Shear pin strength

kubota2630 · Jan 31, 2011

Just went to a local bolt supplier to pick up some shear pins for my snow blower. Manual calls for 6X40X8.8 (PTO) and 1/4 x 1 grade 2 (auger). They sold me stainless steel bolts and said they would be fine. Will they be O.K?

teg · Jan 31, 2011

A knee jerk answer, no. Isn't Stainless Steel much harder?

kubota2630 · Jan 31, 2011

teg said:
A knee jerk answer, no. Isn't Stainless Steel much harder?

They told me stainless is harder to cut but would shear easier.

Argosy · Jan 31, 2011

Shearing is cutting so that makes no sense.

Not to mention you can get 2 or 3 grade 2 bolts for the price of a stainless bolt.

Chilly807 · Jan 31, 2011

Stainless isn't a good idea for shear bolts, it's very tough and will deform before it breaks, making the old pin hard to get out. Grade 2 is pretty light duty stuff, any hardware store should have them, there will be NO hash marks on the bolt head. Some stock grade 5, so be careful, they will have three 120* apart hash marks on the head. 8.8 in metric is similar to grade 5, generally speaking. It's a general purpose bolt.

Sean

kubota2630 · Jan 31, 2011

Thanks. Looks like I better go and get the proper bolts.

Mean Jean · Jan 31, 2011

Go back to the local bolt store.
Find someone who knows what they are talking about this time.

I've never heard of the term cut strentgh.
Who has a coles notes explanation?

teg · Jan 31, 2011

Chilly807 said:
... 8.8 in metric is similar to grade 5, generally speaking. It's a general purpose bolt...

SOB.... I didn't know about 8.8 being metric $^&%*@

:mur:

I bought some for another project thinking they were better than grade 8!!!

So I take it Grade 10 metric = 8 normal (English... I mean American)

RickB · Jan 31, 2011

teg said:
SOB.... I didn't know about 8.8 being metric $^&%*@ :mur:

I bought some for another project thinking they were better than grade 8!!!

So I take it Grade 10 metric = 8 normal (English... I mean American)

More or less, but the common metric hardness is 10.8, not 10. Metric hardware is typically marked as 4, 7, 8.8, 10.8 and I believe 12.9. 4 and 7 aren't much and 12.9 is HARD.

Craig Clayton · Jan 31, 2011

When you find the perfect bolt strength buy several of them and put them in a container marked SNOW BLOWER and put them in your favourite spot. There are rocks and stones and curbs out there lurking under the snow just waiting for unsuspecting augers.
Craig Clayton