joining ply

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H W Keene
Posts: 2
Joined: Mon Sep 12, 2005 9:03 am
Location: United Kingdom

Post by H W Keene » Mon Sep 12, 2005 9:09 am

What is the best method of sealing the edge of ply and joining it to another sheet to make a waterproof butt joint.
regards,
harry keene.
hwk

Rupert
Posts: 6224
Joined: Thu Sep 16, 2004 8:40 pm
Location: Cotswold Water Park

Post by Rupert » Mon Sep 12, 2005 9:39 am

Best method is to scarph it, where you cut each piece of ply several inches (depending on the thickneass of ply) back at the same angle, and then stick the cut edges together. If butt jointing, however, the best way would be to coat the edges first with neat epoxy (no filler) and possibly using a hot air blower (don't let the epoxy bubble) get it to soak in as far as it can. Then you get your extra backing piece of ply (various sizes recommended by whoever you talk to, but at least a couple of inches overlap on 4 or 6 mm ply, and some may say 6") and put your joint together on a flat surface with the backing piece on top, and using slightly thickened epoxy (don't forget the butt) glue it. Weigh it down with heavy flat things, wipe away excess as best you can, and leave it till solid. If doing it on a boat already in existance, you may have to fit the backing piece to the old side first, and the angles get more complex, but the method will be similar, but using fixings not weights.
OK guys, shoot me down in flames...
Rupert

chris
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Location: somerset

Post by chris » Mon Sep 12, 2005 1:38 pm

Have used both methods, exactly as described, very successfully. Only warning is when scarfing ply that only has a thin top veneer. Unless you get the two sides well level and aligned when you glue then it is likely you'll sand through a bit of veneer when you tidy the joint up.

Rupert
Posts: 6224
Joined: Thu Sep 16, 2004 8:40 pm
Location: Cotswold Water Park

Post by Rupert » Mon Sep 12, 2005 4:19 pm

If you cut the top ply vertically, and start the scarph on the next layer down, you can avoid the feather edge.
Rupert

H W Keene
Posts: 2
Joined: Mon Sep 12, 2005 9:03 am
Location: United Kingdom

Post by H W Keene » Tue Sep 13, 2005 1:50 am

Many thanks for input, I will think hard before I start.
Regards,
Harry.
hwk

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