[vishnu]

It is good to discuss theoretical castings, but I have been casting real parts for over 20 years, using a formula I developed. We cast a 18" diameter, 270 deg drum, to .001 ID TIR (AS CAST). We cast a 70,000 lb CNC machining center using a low cost wood mold, and routinely cast grinding machine bases, 4,000 lb to 7,000, using low cost composite molds.

We cast chemical pump bases flat to .002"/36", using wood molds and can cast parts flat to.0005"/36" using wood molds. Our bases are used for a high speed printing machine, replacing a steel weldment, at 50% of the weldment cost. Delivey of a finished base is days, they do not need to be painted and the virbation dampening allows the printer to run faster with better registration.

EG offers a lot of real advantages over other materials, if you know how to do it. If you don't, the results can be bases that never cure or the cure too fast creating air pockets. It is easy to make bad parts.

We do sell the mix for anyone who wants to cast thier own parts.

Can you please post some pics of the bases you have cast, the problem i have come to know is the availability of materials in my country eg. zeospheres, proper resins & small even aggregates. Do you use vibration setting to release air pockets after casting.

[JohnMcNamara]

Hi Castinette

The green grinder casting is interesting….. Particularly the cast in steel ways and the rod or cable ends with nuts. They appear to be the same as those used in pre stressed concrete. Were they post tensioned after the casting had set as is the usual practice?

There is a good discussion of the process here for those that are interested.

http://en.wikipedia.org/wiki/Prestressed_concrete

Also the use of PVC plumbing fittings to form ducts as shown in another photo, they appear to be standard industry practice. I have seen them in a number of manufacturers work. It makes sense, Low cost and easy to customize.

Great job

Cheers
John

[castinite]

John,

The green base is 10 meters long. When picked up on one edge, the deflection on the opposite edge was only .01mm. We cast the steel plates in and had them machined flat to .01mm flatness overall.

You are correct, the base was post stressed. It is filled with several foam cores and has standard PVC pipes cast in for drains along the length in two places. This base was cast in a wood mold.

[romihs]

Castinite,

That is very impressive.

Your last few posts have been very inspiring. Makes me want to go out and build something.. I am very amazed at the accuracy you achieve simply using wooden moulds!

This is not as complicated as I had thought it would be....

Thanks for the info and inspiration.

Sandi

[johnohara]

Terry~

Picture 2: "Bimbo with base"

Bimbo with base?

She seems nice enough. Dresses professionally in an industrial setting. And was certainly willing to be photographed next to your product, with a smile. I'd bet she talks to customers with an upbeat voice too.

Do you realize her image will now be indexed into multiple search engine databases with that caption? (Google, Bing, Yahoo, etc.) Standing next to your product, with your URL and a back link to your cnczone entry?

You might want to delete it before the web crawlers find it -- if they haven't already.

~John

[Steven.ji]

Hi Terry

The steel bar in the green base is almost 6 meters long. There must be bi-metal effect resulting from different thermal expension coeffiencent.

In China, seldom workshop have temperature control system, how to deal with such problem?


Regards

Steven

[Kevin_Johnson]

Hi Terry

The steel bar in the green base is almost 6 meters long. There must be bi-metal effect resulting from different thermal expension coeffiencent.

In China, seldom workshop have temperature control system, how to deal with such problem?


Regards

Steven

Steven, you might consider placing a system of tubes in your piece. You could then circulate cooling/heating fluid to simultaneously drive/regulate the reaction and keep the piece at a more normalized temperature overall. You will probably want a series of interconnecting "manifolds" with multiple external connections. It is similar to temperature regulation in an automobile engine block. With multiple manifolds/circuits you could heat some areas and cool others simultaneously.

By doing this and perhaps insulating the curing piece during temperature extremes you should be able to compensate for an uncontrolled shop environment. Also, the end product should be more valuable because the end user can circulate cooling or heating fluid to bring the piece back to the temperature range that it was manufactured in for optimum accuracy. By creating a grid of manifolds that can be later modified for flow patterns you can allow yourself and the enduser great latitude.

It is a lot of extra expense and trouble, of course. In larger projects such as dams this technique is used because of the great heat released from the large mass of concrete setting.

Good luck.

[RomanLini]

Workers with heaters and thermometers, manually turning the heat on as needed.

Even on small job's I've had some tricky exotherms, needing heat applied for some time to get it moving then grabbing fans in a panic and trying to keep the exotherm under control...

Those non-contact infrared laser thermometers are perfect for casting as they can actually "see" the temperature at the CENTRE of the mold, is it glows in infrared energy from the centre out! Where old fashined thermometers only show the surface temperature and may take seconds to give a change in reading too. I have a number of thermometers in arms reach of the casting bench but the infrared one is the most useful.

[ckelloug]

Hi Roman,

I must admit that my test samples have been a bit small but the only exotherm problems I have ever seen have involved poor choices of hardener. TETA, TEPA, and AEP are very exothermic and too exothermic for E/G.

Isophorone Diamine and Hexamethylene Diamine have low enough activities that they won't even achieve optimal cure properties at room temperature, much less over-exotherm in EG. I've been focusing on Isophorone Diamine as the hardener because of this and doing oven cure at 85C.

Regards all,

Cameron

[yancho]

Hello.Excuse the language but I'm not very good at it.Well there is Google.I have the following question:For epoxy concrete you use gravel and how much.I want to make my machine and generally know how.This product adds a new dimension to the hobby.It removes the foundry and generally heavy mechanical equipment.Castinite-what we produce is great and professional, not a hobby.Thank you all in the forum.Yancho Yanchev

[RomanLini]

Cameron- Sorry I should have qualified that statement as it was not specifically about EG, but other epoxy or urathane casting I do without the aggregate. You can get some nasty temperature runaways depedning on thickness of the cast, mold insulation and room temp etc.

With EG there is almost guaranteed to be the opposite problem, a lack of sufficient exotherm due to the very low epoxy percentage and inert aggregate. An oven cure is about the only way, although you should still watch for exotherm runaway on the centre of the thicker areas as the the temp there will be above oven temp. Maybe an embedded temperature sensor? A LM35 reads linearly in degrees C per volt and is cheap enough to leave inside the casting.

I should have also said re the use of the infrared thermometer "seeing" the inside of the casting temperature that is with no aggregate. A thin casting should see the inside temp even with the aggregate, although I'm not sure how transparent the aggregate is to far infrared so with a thick cast the non contact thermometer may not see to the centre of the casting. There would also be issues with using the non contact thermometer with a curing oven.

Anyway the point I was clumsily trying to make for Steven.Ji was that it's pretty normal to have to take a close interest in the cure and manually have to heat it or cool it, adjusting as needed to get a good cure. Anyone that thinks they can just "mix and wait" and always get a great result is in for a shock...

PS. Even the epoxies will change over storage time and/or with supplier batch and have different exotherms and need different post-cure regimes.

[yancho]

I watched film-Breton SPA-Italy,their machine with such a base.

[greybeard]

Kevin, thank you for your additional examples.
It was your previous ones that threw me off course.

Regards
John

[JohnMcNamara]

Hi All

As I see it nomenclature is all we are talking here. We all have a fair idea of what the process is. Arguing about the semantics is counterproductive.

The reasons I posted the observation that a certain group had renamed polymer concrete to mineral casting were twofold.

1. To propose that I was in agreement. It removes the association with water based Portland and other cements.

2. Raise awareness within this group that other search terms will yield more search results. Results that are not found by say “Polymer concrete”.


The second point being by far the most important, in the web centric world we now live in, when researching we must cast as wide a net as possible. Come to think of it, the same applies at a public library. Thankfully the net makes the results a few keystrokes away.

Cheers

John McNamara

[Kevin_Johnson]

It's counterproductive until an expensive mistake is made by someone attempting to impose or expect rigor on/from a natural language. One can hope that only materials rather than lives are in peril.

In spacecraft design both can be.

Given that formal languages must deal with the foundational ambiguity of negation which is prime, it appears that this general concern will remain with us for quite some time.

Hi All

As I see it nomenclature is all we are talking here. We all have a fair idea of what the process is. Arguing about the semantics is counterproductive.

The reasons I posted the observation that a certain group had renamed polymer concrete to mineral casting were twofold.

1. To propose that I was in agreement. It removes the association with water based Portland and other cements.

2. Raise awareness within this group that other search terms will yield more search results. Results that are not found by say “Polymer concrete”.


The second point being by far the most important, in the web centric world we now live in, when researching we must cast as wide a net as possible. Come to think of it, the same applies at a public library. Thankfully the net makes the results a few keystrokes away.

Cheers

John McNamara

[yancho]

What is the chance to hit the proportions of patented polymer concrete?In patent describes exactly the contents and proportions of all fractions.

[RomanLini]

What is the chance to hit the proportions of patented polymer concrete?In patent describes exactly the contents and proportions of all fractions.

I'm curious about that too. I thought a patent only covers a mechanism or a procedure, not a recipe of ingredients? Which explains why you won't find the Coca Cola recipe patented, they keep it locked up.

[brunog]

I'm curious about that too. I thought a patent only covers a mechanism or a procedure, not a recipe of ingredients? Which explains why you won't find the Coca Cola recipe patented, they keep it locked up.

The original Moglice formula was patented and the recipe details are included.

[yancho]

Work boldly with polymer

[RomanLini]

Interesting! Well I'm probably wrong then!

I just had a memory that a "recipe" ie; amounts of ingredients couldn't be patented I thought it needed to also include some proprietary process or something more than just the recipe amounts.

I just checked "IP law for all";
IP Law For All: Recipes Can be Patented If ...
There are requirements for being "new" and "nonobvious", so it would have to be a recipe of things never mixed together before (new) and things that would not be obviously normally mixed together "nonobvious".

I really don't know either way but still I think you would have a hard time trying to patent a mix of epoxy and any "obvious" aggregate ingredients. Given a patent's need to be non-disclosed publically that probably means you could not patent any mix using aggregates that had been used before as they are publicly known as aggregates which are used.