Monday, March 19, 2012

Good at building. Bad at Posting.

It's been hectic. I've got a lot going on personally, so it's been hard to keep the posts flowing. However, progress is happening! I'm assembling my power cube! There are parts that still need to be ordered and assembled, but things are beginning to look up.

The Cube
I've assembled the Cube (above). It is the frame that holds all the components in place. After welding the corners together, my professor said that it could handle being dropped from an airplane.

The Reservoir
The hydraulic reservoir is air tight and ready to rock (above). I had to fix leaks twice during the leak tests. My PVC plugs held up to high pressures (60 PSI or more) without a problem-- still be careful if you're doing this yourself.

Reservoir in CubeTacking the Reservoir

I mounted the reservoir into the cube. It fit nicely so I tacked it in place. With it secured, I was ready to start positioning the engine mounting plate.

At least I thought I was ready. I had already assembled the engine mounting plate and its supports. The plate with the hole will receive the engine-- the engine shaft goes through the hole. The other plate is a vertical support which holds the plate up.

When placed into the cube I saw the image below. Can you tell what is wrong?

It turns out that the instructions were out of date. The holes they described placed the engine too close to the tank outlet. The intake hose that connects the hose to the pump can't make that sharp a bend. So I had to drill a new hole and move the engine mount away from the tank outlet.

Here is the plate after it has been moved and tacked. Can you tell what it wrong? The horizontal plate is no where near level. I didn't think it would be a problem but, the engine wouldn't fit right with this sag. I cut my tack welds and used a level to get everything square. Below you can see the scoring from the grinder and the new location of the support.

This made the engine fit nicely. You can see in the next image the thin slice of light coming between the engine and the tank. When the plate wasn't level, this clearance was taken up and the engine was resting on the reservoir.

So things are starting to look real. I'm very happy with my progress, though there is still a long way to go. My next post will include a really great trick for locating the holes that the engine bolts will go through.

Wednesday, March 7, 2012

Thinking about MicroTrac

As an American, I am required to want a big tractor. I do in fact want a big tractor. What do I need though? Can I get by with less? Enter MicroTrac (Top Right) a small version of LifeTrac (Bottom Right).

MicroTrac is in the early phases of the development process. It's also a better size for my near future needs. So I've been thinking about making a MicroTrac when my PowerCube is complete. I've been thinking a bit about high level design for such a tractor. My thoughts are below.

Things it should be able to do:

  • Take interchangeable Attachments:
    • Snowblower, Lawnmower, Snowplow, String Trimmer, Mini Forklift, Tiller, others?
  • Powered steering.
  • Optional ride behind or ride in front (depending on whether attachment is pulled or pushed).
  • Low center of gravity. Reasonable stability & Balance.
To achieve this, I'm thinking of something like the diagram below.
Simple Concept for MicroTrac
It's primitive, but reasonably to scale. The cube in the middle is a Power Cube. It would rest securely in a frame. That fram would have two LifeTrac quick connect wheels attached near the midpoint. This keeps the center of mass low (but should still allow for maneuverability).

On the top are hydraulic valve controls which would control the wheels and the attachment. They would be movable so they could be at the front of the cube or the back. This allows the driver to push the attachment (snow plow) or pull the attachment (tiller).

The protrusion between the wheels is the attachment point. The would need to allow either a rigid or swiveling connection to a tool. To allow for loader type attachments (fork lift, bucket) there needs to be a more complex mounting mechanism available-- perhaps uprights at the back of the power cube that arms could attach to.

Finally, the drive could walk behind the tractor, attach a platform to stand on, or attach a seat of some sort.

My current reservations about this design:

  • Geometry - Will everything fit? It should be possible but might be tight.
  • Balance - There isn't a lot of weight in the back to keep MiniTrac from tipping forward. This is a big problem with lifting devices like a bucket, soil pulverizer, and forklift. Would a wheelie bar in the front help with those? Perhaps a caster in the back to keep from tipping backwards?
  • Maneuverability - How agile will it be? What sort of grade could it climb?
  • Ease of Control - The PowerCube is pretty powerful, how jerky will starting and stopping be? This can probably be mediated through clever hydraulics.
  • Ease of implement attachment - The attachment mechanism needs to be strong and easy to work. Perhaps us the same align + cam mechanism that the wheel modules use?
I'd love to hear feedback in the comments below. How can this design be improved? Any suggestions on attachment mechanisms? etc. etc. etc.

Monday, March 5, 2012

Kicking Butt in the Shop

It feels like I've finally turned a corner in making my Power Cube. Things are going more quickly as I hit my stride. With so much progress, I'm going to change my format a little. I've been posting about each day in the shop. With the progress that I've been making that won't be coherent-- I'm doing too many different things to describe them well in a single post.

So, here is a laundry list from the last two weeks. I'll write followup posts with details on each process.

I used the CnC Plasma Torch to cut out the pump plate and engine mounting hole. I used a drill press to attach the engine mounting plate to the angle iron that it will be bolted to. I leak tested the Hydraulic Reservoir at 80 psi! And now for a fun picture:

Steel Pacman eating a green dot =)

Sunday, March 4, 2012

What has this Tractor cost so Far?

If you're not aware, I'm currently building a Power Cube 4. This is an interchangeable power unit that can power a tractor, a brick maker, a lathe, and many other tools. Once I'm done with it, I'll start work on something for it to power. I'm leaning towards a micro-tractor right now.

How much have I spent on this endeavor so far? Has it been worth it? My records say I've spent about $1,365 and 25.5 hours on production so far. A John Deere riding lawnmower costs in this range, but isn't nearly as flexible or durable. As for my time spent, it's been great. I'm learning all sorts of useful skills and applying them.

I'm estimating another 16 hours of work and perhaps $200 more in parts. All told, I'm really happy with the process and experience.