wood working question

[Cobar]

second. Just reinforce each glue joint with it.

[Precision]

second. Just reinforce each glue joint with it.

Thank you sir. That is a good idea that can't make it weaker. So I will try.

Testing out the new long pieces of oak I got. Building a 9' haft. I have 6 layers glued up. Three are just under1/8", the other three are about 3/16. I alternated them and clamped them yesterday afternoon. Once I pull them out, I need to add two more outer layers to get to my thickness. The weather is kinda cold (below the minimum working temp of 50, so my pot time was quicker). Didn't want to have the glue crusting before I got them all together. Two more layers both on the outside should get me were I need to be for thickness.

[Cobar]

I'd like to hear how it works out.

[Precision]

I'd like to hear how it works out.

Not sure what happened, although I have some ideas.

On the first test it delaminated at both fiberglass layers.
The build was 3 layers of wood/titebond III, a layer of fiberglass weave, a layer of wood, a layer of fiberglass weave, then 3 more layers of wood

I applied titebond III to the wood (fairly generously) then laid the fiberglass weave on top of the titebond III. I used the edge of my finger in a sliding motion to make sure the titebond was bleeding through the fiberglass. Then a solid layer of titebond to the piece of wood to go on the other side of the fiberglass. This was repeated with the top side of that piece of wood, fiberglass and the next layer. The entire (7 layers) were then placed between two flat 2x4's and cranked down with wood clamps

The assembly was allowed to cure for 24 hours.

The potential issues.
Perhaps I should have made sure the titebond completely penetrated the weave.

Perhaps I should lightly compress the wood - fiberglass - wood - fiberglass- wood composite. Then once that cures add the other layers. My strong clamping force may have removed too much of the glue before the fiberglass could completely soak

perhaps, my back room was too cold. It was over 50 degrees (minimum for curing) but not by much

Perhaps I need to use epoxy on the part with the fiberglass weave. Cost prohibitive though

[blackeagle603]

if bonding with fiberglass -- have to be sure to completely wet out the glass with whatever the resin or bonding agent is. Otherwise... weak. Any dry non-wetted glass on it's own is brittle.

[Precision]

if bonding with fiberglass -- have to be sure to completely wet out the glass with whatever the resin or bonding agent is. Otherwise... weak. Any dry non-wetted glass on it's own is brittle.

I had assumed the glue on both sides plus pressure would make it work.
Are you saying I need to pre-wet the fiberglass in a trough of glue or paint the glue onto the fiberglass (both sides) then apply to glue soaked wood?

[Netpackrat]

If you want to incorporate fiberglass into your lamination you need to be using an actual resin (epoxy, polyester, vinylester etc) and not wood glue. What you are trying to do is never going to work otherwise.

[Precision]

If you want to incorporate fiberglass into your lamination you need to be using an actual resin (epoxy, polyester, vinylester etc) and not wood glue. What you are trying to do is never going to work otherwise.

not the information I wanted, but still the information I needed.

Will the epoxy by the gallon stuff work. I see where I can buy a gallon of A and a gallon of B for about $80. What I can't find is the bonding strength although it is marketed as table top pour type epoxy so I am assuming fairly weak.

[Netpackrat]

That will be way more than you need probably. It's more expensive, but if you have a West Marine nearby you can get one of the smaller kits of their 5:1 epoxy with different cure speed choices, and measuring pumps that will give you the right ratio. I think people have used the countertop stuff for fiberglass but it's probably not ideal being a 1:1 ratio. In general the higher the ratio of resin to primer used by a system, will generally give higher strength/hardness when cured. Although 2:1 systems are common and will probably do what you need.

One key with epoxies is to mix small batches and spread it out quickly once mixed; this reduces the chance it will cook off in the mixing cup. Also, the more thorough the mixing, the better. Having the ratio accurate is very important.

[Cobar]

Sounds like the wood glue can't stick to the fiberglass which I half expected. The glue not being able to stick to itself around the fiberglass I did not expect. NPR is correct of course that the epoxy will work a lot better. I am just wondering if it will all flex together or if it will shear at the layer lines and delaminate. If it does you might be able to do something like a fiberglass core with a wood outer sheathing. It would look pretty non-period once it broke though.