I present to you, the Grass Cutter Mk II

So a list of upgrades/changes

A new handle, taped up to keep it safter and secure. inside this is a lightswitch embedded in the wood for off/on and the control board.

A new adjustable angle handle, I can loosen the bolt and change the angle so if its not really comfortable where it is, I can change it.

The engine is now parrallel to the ground, much more ‘mower-like’ less ‘weed strimmer-like’.  Also I removed the rubber as it wasnt providing any vibration releif and was just making it smelly. The strimmer line (orange twine) is also attached in a more reliable way: I threaded it through a drilled hole in the shaft head, then tied a double knot on each side so it cant pass through either direction.

And a new height setting/adjustment pole. there will be a wheel on here soon, I tried a couch floor knob but it doesnt slide very well. The point of this is to make it easier to push around rather than having to manually hold it at a certain height. although doesnt mean you cant flip it upside down and go manual if you want to do edges etc.

I planted a lawn out the back of the property where the gardener couldnt get to without a key so I needed something to cut the grass. My lawn mower is a bit pre-occupied and my weed-wacker was wacked. So in the usual recycling manner I made my self the

Graminoids De-lengthener Mk I

Wow look at that, badly thrown together lense flare, a fluro background. This thing HAS to be awesome.

To be honest, the only reason I am calling it MK I  it because its rather hastily assembled and has some design uglies, I’ll probably never rebuild it because it works, and thats all I care about.

So I started with an old hand mixer/blender motor I had lying about, and thought about strapping it to a peice of wood, without anything else more suitable I made a sort of wooden vice with two threaded steel rods and 4 bolts. This worked really well!

I basically just nailed the control board onto the length of wood for now, holds fine, but I had to wire up a switch. In the interim I have some twine nailed to the board, going over the switch with another small peice of rubber, then round a nail and back to the top of the board for a lever.

I also attached some twine to the end of the engine so I could cut some grass. simple; effective.

bill of components

* engine: from a hand blender like: * a bunch of wood I recycled out of an old couch.

* about a 1/4 of some threaded steel I bought a while back
* a 6cm bolt for the lever
* 5 bolts
* cut mains cable I had left from another project.
* some weed wacker twine for the controller and the cutting part.

(goto part 2 -> )

Project considerations

The first thing I needed was a new lens. I picked up a Macro Zoom Ring +10 Diopter from trademe for $15NZD which was pretty similar to this :

My budget point-and-click camera obviously couldn’t mount it so I needed to make some things….

First I needed to make a small extension tube for the lens, and some way of mounting it to the camera. Conveniently, the first thing I laid my hands on, the cap of a bottle of degreaser, just so happened to hold the lens quite snugly. I secured it with black electrical tape, and also wrapped the cap with it several times to block out the light. Then, I cut a hole in the top of the cap, around the size of the existing camera extension tubes so that it could fit snugly on there.

NB: Cutting through the plastic is much easier with the tape applied. It meants it doesn’t crack when cutting it.

To mount it to the camera, I built a small perspex base that attached to the bottom of the camera and extended forward so that I could attach the lens and its extension tube to it. When I attached the camera and placed the macro lens onto the mount, it seemed to hold itself in there quite well. (although I may add another bolt to secure it firmly…)

Now all I need to do is turn the camera on, the lens moves into the hole and I can take macro shots!

Now for some example shots…

(click for big)

The solution: re publish your form and go into every greyed out item, click modify, then click “allow users to edit data in this field by using datasheet or properties page” then republish

(click for big)

I needed a clutch at some point anyway so I started thinking about how I could resolve both problems at once, removing as much load off the engine on startup and being able to clutch the engine.
My plan is to put a small disk on the bottom of the shaft, then create a method of being able to push the pulley onto it; a dry friction clutch, but with a few changes. The clutch control will be a nut that I turn remotely (Likely by another pulley). The reason for this is it means I will be able to apply more force to the connecting plates via the bolt, and possibly later I may be able to automate it (ie, mechanical clutch)
Also it seems like it will be the easiest to build.

This is what I imagine it would assemble like (click for big)

More detail on the bottom of the pulley:

The pulley will turn freely inside the bolt, I may later replace the bolt and bearings with a real bearing perhaps out of a skateboard or something. The bolt pushes the pulley up using the two lower fixed nuts, turning the bolt inside them will push itself up up.

Update 16 July 2010
I started working on the pulley/clutch shaft and bearing. I spent most of the time trying to hammer, screw, grind some washers to the right shape. the most successfull was one that I ground down with an angle grinder except for the middle, then bashed the sides up a little bit. I found a aluminium ring which I think came from a hard drive and installed that and it seems to hold everything quite nice. Its not anywhere near perfect, not even near good, but its usable for now.

(Click for big)

The left picture shows an exploded simulation of how the bearing fits together, surprisingly this doesnt work too bad. The right image shows what it could look like assembled. Note the bit that says ‘Clutch Control’ this is just a bolt and two washers for image purposes. I need to put some thought into how I will turn the shaft, without allowing the spinning pulley to have any control over it. if I used a smaller pulley down the bottom or in the middle (as pictured), I fear it would be too easy for it to slip and the engine would dis-engage the clutch automatically. I also found I will need to modify the holes that the top bolt and bearing fit into; they are too shallow.

Update 17 July 2010
Started building the new base, and resunk the pulley so I had more bolt to play with, I am pretty happy with it. then I sunk a bolt into a wooden beam to go under the engine shaft, I shaped it with a craft knife, chiseled it out a little bit, then wacked it in with a hammer. It feels really solid so I am happy with this part. I in the 3rd pic I have placed it roughly where I expect it to sit. But I noticed I will have to be quite precise, I dont want the too shafts to be mis-aligned because it will mean the clutch plates wont sit true.

I still havent figured out how I can turn the clutch shaft without using too much bolt real estate and keeping it secure so its not able to be spun by the engine. although I am thinking about two small pulleys with some rope attached and wraped around a few times. buy pulling one rope, the pulley will spin the shaft and the height will increase, at the same time another pulley will be pulled and wrapped around the second pulley. I can then pull the second rope to do the opposite.

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