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Lag bolts vs threaded inserts for table legs?

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I am building a 4x7 ft table for my wife's craft room. The frame for it is really strong (probably overbuilt) made from maple. My question is how should I attach the legs? They are solid 3.75 square maple legs. Which is the more durable way to attach these things? lag bolts or threaded inserts?

 

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If your legs are hard wood i'd just drill and tap the wood then attach with bolts. Use a metal tap, Marc and andy klien made those wood taps but they aren't really anything special or necessary.

I've done this quite a few times and it's as strong as any other threaded connection in hard wood possibly stronger because you can use larger higher strength fasteners.

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I'll third the motion. Standard metal taps work fine, but may lack the reach needed in some applications. And I suggest not using a drill or impact driver when tapping blind holes, its easy to strip out the threads. DAMHIK.

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I recently tapped some holes in wood using cheap metal taps for a couple of projects. I was pleasantly surprised how well it worked. In one project I tapped some soft pine and even that worked well. I doubt it would be a good option for very thin bolts or fine threads but for your application I think it would be fine.

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with 3.75 square of maple, a lag of 5/16" x 2 1/2" in maple with no inserts. Or 3/8" x 2 1/2" Be sure to drill the pilot 1/16" smaller than the bolt and wax the threads. An electric driver may not take it all the way home so have a ratchet handy to drive it home.If the legs are constantly taken off then an inserted thread. But for most tables that stay assembled, a lag with a proper pilot in maple, no problem. Stainless would add to my confidence. I'd have less confidence in pine... 

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6 hours ago, curlyoak said:

 Stainless would add to my confidence. 

Confidence in what regard? And compared to what grade of non-stainless?

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1 hour ago, Bankstick said:

Why would you need SS bolts for an indoor table?

My perception is the ss will take more torque. but you got me looking on the internet and it seems my perception is wrong. Unless the steel alloy is junk...

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1 hour ago, curlyoak said:

My perception is the ss will take more torque. but you got me looking on the internet and it seems my perception is wrong. Unless the steel alloy is junk...

Unless you get into some exotic stainless alloys, you're better off with plain old grade 5 bolts.

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The standard fastener for this application is a hanger bolt.  Used for decades.  Google has lots of pictures and sources...........

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We have some Walnut tables that were made in a factory that made school furniture.  They have metal angle braces where your 45 degree wooden "braces" are.  Legs are detachable using hanger lag screws with a nut inside the metal diagonal braces.  They are very sturdy, and even survive being drug around on floors.  I would think the same thing would work for your table.  The nuts allow them to be tightened, if needed, any time in the future, with no worry about damaging any threads into the wood, and also the tables can be knocked down, and stacked by removing the nuts, and taking the legs off.

https://www.rockler.com/steel-hanger-bolts-steel-hanger-bolts?sid=V9146?utm_source=google&utm_medium=cpc&utm_term=&utm_content=pla&utm_campaign=PL&gclid=Cj0KCQjwg73kBRDVARIsAF-kEH9Uz9-xFMN-CDpcueTHaYHxHXYBQ1epH0ywhDUsczA8NYCPW0IimVQaAhnrEALw_wcB

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I would not over torque the bolts in wood.  It gains no strength and may start to strip threads in the wood.  Snug tight is all you need.

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If you are putting a bolt of any type directly in any kind of wood, it will strip out before the bolt head will shear off. Steel, even grade 2, is stronger than wood. Also, what Ronn W said.

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30 minutes ago, Bankstick said:

If you are putting a bolt of any type directly in any kind of wood, it will strip out before the bolt head will shear off. Steel, even grade 2, is stronger than wood. Also, what Ronn W said.

Life experience says this is generally true, but false when stated so universally. 

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Speaking from experience with wood and sheet metal. Stripped out threads in soft aluminum- "Just one more tweak!" People think that one more turn is better than all those already done. My father was an engineer in the appliance industry. The assembly line would turn up their air guns to speed up production. Then plant supervisors would gripe when the sheet metal crews stripped out. Hello????

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4 hours ago, Rapid Roger said:

Most torque specs state "Tighten until you strip the threads and then back off 1/4 turn."

 

My father said the joke in the appliance industry and auto industry was- "Hammer to fit, paint to match."

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Or as we used to see on TV when putting screws into hardware, use a cordless drill, run it all the way in until it stops, and then hit it one more time to make sure it's stripped.

The good design of the hanger bolts allows you to put the lag screw end into the wood correctly, and then any tightening of the leg to the table is done with the nut on the machine threaded end of the hanger bolt.

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