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Grade 8 Strongest thick Lag bolts for pulling tree stumps with a jack?

Grade 8 Strongest thick Lag bolts for pulling tree stumps with a jack?

Old 06-04-23, 03:41 AM
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Grade 8 Strongest thick Lag bolts for pulling tree stumps with a jack?

I have a Hi Lift jack for pulling up concrete fence posts or small tree stumps. It's bolted down on a U shaped 4x4 platform plus two 2x4s angle down from the top of the jack as bracing - basically the configurations you'd see on YouTube where the 2x4 braces preventing the jack from moving, and the base for the same reason plus it helps pull things up higher.

Surpisingly with the tension these jacks create, chain can even get a good grip on smooth round chain link fence posts with no added bolts or anything but it's a little tricky to get the chain just right and it's often trial and error wasting time until it grabs.

4x4 fence posts I can drill-through and put in a Grade 8 carriage bolt and attach my chain around that.
But tree stumps are too wide to drill through and then put a rod through or something for the chain to grab.
I tried pre drilling and install on a downward angle to reduce bending regular Lowes/Depot bin-grade2 (not very strong) thick ~1" lag bolts but they bent - I may have been trying to make the jack do more than it can but my jacks can lift 7,000 pounds, and chain is rated for 5,400 lbs, and I add onto the pump handle a 6 foot section of 2" steel chain link fence post for more mechanical advantage like a breaker bar on a ratchet, so if I can use this to quickly pull a decent size stump I'd much rather then deal with saws-all'ing at the roots and having to re-sharpen the blades during the process because they dull so fast in soil. I pulled many stumps and roots manually with just 4x4 blocks as fulcrums and steel rods to pry but overall a jack to pull it up mostly and then maybe axe/saw at the roots to free it would be quickest.

But they don't seem to make grade 8 aka yellow dichromate lag bolts or anything really strong and thick. All the 'strongest lag bolts' seem to be the structural deck type which basically instead of using a 5/8 Grade-2 Lag/Carriage you can get the same strength from a thinner stronger material that isn't much thicker than a regular screw.

If I can't find such strong thick lag bolts then I'll try to use a cordless saw and notch out areas of the stump for the chain to grab but I think lags which won't bend would be better.
Old 06-04-23, 06:04 AM
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I thing the nature of the product, a lag bolt just doesn't make sense to produce them in different materials, the usages for them are just not as critical as a bolt that is used for high stress situations like suspensions, structures, or engines.

What about a plate with holes for multiple bolts and a eye to hook the chain to, spread the load across multiple fasteners?
Old 06-04-23, 07:47 AM
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You could drill all the way through with a long spade bit and then slide a steel rod through the hole....
Old 06-04-23, 08:16 AM
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Give the chain an extra wrap to increase grip.
Old 06-04-23, 12:08 PM
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Agree with Wirepuller. I wrap a piece of chain around the tree 3/4 times leaving some loose chain at the beginning of wrap. After the 3/4 wraps I connect loose end of chain as tight as possible to last wrap using a bolt (fits through chain loop) and nut. Attach puller to wrapped chain and pull (pulling tightens the wraps).
Old 06-05-23, 10:16 PM
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ok problem solved, I don't even need the lags.
Yes I do multi-wrap the chain and even get it to grip on smooth metal chainlink posts but something for it to grab to is best.
I have a small jackhammer I used for a very large maple we needed taken down and the roots were huge and spanned a 30 ft diameter, but I found it jammed itself in the saturated muddy roots more often than it was worth using, I used the flat chisel bit.

I could just drill upwards about 6" in a few spots into the base of the trunk retained on the stumps with a drill bit wider than the bolts and just slide carriage bolts in the holes - doesn't need pull-out prevention which screw threads make. But I think best is to just cut notches in the trunk/stump while already cutting the dead tree with a chainsaw/pole saw. It's way less likely to just split the wood when the chain is wrapped around the trunk rather than hooking onto bolts.

I'm getting grade 5 instead (to through-bolt 4x4 fence posts and maybe smaller stumps that are hard to wrap with thick chain, although wood 4x4 posts seem easy to pull with hi lift jack on youtube with just wrapping the chain).
Grade 8 is stronger/harder but it's more likely to snap if it fails, and there's a lot of pressure in this apparatus, it'd be safer/better if G5 shows bending and then I have to do it manually or something, plus I think a G5 should be able to pull a concrete fence posts without bending anyway.

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