[Herbertkabi]

I dont understand why to go to glass or ceramic balls or microspheres?
Sands and granite rubbles very well bandage with epoxy.
regards,
herbert

[RomanLini]

Hi Herbert, that was probably me. I wanted to explore options for making small machines (possibly commercially) relatively lightweight BUT maximise strength through use of larger diameter beams and support structures.

That was to keep production equipment easier to make, machines cheaper to make and cheaper to ship etc etc. I'm not sure microspheres are the answer anyway, I think larger voids in the structure would be better at least for the special purposes I was thinking of.

[ckelloug]

Hi Romanlini,

I agree with you that when possible larger cross section tubes etc are a good thing. As long as the loads you need to carry are small enough that shear deformation isn't a large concern, making more efficient beams is one of the most effective designs.

Most E/G research papers suggest that you want to have the material be something like an inch and a half thick if I remember right so better cross sections may increase the difficulty of small designs. I believe that 5 times the maximum aggregate diameter is needed to get full packing achieved in a large mold but if a beam is close to this size, theoretically a different material design is actually optimal in order to provide enough extra fines to counter the container wall effects on packing.

It sounds like what you are interested in doing is building cored structures where areas of the E/G are replaced with non-structural foam that allows you to get a solid but hollow casting. Is that what you were driving at? It's definitely mentioned as a good idea in numerous publications.

Regards,
Cameron

[howard.zhu]

hello everyone

this is Howard from China. I'm very interested in this thread. As my knowledge, there're some munufacturers in China to make polymer concrete bed, just like Rampf, Schneeberger etc. Unfortunately, these companies never operate well in China.

In China, there're tow industries which need the product urgently due to the previous situation, one is semiconductor industry, the other is machine tool industry. Unfortunately, Rampf, Schneeberger etc never cooperate with Chinese companies due to bad operation.
However, Rampf and Schneeberger already trained some of talents for polymer concrete industry.

At present, plenty of Chinese companies need this techonolgy, they can make joint venture with those companies who master polymer concrete techonolgy.

If someone or some companies are intend to develope their business in China, you may communicate with me. China is the biggest market in the world. Once somebody or some companies enter China market, you will find a huge market in front of you, as long as proper operation



BR


Howard

[ckelloug]

Hi to all still following this thread,

I've finally made my first E/G sample big enough to be testable.

The sample was made along the lines of the last recipe I posted however I realized after I started mixing that I had no G200 zeeospheres and used IMSIL 1240 as a substitute since I had it. Unfortunately, IMSIL 1240 is a lot closer in size to G800 than it is G200 so it isn't an amazingly valid test of the recipe. I also ended up adding more epoxy than I intended. It should have had 62g if it was to recipe and I ended up adding between 62 and 100g. The batch was done with 16 g of KR55 titanate, .1g of BYK A525 deairing agent and used IPDA as the hardener in stoichiometric proportion. I preheated the aggregate and the epoxy to 85C before mixing since this is the optimum cure temperature for IPDA cured epoxy and mixed the epoxy, IPDA, titanate, and deairing agent using a 1inch probe in my sonics and materials VCX 750 ultrasonic disperser.

I had an accident in my first epoxy batch whereby I was putting in 20Watts of ultrasonic energy for about 3 minutes and the epoxy got so hot that it flash hardened. Thankfully, I managed to get the probe out of the epoxy before I had an expensive disaster on my hands. Ultrasonic shear energy: a little goes a long way!

I ended up mixing the aggregate and epoxy mixtures with a cedar shimming wedge in a 1 liter container (after sonicating the epoxy, hardener and additives) which was too small to mix about 800ml of material total and so I don't think it got mixed very well. As a result, I discovered a new phenomena I call rat turding where small lumps would not join the rest of the mixture in the mold and needed to be squashed with a stick.

I then placed the mixed material on the vibration table and manually applied pressure to the mold on the running table to get it to vibrate instead of dancing around the vibe table. This was partially successful but I finally resorted to manually applying substantial pressure to the mixture with a ceramic tile sprayed with mold release while on the vibrating table. In the end, to successfully vibrate the mixture, I am now convinced that the mold will have to be bolted to the table. (I used a Williams Sonoma 9x9 brownie pan as a mold, bought for the purpose, as it was sturdy and had a flat bottom unlike the walmart variety). I sprayed it with Mann-release 200 which was partly successful but the packing with the tile caused stickage.

I'm beginning to believe that it is going to be necessary to make a more substantial mold that can be bolted to the table although some of my problems undoubtedly occurred since the aggregate was off ratio and I couldn't mix it as well as I would have liked.

There are shiny spots on top of the casting which indicates that the epoxy distribution is not uniform and even as dry as the mix seemed while mixing it, the shiny spots are evidence of a slight excess of epoxy. There is no sign of the part wanting to crumble.

The part weighs in at 1588 g but the exact epoxy content is unknown due to a measuring mistake but between 62 and 100g or between 4 and 6 percent by weight. I estimate this at between 11% and 18% by volume but due to the irregular surface of the sample, I cannot be sure.

I intend to try to flatten the surface by hard milling with Cubic Boron Nitride inserts on my trusty bridgeport tomorrow running flat out. The piece appears quite strong and very stiff and I am hoping I can confirm this tomorrow on the test column.

At any rate, now nobody can say I'm just over here pontificating! :cheers:

Regards all,

Cameron

[greybeard]

Hi Cameron, and welcome to the club of unexpected oversights

.....I'm beginning to believe that it is going to be necessary to make a more substantial mold that can be bolted to the table ........

Would it be better to consider a bolted-on clamping system, 4 bolts/wing nuts + two beams, rather than modify the mold ?
Gives you a more versatile set up.
Regards
John
ps still with the green vegies ?
pps did you find any good ham ?

[Quad2T]

hello everyone

this is Howard from China. I'm very interested in this thread. As my knowledge, there're some munufacturers in China to make polymer concrete bed, just like Rampf, Schneeberger etc. Unfortunately, these companies never operate well in China.

In China, there're tow industries which need the product urgently due to the previous situation, one is semiconductor industry, the other is machine tool industry. Unfortunately, Rampf, Schneeberger etc never cooperate with Chinese companies due to bad operation...

It's not "bad operation"...it's because they know the Chinese companies will steal their chemical formulations, mixing methods, casting processes, etc and set up competing companies to take away the business, They refuse to play that game because they're not stupid like all the other companies who rushed over there only to get screwed over. YOU want to learn how to do polymer castings....learn it the same way Rampf, Schneeberger, etc did, through trial & error experimentation!!!

[RomanLini]

...
It sounds like what you are interested in doing is building cored structures where areas of the E/G are replaced with non-structural foam that allows you to get a solid but hollow casting. Is that what you were driving at? It's definitely mentioned as a good idea in numerous publications.
...

Yep. I've already worked with designing making and using complex molds and inserts and so I don't see that as a down side. Mainly I'd design from an approach of the structural design providing much of the strength, using maybe an easier/cheaper material than to just make "blocks" for strength out of a perfect material. But that's just me. I like to optimise lots of things together to make a great design rather than just do one or two things the "proper" way.

Congrats on the experiment! The bit about "Rat Turding" made me snort.

I'll try to give a few tips;
1. Its VERY hard to mix aggregate with such a small amount of epoxy, even with your excess epoxy that would have been a problem. Forget any type of displacement mixing (like using a stick)! Instead, gravity mix, think "cement mixer" which only needs to be as complex as a cylindrical tupperware container rotated and/or slowly shaken. You can add a mixer inside the container like a large steel or stone ball. Don't worry about it crushing the aggregate. Mix time should be 5 to 10 minutes by the clock (longer is better), depending on your epoxy type of course.

2. Don't get the epoxy so hot before mixing! You drastically shortened the pot life which made it get thick sooner than needed, and made mixing harder and your rat turds worse. Pre heat epoxy to about 40'C and no more, this lowers viscosity so it mixes nice but is not hot enough to make it prematurely thicken. Then heat the mold AFTER it is poured in.

3. You can make a cheap incubator for curing by getting one of those cheap little fan heaters with digital thermostat control built in, and put it in a big cardboard box with your mold.

4. Don't try to heat to your thermoset 85'C as you tried, as you add heat you will naturally get some exotherm added so you have to be careful, try heat the box to 40'C and check the epoxy centre of mass with a infrared non-contact themometer. For your early tests I woukld err on the side of lowish temps, 50'C to 70'C will probably get you a good cured result but 95'C could wreck it.

5. You can place a flat sheet of flexible plastic under your top tile, this won't stick to the epoxy and makes it much easier to remove the tile and the sheet. Most poly's are ok for this and won't stick.

6. I think the vibrating will be a lot more useful to you than the ultrasonics etc, so you are right in going for a much better vibrating setup and more vibrating etc.

Congrats again, and are you planning to flex and strength test the piece you made?

[ckelloug]

Yep. I've already worked with designing making and using complex molds and inserts and so I don't see that as a down side. Mainly I'd design from an approach of the structural design providing much of the strength, using maybe an easier/cheaper material than to just make "blocks" for strength out of a perfect material. But that's just me. I like to optimise lots of things together to make a great design rather than just do one or two things the "proper" way.

Congrats on the experiment! The bit about "Rat Turding" made me snort.

Hi Romanlini,

My machine plans are in the much longer term than my material plans which is why I feel like I have time. Getting the E/G formula and process right to commercial standards is a personal quest based on a promise I made to myself to make E/G the first complicated project I actually finished. It's changed my career and allowed me to work on much more fulfilling things in my day job. As a result of the knowledge and confidence gained from E/G, I managed to attach myself to the materials science lab at work doing 3D electron microscope imagery algorithm design!

I work by flattening N unrelated problems at a time using the successes of each to motivate myself for the others. I'll get past the materials work in time and on to machines but I have such a nice materials lab at this point that I may do more materials for the joy of it. Because I have a fairly thorough understanding of these types of composites at this point, I have some ideas on special purpose materials for other parts. I keep discussing the original design direction here because it allows anyone interested to duplicate the results.

I'll try to give a few tips;
1. Its VERY hard to mix aggregate with such a small amount of epoxy, even with your excess epoxy that would have been a problem. Forget any type of displacement mixing (like using a stick)! Instead, gravity mix, think "cement mixer" which only needs to be as complex as a cylindrical tupperware container rotated and/or slowly shaken. You can add a mixer inside the container like a large steel or stone ball. Don't worry about it crushing the aggregate. Mix time should be 5 to 10 minutes by the clock (longer is better), depending on your epoxy type of course.

I think your mixing plan is an excellent idea. I will try to adopt it when I make my next sample. I was going crazy for the last month on travel wanting to be back in the lab doing work. I was so excited to get lab time this weekend after cutting the grass and dealing with someone breaking into my house while I was gone that I slightly jumped the gun on making a sample starting without all of the proper materials and equipment improvising from there a bit with what I had laying in the lab.

Part of why it has taken me so long to get to this point is that as a private researcher on what would class as a shoestring budget in the industrial sector, I cannot afford to be wrong too many times as this is a bloody expensive endeavor. It's a lot cheaper to read books and calculate than to mix and test. I could have bought a decent VMC for what I've spent on the capital equipment and space to be able to do this lab work.

I actually mixed the aggregate by placing two beakers on top of one another holding them together by hand and repeatedly turning. I hadn't prepared for this step as I was in a hurry and the tiny samples I've made in the past and epoxy tests are a lot more forgiving. This actually might have done a better job of mixing the aggregate with the epoxy than the stick although a lot of mixing occurred just vibrating the mixture.

After mixing the aggregates, I then poured in the epoxy which had been ultrasonically mixed. One pleasant byproduct of high power ultrasonics is that they very effectively drive out dissolved gases in just about anything. As long as you get the probe into acetone and run a cycle to clean it, this is a very effective way to disperse additives and mix the epoxy.

2. Don't get the epoxy so hot before mixing! You drastically shortened the pot life which made it get thick sooner than needed, and made mixing harder and your rat turds worse. Pre heat epoxy to about 40'C and no more, this lowers viscosity so it mixes nice but is not hot enough to make it prematurely thicken. Then heat the mold AFTER it is poured in.

Heating to 85C didn't seem to be a problem but I agree that a lower temperature might have been better. The full cure for IPDA and epoxy at this temperature is about an hour and a half. It may have gelled a little on me during mixing but it wasn't too bad. I'm not sure that starting at the optimum cure temperature would work well for a large part but 85C gives the optimal cure percentage for IPDA according to a published differential scanning calorimeter measurement in a journal article I have a copy of back in the lab. The Rat turds could have been an artifact of premature gellation but they showed more signs of being linked to poor mixing IMHO as the rest of the part was fine. In that the aggregate ratio was off due to the bad substitution of IMSIL 1240 for G200 Zeeospheres, more epoxy would have been required than for the correct mix.

As an aside, I just did a calculation and realized that my first overzealous ultrasonic application where I hardened the epoxy in the pot put 3600 J of heat via ultrasonic vibration into 60 g of epoxy over 3 minutes. Bad Juju. I suppose I need to cough up the money for the temperature probe attachment for the sonicator. . . At 1J/gK, It would have raised the temperature something like 60C so I ended up with epoxy at 140C which is why I had to yank the probe out to keep from a messy cleanup.

3. You can make a cheap incubator for curing by getting one of those cheap little fan heaters with digital thermostat control built in, and put it in a big cardboard box with your mold.

I'm already a bit more advanced than this. I have a surplus 36 inch by 36 inch by 48 inch Grieve convection curing oven with a very stable temperature controller considering it can't do pulse width modulation. The cake pan has got to go however. It wasn't flat enough on the bottom and the sides don't come off making demolding a pain and flattening the sample enough to test unenviable. I'm going to fab up a sample mold out of A-2 with a bolt flange so that I can attach it to the 2HP vibrating table with socket head cap screws.

4. Don't try to heat to your thermoset 85'C as you tried, as you add heat you will naturally get some exotherm added so you have to be careful, try heat the box to 40'C and check the epoxy centre of mass with a infrared non-contact thermometer. For your early tests I would err on the side of lowish temps, 50'C to 70'C will probably get you a good cured result but 95'C could wreck it.

Being in a forced air convection oven with a sample only 3/8 inch thick in a steel pan, I think that there is enough air movement to counter most exotherm effects at the epoxy level used. The thermal mass of the mostly quartz aggregate is around 830J/kgK and a mass of 1.6kg for the sample. With between 60 and 100g of epoxy in 1.6kg of sample, I think that the exotherm effect is negligible in this case. I'd have to drive over to the lab and pull the study out to find out the exact exotherm energy but IPDA is not a very aggressive hardener and the physical properties of the sample are suboptimal unless the epoxy stays at 85C as long as possible: Not 80C and not 90 C, there is a pronounced improvement in cure percentage and mechanical properties curing at 85C. I may try to thermocouple the part at some point in the future based on your recommendation, especially in a larger sample but I think the 85C temperature is right for the exact circumstances outlined above. Thanks for your caution, it has made me write down my argument for doing it this way clearly and to share it with others out there for discussion.

5. You can place a flat sheet of flexible plastic under your top tile, this won't stick to the epoxy and makes it much easier to remove the tile and the sheet. Most poly's are ok for this and won't stick.

Thanks for your suggestion, I do have some pure teflon sheet laying around from another project which I could throw into the bottom of the cake pan for easier demolding.

The cake pan was an expedient for this sample. My current view in precision molds is use surface ground hand lapped A-2 steel with a silicone mold release. It is very important to get the cast side to come out flat and the cake pan and non-precision molds frequently come up short in this regard.

6. I think the vibrating will be a lot more useful to you than the ultrasonics etc, so you are right in going for a much better vibrating setup and more vibrating etc.

I got the ultrasonic system for some other research I am doing. I have a sonics and materials VCX 750 disperser. It is useless for mixing epoxy with aggregates but excellent for mixing neat epoxy and various additives and also for nanomaterials. It is specifically useful in this case because it creates the highest possible fluid shear ensuring as complete a mixing as possible. There are also several published studies that show that there are beneficial sonochemical effects when mixing epoxy with ultrasound. (I didn't make up the whimsical sounding term sonochemical and it is not new-age mumbo-jumbo). The energy put into the system as ultrasound has such a high intensity (~40kw/m^2) that it is sufficient to cause reactions in chemical side chains on the epoxy or even ring opening! See MacroMolecular Materials Engineering 2005, 290 , 423-429 for a case where a sonicated epoxy control was stronger than epoxy with SiC nano-particles!

Congrats again, and are you planning to flex and strength test the piece you made?

Absolutely.

I spent the day on the Bridgeport mill milling a section of the sample to be relatively flat. I used cubic boron nitride TNG322 inserts in a 1.5 inch diameter 2 insert APT insert mill. These were unfortunately finishing inserts bought for a paying project that never materialized so I was only able to take off a few thousandths at a time. You could hear the mill straining every time it hit an aluminum oxide chunk. The material milled fairly nicely and made a somewhat fine dust. You could see a slight glow where the CBN was cutting and the material cut very cleanly with very little to no tearout. Even the aluminum oxide chunks cut very cleanly.

I was able to feel the material as it vibrated while cutting and you could feel that the vibration was localized to the cutting area and that on the opposite side of the plate there was much less vibration and that almost none of the vibration was transferred to the machine. I think PCD inserts would have worked even better but I don't have any and my spindle only goes 5000RPM which may be a bit low for this. While hard milling worked well and produced a finish like that of very well troweled unswept concrete, it was agonizingly slow. In 4 hours, I managed to mostly flatten a 3inch by 9 inch area of one side removing maybe .050 inches as well as some very narrow .1inch ridges near the edge where I had been squishing with the tile. A total of 54g of material were removed from the 1588g sample in about 4 hours of machining operations. Conclusion: cast the sample to the right shape as you will regret having to do any machining operations. It might have gone a little better with a coarse diamond wheel on an automatic surface grinder but it was still very painful.

I'm impressed with the apparent strength, rigidity and damping of the sample but I didn't have enough time today to get it sectioned and run on the test column. I'll see if I can't get it done tomorrow. Now that I am back, I've got to catch up

Regards all,

Cameron
:cheers:

[RomanLini]

Ahah. Now I understand your equipment setup better I won't again suggest putting a fan heater in a cardboard box.

I still want to clarify that point I made; that you should heat the epoxy to the best temperature for mixing, then pour into the mold, then the mold kept at the cure temperature. Both processes ie mixing and cure have different needs and work best at different temps.

You are probably right that there will be very little exotherm since you have such a small epoxy percentage, but still I would be monitoring cure temp in the centre of the mass for the duration of the cure.

The good thing about the non-contact IR thermometers is that they will read the inside temp of something, perfect for molds.

How do you plan to post cure? Are you going to use a slow cure for X days then an elevated temp post cure? And if you strength test I guess you do know that (generally) the epoxy may not reach full hardness until some considerable time after the inital cure?

Re the testing phase, maybe you could contact a masonry firm that does the smooth surface grinding of granite for tombstones etc and use their surface grinder to process your material to an exact thickness and polished surface each side, that might give greater accuracy to the tests.


You said; "My current view in precision molds is use surface ground hand lapped A-2 steel with a silicone mold release."

That's gonna be a whole world of hurt in itself (for so many reasons), but you'll discover that yourself when the time comes...

[ckelloug]

Ahah. Now I understand your equipment setup better I won't again suggest putting a fan heater in a cardboard box.

It was a good suggestion but as a consumer, I don't like heating my house to 85C so I suspect the thermostat on such a heater may not go height enough.

I still want to clarify that point I made; that you should heat the epoxy to the best temperature for mixing, then pour into the mold, then the mold kept at the cure temperature. Both processes ie mixing and cure have different needs and work best at different temps.

I agree that a lower mixing temperature might be better. I'm thinking that in the future, I will start with the epoxy at room temperature and then use the ultrasound machine to put a few thousand joules of mixing energy in leaving the epoxy at 50C or 60C.

You are probably right that there will be very little exotherm since you have such a small epoxy percentage, but still I would be monitoring cure temp in the centre of the mass for the duration of the cure.

The good thing about the non-contact IR thermometers is that they will read the inside temp of something, perfect for molds.

I'll put an IR thermometer on my shopping list although I think embedding a sacrificial thermocouple might get a better reading of the internal temp.

How do you plan to post cure? Are you going to use a slow cure for X days then an elevated temp post cure? And if you strength test I guess you do know that (generally) the epoxy may not reach full hardness until some considerable time after the inital cure?

I'm not planning a post cure for this formulation at present because the DSC study I read suggests that at 85C that no further heat is generated after about 90minutes. The cure is calculated to be something like 98% there. Post cures definitely benefit some formulations but I'm not sure I need it for Hexion 813 plus IPDA.

Re the testing phase, maybe you could contact a masonry firm that does the smooth surface grinding of granite for tombstones etc and use their surface grinder to process your material to an exact thickness and polished surface each side, that might give greater accuracy to the tests.

This is a good idea. I've been planing to get an old surface grinder and rig it with a vacuum chuck but I ended up needing an analytical balance for another one of my research projects and find myself watching the budget a bit closely right now. I'll look into it.

You said; "My current view in precision molds is use surface ground hand lapped A-2 steel with a silicone mold release."

That's gonna be a whole world of hurt in itself (for so many reasons), but you'll discover that yourself when the time comes...

I've already made one of these and I am fully aware that it is not easy or cheap. The current model is a vacuum infusion mold for making neat epoxy samples. It took me several weeks to do and I ended up having to scrap the seal ring after cracked welds and mill one from solid. The seal has two square oring grooves with rounded corners which I had to hand mill on the brideport. A-2 is hard to mill and hard to drill. It has the advantage of virtually no dimension change on hardening. It also is nice because it is very homogenous, polishes up nicely and is available from my local tool steel service center. I wouldn't recommend it to DIYers making one-offs but for precision parts like test samples or mass-produced parts, I think the strategy is fairly sound.


On another note, I like your idea of using a ball mill for mixing now that I've thought about it more. I wasn't so sure initially because I don't like cleaning dried epoxy out of things but now that I've thought more about it, I realize that when combined with Jon Pry's suggestion in post 3961 of using a Boron Trichloride complex hardener which is latent below 80C that it would work very well. It's also possible that a V blender could be used. Your suggestion combined with John's would make a process that is a lot easier to manage. I'd think that LEECURE 38-239 B BCl3 CURING AGENT would be great.

Regards all,

Cameron

[Steven.ji]

Epoxy at the viscosity of water would have plenty of reactive dilutents and would "blush"several days after cure.Blush is a waxy buildup on the surface.The proper type of epoxy for self leveling is rather thick and will not blush.As you are in Europe...Search google for table top epoxy.For US & Canada...http://www.uscomposites.com/kk121.html
Larry

Hi friend

I can not contact you by e-mail, do you have any new contact information?

May I conmmunicate with you?

Regards

Steven

[ckelloug]

Howdy folks,

My new sample was disappointing.

Modulus 1.56e6psi plus or minus 0.31e6 psi
Strength 3589psi plus or minus 587psi

The explanations I have are the following:

I didn't have g200 Zeeospheres and substituted IMSIL 1240 which has a similar distribution to g800 which was already present. This would have lowered packing density.

I think I used the wrong epoxy mix ratio due to misreading my notes in the heat of battle.

Too much of the potentially incorrectly mixed epoxy was added to the sample due to a lab procedure error.

The titanate to aggregate ratio was off due to the procedure error.

This exercise amounts to a good dry run but the properties were similar and slightly inferior to the samples provided to me by jhudler and greybeard.

I don't think these results are anywhere close to representative of what should have happened so I'll be repeating this test when I get some more material ordered. I may end up with some extra zeeospheres.

Regards all,

Cameron

[RomanLini]

Isn't that modulus very low, like about 4 times too low?

Sorry to hear the results weren't great. But first tests often go like that.

I would suggest a slightly lower temp cure (maybe 70'C or 75'C) followed by a lengthy post cure ot at least a week at about 45'C, then an elevated temp post cure of maybe 12 hours at close to your theoretical perfect thermoset temp, probably about 75'C again. I know you stated that a post cure should not be needed with your material, but from my experience the right post cure procedure makes a huge difference in rigidity and strength. The obvious test would be to make two samples in one pour, then post cure just one and test the proerties of both.

[ckelloug]

Hi Roman,

We're lacking a factor of about 2 in modulus and about 25% in strength. Models indicate that modulus is inversely proportional to epoxy percentage in a nasty non-linear way and since I know too much epoxy got added, it's somewhat to be expected.

I've had good results in the past curing solid Epoxy/IPDA samples at 85C but I'll review the results again when I get over to the lab. As long as the original cure has been done at the correct temperature, a high temperature post cure shouldn't harm the sample and has the potential to make a slight improvement.

Got to go cut grass at the lab today.

--Cameron

[veteq]

Hey Cameron,

Nice to see you got results with your nice lab-setup. cool.

Could you tell a bit more about the process off demoulding, did you had some trouble with it? Since the mould is vibrated and maybe the release agent gets broken? What did you used for the release agent.

For my own machine i`m making some progress to, i got a wooden mould cnc machined and i have to put it together the next few weeks. Then i can take the mould with me to Germany to a big EG manufacterer, here i cann use there mixture and vibrating table etc, they are going to help, so thats pretty cool for me...

Kind regards.

Roy

[ckelloug]

Hey Cameron,

Nice to see you got results with your nice lab-setup. cool.

Could you tell a bit more about the process off demoulding, did you had some trouble with it? Since the mould is vibrated and maybe the release agent gets broken? What did you used for the release agent.

Hi Roy,

I used Mann Release Ease-Release 200. http://www.mann-release.com/erelease.htm The combination of compression and vibration probably did breakdown the layer. This is a silicone based release agent selected for easy availability over the internet here in the states.

Demolding was accomplished by whacking the back of the warm mold with a big stick and sliding a large putty knife down the sides. In general, one probably wants to make a mold that comes apart for a more precise release operation. This was a test done in an ordinary cake pan. The sample was between 1/2 and 3/8 inch thick and as a result, procedures for it probably don't transfer to real molds.

For my own machine i`m making some progress to, i got a wooden mould cnc machined and i have to put it together the next few weeks. Then i can take the mould with me to Germany to a big EG manufacterer, here i cann use there mixture and vibrating table etc, they are going to help, so thats pretty cool for me...

It sounds like you have made some good friends! I wish you the best of luck with your machine and I sincerely hope that you post all about it here when you get it done if your collaborators will let you post it.

Regards All,

Cameron

[veteq]

Hey Cameron,

nice to hear you also used the silicone agent, this was also the same procedure the German Engineer explained to me. Releasing nicely sound a bit difficult.

On the Dutch cnc forum, people also said to me a wax agent was possible, so i was in doubt... Nice you also use silicon, it made me just order 3 cans off it by a local shop..

For my design releasing will become really hard...look at the picture, it is 1 part and the MDF wooden mould is al around/in it, getting it of will be a pain, but for 1 piece its not a real problem, it will be poured from the backside of this view.

Offcourse i will post it here when the proces is done, think that isn`t a problem by the German company, i just called them all and every company just hang the phone on me... Then i spoke to the chief engineer and owner off a nice company, this was the right person!!! He said that he understood the difficulties and offerd me to come to his company and take the mould with me!!!

[johnohara]

Hi Cameron~

Congrats on the sample.

What kind of air entrainment did you see with this piece?

~John

[ckelloug]

Hi Johnohara,

Air entrainment was more than I would have liked but not a lot more than the sample Walter sent me several years ago from one of the commercial vendors. Since the sample had the wrong epoxy quantity and the wrong aggregate distribution due to the lack of G200 zeeospheres, I'm dubious about the usefulness of the results. All I can say is that the damping properties while milling the stuff seemed pretty good.

I'll report more with future samples when I have the right materials and a written procedure that is more resistant to the mistakes I made this time.

--Cameron