[lgalla]

John ever thought

[johnohara]

John ever thought ...

I have thought about how to use precise frequencies. I find this interesting.

[nomedia="http://www.youtube.com/watch?v=EQPMhwuYMy4"]YouTube - Shapeshifting from Vibration and Frequency - Send out Love♥[/nomedia]


The vib I purchased is very well balanced.

~John

[Kevin_Johnson]

I don't have the room for a commercial vibration table so I bought this for the purposes of building something more manageable.



I tried using a dental vibrator last year. No benefit. Resorted to manual tapping and twisting to work the air out.

I think this device will work better.

~John

I used a tiny air turbine to carve porcelain; now I use a 1hp die grinder to work on metal. You have to scale up.

A dirt cheap possibility is an air chisel -- maybe $30. You will need to make a new tool attachment that will serve to trowel and spread the mix.

If you do this a lot and don't want nerve damage or to blow out your hearing (it doesn't come back...) then look into high end counter-balanced chisels -- a few hundred bucks. Obviously don't damage the mold with the device. Maybe a polymer head would work. With yet another quick change head you could rap the side of the mold.

This is why I suggested to look carefully at the chemistry of the other patent. It is designed to be troweled into place and exude the water that acts as a lubricant. Just like dental amalgam (oh my). Their testing did not indicate a severe penalty with strength for the retained water -- which might help with gases too (?).

An interdisciplinary approach to utilizing extant tech/knowledge works well. I have heard some top notch engineering schools like this philosophy too.

[johnohara]

Kevin~

Here's a link to some of the work I did last year.

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

I'm comfortable with my research, selection of materials, sources for those materials, and subsequent trials. I tried many formulas and succeeded in producing commercial grade samples -- along with many others on this thread. (krille356 and ckelloug most recently)

I created the thread to provide a practicum to this thread's theoretical in the hope that more people would discover just how easy -- and fun -- it is to make e/g. Sure there's a learning curve. But the recipes are available. Not only here but on the internet if you look hard enough. Plus, many of the patents have since expired which is why companies today point to their "proprietary mixes," and "specialized formulas."

I had hoped the new thread would foster a different set of questions along with a series of best practices that were based upon user experience. Questions about molds, embedding inserts, achievable flatness, and more.

Your ideas are interesting. So let me be the first to encourage you to go mix some e/g, hopefully in a way that incorporates much of your own knowledge and experience, and then afterward post a bunch of pictures we can all enjoy and discuss.

~John

[lgalla]

Why is there so much concern over the epoxy pooling on the surface?I would just sprinkle some sand to suck it up.No need to get rid of the excess.Epoxy is your friend when it pools thus decreasing your epoxy % in the core.Besides,I assume that pooled side would be the underside of the part.
On the outher hand,if you were casting off a precision surface the pooling could be the beginning of a surface plate which would parallel to the outher side.
Larry

[Kevin_Johnson]

John,

Here is a company that makes scaled up vibration products for manipulating concrete, ergo polymer concrete, ergo epoxy granite. They even have units like the one you pictured. As I predicted, they also have units like the dental Vibra-brush for manipulating and condensing porcelain powder.

Concrete Vibrators

I suspect these types of tools are in use in high end commercial manufacturing operations of e/g and have been for a very long time. The technology looks mature -- highly differentiated and specialized. I was just exposed to the technology in a different field.

Kevin~

Here's a link to some of the work I did last year.

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

I'm comfortable with my research, selection of materials, sources for those materials, and subsequent trials. I tried many formulas and succeeded in producing commercial grade samples -- along with many others on this thread. (krille356 and ckelloug most recently)

I created the thread to provide a practicum to this thread's theoretical in the hope that more people would discover just how easy -- and fun -- it is to make e/g. Sure there's a learning curve. But the recipes are available. Not only here but on the internet if you look hard enough. Plus, many of the patents have since expired which is why companies today point to their "proprietary mixes," and "specialized formulas."

I had hoped the new thread would foster a different set of questions along with a series of best practices that were based upon user experience. Questions about molds, embedding inserts, achievable flatness, and more.

Your ideas are interesting. So let me be the first to encourage you to go mix some e/g, hopefully in a way that incorporates much of your own knowledge and experience, and then afterward post a bunch of pictures we can all enjoy and discuss.

~John

[rusel]

John
We have just made a composite head for our mill. It is working very well.
http://www.cnczone.com/forums/genera...ur_hm45-2.html

Russell

[greybeard]

Hi Russell,
I had looked at your previous post when you first put it up, and was intrigued be the "Phenolic/basalt" reference. Did a quick search to discover the basalt spun fibre, but can't find a phenolic resin that matches what you have done ie a resin that can be catalysed etc.
Can you post a link ?
Regards
John

[johnohara]

Russell~

I followed your thread from the beginning and watched your videos. Congratulations.

Here's a link you may or may not have seen. Bob Warfield has a link to it as well on his website cnccookbook.com.

http://opensourcemachine.org/files/G...%20Machine.pdf

Thank you for posting your work.

~John

[Kevin_Johnson]

Made a pour today with: angular rock we had purchased to stabilize sugar sand on our verge; aquarium gravel; aluminum oxide abrasive from our blasting cabinet.

I used an additive technique to layer the aggregate and low viscosity resin (yes, there is a corresponding dental technique for methyl methacrylate resin and monomer which is then heat cured under pressure). I tapped the mold with a kitchen knife handle and used two distinct techniques to tamp the mixture while I let the resin wet out the aggregate. I vibrated it afterwards using my 44 hp G10 vibrating plate with heater.

I used a Chinese restaurant takeout soup container as the mold. When the set was turning a bit viscous I made a "plate" with a lid and used a Glad sandwich bag as my separating medium. On top of the plate I stacked 140 lb of lead ingots to impart a per square inch internal "hydraulic" loading of approximately 1 bar.

Hopefully commercial quality. We'll see.

[johnohara]

Kevin~

Congratulations. The hard part now is to be patient. Let it set for 48 hours before demolding -- if at all. Then let it rest for another 7 days.

Ziploc plastic containers work well too -- mold release is not required.

~John

[Kevin_Johnson]

Patient -- ? No, I am just ad hoc experimenting.

I pulled (cut off) the container and weighed the cured piece. I calculate 9.2% epoxy to aggregate by weight. There was a bit of gradual flow around the edge that developed over the 16 hours that I have let it cure -- this tells me the lead weights were doing a good job of pressurizing the system. I will be heating it for a fuller cure but I will have to see if I have an old toaster oven around. I did some testing with motor oil on the kitchen stove and managed to get a real powerful sulfur smell to permeate the house. It actually woke up my wife from deep slumbers. She was not too pleased.

[johnohara]

Looking forward to the pictures.

That's a nasty smell. I tried using polyester resin with one piece and had to open every door and window (during winter in Chicago no less) to vent the place. It's another aspect of Epoxy Granite in Practice.

~John

[ckelloug]

Hi all,

I just ran a test with about 12.5% epoxy by weight which is about 3 times the 12% by volume that the model predicts to be required. At a temp of 30 C or so this mixture was stiff enough that my trusty IKA RW20 mixer (only 70W) was having a bit of trouble mixing it and I had to move the beaker around manually under the stirring to get a reasonable mixing.

I added aggregate with the smallest first starting with G200 Zeeospheres and working my way up to #6.

I am using BYK A525 deairing agent 0.5% by weight of the epoxy and about 0.5% by weight of the total mixture KR55 titanate. The titante may be too much as .5% by weight of polymer looks like what the datasheet actually meant.

What was fascinating is that even though I could barely mix the material, the vacuum chamber had a profound effect. It almost looked like the black pillar you get when you pour concentrated sulphuric acid over sugar. I went up and down with the vacuum a few times and much air was released.

I then scooped the mixture into my mold with a gloved hand since that was the only instrument avilable to me that was going to work. I vibrated the mixture on the vibe table and then put it back in the vacuum chamber for 5 more minutes and got more air out. The mixture barely wanted to spread in the mold even under heavy vibration so I did some tilting and tapping.

I then placed the mold on a hotplate at 200C for 2 minutes or so and then vacuumed, vibrated and vacuumed again.

I placed the mixture in the oven at the optimal cure temperature for IPDA of 85C and am currently waiting for it to go through it's 2.5 hour cure cycle.

It appeared that the vacuum forced the remainder of the material to wet which wasn't occurring with mixing alone. In a lot of ways, it looks like the entrained air is a bigger problem than the mixing.

Reading through that Studer patent I posted a few posts back, they recommend a mixing device whose name is translated from German as compulsory mixer. Here is a youtube video of one in action. [nomedia="http://www.youtube.com/watch?v=604ly12MLBo"]YouTube - beba Compulsory mixer to mix glass, resin and catalyst.mpg[/nomedia]

If there are any friendly germans reading here, I would really like to know what this costs: COMPULSORY MIXER by beba Mischtechnik

It looks like there is a company that imports the Collomix company's portable copy of Beba's product for concrete mixing. See Collomix Multiquip Hand Mixer 1.9hp Dual 2 Speed CX44DUO - Ohio Power Tool

I am pretty certain that something like the collomix is going to be required for a low epoxy mixture because a single rotating paddle doesn't look like it produces a mixing action that is very good for paste like material. I suppose that a vacuum compulsory mixture would be ideal.

Regards all,

Cameron

[johnohara]

Cameron~

Husky Mortar Mixer - THD800 at The Home Depot

~John

[Kevin_Johnson]

A few pics. I ground a few mm off the bottom because I wanted to see the distribution better. Looks like at that level I could have used a bit more aquarium gravel.

The center of the top view shows material that was seared by a propane torch. I tried to get as many trials in as possible.

I think that I will modify this to be a curved compression tool on the next trial.

The ratio of 9.2% epoxy by weight is okay for a first attempt but it should be improved.

[RomanLini]

Interesting results Cameron (and Kevin!).

12.5% by weight sounds like a LOT Cameron. What's the specific gravity of granite? I thought it was about 3 times heavier than epoxy so that was about 30% epoxy by volume? And even then you said it was very hard to pour. I think those really fine particles are sucking up the epoxy like flour, making it into a very hard to mix "pastry" texture.

Why not mix the large particles first, then keep sprinkling in the fine stuff later as it is mxing?

(edit) Have you seen these? Planetary centrifugal high g-force mixers;
http://www.thinkyusa.com/products/qu...e-400twin.html

[ckelloug]

Hi Roman,

I'm using an angular aggregate with a density over 3 g/cm^3. I agree the 12.5% by weight still is a lot however and qualitatively seems like more than the slightly dry snowball suggested by roach. I'm running a series of tests lowering the epoxy amount each time. After the disaster with 33% more epoxy than this time, the result is interesting. I've attached a picture of the sample.

I'm mixing the smaller particles first because the titanate will coat them and prevent them from insanely raising the viscosity. I'm thinking that if I add large particles first, there is no guarantee the epoxy-titanate mixture will reach all of the small particles and there will be even more mixing trouble. Also, the deairing agent is making a huge difference in making this work. Were it not for the deairing agent, this mixture would be all voids.

Once the larger particles get added, the mixture jams and then it doesn't want to mix.

I've seen the thinky mixers on the web before but they are too small for even lab batches and as near as I can tell, are very very expensive. Some of the the Collomix and Beba mixer lines are used in building construction and we see that the large Collomix portable is under $1000. Johnohara is absolutely right that something like that husky mortar mixer is a good idea. If the husky actually has the umph to mix E/G, that's the answer and it is much cheaper than a good sized food mixer for example.

Kevin,

Congrats on your test results.

[brunog]

This what I have, I can mix a full bag of concrete mix at a time with it:Power Tools, Woodworking and Metalworking Machines by King Canada

Nice Samples Guys!!:cheers:

Cameron,
when do you intend testing your sample??

Best regards,

Bruno

[brunog]

(edit) Have you seen these? Planetary centrifugal high g-force mixers;
Planetary Centrifugal Mixer "THINKY MIXER" (atmospheric pressure type) ARE-400TWIN?THINKY USA

Roman,
we discussed this a few thousand posts back(post 3323), interesting piece of equipment, it what suggested by someone when greybeard was working on his spincasting project. The capacity (800g) would be good for making samples only or for mixing the epoxy resin only.

Best regards

Bruno