If you want a big CNC machine you need a strong, vibration-resistant base. They build bells out of metal, so that might not be the best if you want something that doesn’t shake. Epoxy granite is your best bet, but what epoxy granite is the best? That’s the question [Adam Bender] answered in a series of experiments that resulted in a great-looking CNC machine.
While this is a project that resulted in a completed base for a CNC machine, this is also an experiment to determine the best formula for creating your own epoxy granite. The purpose of the experiment is effectively to determine the best-looking epoxy granite and uses four variables in the composition of this composite. Play sand, gravel, dye (in the form of iron oxide and liquid epoxy dye), and two-part epoxy were used to create seven different samples. Samples using rock didn’t turn out that great and still had trapped air. This was true even if the epoxy was put in a vacuum chamber for degassing. The winning combination turned out to be a mix of 80% sand and 20% epoxy with a bit of black dye, vibrated for 30 minutes on a DIY shaker table.
With the correct formula for epoxy granite, [Adam] set up his mold and waxed everything liberally. The internal skeleton, or what the CNC machine will be bolted to, is assembled inside the mold and the epoxy is poured in. The result is fantastic, and an excellent base for a machine that turns metal into chips. You can check out the video below.
Nice work!
It is recommended to first mix the sand + epoxy part A and dye and only then add epoxy part B and again mix everything together. This gives you more time for mixing.
Oh and don’t forget to wear gloves :-)
Did you even watch the video in which he clearly stated all of this?
I appreciate the text summary. Videos are great if you need to watch the technique but a two sentence summary (or even a page of text) is a thousand times better than watching a video to glean the same information.
Are you saying that a sentence is worth a thousand pictures?
Also good stuff if you want to put together a DIY optical bench
Would the vibration table make it self level? Hence the usefulness for an optical bench?
It would self-level but the main reason is optics tables need weight and damping. They’re usually run on air bearings of some sort, which does most of the leveling.
By self-level do you mean the resin mixture will level to the horizontal or do you mean that the entire structure will self-level?
I wonder if Corian would be a better alternative the stuff they use for countertops.
Well, it might have similar properties (but according to DuPont, its Young’s modulus is about 8 GPa – about the same as epoxy alone), but you can’t pour it into a mold. Corian isn’t sold in kit form; only as complete pieces. So you can’t just pour it into a mold, or otherwise form it. Because Corian is a composite based on acrylic polymer, you can probably cut it and weld pieces together with acetone, but you’re not going to get the kind of stiffness needed for any kind of machine tool.
Corian is a fine product for countertops. It doesn’t have the density for this application. It does not have the bulk properties or thermal stability necessary for machine bases.
Thermal expansion of concrete(epoxy granite included) is similar to that of steel, and half of aluminium… – should he expect delamination and/or buckling in near future?
Not unless it’s kept somewhere that experiences wild temperature swings.
you mean like my garage that can easily swing 25C in a day? or over 45C between summer and winter?
RE: Mixture composition – https://www.cnczone.com/forums/epoxy-granite/30155-epoxy-granite-machine-bases-polymer-concrete-frame.html
Enjoy reading 400 pages (some of which is real rigorous— materials engineers start breaking out ANSYS and Mogilce gets a mention in there too)
The heat generated from the movement of the gantry to the linear ways generate a non-trivial amount of heat. those linear rails have a pretty significant amount of contact area interfacing with the structure, so I guess you get a win there, but alu has both a CTE and a thermal transfer high enough to cancel out that win. Buckling to actual critical failure? Probably not a concern in this case.
But I wouldn’t be surprised to see some dimensional creep with enough thermal cycling (And even then, I bet the compressive creep would be an order of mag less than the wear on the ways, considering how flame-hardened Hardinge ways end up with a few thou easily, and 6061 is like swiss-cheese comparatively.)
Like ian42 said, ambient temperature swings (daily cycling and seasonal changes) are another factor. And like some other dude mentioned, I’d be interested to see if delamination occurs.
Very intersting. I had not thought of creep issues at all. I’m not sure I understand it that well. Is creep a dimensional change as a result of applied stress, or is it a function of mass flow over time. Or perhaps both?
I guess I will have to re-educate myself on the topic. So thanks for sending me down that rabbit hole!
I think that steel has a coefficient of thermal expansion that is at least one order of magnitude greater than that of cured epoxy solids. The buckling issue is resolved by making certain that the adhesion of the composite to the steel is as near perfect as possible. Meaning, a controlled bond-line thickness that is idealy as thin as possible, zero or near zero voids, and careful cure. The interface between the composite, the adhesive and the steel is controlled by the higher modulus of the steel, it restrains the thermal expansion of the composite to that of the steel. At the molecular level, over time, lots of time, the bondline will degrade and part the adhesive and cause cohesive failure.
Just happens to be a subject that I know a great deal about as a result of adhering UHMW PE to any substrate. The happy result is that the UHMW never buckles with changes in termperature.
How do you stick anything to UMHW PE?
That’s my question too.
I have spent a long time figuring out how to stick stuff to thermoplastics polyolefin’s. Thousands of hours I would guess. The only method I have found that was permanent or close to it, and that increased the surface energy enough to allow the adhesive to wet out the surface is to use very nasty chemistry.
Think in terms of fluorine gas mixed with other elements to create hydroxyl, carbonyl, carboxyl and other molecules that are, for lack of a better term, sort of inverted and ‘screwed’ into the surface of the plastic.
Making F2 out of HF is a lot of ‘fun’ HF is so much fun that a small spill, not instantly dealt with, will cause the fluorine to melt your bones. Don’t try this at home!
The results are impressive though. In a huge number of shear, peel, and other variants of ASTME tests, the adhesive almost never disbonds from the plastic. The adhesive will normally come off the white-metal blasted steel coupon than the plastic itself. Normally the lower modulus plastic fails, but even then, the plastic on the bond-line will retain its normal shape at thicknesses up to 1 inch.
In one experiment we had the VP of R&D of a major UHMW manufacturer in to see an experiment where we heat cycled two 10 foot long by 1 foot wide pieces of plastic attached to steel side by side. One sample was held in place by the traditional welded washer attachments the other was glued on with epoxy.
We cycled it from ambient to 170F a dozen times. In each case the traditionally attached UHMW PE buckled as a result of differential thermal expansion, the adhered specimens never moved at all.
I hired a materials engineering firm to do a comprehensive analysis of the phenomenon and they concluded that the only point the might cause eventual disbonding was at the bond-line itself. Of course the UHMW wears out sooner than any failure could appear to the adhesive.
The comment of the R&D guy was priceless; he kept saying over and over again, I am seeing it, but I don’t believe it.
12L14: But epoxy has a tensile elongation of about 4%, so while your machine may warp with extreme temperature changes if the design allows this, it’s probably not going to break. And don’t forget epoxy’s most useful feature: it sticks to things VERY WELL.
Notably, graphite fiber has a negative thermal coefficient of expansion, and yet people make all kinds of things with carbon fiber and epoxy, and when fabricated correctly, they don’t delaminate or buckle. Not only that, but the composite formed can have nearly zero thermal expansion, as the graphite fiber compresses the epoxy and the epoxy stretches the graphite fiber as temperature rises.
Similarly, in an aluminum-concrete construction as is described in the video, the aluminum will stretch the epoxy and the epoxy will compress the aluminum, so the overall thermal expansion should be somewhere between the thermal expansion of each alone.
The bottom of many older mills and lathes is typically hollow for filling with sand or water. They act as dampeners.
the hollow cavities are more because of weight and ease of casting considerations…
More because of suds ;)
Old mills usually have the cutting fluid sump and pump in those bottom cavities
Yes, in the past they use to make floating concrete slab over a square hole filled with sand to minimize vibration from and to the building. Having lots of heavy machinery in the same room often will cross transfer hits and vibration, especially hydraulic or rotary hammers.
Inevitable pedantic comment: dampeners make things wet. Dampers absorb vibration.
I’m glad you said it because if you hadn’t I would have! My new model is to eschew pedantry. Well, its an old model, I saw it on a bumper sticker when I was at MIT back when cars had bumpers and cranks!
If the mold could be filled inside a chamber with reduced pressure, pouring the resin and filler mix in a narrow stream to let air gas out, that would help reduce trapped air bubbles. Let in normal pressure after filling and it will collapse lower pressure pockets. Better would be to increase the pressure in the chamber after the lower pressure filling.
Flawed methodology throughout, probably due to budget constraints.
His judgement of the end result effectiveness of the solid base appeared to be surface finish only – no measurement of rigidity at all. Sure it looks great, but what about intended function?
It can be inferred during his prototyping phase that the more epoxy he mixed in, the ‘better’ his results, whatever better means to him. So why did he not just make a 100% epoxy block for testing, perhaps with a small amount of dye, then carry out proper testing on the rigidity across all prototypes and compare? I can only think it is due to costs.
The reason why Carbon Fibre is strong is because the carbon connects internally to itself via fibres, is then encased in epoxy. Sand has no such inter-connective force – the entire strength of this part is just due to the epoxy, nothing else. I do concede however that mixing in solids such as sand *may* reduce vibration, but its far from certain.
interfaces of the different density materials of this composite impede the propagation of the ringing vibrations since each material has a different resonant frequency.
Spherical powders are commonly added to epoxies to increase strength and change other properties. They are not strong as filament additives but can still be an improvement versus clean epoxy.
Compared to epoxies, sand is very stiff. A sand-epoxy mix will be stiffer than epoxy alone. It will also be denser and more wear-resistant.
Must be planning on a Kickstarter campaign. Appearance is everything in Kickstarters. I questioned the use of dyes and colorants in the first place, since these can only hurt the properties. I can understand this if you’re making counter tops, but the case of materials whose stated primary purpose is their physical properties, it doesn’t make sense.
However, your conclusion about strength is questionable – first, there was no claim made about the strength of the composite, just the stiffness and loss coefficient. But even beyond that, the same could be said about concrete – the aggregates in concrete don’t contribute anything to its tensile strength, but they do wonders for its compressive strength. And yet people make things out of concrete.
Also, the aluminum frame contributes to tensile strength.
This is an optical device, and so a colorant has important physical properties.
This isn’t a Kickstarter, the hell. Look at the guy’s site, he’s a designer who designs and builds devices for clients and writes up nice documentation online as a sales lead.
Always cool to see a project use artificial stone!
There are some interesting experiments being done to find castable stone formulas for wood stove design.
http://donkey32.proboards.com/board/17/geopolymers
This mix is amateur and the research was not done in a robust scientific manner.
The mix needs functional additives with as few natural harmonics as possible. Sand is ridiculous. Use high aspect ratio minerals like bentonite and wolastinite. It needs toughening with coreshell rubbers. It needs a combination of bis a, bis f and novolac resins and a cooler jeffamine curative. Then it needs a post-cure heat cycle.
Awesome. I’d love to see a full write up with some pictures and maybe even video. Until then, don’t rag on others hard work when you have nothing but a paragraph of empty words to show us.
A few points. I commented on this because it appeared in my news feed. I had no idea what Hackaday was, and its goals. It is an interesting site.
I post under my own name, it adds credibility in my opinion.
I assume nothing about the people who are writing and sharing, this is a good policy in my opinion because it allows me to give knowledgable input in areas in which I have particular knowledge.
You assume that I have some particular interest in machine bases because I posted a reply with some suggestions. This is not correct on your part.
I work in the field of composite materials using both thermoset systems and thermoplastic systems.
One area of expertise I have is in making wear resistant thermoset repair products and coatings. These materials have properties that may be desirable for attempting to cast into machine bases.
I have made many iterations of various formulae and as a result tested a great many of these materials for their physical properties using ASTME standardized tests for engineering properties. I have made several thousand tests over the past 25 years. I know how to design experiments using sophisticated means and have deep knowledge of finite element analysis methods.
When I made my comment, it was to give the group some ideas of other materials that would likely work far better than those used in the experiment reported upon. These materials are for the most part easy to obtain and are well proven to provide great results.
I have the advantage of being able to either design my own epoxy system, or as is usually the case, having a colleague with far better skills than mine do that work for me. If one were to ask, I could put them in touch with formulators who can do the work for them on a commercial basis. The same is true of sourcing the other materials.
As to ‘hard’ working having merit on its own; hard work is a given. If one isn’t prepared to do hard work, then one can achieve little. But to assume that what I am telling you is based on ‘easy’ work is absurd on your part.
However, I do not think that it is possible to make a machine capable of better than 0.01″ precision with high repeatability using these materials to cast bases of any useful size. The reason I think this has to do with the thermal stability of the materials, as well as and more importantly, the thermodynamics of the cure cycle. On top of that, the tool needed for the correct casting is highly sophisticated and would cost at the high 5 or low 6 figures to produce. Not for hobbyists.
A better path would likely be to use fibreglass lay-up techniques in simple tools and machining those after proper cure to achieve the ultimate shapes required.
What on Earth are you taking about? What is this mystery machine that’s required? And seriously: fiberglass? Now I see why most of your post is stating your qualifications: what you’re saying is nonsense.
Jim, what mystery machine are you saying I am talking about? I am speaking about using epoxy composites as a base material to make any precision machinery. You know, the subject of the video, using such a material to make a big vibration resistent CNC machine capable of high precision.
As to the problems of casting large masses of epoxy you need to understand the thermodynamics of the exothermic reactions that bring heat into the resin and cause the initiation of the crosslinking of the polymers. You don’t understand those issues but I do. In fact I know rather a lot about them.
Ask yourself this question. If epoxy composite bases for machines are such a great idea, why are they not used by the major machinery manufacturers in any fields? Do you imagine that corporations like for example HAAS are completely ignorant about thermoset plastics and how they may be useful in their machinery?
As to fibre reinforced composites it is clear to me that you have nothing more than passing knowledge about them and how they work. My guess is that you have never been involved in the aerospace industry and have never created an advanced composite structure. I however have.
I have inventions involving the use of thermoplastic honeycomb cores that have been used for everything from ultra-lightweight helicopter landing pads, to explosive resistant tank parking pads. There might be 20 other people on earth who know how to bond thermoset resin systems to low surface energy polyolefin honeycomb cores and I probably have worked with them all.
These materials do not seem to have natural harmonic frequencies, they do not vibrate easily at all. That materials I listed in my OP have the same properties to a great extent. That was part of why I explained why they would work better than sand and some pigment. They have the advantage of being able to chemically crosslink into the epoxy itself, they become a monolith with the epoxy. Sand, especially untreated sand does nothing of the sort. The best sand can do is form low energy mechanical bonds. Nice if you want to make a counter that looks nice, worthless if your counter has to support high loads.
So imagine this. One makes a machine base out of for example 10 lb balsa wood core material, engineered to take advantage of its natural honeycomb like structure. Then one lays up dry fibreglass using a combination of fibre angles, fibre weights, and where useful, three dimensional fibreglass reinforcements.
Then one make a vacuum bag around the structure and infuses the right resin materials into the structure. The resin is allowed to cure until it can be handled. The resin thoroughly impregnates both the fibres and the core. The core has excelent mechanical properties as a result. The resin to fibre ratio is nearly optimized as well.
One makes as many of these parts as needed for the design and while the parts are still only ‘green’ cured, the parts are assembled using advanced epoxy adhesives. Once assembled the structure is put into a simple oven that can be made easily. The structure is then heat cured over a period of a few days. It will reach about a 99.9% full cure as measured by DSC. It is as strong as it is every going to get.
Once completed the structure is trimmed and finished. Then any metal parts such as linear motion tracks, motors, spindles and what not are glued into place. Designed properly, after a handfull of iterations the result could be a machine that is capable of high precision and complexity.
The probability of this working is higher than the probability of achieving similar results by casting thermoset resins in large masses.
Try not to comment about posts by others if you are largely ignorant about the issues. There are no doubt many things that you know far better than most. But clearly composites do not seem to be your biggest strengths.
Tony Warren (if that IS your real name): Don’t tell me what you understand better than I do. You have no idea what I understand, and are likely wrong. I stopped reading at that point.
The “machine” I was asking about is they hypothetical “tool required” that would cost in the “high 5 or low 6 figures”. You self-righteous ass.
BrightBlueJim, if that is your real name. This question, like the others you refer to demonstrate your lack of knowledge in this particular field. As I said earlier on, I am certain that are many things that you have a great deal of expertise on and from which I may be able to learn something. You have chosen to stay ignorant about thermoset resin systems and the issues their use entails. That is fine.
If you did understand what I was talking about, you would know that a ‘tool’ in this instance is a die or a mold. Molds for this type of work are difficult to design and are generally made of metals. Thus they require precision machining and are therefore expensive.
A relatively simple injection molding die or tool can easily run $50,000 with dimensions of about 10 inches cubed. Pultrusion dies of the same type can easily cost $120,000 or more. I have made smaller casting dies for about $75,000.
Well, something I clearly understand better than you, is communications. If I said something that indicated ignorance or misunderstanding, you should be specific, rather than just going to “I know this stuff better than you do.” But whatever. Have a nice life.
Perhaps you are correct in that I made an assumption because of your questions. But if you look back at what you have said, the comments you made and their context, you might find that I did not find much reason to think that you were asking questions. Perhaps a genius at communications such as you might learn to write in complete sentences and to parse thoughts and questions in full, rather than in easy to misinterpret, suggestings.
I have a very nice life indeed. But thanks for reinforcing the thought.
Ahh yes, the good ole “your opinion isnt valid until you have done the exact same thing” trope… Comment sections are meant for comments and Tony was stating his opinion, if you had a problem with his opinion then you are more than welcome to retort with a logical argument with how his comment was wrong in any way.
You put it far better than I have. Thank you. I thought I was giving free advice from my personal experience in the use of these materials.
Tony could have done a far better job of stating his qualifications in the field and explaining why his opinion was greater than most.
Instead we got an arrogant and oddly constructed rant, typical with people operating at a “higher level” than most, with the suggestion we google his name to find out his authority.
He reminds me much of another HaD poster who is oft accused of being off his meds because he takes a similar approach to commenting which puts people’s backs up and rightly so. It’s called talking down to people.
Well said.
The comment from Dave is interesting to me. I’m personally not much on stating credentials about what I do. I think they make people sound arrogant which I am being accused of here.
My first point is that I think I am subject to a sort of experiential bias. I have spent a long time in the field and have come to believe that I know more about the topic than others as a result of that experience. Obviously though, lots of people know far more about the topic in general than I do.
Couple that with another sort of bias pertaining to being a geezer. Us old guys imagine that we are always correct about the things we choose to blather about.
We are too enamoured in our society by the idea that a credential of some sort conferes unusual expertise. I prefer to think critically about what the person actually claims or does about any given subject, not what they claim their credential gives them authority for.
All that said, so far the only comments on my ideas have been ad hom attacks on me and not on what I wrote. Instead of complaining about my personal flaws, it would be more useful to me and others if someone took apart my posts to tell me why they think I am wrong about some particular point or another.
If my reasoning is flawed or if someone can point to a better way of formulating the resin system using materials I don’t know about or haven’t experienced we all learn something we didn’t know.
But if the best anyone can do is call me names or whatnot, that is of low utility.
Well, Tony, we don’t have a chance to criticize your arguments on their own merits, because all of your claims come down to “you’re wrong because I’ve been doing this stuff longer than you have, and I know more than you all.” (Which in itself is absurd, since you have no idea how much experience the people you are putting down have.)
If you want to tell someone their reasoning is wrong, and you don’t want the response to be personal, then you really should point out their errors, rather than making it a personal thing yourself. To be clear about this: I am not wrong BECAUSE you have more experience. If I am wrong, it has nothing to do with you, and it should possible to tell me HOW I’m wrong, or WHAT is wrong with my reasoning. “Who” shouldn’t even come into the discussion, but YOU brought it in.
You say that we over-value credentials, but if you offer nothing but your own experience to back up your claims, then without credentials how are we to validate what you say?
“Well, Tony, we don’t have a chance to criticize your arguments on their own merits, because all of your claims come down to “you’re wrong because I’ve been doing this stuff longer than you have, and I know more than you all.” (Which in itself is absurd, since you have no idea how much experience the people you are putting down have.)
If you want to tell someone their reasoning is wrong, and you don’t want the response to be personal, then you really should point out their errors, rather than making it a personal thing yourself. To be clear about this: I am not wrong BECAUSE you have more experience. If I am wrong, it has nothing to do with you, and it should possible to tell me HOW I’m wrong, or WHAT is wrong with my reasoning. “Who” shouldn’t even come into the discussion, but YOU brought it in.
You say that we over-value credentials, but if you offer nothing but your own experience to back up your claims, then without credentials how are we to validate what you say?”
Hi BrightBlueJim. Often it is useful to unpack a statement like this to try to get to the truth of the matter.
Ask yourself if at any point you or anyone else has made a claim that I am wrong? I have not been able to detect any such instance. Instead you and others merely engage in ad hom attacks and then attempt to claim that I am forestalling disagreement when I offer alternative construction methods taken from my past experience. Do you want to claim that experience is nothing? Do you want to claim that details about how I came to conclude these things is evil, because I have used actual ‘science’ to inform my conclusions?
The title of the original post is; “EXPERIMENTS IN CREATING THE BEST EPOXY GRANITE.” It states that it was a series of experiments to find out how to make ‘the best epoxy granite.”
My initial comment was that the so called “experiments” were not well done. I said they were amateur. That’s an opinion of mine. I did not go into great detail on the flaws of the experiment other than to say that I had low regard for them.
Here is what I said in its entirety: “This mix is amateur and the research was not done in a robust scientific manner.
The mix needs functional additives with as few natural harmonics as possible. Sand is ridiculous. Use high aspect ratio minerals like bentonite and wolastinite. It needs toughening with coreshell rubbers. It needs a combination of bis a, bis f and novolac resins and a cooler jeffamine curative. Then it needs a post-cure heat cycle.
So far, no one has actually made a comment about why this advice is bad advice. Do you wish to claim that I am wrong in my proposed formulation? So far you have not squeaked out one word on that formula.
Instead the following direct response was made:
“Mbc says:
June 2, 2019 at 7:59 am
Awesome. I’d love to see a full write up with some pictures and maybe even video. Until then, don’t rag on others hard work when you have nothing but a paragraph of empty words to show us.”
Basically this is a statement saying what I ‘should’ do as an alternative and further that because someone “words hard” that they have instant merit for what they have done.
On reflection of this post I knew several things; the issues are far more complicated than could ever be explained by a ‘full write up’ and a few photos and a video. The explanation is more along the line of a book or certainly white paper length discussion of the issues at play in attempting to make “the best epoxy granite.”
Further, the claim of ’empty words’ demonstrated to me that the poster had no idea what I was saying when it came to terms like ‘functional additives,’ ‘high aspect ratio minerals,’ ‘coreshell rubbers’ or the epoxy backbones I was speaking to. In good faith I attempted to educate from my own experience.
Subsequent to that post, I gave you an alternative method of making a machine base.
What followed has never been anything about ad hom fallacy and personal bias in attacking me.
No one has posited a response as to why I might be wrong. Instead the best that you or anyone else has been able to come up with is complaints that I am either overly pedantic or unqualified. My error was to respond to those claims.
Would you magically feel better if I claimed I had a PhD in materials engineering, or perhaps organic chemistry, or aerospace engineering, or some other advanced education? First I keep my personal educational background private. It has zero bearing on anything. Among other things I have studied philosophy, psychology, accounting, finance, and other things. You have no idea if any of those claims are true, and you have no idea if it is a comprehensive list. It simply is not relevant.
I happen to know a lot of highly educated people in a very large number of different fields. Those with phuds rarely trumpet their phud unless it is in some lame category with little academic merit such as education, journalism or some sort of fake ‘studies’ field.
My feelings on the topic is that it seems to me that we live in a time that instead of thinking critically about issues, people have come to believe that a credential is a claim of expertise and that listening to experts is a good thing. My experience has shown over and over again that those ideas are for the most part wrong.
If you want to quit seeming like a complete butt-head, why not critique what I have claimed or if you don’t know something ask a direct question about what you don’t know. I will spend a bit of time trying to educate you from my knowledge base, or more likely give you links to others who are better at explaining these issues than I am.
If not, then by all means keep up with the personal attacks. I will respond with little more than endless lists of the fallacies and biases that your comments contain. What sport!
E&OE
I’m not sure why you found it necessary to duplicate my entire message, but your response to it indicates you did not read it. Whatever. NOBODY said you were wrong about any of the claims you made. Several people have objected to HOW you said it, because you just make decrees without any basis other than your “experience.” Nobody cares about that, because anybody can come in here and claim to have invented transparent aluminum, and there’s no way to confirm or dispute that. Which is why the WHYs are so important. But your posts are completely lacking in explanations. WHAT should the author of the video have done to improve the stiffness of his machine? WHY should he add coreshell rubbers? I ask those specifically because I don’t see how these would help him with his objectives. But you don’t seem the least bit interested in expanding at all in that respect.
I really don’t care what your credentials are. Again, agreed, you can’t prove them, and I can’t disprove them. NOBODY ASKED FOR YOUR CREDENTIALS. YOU brought that up, with your claims to decades of experience as the reason we should accept your opinions. My POINT, which I made at least twice, is that you tell us what he SHOULD have done, without a single WHY. Okay, high aspect ratio additives. Now, I can understand how that would help with TENSILE STRENGTH. If you had read beyond the title, you would have discovered that the subject of the article was interested in increasing STIFFNESS while maintaining a high LOSS factor. If you don’t care to indicate HOW any of what you recommend would help in these respects, you’re just wasting everybody’s time. What he was investigating was the use of an epoxy “granite” overmold on an aluminum frame FOR AN OPTICAL INSTRUMENT, and really doesn’t care that much about tensile strength. He’s not building a fucking machining center. But at this point, I really don’t care to hear anything more from you, since in the absence of any demonstration of competence, I am now convinced that your exceptional knowledge base is all in your imagination. Get a clue – this is the Internet, and nobody cares what you claim to be. Cite relevant principles or STFU.
I have three final points: Ad hom attacks are prima facie absurd and meaningless; I wonder if English is a second or third language for you; and I made the mistake of thinking that Hackaday was a serious site for people working in diverse fields, trying to solve problems on a small and personal scale of effort.
What I guess I missed was the fine-print on the site that also says that Hackaday is a doily admiration society given to a lot of ‘tut tutting’ while taking high tea.
Good bye Jimmy. You might consider taking the word ‘bright’ out of your small name because it is clear to me at least that it does not apply.
Tony, I don’t have experience in this field, but I find this topic interesting. I had to search for almost every word of your original comment, but it starts to make sense for me. What I don’t clearly see is the budget and the readily available tools you assumed here. For example I haven’t heard of core-shell rubbers before, yet where to source them. Example 2: machining or just trimming glass fiber composite with precision sounds like a demanding task.
On the argument about the style of comments: criticism needs to be carefully formed to not feel arrogant (that’s a lesson I learned the hard way). You seemingly failed at this part, and – naturally – received similarly arrogant replies. Even if I ignore your long list of experiences above (so without the credibility), just the mention of those technical terms helps to learn.
I hope you will find a way to express your opinion without triggering srongly emotional responses here. I’d like to read your comments under similar articles, but not the arguments about behavior.
Thank you for your advice and comment. I rarely bother to post replies to ad hom attacks. Style means nothing to me and I have no interest in what someone thinks about me based upon anything at all other than a criticism of my ideas and thoughts. It is always open season on those, facing such criticism can only make me see the errors in my thinking and to improve upon it.
If you are interested in finding out more about the composit in my first post, or about how to perhaps find a better way of making a machine base with more robust structure, I am happy to first inform you regarding sourcing materials and why they are useful and secondly how think through the construction process.
I can go into some level of detail to point you in what I believe is a good direction and you can further your edification with additional reading.
On those fronts I am at your service. As a start, the following:
You can find out about coreshell rubbers at this site Coreshell is a technique of encapsulating materials. In this case nano-rubber spheres are encapsulated in bisphenol A or F or Novolac resins. I recently used them in an interesting formulation with a hybrid of all three resins backbone. The adhesive had to have high chemical/thermal properties AND cure at minus 40C. https://www.kaneka.com/kaneka-americas/products/kaneace
Functional additives can be found at this site. http://www.inhanceproducts.com/offerings/performance-additives/
These were invented by a friend of mine who is a sterling genius. He taught me a huge amount about how to make adhesives tougher and more wear resistent. A side note, the term ‘tough’ is a sort of catch-all word for more rubbery. Adhesives can be brittle and ‘glassy’ or flexible or ‘rubbery.’
Fillers to replace the sand are abundant. They key is that they are treated with a coupling agent so that they bond well with the epoxy. I suggested wolostanite or bentonite thus treated. Other potential fillers for this application include; feldspar, ceramic centospheres and microfibres, short fibre reinforcements, various carbon nanomaterials, and others. In this case I would go pretty heavily into the Inhance particles using a few different sizes and I would include their TiC formulation as well.
These result in pretty expensive formulas. As I said, this past year I worked on a weird project that required a serious epoxy system. We purchased something in the range of 2,000 US Gallons in barrels. Our cost was north of $175.00 per gallon.
As an aside, I think that if one were to actually make such a machine base, I would make it hollow and fill it with a non-newtonian fluid to further dampen vibration.
https://youtu.be/cnQjjkuJXWc
Epoxy concrete has been used for machine beds for multiple decades.
Linked article is neat, even if its somewhat amateur attempt aimed at good look more than serious research on vibration dampening performance. But its kind of sad that Hackaday staff isn’t reading Hackaday, as it was already featured here. You can find it as previous article posted under ‘epoxy granite’ tag used on this one.
Thank you, Tony,
My arch observation about primate behavior didn’t send, and good riddance, but is there any sense in the idea of my colleague’s pouring a self levelling table for his hopeless Chinese cnc, about 80x120cm? Vibration necessary for the levelling, I feel sure. I’m only an old fortepiano builder, my colleague a wildly prolific harpsichord builder, both new to cnc and quite sure that this will replace relentless heavy duty handwork, just in time.
Best, Paul McNulty
I always liked how nice these castings looked but its always bothered me he only used sand.
After many times making my own castings now and doing some comparisons Adam sacrificed a lot of structural integrity for the cosmetics of his machine.
It wasn’t a matter that he wouldn’t use a mix of play sand, beach sand, playground pebbles in his mix it was that he was impatient in getting the proper mix to adhere to all of them successfully. More or less waving the flag and taking the easy path.
I have found some alternatives over the past several years that actually improve casting quality. First of all no need to use any aggregate larger then playground pebbles or 1/2” in size.
In-fact the alternatives I add bring tiny microspheres and are very small additives, powder, dust, that are integrating a a total of 5 various sizes into the mix so you have a tighter and unique covalent bond.
Something to consider if you plan to mix a batch. There is epoxy that has aluminum powder blended into it. You can also buy and mix your own. You can also add cast iron powder, graphene if yoj have a good source, even stainless, or other material alloy powders to create a unique and ultra strong casting with exceptional dampening. At this point whats an extra $100-$200 to know you’ve cast the dream machine. If you added graphene oxide you could make it so its magnetic or pure graphene for its electrical conductivity making for a solid ground to the floor. Unfortunately Graphene isn’t as easy to obtain but if you’re curious like me you will make some. Not for the budget minded, but for high quality we take no short cuts.
Hopefully a few thoughts to engage out of box thinking. Im starting a series of machine castings in the next few weeks myself and this time i plan to make a YouTube Series how I do it and show why its better. It is great seeing all those beginner channels doing it but its finally time to see someone who has done this many times before and has taken the chemical makeup and found a way to make a EG casting 100X stronger with many times over better dampening than what you see here.