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Material for fence post driver on a skid steer?

i_r_machinist

Titanium
Joined
Apr 12, 2007
Location
Dublin Texas
Had a guy contact me wanting a post driver that will fit in a hydraulic concrete breaker attachment on a skid steer. I told him he could buy them all day long, but he ha s his own design he wants. He brought me a chisel? that he used on concrete. I was surprised how soft the the thing was. It did have hard facing on the cutting edge. Cut it with the edge of a file. Just guessing, 25-35RC.
Anyone build these things? Any suggestions on material?
Thanks
i_r_
 

DDoug

Diamond
Joined
Oct 18, 2005
Location
NW Pa
Had a guy contact me wanting a post driver that will fit in a hydraulic concrete breaker attachment on a skid steer. I told him he could buy them all day long, but he ha s his own design he wants. He brought me a chisel? that he used on concrete. I was surprised how soft the the thing was. It did have hard facing on the cutting edge. Cut it with the edge of a file. Just guessing, 25-35RC.
Anyone build these things? Any suggestions on material?
Thanks
i_r_

I have tried to weld on chisels (air hammer) and
tried different expensive "Super Missile Weld" rods & preheats to no vail.

I would think they would use S-7, but the construction industry may doo something different.

Can you use an Xref gun on it ?
 

magneticanomaly

Titanium
Joined
Mar 22, 2007
Location
On Elk Mountain, West Virginia, USA
If customer brought you a tool that fits his hammer, I am going to assume that was so that you can duplicate the shank.

Several companies sell prehardened shafting, 4140 or 4150....I would ask waht is the largst fencepost customer wants to drive, and find a 24" piece of schedule 80 pipe that will slip over it. Then buy a piece of shafting that slips in the pipe, turn down the shank to match the sample, and weld the pipe to the full-sized end. Be meticulous with preheat and postheat so your HAZ will not be brittle.
 

i_r_machinist

Titanium
Joined
Apr 12, 2007
Location
Dublin Texas
I have tried to weld on chisels (air hammer) and
tried different expensive "Super Missile Weld" rods & preheats to no vail.

I would think they would use S-7, but the construction industry may doo something different.

Can you use an Xref gun on it ?

I'd have to locate one, but it may be worth the effort.
Thanks
i_r_
 

i_r_machinist

Titanium
Joined
Apr 12, 2007
Location
Dublin Texas
If customer brought you a tool that fits his hammer, I am going to assume that was so that you can duplicate the shank.

Several companies sell prehardened shafting, 4140 or 4150....I would ask waht is the largst fencepost customer wants to drive, and find a 24" piece of schedule 80 pipe that will slip over it. Then buy a piece of shafting that slips in the pipe, turn down the shank to match the sample, and weld the pipe to the full-sized end. Be meticulous with preheat and postheat so your HAZ will not be brittle.

I mentioned that but he wants a one piece tool. I'll post a pic of one he had welded up before.
i_r_
 

Joe Gwinn

Stainless
Joined
Nov 22, 2009
Location
Boston, MA area
I mentioned that but he wants a one piece tool. I'll post a pic of one he had welded up before.

It isn't obvious that welding sleeve to driver rod is needed. Given that the flat end of the driver rod hits and thus drives the fence post, the sleeve needs only to keep the fence post lined up with the driver rod. So, one could thread driver rod and sleeve, screw them together with locktite, and maybe add a cross-pin as insurance. Making the business end of the driver rod slightly concave may be useful to keep the fence post centered. In time, the rod end will expand, locking the sleeve to the rod.

 

DDoug

Diamond
Joined
Oct 18, 2005
Location
NW Pa


It isn't obvious that welding sleeve to driver rod is needed. Given that the flat end of the driver rod hits and thus drives the fence post, the sleeve needs only to keep the fence post lined up with the driver rod. So, one could thread driver rod and sleeve, screw them together with locktite, and maybe add a cross-pin as insurance. Making the business end of the driver rod slightly concave may be useful to keep the fence post centered. In time, the rod end will expand, locking the sleeve to the rod.


I'm going with the sleeve will have significant side forces on it.

Operator will push down enough to raise front wheels 1'-2' off the ground.
Will be "on the sticks" the whole time, wiggling N-S-E-W to keep post plumb.

BTDT with an auger.

But yes, brazing a sleeve on may be best, no welding onto the tool steel.
 

gbent

Diamond
Joined
Mar 14, 2005
Location
Kansas
The material conversation has happened here before. I think the only information from a reputable source said one manufacturer used 1070 type steel, as supplied from the mill. Instructions for breaker points often say no thermal shaping, grinding only. If below some temperature, maybe 50F, should be warmed before using.

It wouldn't be hard to make a new/special point depending on the detail of the retention notch.

I would take a piece of heavy wall tubing or sch 160 pipe and make a sleeve to fit over the existing point. Retain the tubing with heavy screws into recesses in the point. Weld a piece of 4xxx or better in the center of the tube to be a receiver for the point force and flat surface to drive the post. I think I'd want a tube that covered most of the length of the post after it is driven to height. Depending on the size of the hammer and the chance of finding a buried rock, I could see the fence post shattering. Some fence posts are made directly from used railroad rail so are work hardenable alloys.

A sleeve might not be what the customer wants, but would allow him to try his concept without getting out his big boy check book.
 

Cole2534

Diamond
Joined
Sep 10, 2010
Location
Oklahoma City, OK
I'm going with the sleeve will have significant side forces on it.

Operator will push down enough to raise front wheels 1'-2' off the ground.
Will be "on the sticks" the whole time, wiggling N-S-E-W to keep post plumb.

.

That's the fuckin truth.

As for material selection, I can't help but think 4140ht would be sufficient simply because it will never be the weak link. The tool can be given sufficient section to insure that it will always be the stronger component by a large margin.

Programmed via Mazatrol
 

HappyWyo

Aluminum
Joined
Nov 30, 2019
I wouldn't be too anxious to use pipe, even 80 gauge is meant to be bent in a heavy bender. I would prefer a heavy walled hydraulic cylinder tube. We save the scrapped ones for projects like that. Contact your local hydraulic rebuilder if you don't have any of your own. You can buy new tube from Team Tube or Steel Supply, but a used one is just as good for this application. For the driving portion 4140 prehard or equivalent for wooden posts, may want to go with hardox ( Rolox ) for steel posts, if it is commercial. We weld hardox and 4140 prehard with no problems. If you overbuild it your customer will be happier than if it fails later. Once it is built they will be using it for all kinds of things, shoving it against the ground to push the skid steer out of the mud, pushing the trencher out of the mud, lifting the front to change a flat tire, straightening a bent pry bar, lifting the equipment trailer to change the tire.......... We used to over build our wreckers and still used them past thier limit. Like pulling a washed out bridge out of the river. In the process one of the cables snapped and put a cable clamp through a windshield and onto the driver's seat of a Dodge pickup 50 yards away.
 

Illinoyance

Stainless
Joined
Aug 24, 2015
The connection of the sleeve to the shank will have severe inertial forces on it. I can understand why the customer wants a one-piece adapter.
 








 
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