Using 5200 on wood

Quickstep192

Anarchist
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Chesapeake
I’m re-flooring a porch and there will be a piece of 1x6 trim that goes around the perimeter. I want to miter the corners for appearance and to minimize exposed end grain. Miters are notorious for opening up as the wood expands and contracts.

I was wondering if making the miter a little loose and joining it with 5200 would let it move around without separating. The flooring and trim will get painted.

Thoughts? Other ideas?
 

slug zitski

Super Anarchist
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I’m re-flooring a porch and there will be a piece of 1x6 trim that goes around the perimeter. I want to miter the corners for appearance and to minimize exposed end grain. Miters are notorious for opening up as the wood expands and contracts.

I was wondering if making the miter a little loose and joining it with 5200 would let it move around without separating. The flooring and trim will get painted.

Thoughts? Other ideas?
Nothing adheres to end grain very long

best to use the same method that a teak deck uses

even then a teak deck always fails first at the end grain
 

slug zitski

Super Anarchist
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By this, do you mean a rabbeted miter?
…caulked for many joints

a rabbited mitre might hold for a while but sooner or later the end grain will get you when exposed to the weather

I suppose a dovetail joint , like all the old timers used on cabin house joints, is the best

high movement end grain joint always need some extra detail
 

mckenzie.keith

Aspiring Anarchist
846
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Santa Cruz
I’m re-flooring a porch and there will be a piece of 1x6 trim that goes around the perimeter. I want to miter the corners for appearance and to minimize exposed end grain. Miters are notorious for opening up as the wood expands and contracts.

I was wondering if making the miter a little loose and joining it with 5200 would let it move around without separating. The flooring and trim will get painted.

Thoughts? Other ideas?
If you leave a gap and then fill it with a flexible sealer you might be OK. I am not sure if 5200 is the right choice. I think you want something more flexible. But if you start with the miter closed, it is guaranteed to open, I think. Would you be happy with a 1/8" (3mm) gap filled in with caulk? I would use something designed for caulking wood seams.

Miters open not because the wood expands and contracts in length, but because the wood expands and contracts in width. Plywood doesn't do this because there are layers with grain running both ways. The side-to-side layer can't expand and contract because the fore-and-aft layer won't let it. Basically.

So another crazy idea, you could stabilize the wood against sideways expansion and contraction by putting in splines with grain running 90 degrees to the wood grain. In effect you would be converting the miter pieces into plywood. At least in the region of the miter. Seems like a lot of work, especially if you want to hide it (make blind slots).

Maybe consider but joints or half laps or something?

 

mckenzie.keith

Aspiring Anarchist
846
281
Santa Cruz
In the old days (so I have been told) to split rock without explosives, a series of holes were drilled in the rock along the desired fracture face. Dry wood fibers were inserted in the holes and kept wetted. The fibers expanded in width with a force sufficient to split rock. That is the force you are dealing with if you try to keep a deck miter made of dry wood closed during the damp season. I think this is why it seems like experienced carpenters use a different solution (like leaving the miter open to begin with).

But I am not a carpenter and have never built a deck so what do I know.
 

Zonker

Super Anarchist
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5200 sticks to wood like a son of a bitch and has long elongation (but if the seam is tiny the elongation will be tiny too). Big gap = big elongation
 

Quickstep192

Anarchist
906
187
Chesapeake
In the old days (so I have been told) to split rock without explosives, a series of holes were drilled in the rock along the desired fracture face. Dry wood fibers were inserted in the holes and kept wetted. The fibers expanded in width with a force sufficient to split rock. That is the force you are dealing with if you try to keep a deck miter made of dry wood closed during the damp season. I think this is why it seems like experienced carpenters use a different solution (like leaving the miter open to begin with).

But I am not a carpenter and have never built a deck so what do I know.
It depends a little bit on the wood species, but yeah...
 

Quickstep192

Anarchist
906
187
Chesapeake
I wasn’t suggesting replacing the pipe, just wrapping the rubber thinger around the pipe and then securing it with hose clamps.

Or, there’s this thing which is actually cheaper than a tube of 5200. But, I’d use 5200 on a smallish crack in a heartbeat in a DWV pipe.

1A968A08-5567-4C66-B961-D4B6264CFAE3.jpeg
 

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