[brunog]

John,
Personally I will be going through the mold making process for 3 reasons:

1- securing threaded anchors and steel plates

2- some parts will be mirror images

3- I want to be able to replicate the same parts a few times without having to start over at square one.

Regards

Bruno

[greybeard]

Hi Bruno.
I agree that you have three perfectly valid reasons for using the mold method, and I'm sure that others will have different ones.

Having done some molding in the past, and always being annoyed that the "best" method for me at the time(polyurethane foam into silicone rubber) was also the most expensive one, has always pushed me to look for alternatives where possible.

The number of times I've found my design solution worked better if I turned it upside down keeps me twisting things round in my head, and just for once I tried "inside out" as an alternative.

About a mile from me is a quarry producing graded flint and sand, so if I get to a trial stage aggregate materials are no problem, and I've already got a local epoxy supplier I've used before.
All I need is a clear run at a project.
Ho hum.

Regards
John

[jsage]

Larry,

Have a good trip. I'll have to watch star trek to get full reference ; )

My experience with runaway epoxy cures:

Moving from New England to Texas I has some fast cure catalyst which didn't work to well down here. I ended up augmenting with super slow.

It gets very hot, lots of internal bubbling, yellowing and you get this nice smelling gas/vapor puff ; ) Doesn't end up really even being a useful paperweight.

The torch can be used to burn off the ends of non glass fiber reinforcement but gently.

[romihs]

Sandi, Quartz is a slavic word.

Quartz crystal sweeper

Igalla,

Are you sure of that? In Slovenian, the word for quartz sounds nothing like quartz....

Regards

Sandi

[jsage]

Ah but Sandi,

Explain this one away.

ro·bot /ˈroʊbət, -bɒt/Pronunciation Key - Show Spelled Pronunciation[roh-buht, -bot]Pronunciation Key - Show IPA Pronunciation
–noun
<TABLE class=luna-Ent><TBODY><TR><TD class=dn vAlign=top>1.</TD><TD vAlign=top>a machine that resembles a human and does mechanical, routine tasks on command. </TD></TR></TBODY></TABLE>
<TABLE class=luna-Ent><TBODY><TR><TD class=dn vAlign=top>2.</TD><TD vAlign=top>a person who acts and responds in a mechanical, routine manner, usually subject to another's will; automaton. </TD></TR></TBODY></TABLE>
<TABLE class=luna-Ent><TBODY><TR><TD class=dn vAlign=top>3.</TD><TD vAlign=top>any machine or mechanical device that operates automatically with humanlike skill. </TD></TR></TBODY></TABLE>
–adjective

<TABLE class=luna-Ent><TBODY><TR><TD class=dn vAlign=top>4.</TD><TD vAlign=top>operating automatically: a robot train operating between airline terminals. </TD></TR></TBODY></TABLE>

<HR class=ety>[Origin: < Czech, coined by Karel Čapek in the play R.U.R. (1920) from the base robot-, as in robota compulsory labor, robotník peasant owing such labor]

Quartz, same source

<CITE>Dictionary.com Unabridged (v 1.1)</CITE> - Cite This Source <!-- google_ad_region_start=def -->
quartz /kwɔrts/Pronunciation Key - Show Spelled Pronunciation[kwawrts]Pronunciation Key - Show IPA Pronunciation–noun <TABLE class=luna-Ent><TBODY><TR><TD vAlign=top>one of the commonest minerals, silicon dioxide, SiO<SUB>2</SUB>, having many varieties that differ in color, luster, etc., and occurring either in masses (as agate, bloodstone, chalcedony, jasper, etc.) or in crystals (as rock crystal, amethyst, citrine, etc.): the chief constituent of sand and sandstone, and an important constituent of many other rocks. It is piezoelectric and used to control the frequencies of radio transmitters. </TD></TR></TBODY></TABLE>

<HR class=ety>[Origin: 1750–60; < G Quarz]


German <TT>Quarz</TT>, from Middle High German <TT>quarc</TT>, of Slavic origin.]
<!--EOF_DEF-->
So your both right. ; ) G Quarz was also the first rapper and blingmaster!

[romihs]

Ah but Sandi,

Explain this one away.

Interesting... One learns all the time..

I really didn't know where it came from... Actually had a feeling it was German.

The Slovenian translation for quartz crystal is kremenchev kristal.
So you can see how I missed that one..

Thanks for the explanation.

Sandi

[Zumba]

Would playsand + epoxy work or would it just suck? I'll make a cube later and find out.

[walter]

Larry, hope you have a good time in Frankfurt :cheers:

[davo727]

Hey Zumba, The batches I mixed by volume with 1 part epoxy, 1 part playsand and 3 parts rock worked out much better than the one batch I did with just playsand. That one ended up having a lot of bubbles in it on the surface almost like a foamy effect and yeah it kind of did suck. Its a lot harder to stir the sand mix too without the rock believe it or not. Id say get some kind of non porous rock. I used river rock from Lowes that I washed well. It is various sizes of smooth rock, no limestone or gravel crap in it. Dave

[Zumba]

Good info, Davo.

I tried some playsand + epoxy in a cup and got the foaming effect that you described. I will try river rock tomorrow.

I need to find some dyes because this yellow E/G is pretty fugly. I've got some blue transtint dye for staining wood . I shall see how cool/crappy this turns out!!!!!!

[Zumba]

Here's a piece of E/S (epoxy sand) that came out of a cup. The epoxy conformed to the little seam on the side of the cup (2nd pic) so I guess it picks up details pretty well.

Materials:
West System 105 epoxy with FAST hardener (I had a ton of this stuff from previous projects)
Natural Sand from Home Despot
Cup
Stick

Ratio by volume was about 1:4 epoxy to sand. I probably could've used more sand. I need to find a scale that is sensitive enough to display ounces so I can get exact weight readings.

The color of the final product is kind of a puke/diarrhea mix. I've got a cup of blue mix curing as we speak.

However, texturewise, it's much more aethetically pleasing than mixes with larger aggregate, so I guess the key is to pour the "gelcoat" layer as previously discussed using a mix without large aggregate.

[walter]

Zumba, that looks pretty good!

(btw, here's more info on E/Q...)

Quartz Engineered Stone Countertop Surfaces



The manufacturing process of engineered stone started about 45 years ago in the research facilities of Breton Stone, according to Steve Chambless, co-owner of the local Silestone fabrication and distribution facility in Lewisville.

“It’s all Breton Stone—they got the process down pretty good about 30 years ago, but really perfected it about 20 years ago,” Chambless said. Brenton Stone then sold franchises and product manufacturing equipment (which cost from $25 to $35 million-dollars). About 15 years ago, Coesntino, a 120 year-old-marble and granite-company in Spain began manufacturing the stone, and today Coesntino still supplies white marble and granite as well as the engineered quartz product called Silestone.

About two years ago, Dupont began manufacturing engineered quartz out of Canada. The Dupont product is called Zodiac, which sells for $75-$100 per square foot compared to Silestone at $45-$75 per square foot, according to the Good Housekeeping. Despite the difference in price, both products are produced by the same formula franchised from Brenton Stone.

“The only thing that changes is the quality of raw goods or colors of raw goods, Chambless said. “The percentage of quartz to pigments, resins, binders, has to stay the same, and it does. The hardness of the material is the same. The look of the material is what changes with the percentage of color on a gradient that is put in—not the type. It is still quartz.”

Engineered quartz surfaces do not require sealing because of the resins in the raw ingredients, which make it impenetrable, and the manufacturing process.

Resins, binder, and pigments make up 7% of the product along with 93% purified quartz. Manufacturing quartz begins with the raw white quartz or clear quartz cut out of the mountains. First, the quartz is purified, ground up, and mixed with large quartz particulates—some dime size, some smaller and made into a slab. Through a process of vibration and vacuuming out all air inside the slab, (called vibrocompaction) a 4 and ½ inch slab of engineered quarts can be vibrocompacted down to a ¾ inch slab. After the slab is heated to 180 degrees centigrade, it is polished to a high shine by drums with small diamond bits that act like sandpaper—a process, by the way, that is the same for polishing a granite slab.

(by Dr. Oneida Cramer)

[jsage]

sposi,

Just kidding around. I always find that site useful though. Vaguely remembered robot derived from slavic derivative. Indo Europeans languages, pretty broad group.

Walter,

very nice on the pic, the non consumable looks pretty good too.

On the article I'm still curious about the vibratory frequency. Seems like we had some contradictory findings previously. I believe at a certain frequency (high) the vibration works against getting a good distribution.

Still wondering what grade of epoxy or otherwise they are using. My experience from fly tying, rod building etc, the faster the cure the more prone to yellowing and deterioration. There are also post cured resins which require heat as mentioned. System three has an example. http://www.systemthree.com/p_phase_two.asp . Not to say this formulation is appropriate. More expensive I believe.

Damn, learned metric in elementary but still struggle with visualizing metric scales. I would love to convert, but then I would have to do conversions to communicate to most people.

Excellent article.


Zumba, looking good. What is wrong with puke yellow ; )
Mike

[walter]

On the article I'm still curious about the vibratory frequency. Seems like we had some contradictory findings previously. I believe at a certain frequency (high) the vibration works against getting a good distribution.

I'm trying to chase references and articles but so far, I found nothing. The quote below comes from Italian patent application (describing method of Terastone Technology, which uses cement instead of epoxy):

"...vacuum vibrocompaction of the deaerated layer of mixture by means of application of a vibratory movement with a frequency of 2,000 to 4,800 Hz under a vacuum less intense than 720 mmHg, but not less than 680 mmHg, and for a duration of at least 60 seconds.."

___________________________________________

And here's another take on E/Q:

What is quartz surfacing?

"Quartz surfaces have been around for decades, though the product has only recently gained popularity in the United States. Originally developed as BretonStone about 45 years ago, all quartz surfacing is manufactured in basically the same way — Breton sold the process to other manufacturers such as Cosentino, DuPont, Cambria and CaesarStone.

Quartz surfacing is made from raw quartz crystals. After being mined, the quartz is separated according to size and type, inspected for quality and stored. At the time of production, the quartz and a very small amount of resin and color pigment are mixed until thoroughly combined and then poured into a large tray with a paper liner.

In those instances where two or more colors or types of aggregate are combined to make a color, they are mixed separately with the resin and pigment and combined just before pouring into the mold. Once the mold is filled, it is moved to the vibrocompaction area, where massive presses squeeze the material to roughly half its original thickness. At the same time, a vacuum is applied and the mold vibrated to evacuate the air. Curing is further accelerated by moving the mold with its compressed load into an oven, where it is baked at 100 degrees Celsius for almost half an hour. Then it enters a special chamber where is it air-cooled to room temperature. When it reaches ambient temperature, the product is fully cured and ready for calibration (thicknessing) and polishing. Because of its unique manufacturing process, quartz surfacing possesses qualities not found in other natural, engineered or synthetic materials..."
_________________________________________

[Zumba]

Good info there, Walter.

I'm going to start experimenting with vacuum tomorrow. I've got two Gast rotary vane pumps that I normally use for veneering that can be put to good use. The vacuum chamber will be 6" schedule 40 PVC. I wouldn't trust the stuff under positive pressure, but under vacuum they should be safe. Worst case they implode, rather than explode.

I'm curious as to what the exact purpose of the vibration is. Probably to stir the mix while the vacuum pulls out air bubbles from the surface. Vacuum pressure alone probably isn't enough to pull the air from deeper down in the mix, and it's difficult to physically stir the mix in a vacuum chamber unless you're wearing a space suit.

So I guess the question is, how do you transmit 2000-4000hz frequencies through the mix? The frequency is rather high.... before you posted this, I would've guessed that the frequency would be more like 40-80Hz. I could just tell my friend to bring his 8-speaker bass cabinet and play some jazz licks.

[Zumba]

Hmmm... the more I think about it, the more weird it seems that they'd want to use such a high frequency. If you mounted a high speed router spindle to your mold and spun an eccentric weight at 20000RPM, you'd still only get a vibration of 333 Hz.

I've got a 5hp induction motor lying around.... maybe I'll mount an eccentric disc to the shaft to give me a vibratory frequency of 60Hz. Think that'll be enough?

[jsage]

Tetris,

Never really played it but the vibration should should achieve the best alignment of various shaped aggregates. On the other hand high frequencies could sink larger aggregates or prevent them from penetrating as the smaller particle fill more effectively. Not concerned about perfect but adequate processes. Two factors, possible 3. Frequency, duration, amplitude. Examples, mallet, sander, and how long they are used.

Good info Walter.

[Zumba]

I was thinking that the tetris thing should be done on the aggregate BEFORE the epoxy is added to the mix. Once the epoxy is added, expecially at a 1:10 weight ratio (or 1:14 in the case of the Silestone/Zodiac), the high viscosity would probably prevent any significant shifting of the aggregate. At that point, all you can do is get rid of the air bubbles.

Besides... lets say you had an E/G mixture with the perfect viscosity at the time of pouring. Then somehow, using vibration, all the aggregate fit together perfectly and sank to the bottom. Wouldn't you end up with a pool of empty epoxy at the top?

I'll let you guys figure that one out...

In the meantime, here are some colored blocks for your visual enjoyment. Now that we know what we can expect in terms of aesthetics (the most important part), we can concentrate on the less important stuff like structural integrity. :rainfro: :rainfro:

This time the epoxy to sand ratio was 1:5 by volume. Just like before, it was a medium viscosity West System epoxy. I think a thin epoxy would allow for even more aggregate, as would the addition of larger aggregate (high volume, low surface area). The coloring is Transfast powdered water/alcohol-soluble dye that I bought at the local Woodcraft a year ago. A little went a long way... the amount of blue powder that went into the test block fit on a 1cm section of toothpick.

As you can see from the second pic, "self leveling" ain't gonna happen unless you have vibration and vacuum. Bubbles galore!

And you can probably tell that I screwed up on the top left test block. I used a different type of cup and apparently the bottom didn't have a very thick coating of wax. Stuck for life!

[ger21]

I wouldn't trust the stuff under positive pressure, but under vacuum they should be safe. Worst case they implode, rather than explode.

I still wouldn't want to be standing next to it if it imploded. But, I've been using the 4" PVC ala www.joewoodworker.com with no problems. He says over 200 users have built from his plans, so it should be safe.

Colors look cool.

[RogerH]

We have a couple of machines with cast bases where I work and they are very rigid.

I designed a machine several years ago that was to have a cast base. I never built the machine but I did a lot of research based on information by a company that exibited at the IMTS show in Chicago. I think the campany was ITW Philadelphia. The company appears to be called Chockfast now and sells products for machine foundations and other uses that might be good for machine bases. They used to sell a product intedned for casting machine bases. They have distributers in Europe.

I was going to use granite surface plates as parts of the mold to cast important flat surfaces. The surface plates would still be available for other uses after the base was cast.

http://www.chockfastgrout.com/indextwo.html