Filling a divot

   / Filling a divot #1  
T

tree grower

Silver Member
Joined
Dec 29, 2007
Messages
208
Location
Cuttingsville, VT
Tractor
Ford 1210, Bobcat 742B, John Deere 1050
My Five Star post hole digger's 'business end' is a 2" shaft with a 7/16" hole for a shear pin. Due to stony soil I do not use soft shear pins, but grade 8 bolts instead. The torque of the shaft and the resistance of the auger still bends the bolts to a modified S shape, and it is necessary to cut the bolts out with a torch in order to remove the auger. There has developed a divot at the three o'clock position on both sides of the 7/16" hole which allows the bending of the bolt easier than if the shaft were perfectly intact. I think the best way to fill in this divot is to insert a non-ferrous 7/16" rod, fill the divot with hard-facing rod, drive the 7/16 rod out, and grind the weld smooth. I can't imagine copper standing up to the heat of a welder, so what is a reasonable alternative?
 
   / Filling a divot #2  
Insert a carbon rod and weld up the divots.
 
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   / Filling a divot #3  
Can you just drill it out to say 5/8” or 3/4” and use a bigger pin? I am not sure why a shear pin holding on the auger is necessary. My auger has a hexagonal shank. Even with that the bolt that holds it on is large - 3/4” maybe.
 
   / Filling a divot #5  
I understand you have stony soil, but if the Grade 8 bolt doesn't shear when it's suppose to, what breaks?
 
   / Filling a divot #8  
bdog said:
I am not sure why a shear pin holding on the auger is necessary. My auger has a hexagonal shank.
Click to expand...

Post-hole diggers for AG tractors and CUTs use 2" round shafts and shear bolts. Industrial PHDs (e.g. Danuser) use hex shafts and do not rely on shear bolts.

Our local rental yard switched their Grade 2 or 3 shear bolts to Grade 8 because they shear cleaner, without bending.
 
   / Filling a divot
  • Thread Starter
#9  
Lots of good answers! If I used soft shear bolts, I would need at least one per hole X # of holes per day. Nothing breaks, but I have bent an auger and stalled the tractor. I just try to be careful. I don't have extensive experience w/ post hole diggers, but it appears that this Five Star made in Oklahoma is made to be used with no scheduled obsolescence. I like the idea of drilling the hole out to 1/2", 9/16", or 5/8", but I don't see how that could be done unless I disassemble the gear box and take the shaft to a machine shop. All very doable I suppose, but I don't really need another project. The hardened bushings option sounds good, but that would also involve drilling the shaft to the depth of the bushings. Where would I find carbon rods? What are they normally used for?
 
   / Filling a divot #10  
tree grower said:
Lots of good answers! If I used soft shear bolts, I would need at least one per hole X # of holes per day. Nothing breaks, but I have bent an auger and stalled the tractor. I just try to be careful. I don't have extensive experience w/ post hole diggers, but it appears that this Five Star made in Oklahoma is made to be used with no scheduled obsolescence. I like the idea of drilling the hole out to 1/2", 9/16", or 5/8", but I don't see how that could be done unless I disassemble the gear box and take the shaft to a machine shop. All very doable I suppose, but I don't really need another project. The hardened bushings option sounds good, but that would also involve drilling the shaft to the depth of the bushings. Where would I find carbon rods? What are they normally used for?
Click to expand...

Someone used to make kits available. The rods were an assortment of diameters to accommodate building up oblong holes in trailer drawbar hitches etc. Simple to use and effective. Drop the rod in the hole and weld up the void. Pull rod out.

I haven’t seen them available for years. Perhaps yomax4 knows of some.

I found this link. Rods like this should work.

WeldingSupply
 
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