[RotarySMP]

Doesn't sandblasting sand have an additive to stop it bindng?

[Geof]

..we could pour them out of soap and get better results than our current DIY frames...

I think you exagerrate a little but it brings to mind a thought I had about using a very high melting point wax; something around 300 F. If you had a wax with a very distinct melting point not a wide range it might be possible to cast aggregate reinforced wax.

[wizard]

I just got involved in this thread, but isn't there a huge problem with Aluminum in concrete. My understanding was that the two materials are not compatible. That is the concrete will react with Aluminum and corrode it.

Note that I dropped in because this thread is very interesting. I see cold casted machinery as a practical approach for the DIY person. Personally I was thinking more along the lines of Epoxy aggregate composites. This due to the long cure times for concrete.

These ideas are interesting but we can't fool ourselves into thinking that they are cheap. One offs might be possible but a mold can be expensive. My goal is the integration of the frame/mold with the Epoxy aggregate.

Thanks
Dave

Hi Walter, if you use the deflection calculators, they will tell you that you need tall profiles to reduce sagging in long spans of extrusion supported at either end. If the whole lot is embedded in concrete, the entire length of the span is supported by the concrete, so IMHO you can get away with short profiles.

[Geof]

I just got involved in this thread, but isn't there a huge problem with Aluminum in concrete. My understanding was that the two materials are not compatible. That is the concrete will react with Aluminum and corrode it....

Yes, correct with Portland cement. We are dealing with aggregate and epoxy resin. It is called polymer concrete sometimes but that is a bit of a misnomer.

[walter]

As you guys saw, there is plenty of things you can do with E/G or polymer-concrete- table, gantry, frames.

Now here's my personal favourite: self-leveling-floating-table. I would use that as a table "underlayment", for accurate mounting of linear rails.
.

[JerryFlyGuy]

Walter, I've had some experiance w/ all of this,and have to say that what you've posted is what I'd do next time. Larry mentioned it to me when I was going through the process of leveling my mill and I discarded the idea as to expensive and not what I wanted. Well, now that I've gone through the process of leveling some long rails and getting everthing straight, I think I'll give this route a try next time. I ended up potting my rail mounting plates w/ Epoxy anyway, it just wasn't as simple as what you've got here..

Jerry.. [whats that saying.. about hind sight.. hrrm.. I forget..]

[myinisjap]

Doesn't sandblasting sand have an additive to stop it bindng?

not that i know of the reason for using blasting sand is because it is strong what else can you smash against steel and keep reusing it? and the only way to machine it is with diamond tools even those get worn

[brunog]

Hello all,
I've discovered this thread yesterday and personally believe this is the way to go to build.
However, to go this way I really think that somekind of skeleton must be placed inside the E/G to give it strength and also threaded inserts and/or threaded bars to prevent from having to drill in E/G after it has come out of the mold.

Also I would make several molds to simplify the casting process and there too insert pieces of metal pipe or conduit as sleeves for bolt hole locations and cork or rubber plugs for countesinks where bolts would slide in for assembly with the other sections of E/G.

This way it becomes even simpler for a DIY project, however planning is critical so that no special tooling is necessary.

Best regards

Bruno

[lgalla]

Hi new posters,
Glad to hear your interest and input to the subject.I understand there are many posts,and reading from the beginning and checking the links is necessary.
The cost right now is up in the air.I won't bore anyone with calculations but it appears,depending on resin/aggregate ratio,to cost $5.00 psf/1"thick.
The weight is the same as aluinium,but would have to be much thicker.
The 10%resin ratio is hard for me to phathom.Picture 1gal of resin and 9gal of sand/aggregates.It will be difficult to totaly saturate this much filler.I am guessing us hobyist guys may have to accept higher ratios.This is not a problem for me as any ratio will give good results.The proof is in the puddin.I won't know the obtainable ratio until I do it myself.Guys keep the post and sugestions and ideas coming
Larry my:cheers:worth

[vger]

I know that most epoxy resins shrink somewhat while curing. Would this preclude placement of attach points prior to curing? Another issue I am curious about is thermal stability. Epoxy and polyester resins are a form of plastic. What COE could be expected with standard epoxy's? I found a blurb on a specialty epoxy that looks pretty good, just wonder how many $100/gal it runs. http://www.masterbond.com/tds/ep30lte.html

[lgalla]

Epoxy's are generally considered zero shrinkage if they are"NEET"eg no solvents or reactive dilutents.The aggregate fillers will result in ZERO,ZERO shrinkage.E/G is more thermally stable than solid granite or cast iron.
I keep on seeing "polyester".In my opinion this is a no,no.Polyester has high shrinkage as it may be composed of 40% styrene which evaporates during cure resulting in maybee 2% shrinkage.Result?pulls away from what you are imbedding.Good polyester points?Shrinkage results in easy de-mold.Epoxy is much more of a challenge to release as it does not shrink.Flamibility and smell are other reasons to stay away from polyester.Sound like I don't like polyester?No, it has its place,but not in vibration damping.Also polyester is not stable.It can shrink and cure for years.Epoxy is fully cured and stable in one week.
Larry
My:cheers: :cheers: worth

[walter]

Walter, I've had some experiance w/ all of this,and have to say that what you've posted is what I'd do next time. Larry mentioned it to me when I was going through the process of leveling my mill....

Jerry,
you're the Originator. Reading your threads inspired me to think differently, you've put so much work into that frame!... There had to be another way. Hence the "self leveling floating table".


Larry,
The E/G idea is gaining steam. Congratulations!
Your steel framed 6x12x4 E/G will be a hit here.
I hope to see some cool pictures!
:cheers:

[CNCAddict]

Hmm,
I think the main mission should be finding an inexpensive source of epoxy. I'm thinking that this will be the main cost by far. The least expensive structural epoxy of know of is aeropoxy, and it's FAR from cheap.

http://www.aircraftspruce.com/catalo...s/aeropoxy.php ~$66/gallon in 7 gallon quantities

Another idea is to pour an E/G mixture into that self leveling frame, smooth it out as good as possible. Then after it's setup, poor in a half inch or so of plain epoxy or higher mix ratio E/G so it flows and self levels. That would be a really easy way to make an extremely flat frame using as little epoxy as possible. I just wonder how thin a layer can be poured and still retain it's flatness over a very large area, think 5x10 router base?? Of course anyone doing this should use a 3 point supports if the machine will ever need moving. Having 4 or more legs would surely twist things way out of alignment.

Does anyone know a way to calculate theoretical flatness using this method? I'm sure it would be good enough for 99.99% of cnc hobbiest, but it would be nice to know just how perfect it really is

[lgalla]

I am a computer/dummy.
I E-Mailed the fly guy to post my design as I ain't got a clue how to do it.hope he understands it.Thanks Jerry.
Again I will give this link untill I am blue in the face. www.shopmaninc.com
Epoxy $30/gal.
If anyone overlooked this link please check.[url]www.precisionepoxy.com.Read everything.I am to tired to check again,but from memory,epoxy can self level to .005.Peroid...
Unfortunatly I got a large contract and have to farm out to a cnc shop.Sure need a router now.
Probably the wrong forum(wrong)but I will ask anyways.The CNc shop is charging $500 for solidworks drawing and $80.00per/hr for cutting.Is this a good price?It will save me 15hrs/per cabinet.BTW the router is a Thermwood 5X10,10hp.Max ipm for my material is 200ipm.I could probally buy a $120,000 machine but that would be no fun.I have contracted CNC itus.
I don't know what time zone you guys are in but it is well past sleeping time here in TO land.EH!
Larry:cheers: :cheers: :cheers:

[walter]

Ok, I've been working on my virtual E/G frame again.
Installed a thin layer of mic6 tool plate & THK rails...

(this machine is coming together faster than I thought it would!)

[atenman1]

Hi Larry and Walter
would it possible to use granite by product from these facility
http://www.pyramidgranite.com/index.html.
I bet they would try to get rid of it, or sell to us dirt cheap. And there should be one available close to wherever you live...

[atenman1]

Hi Larry
hope this going to help you upload your design to the thread, just unzip and play. BTW, what kind of bussiness are you in? If you dont mind me asking!!!

[brunog]

Larry/Walter,
This site gives a little more info on making E/G:

http://www.microplan-group.com/pagin.../celith_gb.htm

Regards,
Bruno

[walter]

picture #1 shows E/G self-leveling-floating-table
picture #2 shows the "stand" that is needed for the floating-table

no welding necessary - just use a Home Depot heavy steel rails and lots of bolts!

[the4thseal]

What about using the sand that is a from water jets? Not as the sole material but as a portion of the aggragate?