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Brush blade for Ego string trimmer

 
Posts: 331
Location: S. Ontario Canada
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I bought one of these trimmers and I'm very happy with it but it falls just a bit short on the light brush. I wanted to try some kind of a bush blade. The hardware is (for the most part) easy to find.


In the background is the blade I chose. It has a 1" hole.
1. Looking at the trimmer it looks like these vanes are to cool the motor - we'll need that feature. This means you're going to have to sacrifice a trimmer head to make this work. After buying a new one I went to work on the old.
2. OEM hardware
3. 1/4" fender washer (1" OD)
4. 1/4" fender washer bored to 5/16 ID NOTE: It was just a shade bigger than the 1" OD needed. I snugged the washer on a 5/16" bolt, chucked that in a drill and ran it over a file until it was a snug fit.
5. 5/16 shoulder washer (thicker than the OEM part, same OD)
6. (not shown here) 5/16 fender washer - greater than 1" OD.


Need to cut off all of the string head but the base. This initial setup was wrong. You need to cut on the line in the pic removing about half of the raised boss just below the square hole.

I shouldn't have to remind you that the number of fingers you have should be the same before and after you complete this step.



Now you have this and the center section needs to be brought to the same height. Sandpaper on a flat surface and work carefully, rotating often, checking for square. If this isn't square your blade is going to wobble. Take your time.


Brought down to the same height as the 5/16 shoulder washer. (#5)


Assemble with the cut trimmer head, the spacer, 5/16 fender washer(6) and ..... there isn't enough thread engagement. Especially with the flatted shaft.
You could cut away half of the hex portion of the OEM fastener and you might get enough thread....
You could also space some washers and use a nut and locknut....
I think the best option here is a coupling nut. You would have to bore into it a bit for the unthreaded part of the shaft but you would get the most thread engagement and protect the threads as well.
https://www.amazon.com/Hillman-44768-M8-1-25-Coupling-10-Pack/dp/B00JDTZTAA/ref=sr_1_3?ie=UTF8&qid=1547237149&sr=8-3&keywords=coupling+nut+m8

This is an 8mm thread on the shaft same as a standard M8 bolt.
When I can test it I'll post something but for now it runs straight and true with no vibration.






 
gardener
Posts: 2284
Location: latitude 47 N.W. montana zone 6A
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Great modification Roy!     Thanks for sharing!
 I've had my EGO lawn mower several years now and I got the string trimmer this summer.
I love them both!  Next summer I hope to get the chainsaw!
 
gardener
Posts: 1035
Location: Southern Illinois
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Very nice Roy,

I can't quite discern from your posts, but can your trimmer take standard brush clearing blades?  I have a Kobalt 40v trimmer and I wanted to add something more substantial that .065 line to the head.  Unfortunately, the little post that comes down is too small to fit any standardized attachments.  I did manage to wind .080 line onto the spool so that helped, but my minimal modification was nowhere near as elegant or ingenious as yours.

Good job!

Eric
 
Roy Hinkley
Posts: 331
Location: S. Ontario Canada
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@ Thomas  - The Ego saw is a great product. Very happy with it. Battery life is surprisingly good (in fairness though it has half the kerf of a standard saw). My only complaint would be the oil level window. ... useless.


The Ego is not designed to accept any standard blade as the trimmer head supplies cooling air for the head mounted motor (I think).   I'm not familiar with your trimmer, sorry.
All these electric trimmers are lighter duty than the gas ones so we need to be careful not to overstress their capacity. String is forgiving when you hit something solid.
I originally bought a grass gator (with the 3 pivoting plastic blades) but it isn't going to cut the saplings I'm dealing with so I rejected that pretty quickly.  A pivoting blade type head isn't a bad idea though when you run into solid objects.

I've watched vids of blades on trimmers and they take such a big bite they're barely controllable. This design seems to limit the cutting depth for each tooth so I'm thinking less stress when you hit those thumb sized saplings.
This mod should allow me to use any blade with a 1" hole. If need be another spacer could be made for other sizes.
 
Roy Hinkley
Posts: 331
Location: S. Ontario Canada
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Here is the M8 coupling nut on the left, part of the threads drilled out. OEM nut right.
 
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