Grade 8 vs. Cold Rolled Steel

[Does’ Leap]

Anyone know which is stronger? I had the “plug” – a 5/8″ grade 8 bolt – shear off of my plug yoke the other day. I happen to be using my logging arch and I noticed it just before it went – no big deal. However, in the wrong situation (i.e. a large load of logs on the bobsled going down a steep hill) the results of this kind of failure could be bad indeed. I am in the process of replacing all of the receivers on my poles to a accept a 3/4″ plug and would like to have the plug as strong as possible. Thanks.

George

[irish]

what about grade 12

[Plowboy]

Grade 8 is harder than grade 5 but is also more brittle. I would try grade 5 it will take more abuse than 8 before it breaks.

[john plowden]

did the weld break or the rod itself? I use a 3/4 grade 8 bolt with the head welded on the inside after putting it through a 3/4 hole –

[Does’ Leap]

John:

The weld was fine. The bolt sheared clean through. I do the same thing (head welded on the inside), except I was using 5/8. On a different but related note, instead of drilling through the end of the pole with a steel cap (and matching hole), I have gone to welding a pipe on top of the pole to receive the plug. I also size the pipe just shy of the plug. I drill the end of the plug to receive a cotter pin. Plug goes through the pipe with a cotter pin on the other side. This prevents the neck yoke for slipping off the pole when hooking up the horses. I have also made some other modifications to beef up Les’s design.

George

[PeytonM]

a higher grade bolt that is harder will be easier to break, like stated. I would try a grade 5. or weld a 5/8 round stock in it thats stress relieved

[Anonymous]

George,

I used a 5/8″ hardened hitch pin when I built my plug yoke. Figured they were designed specifically to withstand shear forces in normal application. So far so good.

John

[Ann]

 

Dear folks, A grade 8 is 150,000 psi    or c33 rockwell   never! weld on a grade 8 bolt it makes it very brittle. A grade 5 is 120,000 psi  or c25 rockwell  only weld on a grade 5 bolt if you preheat to a “hiss” heat before welding or it will get brittle. A grade 2 or standard store bolt is 60,000 psi and can be welded on. Best to design your equipment so you aren’t welding on the bolt heads. Weld a stop or keeper next to the bolt hole insted.

[Author]

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