Post pounding questions-- with a bigger excavator- Hyundai 290

[sawmilleng]

Hi,
I have some questions about wood post pounding with a hydraulic hammer. I have seen several posts on this forum about using a hydraulically-driven plate compactor on a small excavator and I'm not sure why the plate compactor is used, apparently a choice over a hydraulic breaker hammer.

My need for setting post advice comes from the soil my "stump ranch" consists of. It is mostly river gravel with rocks up to about 12". It does not lend itself to much of anything but digging a hole with a backhoe, placing the post and backfilling and compacting the backfilled soil. I cannot afford treated posts so I cut and peel my own pine posts and attempt to treat them with various forms of witches brews, most of which don't work. I've heard that soaking in plain old anti-freeze (ethylene glycol) works, or at least some of the wooden boat guys swear by it.

I have heard of two ways the people around here do posts: (1) dig a hole, fill it back in and pound the post into the disturbed soil. (2) pound in a steel rod, about 3" in diameter, to form a pilot hole, and follow with the post. This seems to work with smaller treated posts.

Since I need bigger posts for rot allowance, I will be wanting to get 8-12" posts into the ground 3 and 4 feet. If I have to help out by pointing the posts, it can be done, at least roughly, with a chainsaw during the peeling process.

I recently picked up a Hyundai 290 excavator (for clearing) and have been wondering about getting a hydraulic breaker for it. My consideration would be to use one or two steel rods of increasing diameter, to push any rocks away from the pilot hole before trying to pound the post. I don't think the breaker needs to match the size of the excavator (pretty expensive breaker to match a 35 ton machine) but something with about 1500 ft-lbs of energy that handles a 3" chisel might be in the ball park.

There seems to be at least a few used hydraulic hammers out there for under $5K. Might have to do some re-sealing and replace wear bushings but I'm not sure if there are any other "gotcha's" in buying a used hammer.

The hammer itself can be used to bust up some of the bedrock and huge boulders that lurk along the edges of my fields.

I would appreciate any comments, suggestions and words of wisdom.

Jon.

 

[Phantom970]

Don’t think your gunna see a hammer moil at 3-4’ Long.........

Maybe a hyd drill with teeth for rock might be better??

 

[200lc1]

I'm not sure how much fencing you intend to put in, but for the cost of a breaker you can buy a lot of posts (which will last upwards of 25 years). If you plan it around the frost coming out of the ground in the spring you can simply push them in with the excavator. I have clay and rock ground, which gets more like concrete in the summer, have had posts explode trying to pound them in when its that hard. A simple spike on your excavator for piloting the holes may be good enough, as well as picking the right season to push them in. I simply run a string and 100 meter tape, go along with a 5' bar and pilot the holes, stand up the posts, then have at it. In my experience, a pounded/pushed post will stay in better, the frost can push them up eventually (more prominent in wet ground) . I've augured for posts, but for a few years after they get quite loose in the spring until the ground packs in well enough, with a wire fence they will then lean with the tension of the wire.
In my farming/ranching experience I've regretted trying to pinch pennies where i should have saved and done it properly (a lot of stuff ended up in the burn pile).
Mind you, no one would have dissuaded me either....
Best of luck

 

[sawmilleng]

200lc1,
I do like your last sentence, "no one would have dissuaded me either...." I think that is a basic truism of a lot of "do it yourself" guys!!! I have thought about using commercial posts, treated and all, but they start to get pricey in the 9' long and 5-6-7" diameter range. I need a ton of them. I'll revisit that issue again and see if the pricing doesn't look as bad now that I know what I'm up against.

Your suggestion of simply using the hoe to push in a pilot hole and then bumping a post in took me a little by surprise--I have so little experience with my "new to me" 290 that I hadn't thought about trying that. One thing for sure--she's a heavy biotch. Trucker who brought her in told me 72,000 lbs. Said he was 400 kg off his maximum overweight permit allowance for his dual axle lowbed.

I'm thinking that a pilot hole for 8" +/- home made posts will have to be a bit bigger than a 2-1/2" chunk of shafting (got access to lots of that size of scrap) and maybe have to get to something like a 6" pipe size pilot. But even if I have to work it up to that size in a couple of goes with progressively larger sizes of pilots will still be faster than digging a hole!!

I do have a big air powered bin vibrator from a coal mining bin that will shake the bejeezus about of just about anything. Maybe I will have to dig that out of the cultch pile and see if it has enough jam to help things out.

Phantom,
Your observation as to the length of the hammer you can get with a normal hydraulic breaker is correct. But the farmers secret weapon is time and cheap machine tools. I have a BFOL (Big fn old lathe) and getting a piece of 4140 shafting the length we need is not that hard. Machine one end to fit the hammer. Harden it. The other way to do it is to have a pilot bit that has a cup on the top end where the hammer chisel sits to drive the pilot bit into the ground. Need a helper with this method, though.

Thanks, guys, for taking the time to comment!!
Jon.

 

[200lc1]

Think you'll find, there's no bumping just a push. I was set on buying a plate compactor, till I went out and pushed posts in as fast as I could move along and get to the next one. Trick is doing it at the right time of year. I try to do my hard ground posts in the spring, rocks seem to just move out of the way. Save my soft ground for summer and fall. I keep the bucket in close, so the weight is concentrated and controllable, won't side load the post. My 200 is more than a third lighter than yours and has no issue. I'd just try it, especially this time of year, you just might be surprised.
Not sure what you're fencing for, if it's to keep elk population out I could see for the long posts. For standard livestock (cattle, goats, sheep, etc) we use 4" by 7 foot posts, push them in 2 feet or so around 14 feet apart. 4-5 strands of barbwire, depending if its a partition or perimeter fence. I use 6" 8 foot posts for corners and gate posts.

 

[sawmilleng]

200:
Jeez, you spout a lot of common sense! Now that I think about it, I bury my line posts 36" because the backfill is loose. I do my best to tamp it by pulling the hoe in close because with the older Case machines the lift cylinders can move the boom pretty fast close in and I use the bucket with the teeth straight down to compact the soil. Works pretty well but the extra depth is needed. Gateposts are buried 48" so I cut them an extra foot longer: 9'. Yes, elk are a problem and we would probably stay a little taller on property perimeter fences to keep the $%^&* things out.

 

[Phantom970]

Ha ha. I love your description of your lathe. Love the imagination of DIY guys too..........yes you could make your own hammer tool.

But I like 200lc’s way of thinking.
Build yourself a quick strong spear and jam that in the ground for these pilot holes. Then try and jam your posts in. Sounds like there might be junk on your farm to also build a post pusher with a massive amount of counterweight above it...........

And you have a bloody big heavy digger for a farm machine so that helps as well...........

As silly as it sounds, I have used my grab to hold a huge chunk of concrete to help push 6” posts in hard ground. My little digger is only 17tonne but.
More food for thought for you. A grab might be very handy on your farm........

Post some pics if you can whenever you get around to it.