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Can this bench be structurally sound?

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Forum topic by mahdee posted 01-27-2016 01:42 AM 1004 views 0 times favorited 28 replies Add to Favorites Watch
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mahdee

3555 posts in 1235 days


01-27-2016 01:42 AM

Topic tags/keywords: walnut joining

I want to make a bench like this but it I can’t see how this can be structurally sound. I like the simple look but will it hold 3 people sitting on it?

-- earthartandfoods.com


28 replies so far

View Luthierman's profile

Luthierman

157 posts in 555 days


#1 posted 01-27-2016 01:48 AM

Sure, if you make it out of 8/4 white oak slabs.

-- Jesse, West Lafayette, Indiana

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Luthierman

157 posts in 555 days


#2 posted 01-27-2016 01:49 AM

You can also inlay some angle iron on the underside and use some less costly material as well.

-- Jesse, West Lafayette, Indiana

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mahdee

3555 posts in 1235 days


#3 posted 01-27-2016 01:50 AM

It will be 2” walnut. I am thinking maybe a simple tongue and groove?

-- earthartandfoods.com

View conifur's profile

conifur

955 posts in 619 days


#4 posted 01-27-2016 01:51 AM

You can barely see it on the pic posted, but the legs are dadoed into the bench, cant see the top of it might have a fastener running down from the top into the legs also.

-- Knowledge and experience equals Wisdom, Michael Frankowski

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mahdee

3555 posts in 1235 days


#5 posted 01-27-2016 01:52 AM

Thanks Jesse,
angle iron sound promising.

-- earthartandfoods.com

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mahdee

3555 posts in 1235 days


#6 posted 01-27-2016 01:53 AM

Michael, Thanks. Yes, there has to be some sort of joinery there or it would crash with 700 pounds wiggling around on it.

-- earthartandfoods.com

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conifur

955 posts in 619 days


#7 posted 01-27-2016 01:54 AM

Dont make any difference how many sitting on it if they shift there weight left to right. Personally unless kids I would not want to sit on a bench to eat,IMHO

-- Knowledge and experience equals Wisdom, Michael Frankowski

View johnhutchinson's profile

johnhutchinson

1196 posts in 1097 days


#8 posted 01-27-2016 02:05 AM

I like the idea of a dado connection half way up into the seat.

If it fails, at least they won’t have too far to fall. :-)

-- John - Central Ohio - "too much is never enough"

View Minorhero's profile

Minorhero

372 posts in 2072 days


#9 posted 01-27-2016 02:09 AM

Here is a link to a tool that calculates sag. Its designed for book shelfs but it works fine for benches as well. Assuming 600 lbs running over 6 feet you get .17” of deflection which is considered “acceptable” according to the calculator when your finished shelf thickness is 2” of black walnut. If you bring that down to just 1.75” thick then it jumps to .26” of deflection which is a bit much. Its not hard to reach 600 lbs either if you have a couple of large people or 3 moderately heavy people sitting on it.

http://www.woodbin.com/calcs/sagulator/

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Smitty_Cabinetshop

13738 posts in 2086 days


#10 posted 01-27-2016 02:10 AM

Sliding dovetail.

-- Don't anthropomorphize your handplanes. They hate it when you do that. -- OldTools Archive --

View jmartel's profile

jmartel

6578 posts in 1617 days


#11 posted 01-27-2016 02:12 AM

I think if I built it I would probably put an additional 2×2 piece down the center. You won’t be able to see it from a normal standing height so you still get the visual look, but it significantly improves the strength, both in sagging and in racking forces.

-- The quality of one's woodworking is directly related to the amount of flannel worn.

View builtinbkyn's profile

builtinbkyn

651 posts in 408 days


#12 posted 01-27-2016 02:18 AM

If I had to guess, I say there’s more connecting the legs and seat than a glued dado. I’m thinking bolts covered by plugs. May even be threaded rod going all the way thru the leg.

-- Bill, Yo!......in Brooklyn :)

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Minorhero

372 posts in 2072 days


#13 posted 01-27-2016 02:23 AM

Steel plates. Large manufacturers don’t care much about “traditional” joinery. So my guess is there would be a steel plate embedded in the legs and in the top and bolts going through the plates and into the legs from the top then a veneer covering the whole mess up.

View oldnovice's profile

oldnovice

5733 posts in 2835 days


#14 posted 01-27-2016 02:42 AM

I have seen benches this size where there legs are not one piece but two pieces joined at an angle!
This actually increases the surface area of the leg adding to stability.
Obviously this changes the appearance!

Or, make a tubular steel leg and cover it with wood sleve.

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

View TheFridge's profile

TheFridge

5765 posts in 953 days


#15 posted 01-27-2016 03:24 AM

I’d do it just like the pic. Mortise or sliding dovetail. Tenon with a shoulder. 600+ lbs won’t be in the exact center of the span. 2/3 of that will be near the legs. 2” X 12” or so walnut is effing thick.

Just me. I wouldn’t worry about racking either with a tenon. That tenon will be huge.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

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