my home made hydraulic hedge cutter

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earlgo
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Re: my home made hydraulic hedge cutter

Post by earlgo »

Look on youtube for Helicopter Tree Trimming if you want to see some extreme trimming of trees near power lines. Scary stuff.

--earlgo
Before you do anything, you must do something else first. - Washington's principle.
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warmstrong1955
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Re: my home made hydraulic hedge cutter

Post by warmstrong1955 »

My Brother-In-Law sent me this. He has his own small sawmill. What he can't make into lumber, he sells as firewood.
He was thinking of getting one for his Bobcat.

Clever!

https://www.youtube.com/watch?v=KdXzaGFkWfU

Today's solutions are tomorrow's problems.
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liveaboard
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Re: my home made hydraulic hedge cutter

Post by liveaboard »

Update on the hedgecutter; the blade rotation stopped working, my home-made spline tube failed. There was much disassembly and one tube cut with a grinder to get this out;
twisted spline tube 800.jpg
The splines were made by cutting long strips of a larger tube, drilling every 100mm [4"], and welding through the holes. Slow and crude work.
So I replaced the twisted broken sections, then drilled 50 new holes, and welded through to double the spot welds to one every 50mm.
The problem was that in my enthusiasm for penetration, I penetrated in a few places, and created bulges and drips on the inside.
Another pipe has to fit inside, and rotate. So I needed to bore a 2.2 meter length of 1-1/4" pipe.
I made this crude ugly boring tool with an old ball bearing and a drill bit shank.
Even the lock screw looks bad!
gross ugly boring tool.jpg
The black rod I used is quite not straight, but it was what I had on hand. The work was bouncing up and down as I pulled it along with the lathe carriage. After boring the length of my bed, I rolled the work back, then slid the tool out to take the next cut. I could get it from both sides, so I only had to bore 2x the length of the little lathe.
gross ugly boring.jpg
I set the tool to only cut off the bulges; the pipe is not made round inside. The bearing had a mm or two of clearance. All very nasty, but I was able to reassemble the tubes and put it all back together to finish cutting my hedge the next day.
hedge cutter high.jpg
spro
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Re: my home made hydraulic hedge cutter

Post by spro »

What is the word? It is like dedication and perseverance combined. Great success and very cool are descriptions but pressed to limitations, you shared inspiration of what can be. Yes the traveling bearing? I'm happy with your success.
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liveaboard
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Re: my home made hydraulic hedge cutter

Post by liveaboard »

I did some repairs and mods on the machine over the last year.
My crankshaft bearings failed; not sure why, but I suspect imperfect alignment of the pushrods.
I decided to make a new crankshaft with self aligning bearings. But those are larger for a given load, which made space really tight.
I decided a 1 piece crank would solve that. my first one had the journals pressed in.
This is the old one; damage is pretty obvious.
hedge cutter original crankshaft.jpg
The new one will have a larger wider pulley, I actually spent money instead of using junk car parts I had.
New crankshaft parts + drive belt.jpg
I started with a nice piece of rusty mystery steel.
new crankshaft stock cutting.jpg
I thought I could be accurate enough to get things reasonably true; I was wrong about that. The self aligning bearings don't care but I feel disappointed in myself.
new crankshaft 1 stock marking.jpg
Last cut on the crank.
new crankshaft 2 finish cut.jpg
new crankshaft 3 center and end bearings.jpg
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liveaboard
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Re: my home made hydraulic hedge cutter

Post by liveaboard »

Checking;
setting bore marker position.jpg
centering a punch mark.jpg
Bored end plate
Eccentric raised bore.jpg
New parts ready;
crankshaft parts.jpg
New pulley bored for the bearing;
new pulley bore.jpg
lineup before pressing 1.jpg
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liveaboard
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Re: my home made hydraulic hedge cutter

Post by liveaboard »

Before pressing it together, just a couple of mm are engaged and I lined up the rotation. I tried to keep the center disk true so it could be used for reference.
lineup before pressing 3.jpg
lineup before pressing 2.jpg
In the press; it went too easy, just a few tons [that's an error], so I drilled and tapped afterwards, and added a lock bolt.
pressing crank 1.jpg
pressing crank 2.jpg
The end bearings were finished after assembly so they're true, but the self aligning crank bearings have a little wobble due to the end bores not being a the correct distance from center.
Oh well. I'll do better next time.
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liveaboard
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Re: my home made hydraulic hedge cutter

Post by liveaboard »

The next modification was a complete change of the system I built to rotate the cutting blade.
The first one was fabulously complictaed, it used a small hydraulic cylinder to rotate a cog wheel, that turned a sprocket, that rotated a pipe in a pipe that turned a bevel gear...

The new one is a little 12v winch I bought from ebay uk.
little winch disassembled.jpg
First job was a simple cut so it could be mounted on a flat plate.
litle winch on lathe.jpg
The spline from the winch cut and welded to a small gear from a car transmission; a 3.8:1 reduction turns the blade assembly around at about 15 RPM [1/2 of a rotation is the maximum.
little winch adaptor.jpg
I needed an 80A fuse holder; the fastest way to get what I needed was to make it myself. 2 bits of heavy copper strip epoxied into a slotted bit of polycarbinate. I had the Bosch strip fuses and the plastic leftover from jobs I did 20 years ago.
80A fuse homemade holder.jpg
On the tractor;
winch motor rotator 2020.jpg
Also visible in this picture, the rotation lock solenoid [more on that in following post]
rotation motor 2020.jpg
There's a plate with a bushing for the adapter shaft I seem to have forgotten to photograph.
Last edited by liveaboard on Wed Jun 24, 2020 8:05 am, edited 1 time in total.
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liveaboard
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Re: my home made hydraulic hedge cutter

Post by liveaboard »

The gears from a junk 1985 Ford escort [EU diesel car]
ford escort 1st gear.jpg
Here I've cut the car gear and winch part, and welded them together;
welded gear + spline.jpg
finished in the lathe for a bushing. It's not perfect but it's pretty good.
spline gear finished.jpg
This is the engaging gear, now welded to a larger spline that engages with the blade mount assembly.
It's the drive shaft spline from the same car, that I built on there 5 years ago.
large gear and rotater spline.jpg
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liveaboard
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Re: my home made hydraulic hedge cutter

Post by liveaboard »

Next was the new tooth bars, slotted and riveted, then straightened. these pictures appear in another thread about the rivets.
I drilled the retainer bolts and added zerk fittings. The roller rings are hardened.
drilled tapped mounting bolts.jpg
rivets are pressed; I made the die from some rod I bought, I lost the receipt and I don't know what it is, but it gets VERY hard when heated orange and quenched in water. After pressing 118 rivets, the drill grooves [made before hardening] are still intact.
pressing rivets 1.jpg
new blades grinding rivet heads.jpg
Blade strips are sandwiched between retainer plates
new blade pack disassembled.jpg
new blade pack assembled.jpg
Assembled blade pack fits into the old mounting box.
fitting blade pack in.jpg
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liveaboard
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Re: my home made hydraulic hedge cutter

Post by liveaboard »

Hydraulic upgrades; there are 2 hydraulic circuits that have more capacity, and I wanted to switch the motor to one. But that meant I needed some way of holding one of the other movements in place, because it had to be switched to a circuit that stays open when off.
The 'right' thing to do would be to spend a stack of cash on a more suitable hydraulic valve block. My solution was to add a lock with electric solinoid from a big starter motor that will disengage it during rotation.
This Is to rotate the extension tube that allows me to cut in reverse.
I also changed the 1/4" motor hoses to 3/8" and improved the mount and hose guides.

I had to change the solenoid electrics to switch off the pull coil when the solenoid is retracted. There is a separate hold coil [normal on solenoids of this type]. The old starter contacts are used to keep the hydraulic solenoid off until the lock is retracted.
solinoid modified electrics.jpg
Drillingthe lock pin hole
solinoid mount drilling.jpg
parts on the bench; I had to make the spring from a smaller one. The lock rod fits into a chamber that forms the end of the solenoid plunger.
This makes a hammer effect to help pull the pin out when there's pressure against it.
solinoid parts 1.jpg
solinoid parts 2.jpg
solinoid half assembled.jpg
Ready to attach to the hedge cutter
Solinoid assembled on bench.jpg
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liveaboard
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Re: my home made hydraulic hedge cutter

Post by liveaboard »

After all that work, the machine works much better for heavy cutting, but the new blade don't cut light material as well; it slips out between the scissor blades.
After about 6 hours, the blade plates seized together. Disassembly revealed galling of the plates where the grease squeezed out.
I realized the problem was caused by debris between the blades forcing them apart, levering the plates together behind the bolts.
I didn't get good pictures of the damage, but you can see a little here;
plate damage galling.jpg
So I added guide wheels.
First I smoothed off the damage with a grinder, then reassembled with grinding paste between the plates and ran it for 10 minutes.

I made wheels from delron, and bearing mounts from hardenable steel.
bearings and guide wheels.jpg
Making the mount rods to fit
blade guide bearing mount.jpg
After flame heating and quenching the ends, I tempered at 500C
tempering oven control.jpg
tempering oven.jpg
Stupid! I forgot that the hardening and tempering would leave the rods slightly smaller. My carefully made light press fits are now an easy slide on with copper grease.
blade guides + hose guides 2020.jpg

Now I pump grease in through the mounting / retainer bolts every 4 hours of use. The machine is working well but still has a couple of issues; light material slips out of the blades, escaping. And debris buildup on top of the blades when cutting horizontal is a real problem too, it pushes away material I want to cut.
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