# Rotomec Post Hole Digger - 3/8 x 3 Grade 2 Shear Bolt



## Kris Lentz

Hi all,

First post and I'm looking for some help. I broke the shear bolt on my Rotomec Post Hold Digger and now I cant seem to find the correct replacement. The manual calls for a 3/8 x 3 Grade 2 shear bolt, I went to Washington Tractor where I bought it and they only carry 2.5 and 3.5 inch bolts. Can I just use the 3.5 inch bolt?

I have also been looking online and cannot seem to find the right size. Any thoughts on where I can order from? I have some urgent fence repairs so I would like to be able to pick it up in person today. I live in WA state.

Kris Lentz
JD 3032


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## Hoodoo Valley

Welcome to the forum Kris. You can use the longer bolt and just use some sort of spacers such as the next size up, nut, so that the bolt still cranks down on the auger. 

In other words, the 3 1/2 inch bolt won't be able to tighten down on the auger, so by adding larger nuts to take up the slack, then the correct size nut, you'd be able to mimic the same characteristics as the 3 inch bolt.


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## pogobill

I use grade 2 galvanized carriage bolts that I pick up by the bag full at the hardware store, and I keep them on the tractor as I know I'll need them! If you snag a rock or a root when boring a hole, and you don't react quick enough, you are going to shear a bolt... better that, than busting the gear box. Make sure you have a supply of them on hand, or we may see your auger in the classifieds section!!


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## Hoodoo Valley

That's me too. I have a tray of them on my machine as well. I even run my auger at about 1,200 RPMs engine speed just to be sure and still can hardly stop things in time!


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## sierrasam93614

Any hardware should have them not an uncommon size 

Sent from my VS988 using Tractor Forum mobile app


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## Ed Williams

Hoodoo Valley said:


> That's me too. I have a tray of them on my machine as well. I even run my auger at about 1,200 RPMs engine speed just to be sure and still can hardly stop things in time!


My auger does not work well below 1500 rpm, and tend to break a lot of bolts due to the mid sized rocks in the ground here in central KY. Found you can buy in bulk at Tractor Supply at very reasonable cost, about one fourth of what Ace charges. Have been known to break one or two bolts per hole while setting new fence posts. I keep an ample supply in the tool box while setting posts. Thought of using a harder bolt, but afraid of damaging gearbox on auger. A pain, but have learned to live with it. Also keep an alignment bar in box which really speeds up bolt change. Good luck, I don't have a solution, just advanced prep knowing what to expect.


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## Hoodoo Valley

I actually popped out a few holes for my neighbor here recently, and I actually just let the engine idle, so it's below 1,200 RPMs engine speed. Here in Hoodoo Valley, it's basically river bed. More round river rock than dirt most of the time.


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## Ed Williams

We tend to have limestone floaters bedded in a clay base, which is hard on augers. Sometimes the auger will just bounce in the hole, then the rock breaks and the auger binds up, so low rpm causes a bind and everything shuts down, so higher RPMs keeps you in business, but also results in more broken shear bolts. Just have to live and learn with what we have. At least it beats hand digging with post hole diggers.


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## Hoodoo Valley

Yeah, I think that apart from the hydraulic driven units that skid steers use, units for the wheel tractors aren't really intended for this soil. Years earlier, before we got our larger tractor, we hired some local retired fella to come out and auger some holes. I'm sure he had defeated the shear pin somehow because the first hole was half way down when he snapped his auger clear in half! Might actually be beneficial to ramp up the RPMs on my machine but quite honestly it would spook the heck out of me! 

Even when I mow with the Kubota, I only operate at about 1/3 throttle.


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## Ed Williams

I usually maintain 1800 rpm while mowing to keep 540 at the pto. Mower works quite well at that setting. Then pick the gear to use based on what I am mowing. Heavy brush is usually 1 or 2. Grass fields usually 3 or 4. Not in any hurry equipment very seldom has any problems if I stay in these ranges. Tractor is a Ford 4000, 55 hp, and never loads up. A neighbor likes to push it a bit. He mows in 5 or 6 with t h e same rig and has constant breakdowns. He has about wore out my little 120v DC welder fixing his broken equipment. To each his own. I'll stick with what works for me. After 45 years on a tractor, I'm too old to change my ways now, plus I don't like to have to constantly repair equipment to save a little time each day.


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