Epoxy-Granite machine bases (was Polymer concrete frame?)

[turmite]

Mike - could you revise the link to that story in #23 as your link is only to the picture.Thanks
John

http://www.machinedesign.com/ASP/vie...MDSite&catId=0

Sorry about that.

Mike

[turmite]

I guess my first post wasn't clear enough. The only thing on the structure of this machine that is metal is the bed. Go read the info about it. It is a metal working machine made almost entirely of the PC you have been discussing here.

If you search you will find many articles about metal working machines that have been made that hold better tolerences because they are built of PC.

Mike

[Geof]

That is the link that claims a casting precision which I find hard to believe. Here is a quote:

"A mixture of reactive, high-strength resin and mineral aggregates makes as-cast machine components to 0.0005-in./ft flatness, with hole diameters to ±0.0001 in., and feature dimensions to ±0.0005 in./ft."

[JWOOD]

At my last job we did some experiments with replicated surfaces using epoxy based materials. What we found was that we were able to produce replicated surfaces, using a large granite surface plate, with a flatness within .001" over about 3'. The biggest problem we had was the hardness of the surface. We were running an air bearing over the surface. If any grit got on it tended to get stuck in the epoxy and could end up scratching the way or worse the bearing.

[walter]

Schrupphobel72, thank for posting the pictures. That is exactly what I had in mind!

I've got to talk to those guys... Does anyone speak german...

[lgalla]

found an epoxy supplier that claims 1 to 5 ratio by volume possible with sand filler.If true this would reduce my previous cost estimate by almost 50%.Cost at this ratio would be $6.00/sqft 1" thick.Never beleive what you read.To confirm stats I would buy 1qt resin add 5qt sand and see if it can be mixed.I really don' twant to give the supplier link as it is the most confusing site I have ever seen.
AW what the hell you gotta see this,5billion pages and links.Don't try their search engine.www.epoxysystems.com.
Glad to see interest in the subject.Don't go out and buy a ton of epoxy and sand yet.There is still alot of issues to be dealt with.eg air entraptment ,vibratory compaction, heat generation,viscosity , vacuum de gassing etc.I wish I had the time to do the experiments now so It was my risk only.I only have experince with 50% fill by weight.Some sites have stated 90% filler.I don't know.At this level it ain't gonna be a pouring item.As I said before I have tons of orders now and little time.working 18/7.I have tons more info to post.Questions or comments are welcomed.Try to keep the interest happining.
Larry
Granite chipper sweeper

[walter]

Ah yes, the good old epoxysystems.com lol... 375 product and nothing of use. Actually that's the reason I'm here.

[lgalla]

Hey Walter
If I got one dollar for everytime I recommended these guys I would be rich. www.shopmaninc.com
Low viscosity epoxy like 30bucks a gallon.They don't know me,maybee you can say larry sent you and they will give me a discount.I want to contact them to state our requirements and possibly have a custom system made for us ZONERS
Larry
Epoxy Promotor

[the4thseal]

After reading all of this stuff, I am thinking what about this idea. using steel fiber as aggregate and this stuff "http://www.pavepatch.com/flexset-rapid-concrete-repair-5gal-p-29.html" as epoxy should be interesting. I am at least going to give it a try unless someone here thinks that it is totally daft.

[RotarySMP]

Larry, you are still talking about sand as the aggregate each posting.

You need to use a mix of aggregate sizes based on the part being built. The bigger the better, up to a fraction of the feature wall thickness. The german book I read recommended around 1/5 wall thickness for the largest aggregate, the Zanite site say 1/2. For a two inch thick feature, you are looking at rocks in the 1/2" to 1" range, and below.

Your Epoxy ratio is going to be driven by the surface area of the aggregate, and cubic inch of sand it going to have a hell of a lot more surface area over all it's grains than a single cubic inch rock. It'll end up weaker also. Just note that the vibration damping graph shown at the botton of the link in Post #37 indicates they were using 8% epoxy and 92% aggregates.

Just note that you do not have to make all features massive. You can core this stuff with foam, pipes, cardboard, old rags, beercans, whatever you like...

[schrupphobel72]

Walter,i'm German just ask what you want to know!
Schrupphobel

[lgalla]

Mark
I am always saying sand as other posts are saying quartz aggreates.The large rocks looks good on paper but would have high resin demand as the spaces between large aggriates is large.This would not be true if the rocks were like little bricks tightly packed.I only have experience with 50% filler loadings and micro spheres.Example,a box of spheres any size occupies 52%of the box leaving48% voids for the resin demand.We use a mix of different sized spheres to fillin the spaces.I think basicly we are each 50% right.I will mix the sand and we will put in your rocks.We are hear to try to figure out what a good balance is.I have had filler descusions with I think NC Cams quite sometime ago.He perfectly described the reasons for fines and has seen people using E/G.Hopfully he will respond.
Larry