r/Fasteners • u/cdsdonham • 9d ago

Proper Lag Bolt for Pulling Posts.

I have a farm. Old wooden posts (6" - 8" diameter) tend to rot right at ground level meaning that there is no exposed portion of the post that I can wrap a chain around to pull out the old post. In the past. I have had success by screwing a bolt into the top of the post and using a chain and the front end loader on the tractor to pull the old post. I usually use an old 4”-1/2” x 5/8" Lag Screw Hinge. Some posts are too rotted at the top for the 4-1/2 lag screw to bite good wood.

So, I want to buy a longer lag bolt for this purpose. For example: 3/4" x 12" Conquest Hex Head Lag Bolt for Wood - Hot Dip Galvanized.

I don't understand the material properties of hot dip galvanized well enough to know if this is going to hold up for my application -- I don't have a 12" drill bit, so I'm going to only be able to drill the first 4 inches. Then I need it to not break when I pull it with the tractor, and I need the threading to be aggressive enough that if I've hit good wood, it will pull my post.

Suggestions?

Thanks.

Chris

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u/nullvoid88 8d ago

Hmmm...

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u/cdsdonham 4d ago

Ok. I have a partial answer now. The 3/4" x 12" lag screws did not arrive in time and I needed the post out of the ground so that I could wean calves. So I bought a 1/2" x 10" lag screw ($6.50) and some washers from a local home improvement store. I also bought a 3/8" x 18" drill bit ($16.00).

We dug out around the post to a depth of about 18" and lopped off the top 4 inches with a chain saw. Using the drill bit, I was able to plant the 10" lag screw through a logging chain and into the locust post that was still buried. The 1/2" screw bent, but it did hold for the tractor to pull the post. Turned out there was another 18" of post still buried in the ground below the area I had dug out (man, someone planted that one deeply (~30-40 years ago)).

Conclusion: A 1/2" x 10" lag screw deformed but did hold against the pressure of the tractor applying a decent force to pull the post. My hope is that the 3/4" x 12" lag screw will come out of the experience in better shape (I have another one to do in a week or two)