Grade 5 vs Grade 8 bolts... the hot skinny!

   / Grade 5 vs Grade 8 bolts... the hot skinny! #21  
I don't believe that bolt grade matters. The failure mode is in the bolt (shaft). Type of nut or threaded holes are irrelevant in terms of fastener failure.

I need to pick up some grade 2 bolts - where do I find them??

JayC

Why would you screw a 150,000 psi bolt [grade 8] into a 120,000 psi [grade 5] or a 60,000psi [grade 2] nut and risk the bolt pulling through the nut?
Soft washers are useless; they just squeeze out from under the bolt head. Under dynamic loading the bolts per-load will be lost.
 
   / Grade 5 vs Grade 8 bolts... the hot skinny! #22  
At one time TSC sold metric fasteners by the pound too...it astounded me when they discontinued that line considering so many things have metric fasteners now, including a lot of tractors...

If metric hardware was selling, it probably would not have been phased out.
 
   / Grade 5 vs Grade 8 bolts... the hot skinny! #23  
I agree.. TSC updates it's floor plan often. on the tractor isle.. any items that aren't movers and shakers get tossed fast!

soudnguy
 
   / Grade 5 vs Grade 8 bolts... the hot skinny! #24  
No problem, I get my metric hardware from Grangers.
 
   / Grade 5 vs Grade 8 bolts... the hot skinny! #25  
i thought I would be able to buy stuff from fastenall when they moved into town.. however I have never been able to buy anything there.

I walk in looking for taps, drill bits, and fasteners, and all I hear is that they can order them.

2400sf store.. and nothing in stock.. ?? :(

soundguy
 
   / Grade 5 vs Grade 8 bolts... the hot skinny! #26  
i thought I would be able to buy stuff from fastenall when they moved into town.. however I have never been able to buy anything there.

I walk in looking for taps, drill bits, and fasteners, and all I hear is that they can order them.

2400sf store.. and nothing in stock.. ?? :(

That sounds like our local TSC. What a useless store - I stopped in there once this past summer - I never saw so many empty shelves in one place - I'd bet at least 50% of their items were out of stock.

JayC
 
   / Grade 5 vs Grade 8 bolts... the hot skinny! #27  
this thread got me thinking about fasteners.

for the past few weeks I have been drilling out broken off studs and bolts in a ford 950 I'm restoring.. most if not all of the fasteners should be grade 5. at this point.. I kinda wish they had been grade 2 for a smuch drilling and extracting I have been doing. ...

soundguy
 
   / Grade 5 vs Grade 8 bolts... the hot skinny! #28  
Every application for a washer that I can think of, right off, softer steel is good. When would you want washers to be grade-8 hard?

A hard washer is required when you are using high grade bolts and torquing them to their capacity. The reason for this is you don't want the washer to squish (yield) under the load of the nut or bolt head when a load is applied to the bolted joint.

By torquing the bolt to its capacity you are stretching the bolt (applying a tensile load on the bolt) and compressing the joint flanges. If the washer yields and starts to thin, then the bolt loses some of the tensile preload that you put on it when you torqued it. If you lose enough tensile load bad things start to happen:

Each applied load will cause the washer to yield a little more.
Each yield will reduce the preload a little bit.
The nut will start to work loose, reducing the preload even more.
At some point the two flange surfaces that the bolt has been clamping together will start to separate. Once the flanges separate it's just a matter of time before the bolt fails.

-Jim
 
   / Grade 5 vs Grade 8 bolts... the hot skinny! #29  
Ever since switching to all grade 8 hardware at my place of work (which is going on 15 years now),we have had ZERO hardware related problems.:thumbsup:


Greg
 
   / Grade 5 vs Grade 8 bolts... the hot skinny! #30  
Jim, thanks for the reinforcement, that is what I said back in post 21.:thumbsup:
 
 
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