Weed/ brush hacker head

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jpfalt
Posts: 982
Joined: Sun Jan 05, 2003 12:55 pm

Re: Weed/ brush hacker head

Post by jpfalt »

I designed those type of heads for several years. For what you're doing, nothing beats a fixed line head. Our most successful was an aluminum cup with holes in opposite sides of the head. End users would take a 20" piece of line, tie a knot in the middle and thread the lines out the opposite sides of the head. With two holes, you have a 2 line head. We also had heads with 4 holes, using 2 pieces of line, called a 4 line. Stop by a landscaping supply and pick up some .155" line and be ready to murder small trees and the line lasts a good long time even edging along concrete.
spro
Posts: 8016
Joined: Mon Feb 20, 2006 11:04 pm
Location: mid atlantic

Re: Weed/ brush hacker head

Post by spro »

Great info Jpfalt. It ties together and I never saw the .155 line. The Stihl Polycut head does have two small bushed holes, not used with legs and I wondered about that. It is all good and now see the other possibilities. I will remember and find the heads you made.
This is good stuff. They aren't too heavy because they are 2-cycle but they have serious power. Vests, shoulder straps for stability. The line you mentioned, long pants and shoes. The guard is gone with that length but I can see it tearing up anything. We go back to engineering in a way. The line contacts and folds creatting a shearing action as it swipes across. A machine as this can work very well but the oil/gas ratio has to be right. Not all 2-cycle oils are the same. These can work like flying monsters when the fuel ratio is too high and then burn out the engine. It is too good for that to be a possibility. New fuel, proper mix and a touch of Stabil. Those weeds aren't worth destroying that engine.
jpfalt
Posts: 982
Joined: Sun Jan 05, 2003 12:55 pm

Re: Weed/ brush hacker head

Post by jpfalt »

The new engines are usually designed to run a 50:1 fuel to oil mix. I prefer to run Sea Foam instead of StaBil. At the end of the season we always advised to drain the tank, start the engine and run til the engine dies. Then put a couple of drops of engine oil into the spark plug hole and pull the engine over to spread the oil in the cylinder. Then the engine will stay pristine over the winter.

The trimmer head I was referring to was the Shindaiwa fixed line trimmer head. http://www.ebay.com/itm/like/3514902992 ... 7042763688

They want an arm and a leg for the head. If you have turning capability, you can make something close enough, about 4-1/2" diameter. The only real trick is to radius the line exit holes heavily. The heavy duty fixed line head had a 5/8" exit radius, but anything over 1/4" will work OK. I saw a Brazilian knockoff that was poorly molded from remelted soda pop bottles. The glob of plastic was turned on a lathe and the line holes put in by hand with a hand drill. I was surprised by how well it ran.

Another trick is to keep the trimmer line in a bucket of water. Nylon will absorb up to 20% by weight and gets really brittle when much less than 5% by weight of water. We always had issues with trimmer lines and nylon trimmer heads that were warehoused for several months in Arizona.

I worked at Shindaiwa until Echo acquired Shindaiwa in 2009. The head was actually set up to accept 3/16" line like that used in DR walk behind brushcutters.

The biggest unit I saw that head on was a German homebuilt that used a backpack blower engine on a brushcutter shaft. The brushcutter would turn the .155 line in a 36" swath. It was an absolutely brutal machine.
jpfalt
Posts: 982
Joined: Sun Jan 05, 2003 12:55 pm

Re: Weed/ brush hacker head

Post by jpfalt »

Here's a better picture of the head and a better price. I have no affiliation with the seller.

http://www.partstree.com/parts/shindaiw ... line-head/
spro
Posts: 8016
Joined: Mon Feb 20, 2006 11:04 pm
Location: mid atlantic

Re: Weed/ brush hacker head

Post by spro »

First I need to thank you for this information. There is a lot to absorb when I only scratched the surface. You Know stuff and it may take a while. Armed with this info, better choices and more strict preservation of a grand unit.
It will be awhile before attempting huge swaths yet we must know these engines are capable of running seemingly well when they really aren't fed right.
This little topic is going to help many users of this equipment.
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