Bolt recommendation

[Erik B]

I have broken about 3 bolts on my speeco splitter over the years. It is the one holding the wedge to the ram. Size is half inch by 3 inches. I have been replacing it with a grade 8 bolt and it lasts for maybe 5 years. It is real easy to replace but I was wondering what others are using for that part. Is there something better than a grade 8 bolt?
Erik B

 

[cus_deluxe]

1/2" bolt is pretty small, go to a 3/4" and it will never break again.

 

[Erik B]

1/2" bolt is pretty small, go to a 3/4" and it will never break again.

Not sure if the hole thru the ram and the wedge is large enough to handle a 3/4 inch bolt. It seems to break at the beginning of the threads.

 

[BWS-LLC]

I'd say 5 years isn't that bad... Especially a bolt so easy to change...

 

[matt167]

buy grade 5 and it wont happen again most likely. Grade 8 is harder, so it can take clamping force better. But side loading, they have no tensile strength. Grade 5 will stretch. Grade 8 will snap

 

[Erik B]

Thanks for all of the replies.
Erik B

 

[jrider]

I moved to grade 5 on my I&O and have had no problems.

 

[Whitespider]

buy grade 5 and it wont happen again most likely.

Agreed...
*

 

[les-or-more]

http://tinelok.com/grade-5-vs-grade-8-fasteners/

 

[ChoppyChoppy]

buy grade 5 and it wont happen again most likely. Grade 8 is harder, so it can take clamping force better. But side loading, they have no tensile strength. Grade 5 will stretch. Grade 8 will snap

Sorry, but that's not correct. Yes a grade 8 is harder but its also stronger than a Grade 5.
A grade 5 will likely have already failed by the time a grade 8 is stretching.

Bolt strength is generally measured in tensile and shear. Look in the Machinists Handbook in the bolt charts for the numbers.... I don't feel like digging mine out right now.



If a grade 8 breaks, a grade 5 will certainly fail.


Edit.... welll... didn't see that link above till after. Explains with detail what I posted.

 

[cantoo]

I also have a Speeco and have replaced my bolt 3 times. It's a pretty easy 2 minute fix. Do you wonder why they don't put a Grade 8 in it 1st? Do you really think it's to save a few dollars or maybe it is to save from a more expensive breaking point. I like to think of it as a shear pin on a snow blower or bush hog. Much cheaper an easier to fix a bolt than to fix a bent blade, auger or cylinder.
Treat yourself and put a new bolt in it every year on your Birthday.
I like to make an easy to fix weak point on most stuff I build.
Work smarter not harder.

 

[Erik B]

At least I picked up a couple of spare bolts so the next time it happens I won't have to drive to the hardware store to get a new bolt. They were only 2 bucks each. I thought I had a spare on hand but couldn't find it. If I only can remember where I put these two the next time one breaks

 

[H-Ranch]

At least I picked up a couple of spare bolts so the next time it happens I won't have to drive to the hardware store to get a new bolt. They were only 2 bucks each. I thought I had a spare on hand but couldn't find it. If I only can remember where I put these two the next time one breaks

Sometimes the best place for a spare like that is right on the machine. Find a handy location and attach it with a nyloc nut. Or even drop it in a hole you drill on a vertical surface if the splitter doesn't travel down the highway.

 

[cantoo]

H-Ranch is right, I do the same thing. I swear I lose more stuff than I use. I black tape or zip tie spare parts to machines. I even carry a couple of nuts around in a spare bag with me so I don't lose them, you never know when the wife is gonna want them.

 

[kevin j]

You said it broke right at the thread. Is the thread in the bending area?
Use a longer bolt so the unthreaded shank goes through the entire connection and nut just runs out of thread as it is tight. Then cut off the extra threaded length.
Is the bolt supposed to be taking the push force? I would expect the end of the rod to be contacting the back of the wedge somehow and the bolt just taking the pull return force.

 

[tla100]

You know, when you have a couple spares right on machine, you won't break one.

Or, drill out and get a pin to fit, cut off where needed, drill hole for cotter pin. Done.

 

[Mike Mulback]

There is a grade 12 or 13.2 availe out here, be interesting how they hold up. be glad to send you one.
I was cutting thru different grade bolts for a spacer Comparing grade 5 to the hardened 13.2
Difference like between pine and oak. I dont think you could snap these

 

[Whitespider]

Sorry, but that's not correct. Yes a grade 8 is harder but its also stronger than a Grade 5.

Yes, a grade 8 is stronger in both tensile and shear... but it won't hold up as long in an application where it's allowed to flex even a tiny bit.
If I'm understanding this correctly, we ain't lookin' for tensile or shear strength in this application... we're lookin' for something to hold up under repeated deformation.

If I'm understanding the OP, the bolt is used more like a retaining pin than a clamping fastener... it ain't "clamping" two (or more) pieces of metal together. Meaning every time the thing is stressed with side load it's allowed to flex (or bend) a bit... and in that situation a grade 8 will become brittle much faster than a grade 5. The grade 8 starts out stronger, but weakens at a faster rate... likely the grade 5 can handle the tiny bit of flexing (or bending) without any appreciable degradation.

Take two bolts, a grade 5 and a grade 8, clamp them in a vise.
Bend them over one way an inch or two and than back the other way a couple inches, repeat until the bolts break.
Which bolt breaks first??
*

 

[Erik B]

You said it broke right at the thread. Is the thread in the bending area?
Use a longer bolt so the unthreaded shank goes through the entire connection and nut just runs out of thread as it is tight. Then cut off the extra threaded length.
Is the bolt supposed to be taking the push force? I would expect the end of the rod to be contacting the back of the wedge somehow and the bolt just taking the pull return force.

Kevin j, you are right. It looks like the end of the rod is contacting the back of the wedge. I have tried looking for a bolt that has a smaller amount of thread on it so the threaded part is not being stressed but I cant find one. I do not have the tools to cut a hardened bolt down to size. A hardened draw pin with a cotter key would be the best way to go. Pics are attached of what I have now.

 

[H-Ranch]

The photos may be deceiving but it appears the bolt is bent a tiny bit already. I'm guessing the bolt takes some of the force until the ram contacts the back of the wedge so the bolt is flexing slightly every cycle. Can you attach a shim to the end of the ram to be sure it is doing all the pushing force?