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Old 2nd November 2002, 07:59 PM   #1
remp is offline remp  New Zealand
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Default DIY electric garden mulcher

In our garden we have a lot of small trees and scrubs. Camelia, Rhododendron, Fushia, Protea and lots more.
Every year they grow a bit taller and need pruning. I spend about a week climbing ladders cutting them back. Its well worth doing because you can shape the bushes and they seem to do better for the pruning.

On the ground afterwards is a small mountain of prunings. Too green to burn. Too many to just leave "somewhere". Being mainly twiggy branches they do not compost very well.

So what to do. I did try burning them with petrol and forced air from a very powerful industrial air blower and they did burn good but the smoke from the green material was like WW III had started early. After being ticked off by the fire brigade and looking at a $500 fine if there was a next time I decided burning was out.

We looked at mulchers. Petrol powered machines that take in small branches and reduce it to a heap of finely pulverised material like sawdust. Tried one on apro. Not enough power and you had to feed the prunings in at a very slooooow rate, very noisy and quite expensive as well.

We decided to build a mulcher. It had to use an electric motor because I had one. It had to be strong and sturdy and it had to be cheap. And it had to work.

I experimented with two small hatchets attached to a rotating spindle. Apart from the very dangerous aspect it was completely useless. Just bounced off the thicker prunings.

The next plan was more realistic. I happened to have in my garage an old shearing shed comb sharpening device which consisted of two steel plates about 18 inches in diameter 1/4 inch thick bolted onto a 1.5 inch shaft fitted on two plain bearings. One thread was right hand and the other was left hand. In normal operation this machine was bolted to the shearing shed wall near the shearers and driven by an electric motor. The steel plates had some kind of sandpaper glued on. The idea being that shearers who were paid by the number of sheep shorn could sharpen their shearing handpieces very quickly with almost no down time.

The cast iron base holding the shaft was about 24 inch long weighed a 100 pounds or so and was all rusted and seized.

After soaking in kerosine for a few days it freed up. I took it apart cleaned and checked the bearing play and the end play. It was quite good. Almost no bearing play, small amount of end play which was taken up with some large washers.

After making a wooden tray with two wheels, the casting was bolted in place and a blade made from a used motor mower blade.

Initial trials were very dissapointing.

The speed was too high causing the contraption to rock back and forth in a dangerous manner.

The blade hit a moderately thick pruning and the nut simply unwound.

Using a large dia wooden wheel we got a large speed reduction down to about 200 rpm

Now it was starting to cut the prunings but we needed an anvil for the blade to cut against. Did this with a length of steel plate slightly ground so as to have an undercut.

The anvil made a big difference but still not satisfactory. It needed a lot more weight at the blade.
Fitted two heavy steel blocks. One under the blade, one opposite to balance and it works very very well.

We have a downwards inclined shute longer than your arms. Load the prunings onto the shute, push them down with a wooden pusher or other prunings and they are cut into 1 inch long segments.

It is very fast. It cuts as fast as you can load the shute and throws the mulched bits into a bin. It can reduce a heap of prunings as big as a car to shredded mulched parts about the size of a wheel barrow in couple of hours. And the motor (3/4 hp electric motor) doesn't even get hot.

Safety. Initially everything was exposed and dangerous but have fitted 3/4 inch exterior plywood covers over the belt, shaft and cutting blade and now its very difficult to get close to anything dangerous.

If I was doing this again the frame would be steel. Even 3 lengths of 4 x 4 solid dry timber bolted together bends under the cutting pressure so I cannot get the blade and anvil as close as I would like. Presently it has 1/16 inch clearance. I would like it closer but 1/16 inch does work very well

I would have two or three times the weight on the blade. Its the rotating weight powering the cutting blade that does the work not the electric motor. That just spins it up to speed between cuts.

The threaded shaft securing the disk and blade is an excellent safety measure. Occasionally bits of hard prunings over 1 inch diameter get put in and the blade stops, the nut unwinds and no power is transmitted. No damage.

Total cost of manufacture $20 for a pnematic tyre. Everything else I had.
Time to build about 6 weeks. Couple of hours a day.

Since most people are unlikely to have an old shearing shed machine the next best thing is a car engine to provide the shaft and flywheel.
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Old 2nd November 2002, 08:01 PM   #2
remp is offline remp  New Zealand
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And this one
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Old 2nd November 2002, 08:08 PM   #3
jleaman is offline jleaman  Belgium
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gardening isnt audio..



mabey there is a site for gardening..

www.diygardening.com.

MABEY..
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Old 2nd November 2002, 08:23 PM   #4
remp is offline remp  New Zealand
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To be a good DIY AUDIO person you have to be relaxed and feel creative. Gardening is ideal for that. Quite often while cutting the grass or pruning trees I am thinking about some aspects of large screen video projection. Or what new piece of test gear I will build. Besides it uses an electric motor. I may even fit an automatic motor controller and sensor to determine the thickness of prunings and make necessary adjustments with an audio annunciator and a logger. All within the scope of DIYAUDIO dont you think.
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Old 2nd November 2002, 09:57 PM   #5
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So what caps did you use on the motor suppressor, normal polystyrene, or did you go for polyprop film?

I assume you used solid silver cat 5 cable for the power supply, with a mains laid in especially by your local utility co. with a clean earth bond back to the substation.

I have personally had great success with rewinding my motor coils with pure titanium cobolt alloy wire, I find it gives much greater headroom for the bigger branches, and it gives a great square wave response when you measure it across a scope!

Isn't it nice when it's quiet

Remp- dead cool mate!!
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I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort
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Old 2nd November 2002, 10:11 PM   #6
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Default PRUNING

Hi,

Quote:
I spend about a week climbing ladders cutting them back. Its well worth doing because you can shape the bushes and they seem to do better for the pruning
Funny.Same goes for my employees.

Sarcasm aside,
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Old 2nd November 2002, 10:31 PM   #7
remp is offline remp  New Zealand
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Do you want to contract me to shred your employees

Satisfaction guaranteed.
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Old 2nd November 2002, 11:01 PM   #8
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Default THAT GOOD HE?

You wish.

Sorry mate but from NZ you'll a pretty good toolbox to satisfy these b****s.

Sarcastically yours,
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Old 2nd November 2002, 11:11 PM   #9
remp is offline remp  New Zealand
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What the ******* does

Sarcastically yours mean

Are you trying to be a prick or does it just come naturally.
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Old 2nd November 2002, 11:20 PM   #10
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Default SARCASM?

Remp,

Relax.

Quote:
Do you want to contract me to shred your employees
You're not going to tell me you were serious here either?

That is sarcasm.

All,

Just exchanged some mail with Jocko.
He hasn't changed a bit,so I assume he's fine.
Jocko,please post something O.K.

Cheers,
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