Simplify Gardening - Close to perfect tools?

@ "M": Thanks, I should have probably considered contacting them directly, ahaha. I'm actually in my second year (and it's incredibly busy, fun times) although when I start my final year, I'm going to go into something based around sustainable/eco-design (I have a design for a 'free' energy generator in mind).

@ fat controller: Oh no I totally understand it's perfectly fine - I should have probably been much clearer when I started my "investigation", ahaha. I'm incredibly grateful for all the input the members have been putting in - it really does help me out; I'd rather not skulk around garden centres interrogating shoppers, ahaha.

 

@ shiney: Thank you for the information, it was actually very helpful and enlightening. I've been reading about, well I'm not sure if calling them 'mobility issues' is correct but restraints in certain actions while gardening (e.g. not being able to reach towards the end of the flower bed or perhaps there are joint pains which may prevent oneself from performing at maximum potential).

So I had a look around and found that they do design tools for the more 'seasoned' among us which are essentially, from what I can see, normal hand tools at the end of a stick:



At this point, I had a thought - why not take this a step further and make the set-up a bit more intuitive; now this may be a bit overkill but what would you say (and I'm asking everyone, ahaha) to the idea of an basic arm exoskeleton with the ability to map the positions of the fingers. Something that is a very basic version of this:



I apologise in advance if I lose anyone here, ahaha … So the device is worn on the forearm and you have a glove (or similar contraption) which you insert your hand into - it monitors the position of your fingers and sends the data to a robotic hand which will basically copy the motion.

Now this robotic hand is at the end of an 'extension' pole so essentially, you can pick up tools, pull out weeds, etc. as you would normally (well, more or less) but now with an extra 1m or so extension and hopefully less joint pain.

Theoretically it sounds all well and good but I'll have to develop it further, etc. and I'll post a sketch once I've got it sorted.

What does everyone think about it?

 

Knee jerk reaction? Expensive

 

@ "M": Ahaha, yeah that's true - well I'm sure I could get it sorted for under £200 but that's not really a 'feasible' product.

@ shiney: Ah, I see. Well as you've said, something that precise is better done by the individual than a tool so that kinda puts my idea out of action, ahaha.

At this point, I'm going to continue with the self-adjusting shrub trimmer since that's the only idea that's been approved, not over exploited and actually fits in with the provided brief.

I may be requiring some test candidates soon (if I finish it in time) so if anyone's interested in potentially sacrificing some bushes, please let me know.

 

I've been reading this thread with interest. Welcome to Gardeners Corner AK.

Down the years no one has managed to produce a lightweight, electric hedge trimmer. I have nearly 200 feet of hedging surrounding my property and being of the older generation and female, handling my current trimmers is very difficult for any length of time, particularly when my arms have to be raised.

There are a few trimmers on the market that are lighter but they are also smaller and couldn't handle a great amount of hedging, they would be more suitable to individual shrubs. I realise the weight is mainly due to the motor but surely it's possible to produce lightweight components to at least reduce some of that weight.

I'll be interested to hear what you think about this please.

 

@ Sheal: You're perfectly right - for the electric hedge trimmers, the motors tend to be quite large but there also tend to be other factors involved.

Starting off with the motors, there are two main types - brushed and brushless. Brushed are heavy and less efficient by easier to run (literally apply a voltage at the terminals and it'll spin); brushless motors however are much more efficient and lighter but require some control electronics to actual have them turn.

So I guess most hedge trimmer manufacturers chose the brushed motors to save on cost since you basically connect a battery through a switch to the motor - press the switch and the motor turns.

Then you have the blades which for the larger models go up to about a meter in length (if I'm not mistaken); now these operate (as you have no doubt seen) on a basic oscillating principle - the bottom blade is fixed with the top blade moving backwards and forwards for a fixed distance; effectively cutting the branches that get caught between the gaps in the moving blades.

Now the issue I've seen with this is that you have two solid steel blades but only a small surface area doing the cutting so a lot of unnecessary weight; and of course as you've said, it becomes incredibly uncomfortable to hold for extended periods of time which isn't made any easier when you have to tackle odd heights which strain the back, etc.:



At the end of the day, for mass manufacturing they want to keep prices down so they'll pick motor's that just do the job and parts (like the blades) which are just easier to cut out of one material; it's all about the money.

My design tends to tackle these issues in quite a few different ways. Firstly, with the ability for the blade to self-adjust, if you had to, for example, cut a large vertical surface of a hedge, the blade would always adjust itself (with the aid of sensors, etc. within the device) to always be vertical so you could stand and hold the handle in any way you found comfortable without having to worry about an uneven cut - hopefully eliminating any muscle strain.

The second part (which is proving to be quite difficult) is the redesign of the cutting mechanism - I've opted to use a brushless motor so that'll reduce the weight without having to compromise on speed/torque and as for the cutting bits themselves, I have a few ideas:

- As only the blades are used for cutting, I had the idea to replace most of the (blade's) body with something more lightweight (carbon fibre or some form of high strength plastic) with only the blades remaining as metal parts; that way you end up reducing about 70+% of the net weight (see first attached image).

- The other idea was to remove the idea of having a blade and perhaps something like a piece of vibrating razor wire; totally random and quite dangerous but yeah, something out of the box and new - still working on that part, ahaha.

The design I'm working on is more of a shrub trimmer (in regards to size) to limit the amount I spend on this project but the principle can be scaled up for large hedge trimmers.

So to summarise, the concept has a greater efficiency, lighter blades and 'intelligent' design reducing muscle strain and making the experience more comfortable/enjoyable in general. The only downside is that the battery size probably won't change since I'll be using off-the-shelf components and mainstream battery technology hasn't really improved drastically over recent years. In regards to cost, it'd probably be slightly more than your average shrub trimmer but then again for the added functionality, etc. I believe it'd be a worth while investment (but that's just me, ahaha).

As a whole though, what are your thoughts on the design (I believe I posted an image of it on a previous page) and my way of going about it?

P.S. I've also provided a rough handle design I'm going for (see second attached image) which is loosely modelled off a sword handle/hilt - I found during my time fencing the actual handle was quite ergonomic and provided for a variety of different hand/arm motions (can't remember and terms, it's been far too long ) to be carried out with great ease; something which for this smaller model is something quite useful to have.

 

I think you're massively over complicating a simple concept.

Hedge trimmers are so pathetic for their weight for one reason. Safety. The blades do a relatively useless oscillation as you say. They do this so that if you shove your arm in it, at worst you'll get a minor nick. Painful no doubt, but you'll live, and you'll still have your arm.

Contrast this with a chainsaw. Extremely efficient, but lethal. A chainsaw is so efficient because the blade is moving in a linear way, no force needed to make it change direction several times per second.

Trouble is, if the chain breaks, it can whip round so violently as to fillet you like a kipper. Even if the blade doesn't break, it can still rip you up if you touch it.

Imagine the constant motion of a chainsaw blade, but with the protection of feeble trimmers. You'd have a light yet powerful hedge trimming tool.

 

Hedge trimmers that are easier to use than electric ones already exist. I'm not exactly in the first flush of youth, and having well over 200 metres of hedge to trim twice a year meant that I had to choose carefully.

More important (in my opinion) than the weight is the balance. Thats the thing that makes a trimmer easiest to use.

 

Better off using a slightly heavier petrol trimmer rather than a slow electric one imho. Its all about fatigue. A 10 minute burst of energy is easier to deal with rather than faf about for 20 minutes with a weedy electric trimmer.

A way to ease the weight problem imho would be to focus on designing a counter balance mechanism that could be used with power tools petrol and electric rather than focusing on weight.

 

A good idea providing that the replacement doesn't shatter with stress.

Are you referring to a re-chargable battery here. If so, surely this adds further weight to the trimmers. Mine are purely cable from trimmers to socket.

I can only see one handle on your image, that would make it impossible to maintain stability whilst using the trimmers and ultimately dangerous.

 

I've not seen these unless you are referring to petrol driven trimmers Sandy.

.....But I wouldn't be able to use these because of the extra weight, which is exactly what I've been referring to. I also can't stand the horrific noise of petrol driven trimmers, strimmers etc.!

 

You wouldnt be aware of the weight as it would be counter balancing the weight of the trimmer.
Sort of like its easier to carry 2 light buckets one in each hand, rather than just 1 heavy bucket in 1 hand.
I use foam earplugs when trimming the hedge when i can find the little devils that is

 

@ clueless1: You're perfectly right about the safety (although I must admit, the larger trimmers could easily slice off a finger or two, haha) and yeah about the blade, I had an idea about something like that today - a bit like a bandsaw blade (less heavy duty and when cutting bushes, less likely to snap).

@ Sandy Ground: That's a good point - I'm trying to keep as much of the weight as close as possible to the handle so you need less force to move it about (with the ergonomic handle hopefully making the moving around process easier too).

@ WeeTam: I like the idea for the counter-balance mechanism - I mean, I've seen different types of harnesses for the larger tools (I'm not sure if they're helpful) but I think for the smaller handheld tools, it might not be that necessary.

@ Sheal: Oh so your trimmers are mains powered - yeah I was talking about the battery powered ones (part of our spec is to design a 'battery powered' hand tool so that's something we have to consider); to be honest, modern LiPo batteries are quite light (compared to their NiMH counterparts) so another 100-200g would be the approximate added weight.

Ah sorry, I'm not sure if I mentioned this but I'm doing a handheld shrub trimmer, one of those smaller ones; kinda like the one below so you don't really need two hands for control (although I'll be adding a form of extension pole to assist with 'hard to reach' areas so two handed grips would be available there).