[Mcgyver]

Walter, don't be disappointed, I'm not talking it down, just trying to be realistic with it but a sock and toothpaste now you're talking - add some straws and maybe an ultra-lite aircraft? ...naw not from this guy, the handle was a nic given years ago, i have no affinity with the celluloid character, don't even spell it the same. no Hollywood magic here, just another weekend warrior.

[stlc1]

we manufacture lead screws & Linear guides using high strength polymer
It works very well in dirty inviroments, no rolling element to clog.
you might check ITW -Zanite for base material.
john

[lgalla]

Removing entrapped air with a blow torch.(flame2) (flame2)
I this guy crazy?Yes and no.I will describe what we do with table top epoxy,you know the thick clear coating on bar tops.You pour the epoxy in the middle and let it flow over the top and down the sides,then Lick the epoxy with a blowtorch possibly moving 100 to 200ipm or faster.You will be amazed seeing thousands of bubbles popping at the surface.This is because the entrapped air is expanding and being forced out.Although I have done it many times it does not feel right having a flame licking epoxy.A paint stripping gun also works.Just never hold either in one spot.Another plus it thins the epoxy and heats for faster cure.What use to us?I would recommend doing small 1/2"to1"pours with sand at high epoxy ratios.The heating and air release will result in puddles of epoxy.Now you could sprinkle in the large aggreate and tamp it down with the end of a 2"X4".Any risidual wet epoxy can be sucked up by sprinkling in sand.I you are following my previous advice on slow curing epoxy, in another 5or10 minutes more will pool and you can add more dry filler.
The viscosity of epoxy significantly reduces with heat.If I have too stiff a mix I may put the mix pot in a tub of hot water and stir.Now it will flow and I make the decision to add more filler or pour.Remember any added heat will reduce pot life.How do I know when I may exceed pot life?Put your gloved hand on the side of the mix container.If its too hot to hold,ya gotta getit in the mold pronto!!
I hope I am not over complating, it's not rocket science.I know my material and do a lot of mixing by "feel"or what looks right.
I don't like to put down any suppliers,but If you use an epoxy with East or West in the name,you will be paying a premium price,but is readily available
and I hope they provide good support.A large formulator won't give you the time of day.Any questions welcomed.
Anybody have a 26to28Hg vacuum pump?I so I can elaborate on vacuum de gassing.Please ask.
Larry(flame2) (flame2) (chair)

[atenman1]

Hi Larry
Thanks for your reply!
is this what you looking for?
http://cgi.ebay.com/Gast-Vacuum-Pump...QQcmdZViewItem
calvin

[walter]

Thanks Larry. Good info, as always.

Is it possible to mix "polymer-concrete" products with epoxy?

[atenman1]

Hi Larry
please elaborate on vacuum de gassing process...
Is it almost the same as this gentleman site ?

http://www.corsair82.com/corsair/vacinfs/

calvin

[lgalla]

Calvin good find,Gast pumps are easy to find surplus and 26Hg is probably the max vacuum you would want to subject a resin to before vaporizing some of the chemicals.When you subject a mix to negative pressure the entrapped air expands or boils out the air.Suitable vessels are vacuum bell jars[very expensive]or what I came up with,I use a 10gal Binks pressure pot as the vacuum chamber.I mix 1 gallon of material in a plastic pail and put it in the "vacuum chamber"The mix will foam or expand 3X the volume as the air is released.It is only safe to de gass 1or 1&1/2 gallons at atime or it will overflow.Negative pressure is very powerful that is the reason for a pressure pot.Vacuum can be stored like an air compressor tank four reserve.An aircompressor tank will collapse under vacuum.This is to illistrate why you must have a vacuum bell jar or paint pot as a degassing vessel.I did not really want to post about this as I figgured it was beyond the hobyist.If you get a Gast pump cheap it would also be useful as a vacuum clamp or hold down on a small router.My pump is a busch capable of 28.8Hg.This gives a pressure[for clamping]of nearly 15PSI this translates to something like 2000lbs on a square foot. Very heavy clamping.On a larger note a 4'X8' vacuum table needs at least a 15Hp pump because of CFM required.A small gast pump would be a handy item in a small shop.
Walter"Is it possible to mix "polymer-concrete with epoxy"?I don't know.Polymer concrete seems to be a generic name for regular concrete with additives,polyester based concrete,or even E/G.I have also had thoughts as other posters of "stealing the padio stones "and encapuslating them in E/G.Concrete takes years to stabilizeThe Hoover Dam is not fully cured yet.
Why take the chance.After a week epoxy is fully cured and extremley stable.
I always say"don't beleive everything you read"If you guys are interested in these subjects,don't beleive me totally,Do some of your own research on the subjects I am refering to.
Larry

[Geof]

Regarding vacuum degassing.

Go to the Princess Auto website or get their catalogue. They have a vacuum oil extractor that is powered by compressed air. It is a 5 gallon tank with a venturi vacuum generator on the top and an inlet hose with long thin tubes that fit down a small hole to extract the oil.

On 100 psi air the vacuum generator can evacuate the tank to a vacuum of about 15 to 20 inches which is plenty for vacuum degassing. It is possible to use the tank as avacuum reservoir, evacuate it as far as possible and then turn on the inlet valve to apply this vacuum as quickly or slowly as you like to something.

The regular price is $CAD199 but it comes on sale sometimes at $CAD150

[lgalla]

Walter
sorry I was composing a post before seeing your post.I am sorry I dont have time right now to full read the good link,but I beleive I know the jist of the subject.Other members have asked about pulling a vacuum and "injecting the resin"Great idea I must say as I tryed it years ago.It dosen't work.
Rather than directly refering to our E/G,I will refer to RIM and you can figure it out yourself and why it has no use to our process.
Resin injection molding a process whereby a two sided mold or 2 part mold is injected with resin.Fibre reinforcments are laid into the mold and it is closed.A tube is fitted to the injection port from the resin pumps.To ensure void free parts it is recommended to pull a vacuum to remove the air first before injection.A thought occurs "why bother injecting,let the vacuum suck in the resin.Another one of my great ideas bites the dust.It would take like 5 weeks for the resin to"suck in"The resin pumps inject at 1000psi or better.I hope you get the relationship.We are not going to suck epoxy through sand for wetting.
I am sorry to say my experience is from bright ideas and blowing it.Example:
puffed wheat as a light weight filler?naw performes much better as breakfest.
Beer cans as a light filler.Yes good idea.Picture a cavity say 5"X5"X7"we have to fill with Epoxy/sand.One pour will save time but the exotherm will be too high.Solution put a beer can in the middle.This will allow less material and a path for the exotherm heat to escape.I must specify the can must be empty.:cheers:
Larry

[walter]

I must specify the can must be empty.:cheers:
Larry

Again, good info.
I was about to put the whole can in there...

[ger21]

You can make a cheap venturi vacuum system. I spent about $60 to make the one I use for veneering. Check out www.joewoodworker.com for info.

Larry, I'm assuming you mean that vacuum infusion won't work for this application. There'a a ton of good info on the subject, but you're probably right, sucking resin through sand is a diffferent story.

[lgalla]

Geof I cannot find the oil extractor in the Princess Auto website.If it is a tank without a lid it is of little use.You need a removable lid so you can put in the mix container and not have to clean the tank.
Ger,after looking at Calvins link,I am glad to see this works.It is the same as RTM without the double mold and lower pressure and slower injection or sucking.The vacuum venturi is really cool,but I assume it requires a fair CFM or large air compressor.For continious use an E-bay Gast pump may be cheaper in the long run.Sucking through sand could work,but requires lots of expencive experiements.Anyhow every shop should have a vacuum,venturi or pump as they are useful as clamps or hold downs.
Larry

[Geof]

igalla here is a picture. You will find it in the automotive section on the Princess Auto site. I was not thinking about using this as the vacuum chamber, just the vacuum generator and a vacuum reserve tank.

[walter]

Here are few more machine frames- what do you guys think?
.

[myinisjap]

i have personally done some epoxy casting on a small scale and as mentioned some where in this thread i used blasting sand and the part i made was insanely and dense and extremely difficult to drill (it destroyed a couple titanium bits) i would show pics but the part was thrown out due to a mould mess up on my part and i have never tried again although i think i may

[atenman1]

Hi Walter
Are those granite or epoxy granite? Seem like they was able to place a lot of insert.

[vger]

i have personally done some epoxy casting on a small scale and as mentioned some where in this thread i used blasting sand and the part i made was insanely and dense and extremely difficult to drill (it destroyed a couple titanium bits) i would show pics but the part was thrown out due to a mould mess up on my part and i have never tried again although i think i may

Not sure which sand you used, black beauty ? Most naturally occuring sand is fairly hard stuff. SiO2 in the form of quartz makes up a lot of it. Some comes from weathered granite sources. If you use tooling that is used in the granite industry you should be able to machine, drill, polish, etc.... Diamonds are forever... sortof

[atenman1]

I hope you guys keep working on this! We have been working on epoxy-granite mill bases for a small mill that we are developing (and will be releasing to market soon...we hope!). There are many tricky aspects to it, but the final results are worth it. Through many months of research and testing we have managed to create a small machine with the vibration damping and rigidity of a much larger machine. With knowledge, careful design and planning--a similar machine is within your reach. Don't be discouraged by the unknown.

I hope I can answer any questions about this process. I will try and write up a tutorial on making your own. For now, I will just leave you with some pictures of one of our prototypes that served as a development test bed. Sadly, it has been cannibalized for the benefit of newer prototypes, but it was a great machine and is a good goal for those up for a challenge.


Good Luck!
Matt

Hi Matt

How is that turtorial coming along? Just coulld not wait!!!

[walter]

Hi Walter
Are those granite or epoxy granite? Seem like they was able to place a lot of insert.

Seems like a granite to me. These are just examples- we don't have to match their material, rigidity or anything- we could pour them out of soap and get better results than our current DIY frames...

[lgalla]

I had sujested previously sandblast sand as it is readily available and graded.BLACK BEAUTY is not quartz orSiO2.It is a coal slag product.
Larry