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? Expansion/contraction Bar-top Corner?

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Forum topic by saw4fun posted 10-05-2015 02:36 PM 516 views 0 times favorited 5 replies Add to Favorites Watch
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saw4fun

174 posts in 2802 days


10-05-2015 02:36 PM

Topic tags/keywords: bar black walnut joinery bow-ties expansion contraction help

I am going to be building a bar out of 2 natural edge Black Walnut slabs 2”thick. Where the ends will be 45ed and joined for the 90 corner they are roughly 20” wide. My concern is what is going to happen at this joint if there is any expansion or contraction. Has anyone done something similar at what were the results in the long term? Was thinking of using the slot and bolts underneath and a couple bow-ties across the joint on top.


5 replies so far

View oldnovice's profile

oldnovice

5723 posts in 2830 days


#1 posted 11-08-2015 06:20 AM

Your concern is expansion/contraction but my concern would be getting the miter cuts to match because you will actually be miter cutting over 28-1/4” (1.414 × 20”, over nearly half the width of the pieces) on each 2” thick piece. In my opinion making those two edges match to satisfactory joint will be the more difficult and time consuming task.

However, if you are successful and satisfied with the resulting miter joint, the grain in both pieces will essentially be going in the same direction (just facing each other) of most expansion/contraction and should be nearly identical and the joining methods could be same method used on kitchen countertops, or plywood splines, or large dowels.

I used 1/4” plywood splines on my oak table which had an 8” miter joints.

-- "I never met a board I didn't like!"

View Monte Pittman's profile

Monte Pittman

22005 posts in 1800 days


#2 posted 11-08-2015 09:45 AM

A good straight edge should keep the mitre cut 98% straight. Just a little clean up.

As far as expansion, I like your idea of butterflies. However, I have not seen them used to hold endgrain to endgrain.

-- Mother Nature created it, I just assemble it.

View jerryminer's profile

jerryminer

528 posts in 904 days


#3 posted 11-08-2015 08:43 PM

Remember that when the wood expands/contracts it will actually change the miter angles (bc the expansion/contraction will affect the width more than the length). So button up the miter joint but let the “legs” of the bar float to accommodate the movement.

View rwe2156's profile

rwe2156

2192 posts in 943 days


#4 posted 11-08-2015 09:18 PM

I think what you want to do will work.
Any shrinkage can be dealt with by retightening the clamps.

Most critical is not the absolute accuracy of the miter, but how straight the egdes are.

-- Everything is a prototype thats why its one of a kind!!

View saw4fun's profile

saw4fun

174 posts in 2802 days


#5 posted 11-09-2015 03:22 PM

Thanks guys! The slabs are coming out of the kiln today so I’ll be building this project this week. Have a better piece of mind with these insights. As long as my outside corner matches up nicely I can just blend the end side with a grinder I believe. Thanks again, will post pics when its done

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