Ready Steady Eddy

[njhussey]

I was told by someone to mix it in one container and then transfer it to another for the final bit of the mix and that way any unmixed bits round the sides/bottom edge etc. either get left or poured into the new container and you don't get any soft sticky bits...

[Wobblycogs]

Brilliant update Eddy, great idea with the draught excluder.

I've watched a few videos about clear coating wood with epoxy. To get the air bubbles out they normally play a blow torch flame over the surface for a fraction of a second. I guess the faster you can apply the heat the less you move the epoxy around. They always remove the majority of the bubbles before pouring though and I've seen two good techniques for this. The first requires some skill, you pour the epoxy from one container to another but lift the top container up as high as you can creating a very thin but constant stream. It seems the thin stream forces the bubbles out on it's way down. I've tried this and it works but it's easy to screw up and end up with epoxy everywhere. The other is to pour the epoxy into a big tub and put it under slight vacuum which will suck all the bubbles to the top, obviously you need some way to make a vacuum though and you've got to be careful not to fill your vacuum making device with epoxy by accident :-). Next time I need to de-bubble some epoxy / resin I'm going to give the vacuum method a go as I have a spare vacuum cleaner hanging around.

What are you planning on doing about the meniscus? I was wondering if it might be worth trying to route a chamfer into the epoxy as that would remove the meniscus, clean the edge and help stop it chipping all at the same time.

[EddyCurrent]

What are you planning on doing about the meniscus? I was wondering if it might be worth trying to route a chamfer into the epoxy as that would remove the meniscus, clean the edge and help stop it chipping all at the same time.

I'm thinking it would be difficult to control a router for that operation. The method I propose is to use a file where you stop when the central epoxy starts to show signs of contact, then run a bead of liquid nails along each edge of the epoxy, run your finger along, thus creating a nice fillet between the epoxy and the underlying metal.

[EddyCurrent]

Neil,
The heat I tried with the hair dryer was not enough to affect the foam, I kept it moving, but the thing is in my case it did not help with the bubbles. Maybe heat with less force would work ? it's just that with the draught excluder method there is not much room to create a tidal swell in the epoxy,

[njhussey]

Hair dryer and heat gun are different beasts though...hair dryer will never get hot enough to melt the foam. Heat gun would if you hovered in one place too long I'd wager...

[njhussey]

It's a compromise with the foam of enough heat to expand the air bubbles to pop them and not too much heat to melt the foam :)

[EddyCurrent]

Dragging the tooth pick worked for me and it physically moved the epoxy about thus aiding the self leveling process.

[njhussey]

You can't beat low tech...I can't wait to start playing with the epoxy next week!

[EddyCurrent]

It's done !

This is before showing the moat in place. Clive S recommended 10mm epoxy each side of the linear rail so with my rail being about 20mm wide the epoxy bed has to be 40mm wide. Because my support beam is 50x50x3 box section it only left 5mm spare each side which meant the draught excluded would have been on the radius of the box section, that's why I clamped strips of wood each side so as to fully support the draught excluder. You can see I've coated the joints and any gaps with sealer.



The gear used and the environmental conditions at the start. I used an old ice cream tub and a sawn off milk carton, the epoxy was mixed in the milk carton then poured into the ice cream tub with a thin stream as suggested previously. I'm not sure this did much but at least there was no mess created. The ice cream tub had a 7mm hole on one side, right at the bottom, with a piece of tape across and this proved to be perfect for pouring. Humidity is quite low because I always have a dehumidifier in there.
The calculated volume of my moat to give 5mm depth of epoxy was about 605300 mm^3 and it worked out that 500g of epoxy plus 250g of hardener was just right.



This is after the pour, you can see the meniscus. There were no leaks and there was never any risk of it overflowing the moat. The epoxyducts were about 10mm wide and I'm thinking they could have been wider, definitely no smaller, the reason being that with this viscosity it needs a decent channel to flow down otherwise I would not be confident that the whole surfaces were at the same level.

[Clive S]

Eddy That looks nice re the moat I did find that my moat could have been a little wider although I did have two of them. I am sorry that I forgot to mention that before but you have plenty of width now in the centre even you don't get rid of the meniscus. ..Clive