Oh Joy Resto 01/27/10

[CharlieCobra]

Over the past couple of weeks, I've been working on fabrication of the clamp to replace the rotted section next to the chainplates which prompted this tear down. I made a new clamp using three pieces laminated together with MAS epoxy and then planed and shaped.



Then, using the bandsaw, I set the notches.



and



I later cut them out using the multi tool. We then did a test fit.



Today, I mixed thickened epoxy (using Black Locust sawdust) and we set the clamp in place.

Aft joint, notice the clamp shim to keep the clamp from sticking and to get even pressure?



Aft lower chainplate in it's slot.



Forward lower.



Looking forward from inboard.



Looking aft from inboard.



Forward joint (not quite as tight as aft but close enough. Notice the height mismatch? The clamp thins forward so I'll hand plane it down to match.



A look at the upper chainplate in it's notch from outboard.



Outboard looking forward.



I'll let it cure and then plane and fill as needed. I'm thinking of running a couple of bolts down through the center of the joints for insurance. Once I'm done with this, we can go forward the the ribs starting aft.

[poopdeckpappy]

Out of curiosity (mostly ignorance), why would you use sawdust in lieu of a glass filler or even flour? In my inexperienced brain, sawdust would be a impurity effecting strength of the bond.

[CharlieCobra]

Using sawdust for a filler (thickening agent) with epoxy is an old, or at least, as old as epoxy use on wooden boat technique. Apparently, there's no real loss of strength as the sawdust is epoxy impregnated. The glue joint is still stronger than the wood it joins, especially with a scarph joint.

[Sabreman]

Using sawdust is a woodworkers trick for hiding minor imperfections in finished work. In this case, colloidal silca would work just as well. Since I suspect that the clamp will be painted, either thickener will suffice. The thickener is used to make a paste and keep the liquid epoxy from running. The paste bonds the gap in the scarf.

Nice job.

[Stillraining]

Charlie...I thought you were going to replace the chain plates??

[CharlieCobra]

I'm gonna have them magnifluxed first. I can still pull them with the clamp in place...

[CharlieCobra]

Thanks Sabreman, that clamp is sawn rather than steam bent. I didn't want a repeat of the splitting that occurred at the chainplate notches in the original piece because of bending stresses on the outside of the piece.

[Faster]

Keep 'er going, Charlie.. looking good. Are you having any problems (outside of cost) locating decent material to work with?

[poopdeckpappy]

see, told ya it was mostly ignorance; I do the sawdust & glue as a filler for nailheads and such, just never thought about sawdust as a epoxy filler.

[CharlieCobra]

No, no real problems finding materials thus far. That may change when I start looking for a chunk of old growth Honduran that I'm gonna need later...