Shear pin strength

[kubota2630]

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

I do exactly that. I have them in a container but was getting low and thought I would restock. I don't use many but wanted a few extra just in case.
Thanks everyone. I'll get the correct bolts. Why take a chance.

 

[Chilly807]

This page will help illustrate the relative strengths of different fasteners.

Bolt Grade Markings and Strength Chart

Sean

 

[kubota2630]

This page will help illustrate the relative strengths of different fasteners.

Bolt Grade Markings and Strength Chart

Sean

If I understand the chart correctly 8.8, garde 5 and stainless are very close in tensile strength. Maybe he is correct in saying stainless could be used for 8.8 but not grade 2. Grade 2 are much lower. Grade 2 bolts I can easily get at the local hardware store.

 

[Chilly807]

My impression of stainless is the way it breaks, it's not ideal for a shear pin. The specs refer to tension load, not shearing stress. Threaded fasteners are meant to hold tension, they're not designed for a shearing type strength. If it weren't for threads to hold them in place, we wouldn't use bolts, or capscrews actually, for shear bolts at all.

If you want to give the stainless a try, it's your machine after all.

Sean

 

[kubota2630]

My impression of stainless is the way it breaks, it's not ideal for a shear pin. The specs refer to tension load, not shearing stress. Threaded fasteners are meant to hold tension, they're not designed for a shearing type strength. If it weren't for threads to hold them in place, we wouldn't use bolts, or capscrews actually, for shear bolts at all.

If you want to give the stainless a try, it's your machine after all.

Sean

Thanks Sean. It's not worth taking a chance. I'll go and get the correct bolts.

 

[chopped]

Iwent to Lowes to buy a box on bolts today ..just in case.
WOW carriage bolts 1/4 up from 9 cents each to 12 cents each if you buy the contractor box.
Beware though if you go through the self serve you dont get the contractor discount..Box of 100 cost me 15 dollars even and not 12 cents each..grrrrNot much you can do when self serve is only one open ..Except the long contractor line..

 

[jinman]

The very best prices for bolts in my area is Tractor Supply (TSC). Their grade 2 hardware (nuts, bolts, washers) is the same price by the pound and less than $2 per pound the last time I bought shear bolts. I just bought grade 5 bolts at $3.49 lb and grade 8 were $4.29 lb. They do not have bulk metric bolts. Those are in bins and packaged individually at higher prices. You could probably do better ordering those on the internet and have them delivered. Here's one source.

 

[JMynes]

TSC is THE place for ASE bolts. They also have a nice selection of Grade 2 bolts, priced by the pound. I finally smartened up and have a small ziplock bag of bolts and nylock nuts in the tractor, along with two wrenches so I can replace shear bolts 'on the fly'.

 

[Jay4200]

If I understand the chart correctly 8.8, garde 5 and stainless are very close in tensile strength. Maybe he is correct in saying stainless could be used for 8.8 but not grade 2. Grade 2 are much lower. Grade 2 bolts I can easily get at the local hardware store.

I could only find grade 5 at the hardware store. Can't find grade 2 anywhere. Grade 5 shear strength is about 50% higher than grade 2 (85kpsi vs 55kpsi).

My blower's PTO shaft is rated for a 8mm grade 6.6 bolt. My local HW store only sells grade 8.8 and 10.8 metric bolts. The closest thing I could find at the hardware store was a 5/16" grade 5, so I picked up a few of them (only 2.4 thousandths small). I've been using 5/16" snowblower shear bolts, which I assume are grade 2. I broke 2 so far w/o hitting anything nasty, just crunching through heavy snow. I broke one (while my blower was packed solid with snow) when I engaged the blower at idle, so I think the grade 2 rating (or at least whatever a blower shear pin is made from) is undersized as it evidently can't transfer anywhere near the 40HP rating of the blower.

I can ever find grade 6.6 metrics, I'd like to get a pile of the right bolts.

JayC

 

[Jay4200]

Iwent to Lowes to buy a box on bolts today ..just in case.
WOW carriage bolts 1/4 up from 9 cents each to 12 cents each if you buy the contractor box.
Beware though if you go through the self serve you dont get the contractor discount..Box of 100 cost me 15 dollars even and not 12 cents each..grrrrNot much you can do when self serve is only one open ..Except the long contractor line..

Heh. Of course, you can't flag down an employee to fix the problem and get your the discount, because they are all too retarded to run the register systems. You'd get your money, but you'd be stuck there 3 hours getting it. It's almost like when you show up at the register with an item that doesn't have a scan tag on it. Al he*l breaks loose and you're stuck there for an extra 1/2 hour at least.

As much as I hate Home Depot, I don't go to Lowes anymore - they are far worse than HD when it comes to raw stupidity of employees (and they are more expensive than HD).

JayC