The family business has been building fences here in Canada; going on a few decades now. And my dear father is a closet mad scientist - as we use prototype machinery built from scrap - self taught through many failures and dollars spent.
Using a dual tensile springs, high return flow solenoids, and a handy dandy high pressure water spear pilot mechanism he’s been able to pound posts into virtually all surfaces at virtually all times of year.
Now he’s got about three pounders specialized for various types of jobs, modified to be mounted on a variety of machines (truck, tractor, skidsteer). But he’s sure his newest pounder has recently lost some impact force relative to his older incarnations. He’s charged me with asking “those Straight Dopey fellows on cyber space” about a relatively cheap and simple method of gauging impact.
A strictly bush method I thought of to only gauge relative impact between machines would be cutting precise slices of some heavy walled pipe, and comparing deformation between machines if the pieces were squashed ontop of a cemented 4x6 or some such. Though that seems desparately inaccurate.
Is there any method of gauging impact in such a circumstance that I’m unaware?
How about obtaining some sort of deformable plastic in sheet of a standard thickness, then pounding a strong pipe into that and measuring the depth of the impression this produces? Or obtaining standard spheres of some deformable material, pounding them between strong steel plates, and measuring the deformed diameter?
I like Xema’s idea. You’d have to control the hardness of the surfaces hitting the ball, and also if they have any coarse texture to them. Also, the pounder would have to hit vertically, with the surfaces parallel.
Another vote for the ‘squash something and look and look at it approach’; it won’t give you hard numbers, but should work for comparative purposes. Perhaps some variety of Plastigauge would be more accurate than pipes or lead, it being purpose made to be crushed and measured-and readily available at auto parts stores to boot.
Before I did anything though, I’d look back over the latest design and make sure there wasn’t anything obviously impeding hydraulic flow or altering the spring properties.
As an ex-fencer (and mechanical dilettante), could I ask for a rough outline of the machine? It sounds ingenious. And what the devil is a water spear? Spear fishing? Well drilling?
The first successful generation was front mounted on a New Holland skidsteer. On a fairly straight forward rectangular base (with standard quick attach) was mounted small simple stabilzers with huge sphere shaped rollers (to put up with the punishment of stones, roots, minimum wage negligence etc). A length of pipe the width of the skidsteer about 8" diameter constituted the central control arm, which the pounding mast was mounted on the operators left side. One cylinder controlled pitch (left/right tilt from the skidsteer operators perspective) and also lay the mast flat in transit, which is very important to do as it’s very heavy and as you can imagine the rocking and shifting that a skidsteer imparts many of the components dealt with extreme wear.
Two smaller cylinders controlled a canteliver roll mechanism, giving front back tilt from operators perspective. And finally one large cylinder inside the mounting pipe which controlled slide, left/right lateral motion. Most the brains went into packing all the appropriate goodies into the mast, as it’s a tight space that’s got to take ridiculous punishment and also remain servicable. The best generations used two telescopic (one way) lift cylinders mounted inside two large (6’) tensile springs. This resistance and subsequent downward thrust smoothed out the pounding stroke, and virtually doubled impact force. Clearly your two biggest enemies for pounder power are moving lift cylinder oil, and stroke friction. Lots of leaky cylinders, and a solenoid controlled dump valve that piped directly to the oil resevoir remedied that. The secret (we think) is in the “foot”.
Packed somewhere in all this is one downward cylinder mounted on the stationary chasis of the mast. Lowered for each post this foot would create a stabilizer leg directly beneath the pounder. It helped focus much more impact directly in the post, and stopped about 80% of the jolt that normally rattles through the machine afterward. It was somewhat U shaped also, which helps you control the post at the ground. The water spear was just a 4" chunk of round steel, sharpened to the shape of a post and extended with foot hyperextension, which you would press into the ground (about 6") and blast water through the piss hole in the end, giving you and small lubricated hole to start your post in. The water pump was mounted on the cross member between the arms of the skid steer, and the water was stored IN the arms of the skid steer.
Of course the whole operation requires two people. The posts are carried in two large curved forks mounted forward of the pounder, angled just so that you could pick up a bundle so long as you had a tree or truck tire to push them against. We put some steal tracks on the skid steer for extra floatation, tensioned wire spools at the back (put in posts and run out wire simultaneously), eventually electric controls with a gyro auto-center, and a cigarette lighter. That was our work horse for a number of years, until we made the forks attach with an inverse quick attach, which allowed you to mount the entire shebang on the back of a truck, virtually seamlessly. The trucks proved to be better for 50% of work, because you weren’t towing a trailer, and could move around faster in general.
Still, that skidsteer with a skilled team could pretty well fence a mob of cattle in a paved parking lot, muskeg, or a slope just short of a cliff. Flat out we could start and finish a 2 mile stretch of 4 barb in one day.