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Joining boards. Should boards be even and when to use biscuits

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Forum topic by ppg677 posted 02-25-2016 06:05 PM 521 views 0 times favorited 5 replies Add to Favorites Watch
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ppg677

78 posts in 321 days


02-25-2016 06:05 PM

1) If I’m creating a 20” board out of 5.5” boards, is it considered “finer” to join 5 4” boards or to just trim 2” from 4 joined 5.5” boards (4*5.5 ==> 22”)?

2) When should I use biscuits? Whenever possible? Or just for something that takes load?


5 replies so far

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jdh122

879 posts in 2282 days


#1 posted 02-25-2016 06:11 PM

1) I don’t think it matters. Go for the best grain match you can would be my advice. Don’t try to glue it up to the exact size you need, cut it after glue up.
2) Biscuits help with alignment but add no strength. Instead use cauls to keep the glue-up aligned.
I would do this in 3 glue-ups (one 15 and one 10 inch and then glue them together).

-- Jeremy, in the Acadian forests

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Mark

820 posts in 1439 days


#2 posted 02-25-2016 06:11 PM

1) depends on the look you want.. If it’s for a table where it will be noticed I would go with 5 X 4” boards with a bit extra on each side for trimming later.
2) I’ve built several tables for the living room and a large dining table. Never used biscuits. I’ve always used a GOOD blade in the table saw, and have been very careful of my glue up (after the first one.) :)

-- Mark

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ppg677

78 posts in 321 days


#3 posted 02-25-2016 06:57 PM

Thanks. I guess I don’t see how biscuits help with alignment. I’m just creating a panel that will be trimmed, and the boards will be under clamping pressure. If they shift a couple mm, who cares as I’m going to trim!

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MadMark

978 posts in 918 days


#4 posted 02-25-2016 07:34 PM

Biscuits are mis understood. They do help joints with transverse stress (shear on a glue line) by disrupting the shock wave. They are a tremendous help in big pieces because the will help with alignment as you assemble. Biscuits also help with T-joints because the biscuit is cut on a bias and neither side of the joint wiil be aligned with the grain. They are not perfect and a cheap cutter will give you slop in the joint. The biscuits keep up and down motion from entering the joint.

Tip: butter 1/2 of the biscuit with glue and insert in one side and let dry. Then assemble the two pieces and it goes together like tab A in slot B.

You should rip all your 1×6’s down to 5.0” before starting. If you leave 3×5.5” then the 4th is narrow (3-1/2”) and may look odd.

M

-- Madmark - Madmark2150@yahoo.com Wiretreefarm.com

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jdh122

879 posts in 2282 days


#5 posted 02-25-2016 08:30 PM


Thanks. I guess I don t see how biscuits help with alignment. I m just creating a panel that will be trimmed, and the boards will be under clamping pressure. If they shift a couple mm, who cares as I m going to trim!

- ppg677

The alignment we’re mentioning is with respect to the thickness of the board, not the length. In other words, when you have long boards, the biscuits are one way to ensure that the final panel doesn’t have one board that sits proud of its neighbor and so has to be planed or sanded down to flush.

-- Jeremy, in the Acadian forests

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