Epoxy granite or mineral casting

[mike mcdermid]

Has anyone actually done this in the UK or found a recipe that works for small machine bases

Thanks

Mike

[boldford]

I can't help thinking aggregate of the appropriate size bonded with Biresin G26 Resin (5kg) (http://tinyurl.com/bmywaja) may be a way forward for DIYers.

[mike mcdermid]

The resin system isn't a problem as I do composites in my day job I really cannot see a way of reading the 380 odd pages of theory on CNC zone and coming up with aggregate sizes
so was hoping someone here might have done the deed already

[boldford]

The resin system isn't a problem as I do composites in my day job I really cannot see a way of reading the 380 odd pages of theory on CNC zone and coming up with aggregate sizes
so was hoping someone here might have done the deed alreadyFor economy I'm guessing the trick is to use as much aggregate as possible ensuring it is adequately embedded/wetted (IYKWIM) in the binding (resin?) material.

[Jonathan]

For economy I'm guessing the trick is to use as much aggregate as possible ensuring it is adequately embedded/wetted (IYKWIM) in the binding (resin?) material.

Yes that's the general idea - I've read the thread on CNCzone and a lot of it is discussing what threshold is too much aggregate since they want to save money on epoxy.

A lot depends on what you want to use it for. The thread on CNCzone is so long because they are trying to find a mixture capable of providing a stable accurate surface which will directly support linear guides. If you're only using it to fill gaps in a casting for damping, or if you embed pieces of metal and fasteners which can subsequently be machined then clearly the requirements aren't so strict...

[mike mcdermid]

Yes that's the general idea - I've read the thread on CNCzone and a lot of it is discussing what threshold is too much aggregate since they want to save money on epoxy.

A lot depends on what you want to use it for. The thread on CNCzone is so long because they are trying to find a mixture capable of providing a stable accurate surface which will directly support linear guides. If you're only using it to fill gaps in a casting for damping, or if you embed pieces of metal and fasteners which can subsequently be machined then clearly the requirements aren't so strict...

Jonothan for me its easier to mould something that is all and its what im used to working with, i have the skills to mould things and this means i can do stuff at home very easily rather than pay for it machining or casting ,its as easy to mould and epoxy into place as it is to machine metal to thousandths, I suppose it depends on your background I know we have had cast bases supplied before and its purely position and glue that gets the tolerances

That was my worry they are being tight on the resin volume.Jonothan did you gleen anything on the start point for sizes you could quickly post up I have read that many combinations on there?
I do know the companies that pour this its done with technology (equipment) not dissimilar to laying concrete foundations I have seen it done and it is a lot wetter than anything aproaching the 10 percent figures I have seen touted towards the end of the thread, The rails (precision rails) were mounted on grout which was similar to moglice but with ceramic spheres in it and it did indeed look like grout till it glossed over,this glossing seems to indicate far more resin richness as the heavy particulates sink

Im assuming its coming down to a scaling factor some of the aggregates they put in the grinding bases of the carbon machines we design are up to 25 odd mm I'm thinking the smaller the machine base you scale accordingly with a wall shickness ratio

I might just have a go this weekend

[mike mcdermid]

Ok an update

DO IT IT IS EASY

if you want to read through 400 pages of guessing suggesting and theorizing go follow the cnc zone "experts"

I recently visited 2 companies who manufacture epoxy granite machine bases and actually are "experts" One manufactures CMMs the other very LARGE gantry mills made from Carbon fibre basically it is rocks in resin the guys gave me the full tech spec right down to the epoxy resin system which comes from HUNTSMAN ,nothing fancy rare special about it ,the rocks are quartz ,as guessed scaled to fit the section that is to be filled nothing fancy no fillers of spheroidal this that or the other ,just different sized grains and some fibres

there is nothing clever about it fill a mould and vibrate it

no flaming off with torches to burst bubbles etc analyzing sizes to the nth degree the applications engineer even pointed out how complicated lots of folks think this is ,cost to cast a machine 1000 a ton which was still cheaper than cast iron for a hobby sized machine your talking 100 quid

[Peter.]

I love it when practical experience makes a mockery of the theorists :glee:

[boldford]

Ok an update

DO IT IT IS EASY

if you want to read through 400 pages of guessing suggesting and theorizing go follow the cnc zone "experts"

I recently visited 2 companies who manufacture epoxy granite machine bases and actually are "experts" One manufactures CMMs the other very LARGE gantry mills made from Carbon fibre basically it is rocks in resin the guys gave me the full tech spec right down to the epoxy resin system which comes from HUNTSMAN ,nothing fancy rare special about it ,the rocks are quartz ,as guessed scaled to fit the section that is to be filled nothing fancy no fillers of spheroidal this that or the other ,just different sized grains and some fibres

there is nothing clever about it fill a mould and vibrate it

no flaming off with torches to burst bubbles etc analyzing sizes to the nth degree the applications engineer even pointed out how complicated lots of folks think this is ,cost to cast a machine 1000 a ton which was still cheaper than cast iron for a hobby sized machine your talking 100 quidThat's really interesting. Like much "technology" there's always those that want to make it seem like Black Magic.

Then an honest broker comes along and all the hype disappears.

[martin54]

Being new to all this I went & had a read of a couple of articles when I saw this thread so I would have a better understanding of what it was all about.
I could be wrong (often am) but from what I picked up what they are trying to achieve is not the same as filling a machine to increase it's weight or help with vibration dampening. Haven't read the long thread on their forum but I think that is why they are still theorizing & testing different mixes.

[audioandy]

Ok an update

DO IT IT IS EASY

if you want to read through 400 pages of guessing suggesting and theorizing go follow the cnc zone "experts"

I recently visited 2 companies who manufacture epoxy granite machine bases and actually are "experts" One manufactures CMMs the other very LARGE gantry mills made from Carbon fibre basically it is rocks in resin the guys gave me the full tech spec right down to the epoxy resin system which comes from HUNTSMAN ,nothing fancy rare special about it ,the rocks are quartz ,as guessed scaled to fit the section that is to be filled nothing fancy no fillers of spheroidal this that or the other ,just different sized grains and some fibres

there is nothing clever about it fill a mould and vibrate it

no flaming off with torches to burst bubbles etc analyzing sizes to the nth degree the applications engineer even pointed out how complicated lots of folks think this is ,cost to cast a machine 1000 a ton which was still cheaper than cast iron for a hobby sized machine your talking 100 quid

Mike this is something I have been thinking about having a go at now for quite a while but not had the time to chase down the final ratio of the mixture. If you can help with your experience and suppliers of the best resin to use etc I for one would be most grateful.

Thanks

Andy

[JAZZCNC]

Mike this is something I have been thinking about having a go at now for quite a while but not had the time to chase down the final ratio of the mixture. If you can help with your experience and suppliers of the best resin to use etc I for one would be most grateful.

Thanks

Andy

Me too.!! . . . Yes please Sir.!! . . . (Would also mean Andy and I could play in the slap dab together. . lol)

[Jonathan]

I love it when practical experience makes a mockery of the theorists :glee:

It's a case of different objectives - I think what the 'theorists' are mainly discussing is a more demanding application than what mike has found out about.
I think the difference is that in the long thread on CNCzone they are (or were) trying to find a resin/aggregate mixture that would when set leave a surface smooth, accurate and stable enough to mount the linear rails directly to it, hence the suggestion of using a flame to remove bubbles. However if you're just making a base or frame with it and embed steel strips, or other means, to mount the rails, that can subsequently be machined or adjusted to obtain the required accuracy then you can get away with all sorts of things. There are quite a few examples of where people have not used fancy resin etc on their machine and got good results, such as this one (http://www.usinages.com/projets-fraiseuse-portique-usinage-cnc/fabrication-une-fraiseuse-granite-epoxy-t15107.html).

[JAZZCNC]

It's a case of different objectives - I think what the 'theorists' are mainly discussing is a more demanding application than what mike has found out about.


C'mon Don't get much more demanding or accurate than CMM's thou does it.?. . . . Most of that thread is over complicated Bullshit.

[Peter.]

I could have brought home half a dozen bags of fast-setting concrete from site last night that would do a pretty good job. I don't know what it's proper name is but the track workers call it 'Boff' - it comes in small bags of about 15kg, mixes directly with water, pours, doesn't shrink and crack and you can run trains on it within an hour of pouring. Very fine aggregate in it but by God is it tough, I dread having to break it - even with the demo robot it's hard going.

[boldford]

I could have brought home half a dozen bags of fast-setting concrete from site last night that would do a pretty good job. . . . .Does that mean NR will need to keep that firmly under lock and key henceforth? :adoration:

[Peter.]

Dunno what you mean...

Actually, the stuff does shrink somewhathaving thought about it as I have seen cracks in large pours - no getting away from it when it's mixed so as to be pourable I guessbut I bet if you mixed it dry enough it would be reduced to a minimum. If you cast it into a steel form why would it not be good enough to fix rails to it directly?

[Swarfing]

I've been catching up on things with the forum and found this thread to be very interesting. Many years ago i worked in the flooring industry. The type of flooring our company did a lot of was expoxy resin coatings and floors. We used to do a lot of sculptured floors which had to handle high loads.

Granite was used as a high density filler for the hi loads. Silica sand was used for general use and mixing both together gave a happy medium for general use. Do'nt ask me for quantities as i can not remember but a company we did use was Flowcrete. We could order the stuff with fixed curing times.

Looking at the other thread in that link with the French build, i would have considered concreate with the thicknesses he was pouring. The advantage of epoxy resin is that you can get away with thinner sections (reinforce with mesh).

Things to think of are:

All fillers must be dry
Pea shingle makes an excelent cheap filler (wash and dry it before use)
Silica sand (paving gap filler from wickes)
This stuff shrinks
Always use mechanical mixing
Pouring too thick in one go is bad (add mesh to key pieces together), do it in a couple of pours before removing from the mould.
This stuff gets very hot so pour into moulds outside to avoid the nastys
Clean all items with thinners that are being sed within moulds
we worked to a max of 60mm for screeds in one go

if you use a release agent in the mould then you could use a gel coat to give you nice surface to paint afterwards.

Hope this helps

[Washout]

I've done some composite work and make the odd flight case for people using sheets of a carbon/kevlar/glass mix - the easiest way I have found of getting a glassy smooth finish is to use vacuum infusion onto a rigid sheet of perspex "mould" on a flat surface - you get glassy smooth finish with no bubbles.

Not sure, but you might be able to pull a thin infusion type resin through large sized grains of "rock" of some kind mixed with chopped fibres (I keep all my carbon/kevlar/glass off cuts for this purpose). If you can't vacuum through the aggregate, then pouring into a box mould with a perspex bottom should achieve good results. All the bubbles and crappy surface will be on the top and the shiny flat surface on the bottom, which you can then demould and flip over.

Heat would be my only concern, as large volumes which don't have a matrix of some kind tend to go off with cracks in them, but a few sheets of glass or carbon layered in the mixture should help solve that.

(Eyes up the gallon container of resin on the other side of the cave ;-) ).

Edit - nearly forgot - this link might hel with ratios http://www.talkcomposites.com/11/Resin-infusion-resin-usage-calculation

[mike mcdermid]

Strangley the chap Xavier mentioned this relies more closely on the principles of precasting concrete than my field of expertise which is composites and as such its just a different binder which is low enough not to exotherm with slow ARADUR hardner

Will drop the details to you guys wanting to have a play on wednesday when i'm back at work even for us in industry its a damn sit cheaper than having a machine bed fabbed they are sending me some bags 5 of quartz for trials and the Resin we already have ,and its easily obtainable

the only thing that need to be scaled down is the vibrating table

[mike mcdermid]

I've done some composite work and make the odd flight case for people using sheets of a carbon/kevlar/glass mix - the easiest way I have found of getting a glassy smooth finish is to use vacuum infusion onto a rigid sheet of perspex "mould" on a flat surface - you get glassy smooth finish with no bubbles.

Not sure, but you might be able to pull a thin infusion type resin through large sized grains of "rock" of some kind mixed with chopped fibres (I keep all my carbon/kevlar/glass off cuts for this purpose). If you can't vacuum through the aggregate, then pouring into a box mould with a perspex bottom should achieve good results. All the bubbles and crappy surface will be on the top and the shiny flat surface on the bottom, which you can then demould and flip over.

Heat would be my only concern, as large volumes which don't have a matrix of some kind tend to go off with cracks in them, but a few sheets of glass or carbon layered in the mixture should help solve that.

(Eyes up the gallon container of resin on the other side of the cave ;-) ).

Edit - nearly forgot - this link might hel with ratios Resin infusion; resin usage calculation (http://www.talkcomposites.com/11/Resin-infusion-resin-usage-calculation)

My interest in the bases was piqued because of previous works with carbon gantry mills,there have been discussions for stiffer machines and carbon does the job nicely

My original question was to ascertain if anyone had done this granite thing in the UK
It seems getting on to a company that can answer the questions as they manufacture the machine bases cleared all this up nicely

[Swarfing]

To answer your question ..Yes!

This was for platorms at low level height in clean rooms for machinery to sit on. One thing we added was loose fibreglass to the granite resin mix. As far as a workable idea? the answer is yes and a good one.

[audioandy]

Me too.!! . . . Yes please Sir.!! . . . (Would also mean Andy and I could play in the slap dab together. . lol)

Mike looking forward to the info,looks like myself and Jazz could be playing in the slap dap after all :couple_inlove:

[D.C.]

You may want to have a chat with these guys they make an entire lathe out of concrete, not just the footings or the base and they do attach the linear rails straight to the concrete. Aparrently they were used all the time in WWII (along with concrete ships) because all the metal was going into things that kill people.

MAKE | The Concrete Lathe Project (http://blog.makezine.com/2012/04/12/the-concrete-lathe-project/)

http://concretelathe.wikispaces.com/Current+Design+Drawings

[WandrinAndy]

Many years ago, long before the internet, and when I lived in warmer climes, I had the whacky idea of building an outdoors pool table out of concrete instead of slate but it ended up on the round tuit list.

Now this thread's got me thinking about the idea again....:abnormal:

[irving2008]

INterestingly I was musing on the idea of a reinforced concrete z-axis support to replace the round column on my mill... one day in the distant future

By way of experiement I did the FEA on a 100x 100mm 5mm wall steel tube and a 100mm x 100mm concrete post, both 750mm high.

Ignoring any difficulties fixing the concrete post, the torsional stiffness wasnt so different. With an applied 200Nm twisting load 500mm out from the centre of the post :

Steel 0.34mm movement. Weight of column 34kg
Concrete 0.45mm movement, Weight 19kg. (thats with no reinforcement inside)

So with some refinement it certainly looks doable...

[Ger21]

. . . Most of that thread is over complicated Bullshit.

I agree with that 100%. My gut feeling says a bag of sand and a bag of gravel is all you need to make an incredibly strong machine base.

[audioandy]

I agree with that 100%. My gut feeling says a bag of sand and a bag of gravel is all you need to make an incredibly strong machine base.
Someone agreeing with Jazz! That's a first!

[m.marino]

If you want to talk to folks who work in some of the truly interesting end of Cement and ferrocement then you might want to look here Ferrocement Educational Network (http://ferrocement.net/) As they have been doing work with mesh re-enforced cement and other strangeness that makes some very interesting reading.

Michael

[steven.ji]

I do mineral casting 7655

[JAZZCNC]

I do mineral casting 7655

Thats great so how about some info on how you do it.?

[D.C.]

I do mineral casting 7655

That is a nice looking machine, if you don't mind sharing what mix do you use and how do muppets like me go about doing this?

[steven.ji]

the machine base is for engraving machine

In terms of recipe and process, it's not easy to say in short words

[njhussey]

the machine base is for engraving machine

In terms of recipe and process, it's not easy to say in short words

That's ok I understand long words ;-)

Would be interesting to know what mix and process you used. You can't just post a nice pic of a machine like that and leave us dangling :-)

[JAZZCNC]

the machine base is for engraving machine

In terms of recipe and process, it's not easy to say in short words

We like reading good long novels so please crack on because we are all keen to learn.!!

[m.marino]

That is a nice looking machine there. The type of mineral base and how you go about it would be of interest to a good number of us for many different reasons (not just machine building). IF it is part of your day job I could see a bit of reluctance to part with the information. If it is not in that type of area please do tell and as far as long words and thick reading, have you ever looked at a TM or FM for a vehicle from the US military (6 pages on how to check and change oil and that is not including any special models of the vehicle).

Michael

[njhussey]

That is a nice looking machine there. The type of mineral base and how you go about it would be of interest to a good number of us for many different reasons (not just machine building). IF it is part of your day job I could see a bit of reluctance to part with the information. If it is not in that type of area please do tell and as far as long words and thick reading, have you ever looked at a TM or FM for a vehicle from the US military (6 pages on how to check and change oil and that is not including any special models of the vehicle).

Michael

Or indeed ever had the pleasure of having to read through up to 40 different specifications anywhere up to 400 pages long each cross referencing other specifications. I'm an internal sales applications engineer and have to read these type of specs for API614 oil systems for offshore platforms, FPSO's etc...a bit of wading through mineral/epoxy tech info will be fun in comparison :)

[martin54]

Give the guy a break, he's only trying to make a living selling his machines lol

[John McNamara]

Hi All

This is my first post at MYCNCUK

This is an old thread but I hope the information helps, I have made a machine using Epoxy. It has a cast base and also two cast carriage ends. And these have a low friction cast in bearing surface on round shaft.

The machine is loosely based on the Worden grinder, however no sheet metal is used. It is very solid I can just lift it. There is very
little vibration.

As far as the epoxy mix is concerned I just used fine screened quartz gravel from a garden supply and washed sand. And Yes I used a little steel reinforcement. It is not hard to do and you do not have to use advanced calculus and have a chemistry degree to get a good result. Most resin suppliers are familiar with casting with epoxy aggregates.

I apologise for just posting a link here but I did the write up about two years ago here: New technology in Model Engineers Workshop | Model Engineer (http://www.model-engineer.co.uk/forums/postings.asp?th=51617&p=2)

It is a fairly lengthy post. there are many photos.

The machine has been in constant use ever since, I use it to grind lathe tools, the finish is almost mirror with a diamond wheel. No chatter.

Since then I made a CNC router with a mate for a community project A "Mens Shed" Located at Bright Central Victoria Australia.
Most of it is laser cut 5mm steel.

If anyone is interested it can be found here:
Laser Cut Frame CNC Router New build (http://www.machsupport.com/forum/index.php?topic=23730.0)

Next up is a new router for me this time. I will post directly when I start it. It will also be based on laser cut parts.

Regards
John

[JAZZCNC]

Hi All

This is my first post at MYCNCUK

Thanks John and Glad you did.:encouragement: . . I will probably be in touch picking your experience has I've got some ideas to use epoxy granite but not just yet. It will be quite a bit larger than your Worden thou.!!

[compositepro]

John

I figured out this stuff a while ago, kind of had to, anything to do with composites has always been a bit of, ask the people who say they can how they do it,when they tell you it will cost lots and they will half heartedly supply you with information or a product that only they say they can make

most of the time its easier to tell them to p*** of and do it yourself

Nice to see someone who is trying to teach the old dogs new tricks over there ...

im pretty sure eventually making machines out of metal will be raplaced by gluing them together

[JAZZCNC]

I figured out this stuff a while ago, kind of had to, anything to do with composites

So why not share with us then.!!. . . . . Start by telling me some where local that's cheap for Epoxy.??

[compositepro]

Epoxy isn't cheap here like everything here you pay thru the nose,
Theres a firm called fibreglass supplies in leeds and im not sure if Scot bader are in leeds anymore

Locally your pretty SOL as far as the structural systems go

Huntsman do aradur ...get your wallet out though I use SP systems on the isle of wight i used to buy 25 litres at a time for about 230 quid, it goes a lot further than you think it does

[gavztheouch]

What ever happened to the guy who was going to test out a mix with 5 bags of quartz he was given?

[gavztheouch]

Not really an expoxy granite cast machine but still somewhat relevent and interesting

https://www.youtube.com/watch?v=9WPmIYosonI

A real diy EG machine

https://www.youtube.com/user/cawedog/videos

[magicniner]

the machine base is for engraving machine

In terms of recipe and process, it's not easy to say in short words

Use long ones then, we're moderately smart here ;-)

[JAZZCNC]

Use long ones then, we're moderately smart here ;-)

Very funny but you do realise he posted this 15mths ago. . . Lol