pillot holes for 3/8 lagbolts

carl reitnauer · May 25, 2015

posted earlier about bolt failures. What size pilot holes did I need to use in the yellow pine?

60 acre hillside · May 25, 2015

1/4 inch and do not drill full depth

mtf · May 25, 2015

I really like the timberlok screws. The box claims they are as strong as lag bolts. No pre-drilling required. I have used them in seasoned oak. Nathan

Dick2 · May 26, 2015

Lots of variables to that situation. Much depends on the individual wood and grain pattern, moisture content, etc. Guess it boils down to a "trial and error" situation.

JOB · May 26, 2015

Years ago an old carpenter told me to drill holes the same size as you would to tap a hole for threads. So in your case 5/16 hole for 3/8, 16 threads per inch. If memory is correct. I have always gone 1/32 smaller than tap size without problems.

Dick L · May 26, 2015

We sell Cub Scout Cubmobile wheel kits with 3/8" lag bolts and advise 5/16" drilled holes into the 2" X 4" axles to keep the 2" X 4" from splitting with the weight and bumps.

glennster · May 26, 2015

Get a bar of ivory soap and rub it on the bolt before installing. The soap will lube the bolt so it wont break.

K Effective · May 26, 2015

When assembling my wagon decks this Spring, I was using 1/2" lags, drilling 3/8" pilot holes, and coated the whole thread length in grease before driving them home with the air impact wrench. Did not break one in rough-sawn Ash.

pillot holes for 3/8 lagbolts

carl reitnauer

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60 acre hillside

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mtf

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Dick2

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JOB

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Dick L

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glennster

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K Effective

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