion. I doubt this is necessary in these applications.

Again my background is in energy absorption (read rubber) and not in rigid materials.

[lgalla]

Yes Bruno turbulent mixers are excellent for mixing epoxy,but are only usefull with dispencing machines or dual cartridges.
Larry

[DAK3333]

Qustion about Vibration though.
Quartz is peizio electric.. Would zapping the mix with 60hz 110 v make millions of small vibratiors?:stickpoke

[lgalla]

Qustion about Vibration though.
Quartz is peizio electric.. Would zapping the mix with 60hz 110 v make millions of small vibratiors?:stickpoke

I really don't know,but to experiment I would fly a kite in a thunderstorm,you know the rest of the story.

[brunog]

Qustion about Vibration though.
Quartz is peizio electric.. Would zapping the mix with 60hz 110 v make millions of small vibratiors?:stickpoke

Making a single pure quartz crystal vibrate is one thing, making a bucketfull of quartz aggregate of different sizes with impurities vibrate in harmony and being able to adjust frequencies and amplitudes, now that's a challenge I am really not ready for.

Best regards

Bruno

[davo727]

Hey, when yall gonna build something? Dave just kiddin

[walter]

Hello, All
I have finally read all posts. Whew!!

Thank you for joining the discussion. All comments and ideas are welcomed and much appreciated!

And, I would encourage all new members to get on with reading while the thread is still relatively light weight.

[ckelloug]

I think the turbulent mixer might be a good idea. The epoxy will be vicious enough to start a back alley brawl and will be hiding brass knuckles in it's folds, but it will only be so nasty once it gets aggregate in it. I theorize that adding hardener after the aggregate will be an almost sure way of preventing the hardener from dispersing correctly. Larry is right however that with aggregate, it would tear up a static mixer that was not made from nuclear grade stuff.

Larry had commented asking about safety factors for beam calculations some posts back. From table 8.4 of the Mechanical Engineer's Data Handbook by J. Carvill CRC press 1993, it looks like a factor of 6 is probably what corresponds to what we're doing. Safety factor is defined as the ultimate strength/stress the part will normally be subjected. I would say however that the safety factor we will achieve naturally will be so far and above 6 that it may not be worth computing. Basically, trying to hold deflections in the thousands or ten thousandths our members are already likely much stronger than a factor of 6 over what would cause the beams to fail. I suppose that a calculation has to be done to prove this but it isn't at the top of my list of real worries.

DAK,

Thanks for the post. This is a massively complicated subject and it sounds like you have a lot of experience. All the info I have personally posted has been based on analysis from first principles as I have no experience yet. Everybody I've met on the thread wants more experience based info.

Can you elaborate on your brake caliper load cell or perhaps provide a link? It is intriguing. I currently expect from theory that a small compressive sample could fail at a force of about 5 tons.

Do you have any more comments on reinforcement with silica fume? I've been a big proponent of silica fume, carbon black and even smaller particles from www.nanoresins.com. In general though, items of this class are dispersion hardeners and have a limited strength improvement in a rigid composite according to my references like Callister. It's my current belief that they are only part of the equation.

Finally, can you elaborate more on silating agents? I've been a big proponent of them after some of the research on their effectiveness posed by brunog and lgalla. You say bad mojo but why? I don't have any perspective so they only look like a large helpful coefficient in the strength equations.

From datasheets like the attached ones for dow z6040 it just seemed like a strength enhancement combined with some easier to deal with properties. Additionally cabot cabosil ts-530 silica fume is already silated. Also, how are these related to refractory oven coating repair materials? I'm lacking a clue and I don't get the reference.

In reference to your piezo electric quartz vibratory compaction theory, It appears that voltages in the thousands of volts would be needed for it to work and they are hampered by the epoxy matrix and the inability to make connections to any of the larger quartz crystals. This is a 45 second wikipedia troll, not a thorough analysis.

Dak et. al.,

In general, It's my view that the goal of most folks on the thread is to find a way to produce parts like beams which might be up to 6 ft long and 6 inches square sopported at the ends with a displacement under a 100 lb dynamic load at the center of the beam between about .005 and .0005 inches. Generally speaking, I've been assuming that the readership here wants to create a material with the highest possible modulus with the constraint that it can be produced without needing expensive capital equipment or require handling substances that are significantly more toxic than oil based paint.

Generally speaking, this seems to require the use of larger aggregates than silica fume to go from a dispersion hardened epoxy to an epoxy aggregate composite with dispersion hardening. My research has indicated that dipping below the size of silica fume is where you go from affecting strength via the physics of the composite to affecting strength via the chemistry of the composite. In essence, you can and should do both. It's my current belief from a few posts back that under these constraints that a factor of 40 improvement is possible over just throwing together some epoxy and sand and hoping for the best.

<h4>
If anybody has any comments about my mission statement above, please feel free to comment!</h4>

[walter]

Good to see you Davo!

How's the machine?

[davo727]

Hi Walter, It should be back up and running by this weekend. did some more mods to it : http://www.cnczone.com/forums/showthread.php?t=36317 Its funny some of the guys in the vertical mill forum and Industrial hobbies forum here think my epoxy fill on my base is a waste of time and wont do any good. Oh well, some people you just cant reach My base is strong like a mofo now! Catch you later. Davo

[walter]

Thanks for the pictures Davo - vibration damping at it's best!


Cameron,

The Mission Statement was awesome. Someone should encapsulate it in E/G and put it on display in page one of this thread.
_

[davo727]

My R45 mill is getting me started and it should be cnc within a couple months. Next year I would like to build a large vertical mill using epoxy granite construction and linear bearing ways. I have a use for a mill with 24 inches vertical travel and 40 inches clearance between the spindle and table at full height. Table travel about 40in X and 24 inY. Its gonna be a huge b!tch. Later, Dave

[ckelloug]

I was looking the other day at this paper from the North Carolina Department of Transportation and realized that it might be possible to get our material properties from a vibrational or sonic measurement without having to rig a big test machine.

Today, I found www.grindosonic.com that makes such machines. They had the GS0078.pdf paper from NASA on their web site (I can't get it to upload even after zipping it) which gives some formulas. Looking at the frequencies measured in the study, it looks like one could do similar work on a PC with a sound card and a microphone.

<h4>
Given a bit of software work and carefully measured sample dimensions, it seems anybody on the thread should be able to get accurate measurements of the flexural modulus of their own material with equipment they already have.
</h4>

The only limitation is that the samples have to be made very accurately to size.

Footnote: Original paper for NC DOT.
http://www.ncdot.org/doh/preconstruc...06proposal.pdf

[BobWarfield]

Hey, when yall gonna build something? Dave just kiddin

And, I would encourage all new members to get on with reading while the thread is still relatively light weight.

Now that's funny after over 1000 posts!

What this thread needs is a checkpoint so people don't have to read 1000+ posts. Someone needs to step up as thread secretary, do that lengthy read through, and produce a summary of what has really been learned and concluded without all the chit chat. I would bet that if the summary were well written, the powers that be on CNCZone might even make that post a sticky so it can be referred back to, but great care needs to be exercised that it not get so out of control. I would also be surprised if the real pithy boiled down data takes more than 2 or 3 pages of post at most, not 95+ pages!

:idea:

The second thing the thread desperately needs is to act on Davo's remarks and build something, anything? So far, Davo is the man when it comes to building something here with E/G.

:cheers:

Just constructive feedback guys, don't get ruffled! Some us are very impatient!

(chair)

Impatient or not, it often turns out that the real progress doesn't begin until we stop research every little point on the web and actually go try to put the theory into practice.



After all guys, we are not machining solid green unobtanium to a millionth of precision. There are guys out there building nice routers out of particle board. How about a quick "almost right" proof of concept gantry router? It doesn't have to be huge. Take a look at Widgitmaster's gorgeous little mini-router. How about something in the 2 foot by 3 foot range? Use v-groove pulleys or the railing system of your choice with an E/G bed to provide mass and rigidity. Drive it with acme rod. It can be upgraded later if you like the results with more bells and whistles. If this E/G stuff is all its cracked up to be you ought to be able to cut aluminum very nicely with such a machine and prove your point.

Cheers,

BW

[lgalla]

[QUOTE=BobWarfield;293062]Now that's funny after over 1000 posts!

What this thread needs is a checkpoint so people don't have to read 1000+ posts. Someone needs to step up as thread secretary, do that lengthy read through, and produce a summary of what has really been learned and concluded without all the chit chat.

:cheers:
Bob walter has done a fine summary in the past,but I don't know if he has the legs to be the secretary.
Just constructive feedback guys, don't get ruffled! Some us are very impatient!
Iam guilty as charged, Bob.I am possibly a dreamer just trying to help out.I have been using epoxy/granite/sand/cabosil/minex/carbon black/milled fibers/ Zeeospheres for 25 years and the posts have helped me to understand what I was doing.E/G is my only experiance and I hope my posts have helped.I want to build,but lack electrial skills and mainly confused about CAD/CAM etc.
Not to ruffle feathers,Bob, but what are you planning pertaing to E/G machinery?
Larry:cheers: :cheers:

[BobWarfield]

Not to ruffle feathers,Bob, but what are you planning pertaing to E/G machinery?

Larry:cheers: :cheers:

For me I think a decent sized gantry mill is the right idea, although I may also succumb to the thought of building a lathe whose ways are linear slides mounted on E/G.

I have presented the gantry mill concept lo many posts back, and not once but twice. You may recall the image of a zillion hex inserts:



I have a thing or two ahead of it currently on the priority list--a nearly completed CNC lathe conversion and a shortly to be started Industrial Hobbies mill conversion. For the latter, I intend to follow in Davo's footsteps. He has pretty much the same mill, and I think judicious use of E/G will improve the machine's rigidity and performance, so I was very pleased to see his posts. That will likely be my first E/G project, come to think of it.

I had a strong interest in this stuff before the E/G thread got started, having read about using concrete to dampen weldment machine frames. That would be the MIT PhD thesis I also mentioned in this thread lo a great many posts ago by one Dr Bamberg called, "Principles of Rapid Machine Design". It has a lot of fascinating information on the efficacy of this approach to dampening vibrations and on the role rebar plays in helping with all that. I've mentioned the same thesis in several other posts on CNCZone, as well as on my own www.cnccookbook.com web site.

Bamberg built a precision 5-axis CNC tool grinder that became a commercial product using these principles that are documented in the thesis. His point is you can build amazing precision CNC with a little bit of welding and no need for massive cast iron casting or hand scraping, so I highly recommend reading it if you want to build these sorts of machines.

Welding is pretty easy and fun, I learned at the Community College:



A little bit of welding, a little bit of E/G, some surplus eBay servos, ballscrews, and linear ways, and Haas look out, we can build these here CNC machines right here in our garages with ghetto techniques and they work great!

Seriously though, you guys have a lot of data here, but it does not feel as though the thread is converging. You're now embarking on a program of lots of testing, but to what end? What do you need to achieve and how do you know you have achieved it? Dive in, start swimming. You will get there sooner. Build the trial gantry mill. Overcome your fear of electronics and cad/cam. CNC is ultimately not going to happen for you if you don't anyway.

The electrical skills you fear are not that hard. It's all cookbook and connect-the-dots. Here is a set of electronics I built for my lathe:

http://www.thewarfields.com/cnccookb...CNCDrivers.htm

Many others on these boards have done the same or better.

Dive in! The water is warm and welcoming! Even a very simple CNC machine is enormous fun:

http://www.thewarfields.com/cnccookb...iniRouter.html

Cheers,

BW

[davo727]

Hey Bob, If theyre gonna use Eg to build a hull for an inter-planetary battle cruiser with twin zenon hyper drive system, a little more engineering wont hurt anything so leave them alone! Me

[walter]

Larry,

You really need to get moving with that 5'x10' project. It's a dream for every machine builder!

The woodworking routers are so cool and it would be so much fun to build one...

You do need some hot Japanese Steel however, moving at 600 ipm on a V groove junk is a big no no.
Just make sure you buy quality components, not some hobby junk.

Buying hobby components for a prod machine will end with a payment book on a new Thermwood

:cheers:
_

[DAK3333]

CKelloug and all,

1. Load cell reference
Mr. Nakka has updated his site since I last visited. He has now added his own pressure transducer. In my load cell, I simply used an oil pressure sending unit (~2.00 USD). I am not sure if the load cell can achieve readings to a 10K lbs failure point but I am confident it will allow an accurate measure of applied load (mimicking those anticipated in the application) to then measure beam (member) deflection. Mr Nakka’s site is http://members.aol.com/riccnakk/hydlc.html

2. B.S. in Chemistry and I still kan’t spell (I fit right in huh)

3. Silylating Agents (silating agents Bad Spelling)
These agents are commonly used to deactivate certain (chemically) functional groups within a molecule under study. This deactivation or substitution helps to better isolate and characterize a molecule particularly in gas chromatography. These agents are water sensitive and will smoke and generate respectable heat when exposed to room air with humidity >= 40% (~4 ml). In general a material which has been treated is safe, but a DIY silylation should be fully understood before an attempt is made. These agents will substitute themselves into the surface chemistry of the aggregate, in place of easily mobile or weakly bound constituents, thereby presenting a more rigid surface for bonding to the epoxy.

I have attached a pdf which gives more insight to the oven repair material which may be helpful. It is a SiO2 spray on coating which presents a stable surface chemistry to the epoxy, however I have not taken the time to understand how it may bond to the aggregate (my application was for refractory repair).

4. Your analogy of the tinker toys, ping pong balls, and bowling balls, was very good.
But think more like Velcro spigetti (hooks and loops in strands). Loops on loops don’t bond well, hooks on hooks bond fair, but hooks on loops is best. Epoxy is mostly hooks except where it polymerizes to itself (even stronger). All other material is, hook, loop, or inactive. Fumed silica presents loops to epoxy so that the strands are less likely to slip past each other. Silyating agents are like a lint brush which removes loose loops from the surface of aggregates which don not contribute to bond strength.

I hope this helps.

[ckelloug]

Bob's suggesting about getting on with it and Larry's suggestion about checkpointing are both excellent. They are also right that information is falling off this thread just because some of it was contained in early posts.

I've begun manually writing an index to the thread and will end in a summary when I'm done and able to use the index to figure out what was said. I have stated at the beginning and currently indexing at post 409.

Since I might be a contributor to the reasons behind the unobtainum and battlecruiser comments, I do want say that some of the effort on this thread is based on doing the science well enough to OPTIMIZE an E/G mix for DIYers that have minimal capital tools but would like the flexibility of using unreinforced E/G for parts.

Ultimately, I think it is not the same kind of engineering problem to use common sense like Davo and fill machine parts with E/G. Most anything will work for this application.

My research is in trading the need for big expensive tools for a mixture engineered to mitigate the effects that would ordinarily need tools. Ultimately, I'd like for us to be able to post a recipe, a process, and flexural modulus numbers such that the recipe and process reliably produce the flexural modulus and the modulus is as good as reasonably doable with DIY tools.

Since ultimately this is a thread/site about building E/G routers, does anyone think maybe some of the more technical parts of designing E/G need for this application need to be moved to a different thread?

--Cameron