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Tabletop Bowing

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Forum topic by Wondermutt posted 02-09-2016 03:39 PM 399 views 0 times favorited 3 replies Add to Favorites Watch
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Wondermutt

69 posts in 323 days


02-09-2016 03:39 PM

Not sure if this is the right place to post this or not, so here it goes.

I made two different glue up table tops. One is reclaimed cedar 1×6 ’s milled to 5” strips and the other is a maple and walnut top 4/4 thick with the strips appx. 2 – 2.5” wide. Overall dimensions are roughly 24” w x 36” L.

Here is the issue. After glue up, they are bowing up in the centers after being laid out flat 24 hours after glue up and removed from the clamps.

Here is the work flow for these tops. Mind you it had been no warmer than 47 deg Fahrenheit but has not dropped below 25 at night in the shop.

- Mill the blanks straight and cut to rough length
- organize the blanks to the desired pattern
- Lay the blanks in lower parallel clamps (6 clamps for the bottom)
- Glue the blanks together with 1 hour of milling with Titebond 3
- Tighten lower clamps.
- Install another (6) clamps on top
- Install cauls on both ends
- Tighten clamps about 1/2 turns past snug
- Let dry in the shop for 36 hours and remove clamps
- Bring inside the house and let set for 24 hours to apply finish.

Its somewhere in this last step where the bowing occurs. Any ideas? Thanks


3 replies so far

View dhazelton's profile

dhazelton

2326 posts in 1763 days


#1 posted 02-09-2016 03:44 PM

Either the orientation of the grain is doing it, clamping pressure too much or the wood wasn’t fully dry and your house is much hotter and drier than the garage. Are you in the north and your thermostat is set high?

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MadMark

978 posts in 919 days


#2 posted 02-09-2016 03:44 PM

The laying flat while unfinished causes bowing. Stand it on edge and let it flatten and then get a couple of coats of urethane on it (top & bottom) Did you alternate the boards? Crown up / crown down etc.?

M

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

View Wondermutt's profile

Wondermutt

69 posts in 323 days


#3 posted 02-09-2016 03:50 PM

Dhazelton: Yes I am up north and the house is about 35 degrees warmer than the shop. I was wondering about to much clamping pressure. The wood is very dry.

MadMark: I did not know that. This is the first time i have seen this. I did alternate the crowns as I had a cutting board do this from having the crown up.

Good stuff guys. Thanks for the help!

WM

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