[PropellerHat]

Hi gurus

As the topic tells, my machine base looks like a failure. I finally have managed to have time to fix several skull crushing out-of-nowhere issues after making the extremely laborious EG base, and as I was doing some simple test pieces I noticed the rather mild clamping force was enough to push dents into the gravity cast surface - the f***er is still soft! I was hoping it would just be "nice dampening-in-the-contact-surfaces-kind-of-softness" but no, stuff sinks into it.

What to do? I guess it´ll never get hard if in half a year it hasn´t happened. What´s the best way to get about 5mm of crappy "gummy" epoxy off of the machine base?

What a nightmare......

-PropellerHat

[joeavaerage]

Hi,
what epoxy did you use?
How did you measure the proportions of the components? I weigh epoxies these days, its really the only way to get it 100% every time.

If the surface has not gone solid, then either the ratios were incorrect or it was not mixed properly. The problem is that the body does not develop the properties
that it should, ie it will be 'squishy' all the way through. If that's the case then start again.

Craig

[PropellerHat]

Hi

I used this one:
https://kandydip.de/ecom/prestashop/...in-diponr.html

I weighed the liquids with a digital scale and stirred even with ultrasonic cell disruptor. There were some lumps in the other canister (Can´t remember if it was the hardener or the other, the resins had stayed a while at my workshop) that needed to be sonicated to get it completely runny. Guess I should´we bought fresh resin or then I screwed the weighing.

[joeavaerage]

Hi,
well that epoxy system sure looks like it should have worked, and if you weighed it out then the ratio should be right to.
Could possibly the lumps break down, but not completely? Maybe in agglomerations of a number of molecules enough to interfere with the
reaction? Did you use any solvent? That is a non reactive component and usually screws with the properties of the cured product.

Does the manufacturer of the resin system have any ideas?

I can only but agree it looks like an expensive nightmare.

Craig

[routalot]

I'm another in the always weigh epoxy components camp.I suspect the problem may not be in the mix ratio as we are told that steps were taken to agitate and weigh the components.What we don't know is the age and the storage conditions for the material.It seems to be a lost cause.My only suggestion would be to try heating it to the temperature of a warm summer day to see if that does anything at all to help.If not,take the experience and repeat with the same care and new supplies of epoxy and it ought to be a better outcome.

[PropellerHat]

Yeah I casted it in last summer

Anybody knows how to peel the stuff off? Angle grinder?

[mactec54]

Hi gurus

As the topic tells, my machine base looks like a failure. I finally have managed to have time to fix several skull crushing out-of-nowhere issues after making the extremely laborious EG base, and as I was doing some simple test pieces I noticed the rather mild clamping force was enough to push dents into the gravity cast surface - the f***er is still soft! I was hoping it would just be "nice dampening-in-the-contact-surfaces-kind-of-softness" but no, stuff sinks into it.

What to do? I guess it´ll never get hard if in half a year it hasn´t happened. What´s the best way to get about 5mm of crappy "gummy" epoxy off of the machine base?

What a nightmare......

-PropellerHat

This is quite normal for epoxy's some plastics have a harder surface than epoxy, it is not normally suitable for a direct mount machine table, what you need to do is add a tooling fixture plate on top then you should be ok, make this plate to cover the whole area, you can then mount your work vices Etc., direct onto the steel or aluminum surface

Granite is hard epoxy is softer than the bones in your body

[PropellerHat]

So to use big surface area against the epoxy? Darn, I was especially planning to use it as a direct mount table, with resin printed disposable standoffs (that for the cost should be as small as possible, not with big surfaces). Well gotta try with something bigger and maybe just not care if the table gets ugly.

-J

[routalot]

Is the machine sufficiently complete that you could take a light skim to remove the amine blush and examine the core of the epoxy?If so you might have a decent base for a metal surface.I suppose one lesson that might be passed on to others contemplating an epoxy cast machine is that a modest volume test mix before the big pour might save a lot of anguish.

[mactec54]

So to use big surface area against the epoxy? Darn, I was especially planning to use it as a direct mount table, with resin printed disposable standoffs (that for the cost should be as small as possible, not with big surfaces). Well gotta try with something bigger and maybe just not care if the table gets ugly.

-J

If the table gets ugly from doing this then you will have high and low spots, as it compresses, it will go up as well as down, a plate on top is what will make it work as a table

[mactec54]

Is the machine sufficiently complete that you could take a light skim to remove the amine blush and examine the core of the epoxy?If so you might have a decent base for a metal surface.I suppose one lesson that might be passed on to others contemplating an epoxy cast machine is that a modest volume test mix before the big pour might save a lot of anguish.

Would not make any difference if you did a test or not, you still would have the same outcome which epoxy by itself is too soft

[PropellerHat]

I actually did a test cast with the same stuff before, and using the same resin that had been more than a half a year standing, forming lumps, might have been the mistake. Beware of lumps, where ever you find them

[routalot]

Would not make any difference if you did a test or not, you still would have the same outcome which epoxy by itself is too soft

I would agree about unadulterated epoxy being soft.On the other hand,I have used very hard epoxy tooling block and it isn't hard to buy it.It still wouldn't be my choice for machine building,even if it is soft enough to use for small run press tooling.Hardness and rigidity are the qualities we should be seeking.

[mactec54]

I would agree about unadulterated epoxy being soft.On the other hand,I have used very hard epoxy tooling block and it isn't hard to buy it.It still wouldn't be my choice for machine building,even if it is soft enough to use for small run press tooling.Hardness and rigidity are the qualities we should be seeking.

You can use urethane / rubber for press tooling and 3D printed plastic parts also, it all has a place and use

It is fine to build machines using epoxy, but you have to add steel insert to bolt tables / linear rails Etc. to there are a lot of successful hobby builds using epoxy granite mixes. even high-end grinders Mill and lathes are using epoxy granite bases

[elmerfud]

Try a wet towel over it for a few weeks, i remember hearing epoxy likes moist air when curing.

[joeavaerage]

Hi,
epoxy that does not go off is a plain f...up, pure and simple. It was either not mixed correctly or was in some way faulty. If its soft on the surface
then how bad are its volume properties?.

I've used hundreds of liters of epoxy on boats, and any, and I mean ANY epoxy that does not go off will absorb moisture, which in a boat is another name for leak!
and is a pure disaster.

Craig

[peteeng]

Hi - Epoxy does not like moisture when wet or dry. Do not place wet towels on it...Epoxy absorbs water and water is a plasticizer and makes all plastics soft. If you have an electric blanket wrap it around the part and run it for a few days to see what happens. Place a sleeping bag or doona over the e blanket and keep the heat in. If epoxy is still soft after say a week under heat then you mixed it incorrectly in the first place. Epoxy resin and hardeners do not degrade over time (if keep in sealed containers) so even stuff 5 or 6 years old will still work if mixed correctly. I've used stuff 10 years old and it worked fine. If the manufacturer has a hardness spec for the cured material you can use a hardness tester to check for cure.... Good luck Peter

[routalot]

If it hasn't cured by now,its a lost cause.However much time and effort,not to mention cash that you have put into it can be written off.Better luck next time.