West System epoxy

I have used the West System quite a bit. It is probably best to coat both sides but a little to late for that. You will consider yourself lucky that you were applying the epoxy on the edge grain of the wood. I don't think you will have any issues with this glue up. Next time I would suggest coating both sides.

This epoxy gets absorbed into the wood quite readily. ANd it is possible to end up with a dry joint. It looks like you have enough squeeze out to get a nice joint.

If you used straight resin ad hardner without adding any 205 colloidal silica there might be adhesion problems due to glue starvation. To correctly llaminate spread some straight resin on both sides of the joint. Allow to go off for a little while in your case several hours as you used slow hardner and unless yuu are in Mexico will take a while to set. After the first coat gells mix up another batch but add the colloidal silica to it. This will reinforce the resin and help bridge any gaps. It should be a consistancy between mayonnaise and peanut butter. Don't breath the powder wear at least a dust mask.
Spread that on there and clamp it up. This is not too hard on blades but putting an old set in for at least the first couple of passes will help.

Leo G said:

I've never had to go to those extremes to use the epoxy. Just coat both sides and clamp. Not to hard as you don't want to squeeze out all the epoxy. I only use fillers when I am filling in some kind of a big hole or making molds.

Have you had issues Nap?

Click to expand...

Yes
What I just said is stated in the Gougeon Brothers manual.
You are right about not too much clamp pressure and only one side wetted out could become an issue too. But since you aren't supposed to squees the bejezus out of the joints the filler will allow for some bridging.
Also look closely there are shims shown in the pictures so I know for a fact there are gaps.
Oh and one final thought. West is not very UV resistant so it will have to be coated with something that is like a paint or a UV inhibiting varnish.
The PO realy needs to read the guide to using West system.

I had it clamped by lunch today. Set the heat in my shop to 60 and plan to take it out of the clamps after lunch tomorrow. The directions said 10 to 15 hours dry time with temp range from 60 to 90.

If I am not happy with the joints I will go back to using urithane. The problem with urithane is working time and the huge mess I make when using it. I hate having black fingers for days after using it. I guess I should keep my gloves on but it is so hard to work with them on.

Thanks for all the great advice. It would have been more helpfull if I had asked these questions before I did anything. Next time I will ask questions first.

Dave

Crovello,

West Systems. Nice. I only know about procedure for boat building and there's some nice info if you search for it.

Anyway, strength and bond. From what I understand, building transoms for boats, is that you coat the wood you are bonding once for absorption and let kick or close. Then you do another coat either thin or thickened with silica as mentioned or micro balloons. Wood flour is another filler. Mix to the thickness as mentioned, mayonnaise to peanut butter. The question is what level of bond you want. Complete with no air voids? Or just a fairly good bond with some voids. "Using and oozing" gives you a good void free bond.

Then clamp and let harden. "Drying" isn't really a term for resin sets, it's a chemical cure that is effected by heat, humidity, and ratio of resin to catalyst.

As far as cleaning it up. Resin is plastic. Pure and simple. You can use most wood working tools on resin (fiberglass). In your case you didn't use any glass, so the dulling should be minimal. You will need to clean your knives or blades if you cut a lot of resin. It's build up will be akin to cutting sappy pine.

As said, Acetone is the agent of choice. MEK works too. I'm sure West Systems included the thinning agent in their instructions. That's what's used to clean up.

Nice build BTW. Looks like it's a great project.

JamesK

P.S. You could just use 80 grit in an orbital sander to knock it down before surface plane, or just sand it period. The resin, if properly cured, shouldn't gum up the sand paper too bad. I've used my 4" grinder with 100 grit to (carefully) smooth out ooze before.

I went to my shop this morning to see how my curved treads came out. I removed all the clamps and so far so good. I had less spring back than I anticipated. I would estimate less than 1/2" and I set my forms about an inch smaller in radius than required. I am not sure if it will continue to relax or if it will hold the shape it has now. Either way I am sure I can force it into shape when I fasten it to my stringers.

I ran them thru my portable surface planer and it did not seem to be working that hard.

There are a few spots where the joints are not as tight as I would have liked but they are filled with resin and seem solid. The one mistake I made is not randomizing the strips. It was not so noticable when everything was covered with dust and resin. Now that I see them cleaned up it is more noticable. I will pay more attention on the next tread.

Two or three more of these I will have it figured out. Unfortunately this is only a three tread stair :blink:

I glued up my second tread. This time I coated both sides of every strip. Much better coverage but a little more mess. I made more of an effort to mix up the different colors this time. I think the second attempt will look better.

I did have issues with my spacer popping out. I have spacers because this is actually three seperate boards that make up each tread. As the spacers popped up it forced the strips to bow up as there was now a void at the bottom. I had to clamp some boards across them to hold them straight. This was not an issue with the first tread. I am not sure why it is now. If it is because of resin overflow I may have a hard time getting the three pieces apart later.

I think the over flow of resin my come back to bite me when I unclamp it. I will find out tomorrow night when I head back to my shop.

Thank god this is only a three tread set of stairs.

Dave

Leo G said:

You can wax the heck out of the shims to keep the epoxy from sticking to them (next time). If the shims get glued to the treads (they will ) all you need to do is cut them out with a jig saw and then belt sand the remains off.

Click to expand...

I am learning. Thanks for all your advice.

I often used wax paper to separate things I don't want bonded together but with this tread being 12' long and curved it is not so easy.

I guess I could have wrapped a small piece of wax paper around the shims.

Dave