Robot under-tree bramble destroyer

Fed up swinging a billhook and having the lines break on my weed eater. Contemplating building a robot to tear out brambles under old orchard trees. Think 15cm ruts, 40cm clay ant hills, 1.5cm brambles as well as docks, fences and netting round trees etc.

A full on agricultural mower does the main rows OK but under the trees is a PIA.

Looked at a few designs and they seem like toys but some have the germ of an idea. The choice seems between brute force & ignorance or not quite so much force and a bit of intelligence. Thinking so far some kind of cart with a rotary blade strimmer head on a hydraulic arm with OpenCV on a RPi to tell the difference between my leg and a tree stump.

Has anyone seen or done something similar.

This is what pigs were designed for.

Use a steel brush cutter blade rather than cords on your strimmer / weed eater ?

Former work had two strimmers for grounds maintenance - a small Homelite two stroke unit with a twin cord head & a larger Stihl 2 stroke unit with a steel 3 edge blade like the one shown in the link. I don't recall this having any trouble with brambles, saplings etc that the Homelite would not touch.

Nigel B.

+1 for steel brush cutter blade (per mgnbuk). We have 2 hectares of land, and on one side is a steep drop, with loads of spiky hawthorn bushes growing along one side (my neighbours) - they seed and grow very quickly, and the only way I can keep them down is using a steel brushcutter blade. It will easily go through a sapling up to about 3 cms thick, driven by a 50cc motorscythe. There are many variants about - 3 and 4 blades, and on the chinese sites there are types with articulated blades attached to a central head.

Its not uncommon here for people to make their own - a wide flat metal bar, sharpened a la lawnmower, but they are easy enough to buy - just make sure you get one with the right central hole - they come in several sizes.

Yep ! The Brush cutter blade is the one for the Job. I got one with the wrong size hole - just machined up an adaptor - bingo ! Noel.

If I remember correctly, there are Brush Cutter blades specifically for brambles and the like. They resemble a two winged Brush Cutter blade with downward facing tips. Check compatibility with your particular Brush Cutter as I suspect they need a little extra power.

For this type of work Stihl make a scrub cutter attachment, rather like a stubby hedge cutter.

Depending on your upper body strength I would go with a long reach adjustable angle hedge cutter. Used with a suitable sweeping motion you don't get bogged down it the way a strimmer will even with a steel blade

+1 for the scrub/hedge cutter attachment.

I've tried everything there is over the years for thick brambles in tight spots and these are your best chance. The advantage they have over a rotary blade on the end of your brushcutter is that you can constantly turn the attachment and chop up the cut material to get it out of your way for the next swathe of cutting. You can't do that with a rotary blade; with these, if the brambles are at all thick or tall, you get bogged down as Tris says.

Thanks everyone. I will go with the hedgecutter idea, I already have something suitable with an adjustable head and a long handle.

I tend to come up with complicated ideas for simple problems.....

I am a bit windy of a rotary blade on the strimmer - read of some chap who managed to cut through his ribcage with something like that - not fatal but a bit painful I guess.

While we're on that topic, Roger, this is worth a read.

Brush cutters are the conventional tool for this sort of job, for the specific job you describe I would think the walk behind type is what you would want, useless for a fine finish but loads of grunt and quite manouverable.
No association with the website, just the first google hit to show examples.

**LINK**

I use a brush cutter with steel blade, but I'd rather have a robot. Especially if it can pull weeds too.

Trying to imagine how someone manages to cut into a ribcage while operating a motorscythe/brushcutter - the head on mine is separated by a long length of aluminium pole from me - I would really have to do some gymnastics to get anywhere near the head when its in use, and then I would probably have to let go of the controls, thereby switching it off - biggest problem is chunks of wood/earth kicked back towards my shins - and boots and overalls stop that.

Whether they use plastic line or metal attachments, potential damage to the trunks of Roger's orchard trees would rule those out for me.

Very easy when it's your workmate's ribcage.

While we're at it, have a read about the fate of Anthony Robinson.

EtA: And there can be worse self-inflicted wounds than wounds to your ribcage.

EtA no.2: On the other hand, wounds to your ribcage can be bad enough.

Edited By Bill Phinn on 13/07/2023 19:14:04

Anything that can clear brambles will be capable of harming even quite mature trees, the operator needs to be careful where they point it! The 4mm line on my brushcutter would easily kill my 10 year old apple trees if I was careless with it.

I'm sure it would be possible to constuct some sort of stand-off guarding for the wheeled machines,but it would be rather unwieldy, better to watch where you are going.

It isn't mentioned in the article, but I believe this was the first ever instance of an EU wide product ban arising from the product alert system. Of course now you can buy all manner of lethal power tool attatchments direct from your favourite website, particularly mind boggling is the version of said brushcutter chain attachment that uses chainsaw chain for added "spice".

I cringe whenever I see those.

Rob

I'm sure you'll agree, though, that not everything that can clear brambles poses an equal risk of harm to adjacent trees. In my 42 years of experience doing this sort of work on other people's land, I believe the reciprocating blades I and others recommend would be the best solution in the circumstances Roger describes. In order to cause any significant damage to orchard trees while using reciprocating blades to cut brambles that are growing under them, you would have to be the sort of person who is not fit to be in charge of any garden tool in the first place.

Though then you would be unlikely to be able to reach right up to the trunks of the trees and get all the brambles you need to.

Yes, I discussed this in a thread two years ago.

I wonder if one of these may help? Although probably a bit pricey...

Links to https://interestingengineering.com/innovation/new-farming-robot-uses-ai-to-kill-100000-weeds-per-hour

Rob

Thanks for comments. I tried my battery electric hedgecutter under the apple trees.. Not enough guts in it to be really usable. I do have a Stihl petrol hedgecutter and that would do the job but I would have to kneel do swing it left and right. You need a bit of overkill for this job.

My strimmer is a cheap unbranded job with a 9.5mm spindle. I could make an adaptor for a circular blade and could fix it so it cannot come off. Still a bit windy of whirling blades.

I do have the bits of a high power YAG laser but the 4 kilowatt lamp and cooling water add to the aggravation factor to say nothing of the fire and blinding risk. Next door farmer won't mind if I do a bit of hoof and horn pruning....

Overall I feel I will be getting out the kneeling pad and Stihl hedge cutter. The tale of a chap cutting his rib cage did come from a two-man team. So harsh words probably. Locally a tree surgeon managed to embed a chainsaw in his chest - but lived to tell the tale. Me, I do use a chainsaw but don't climb trees with it.