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

[ckelloug]

John,

It was Gamsky and later Gupta that came up with this criterion. I'm absolutely buried but if you search the thread for Gupta, there should be quite a few links to his paper. If this isn't enough, it will be after Saturday before I will have time to look.

--Cameron

[jhudler]

www.ribelin.com in Garland, Texas about 20 minutes from my house.
They offered to sell me G-800 at $30.50 and G-200 at $37.50 which is their pallet price per 50 lbs bag.

Well now that much better... not as good as the Cary Company, but then it’s probably a wash with shipping.

Just a note: DO NOT OPEN Zeeospheres on your desk to play with! This stuff is insidious! I’ve cleaned and blown my desk off 3 times already, and still when I move papers around I can hear those little gritty particles laughing at me! It’s time to take my lithium .

This stuff is going to play hell with vacuum chamber seals and knife edges!

Jack

[jhudler]

Today I did an experiment while I was changing the filter sand in the pool.

I took about 2 cups of fresh filter sand and poured 20% HCI or Muriatic acid and let it dissolve away the embedded calcium and metal products.
All I can say if wow what a clean aggregate. About 50 - 500 microns with some larger junk that makes up about 2% and easily sieved out. Some of the larger junk looks like gold flake, but its probably pyrite.

Both sand and muratic acid can be had at any pool supply house.

Next; make some test pieces from it and send them to Cameron!
Only damn, someone wants me to work for them so the mega free time just went out the window in exchange for the mega bucks .

Jack

[307startup]

Speaking of reinforcements and internal structural forms, has anyone considered FRP products? like these.... http://www.fibergrate.com

[MaX-MoD]

Originally Posted by WYLD Speaking of reinforcements and internal structural forms, has anyone considered FRP products? like these.... http://www.fibergrate.com

their products seems interesting when high rigidity to weight ratio is important, but it does certainly costs the skin of my nutsack!

not sur it will be very usefull in a machine base tought...

[greybeard]

Originally Posted by ckelloug John, It was Gamsky and later Gupta that came up with this criterion. I'm absolutely buried but if you search the thread for Gupta, there should be quite a few links to his paper. If this isn't enough, it will be after Saturday before I will have time to look. --Cameron

Thanks Cameron.
I'm picking this up in Holland at the moment, so it will be a week before I can get back to my own laptop and look for Gupta.
I remember now, so I know what to look for.
regards
John

[dang]

Hiya,

This is my 1st post on this thread. It's amazing so far! I apologize for bringing back old business but I'm not sure if I understand what I'm looking at in these photos, which I found in post 649. These "lines" are obviously some sort of form to mold the EP/GRAN, but what is it exactly? Could molding for this material be accomplished with a simple vacuum formed slab o' plastic, Or would heat curing preclude that?

[ckelloug]

dang,

Glad to have you aboard. Fun isn't it!

These photos are from a German group that we found out about earlier. (I don't read German so I didn't investigate too far) They are a combination of metallic reinforcements and bars for mounting tooling/accessories. I assume the brass/copper portion shown at left is a coolant drain.

It appears general consensus here is that the smaller particles in the mix will make vacuum forming difficult although I don't think anybody has tried it yet.

The low viscosity Reichhold 37-127/37-606 epoxy we've been discussing will cure at room temp but for best results, it probably wants to be cured at about 160F for a few hours after it has visibly hardened based on information gleaned from the datasheet and sheets for similar epoxies from other vendors.

Best of luck in your endeavors and be sure to ask any questions you might have. While the answer may be "Idunno" until it's figured out, it's the questions people have asked here that have made this thread what it is.

Regards all,

Cameron

[dang]

Thanks Cameron,

I mean that the mold is a vacuum formed shape with the Epoxy and Granite mix poured into it cold. As I said this would only be viable if the casting were cured without any heating.

Another idea I had about those photos was that some of the curing heat might be transferred through the metal inserts in the casting for faster solidifying on larger pieces. IE, the center could be cured as well and quickly as the outside and thinner portions of the casting.

And yeah! This is an awesome prospect. So many things could be built with such relative ease. The applications are mind-boggling.

[ckelloug]

dang,

Walter, the originator of this thread, probably knows more about casting E/G than anybody who hasn't signed a non disclosure agreement with one of the big tool manufacturers. lgalla, one of the other big posters here has a lot of experience with manufacturing things with epoxy. Others on cnczone like WilliamD and a few others have cast samples and parts with various results.

Check the E/G thread index thread for the last post by me with links to thread topics and then look for items noted as having pictures and other info of interest. (The first two or three of these posts have broken links due to the way the V bulletin software works.)

Regards all,

Cameron

[brunog]

Originally Posted by dang Thanks Cameron, I mean that the mold is a vacuum formed shape with the Epoxy and Granite mix poured into it cold. As I said this would only be viable if the casting were cured without any heating.

Dang,
I don't see why not, however you must make sure that the mold is solid enough to hold the weight of the E/G pour. The use of structural supports would greatly help in doing so.

Vaccuum forming the shape would infact complicate the whole process (make a shape or mold to vacuum form, then reinforce it) unless you want to use the vacuum formed shape as part of the finished part.

Best regards,

Bruno

[RotarySMP]

Dang, Those lines you ask about are there because that mold was make by stacking a number of CNC cut 2D shapes, cut out of a non-stick plastic. The plastic had a black core with white face sheets. When stacked the face sheets formed the lines you see.