Tuesday, June 17, 2014

Failing: Learn From Your Mistakes

Usually I talk about what has gone right.  Seldom do we like to dwell on what has gone wrong.  But in this case, I fought a good fight and so don't feel too badly about acknowledging when it was time to call it quits with a repair job that just didn't want to be.

It all started when I reassembled a mower deck after obliterating the spindle housings after hitting a fist size rock.  In that case, I was fortunate enough to find ereplacementparts.com, and was able to get replacement spindle housings for less than the cost of a new deck.  A week later, I had my mower back in operation but I failed to consult a parts diagram, and as I now know, omitted an important spacer.  With the spacer between the top of the spindle housing and the bearing missing, the pulley rode directly on top of the spindle housing, creating a lot of friction and heat.  Eventually the, the somewhat toothed hole in the center of the pulley wore smooth, and then as it loosened, oblong until it was so worn it had no more ability to hold the mower belt in tension and it failed with much noise.

I was able to purchase a replacement pulley for $13, and was back in business.  That is, until late last week when yet again, I discovered the same pulley wearing out. Fortunately, I caught it before it was bad, but it was definitely spinning free.  Exasperated, I pulled things apart and discovered that the spindle itself had worn to the point where there were no more ridged teeth to engage the pulley.  So, I got back on the parts site and ordered a new spindle.  While doing so, referencing the part diagram for the part number, I noticed the spacer.  It all clicked in a moment of realization - the spacer was the problem.  Without it, the spindle and pulley could not hope to function properly for long.

This is where the fail really starts rolling though.  So, first lesson learned: consult a parts diagram and make sure you have everything when you reassemble something.  Not being one to give up easily, and wanting to mow my lawn while waiting on new parts, I devised a way to get the spindle and the pulley to lock up and work as intended.  All I needed was a little machine work and a suitable washer to turn down as a temporary replacement spacer.

As you can see below, with a little drilling and filing, I created an index slot in the pulley, and a hole in the spindle to receive a set screw which I imagined would engage with the slot.

Notion courtesy of: "507 Mechanical Movements"
In theory, this was a sound mechanical principle.  I made a couple of miscalculations, however.  First, my set screw was just a happy find in the parts bin.  I had no idea what the strength of the material was in terms of hardness or even composition.  It might have been mild steel from the ease with which it failed.  Second, I drilled and tapped the hole in the spindle, but the spindle was hollow, and the wall thin, and getting my hand held tapper to cut threads correctly was a challenge and it didn't go so well.  As a result, the screw jammed in the threads and turned itself in half with the torque of the vice-grip pliers I was using to insert it.

SO close, but not working out.  I reasoned at this point that if I had spacers, I could make it work, so I drove all the way to the hardware store hoping to get a replacement pulley and maybe find a lucky washer that would match the spacer dimensions.  I found one with the right ID (inside diameter), but not the right OD.  So I thought - no problem, I have a metal lathe, I'll just put the washer on the outside of the chuck, turn it down and have a spacer.

Unfortunately, my bench lathe is a 7" made for larger, heavy duty work.  I haven't a chuck small enough.  My machinist mentor later asked me: "Did you try putting the washer on a bolt and..."  "DOH!"  Yes, I could have mounted it to a bolt with a couple of nuts and put the bolt in the chuck.  Duh.  But, by the time I learned that, it was 24 hours past the time I humbled myself, gave up on trying to repair my mower with make-do parts, and wandered down the street to borrow my neighbors riding mower.  The grass looks great.  His new John Deere all-wheel steering mower was a beast and got the job done with nary a complaint. I might have to upgrade... some day.

I strive to learn from my mistakes so that I might not repeat them, and that I might learn to be more thorough, and careful, in the future.  I hope this little story helps someone else avoid similar pitfalls!

Tuesday, June 3, 2014

Creating Additional Parking

America is a funny place.  Even some of the poorest people have a small herd of cars grazing in their front yard.  There are .797 vehicles in the US per every 1 citizen.  Considering that many of those people are only legally passengers, and that many who are of legal driving age don't even own a car, it's actually a lot of cars.  Like most families with more than one driver, we have more than one car.  Part of this is strategy, and part if it is just God's grace.  Long story short, I couldn't sell the old Dodge mini van when we upgraded to a used Honda Odyssey, but it has worked out very well having a paid-for backup vehicle.

This blessing, however, presents a problem.  My driveway is only 20 feet wide and 78 feet long.  Crammed end to end, I could fit about 6 cars in it. Our garage (crammed with other stuff) is attached and faces the street, so while urban neighborhoods often have a detached garage in the back and a back yard to stuff an extra vehicle into, our driveway, so far, has been the only parking available for us.  This has made shuffling the vehicles a bit awkward at times.  The solution dawned on me last fall - I need (just like a couple of my neighbors have) an extra parking spot. Thus began a seemingly simple project: kill the grass, spread some gravel around, call it good.  Alas, "simple" quickly led to "expensive" as my over-developed sense of perfection took over.

Here's the final bill of materials.  The initial grading was "free" since I already own the 1973/4 International Harvester 284 which I used to scrape the area bare.

Fuel for Tractor and Hauling
Pressure Treated Landscaping Ties
12 Tons of 305 unscreened gravel,  delivered
Bobcat S150 Rental, w/ Trailer
Dr's Visit
Total   :-/$741

The lumber yard got me for $36 each on the 6, 6" x 6" x 12 ft landscaping ties.  Once upon a time you could get them a lot cheaper.  My dad and I built a lot of stairs and retaining walls when I was a kid and I remember they were closer to $8 a piece back then.  But, they make in my case what is essentially a weed barrier and retaining "wall", albeit only about 2" tall.  I buried them 4" in the ground to keep them from sliding out of place, and to keep grass rhizomes from creeping under them.

Why 12 tons of gravel?  Because I wanted the gravel bed to be deep enough that my vans wont sink into the wet clay beneath after a heavy rain.  And I needed some extra gravel for an upcoming project.

The Dr's visit was for a hernia.  Yes - long heavy beams should not be lifted up by one person.  Turned out to be minor enough that with care it went away,  for the most part, in a few months time.  It did slow me down quite a bit last fall, however, when I began this project.

While the project started with grading the grass off last fall, followed by digging long square trenches by hand with a spade, the gravel was dropped in the street last night and I had it scraped up, spread around and packed down with the Bobcat by this afternoon.  The results are probably not all that impressive, but the suddenly open driveway feels spacious.

Bus Parking Only

A somewhat separate project was the disposal of the dirt that I scraped up to make a level spot in the yard to begin the project.  I had thought about using it to level a part of the hill in the back yard, but there wasn't enough to make much of a difference.  Instead, I decided to cover it with a truck bed load of mulch ($40) and plop a Sand Cherry tree in it ($37).  The rock border was a happy find that I discovered on my property when I was trying to dig a flat spot into a hill to park a future gazebo.  In my way was a vein of sand stone. It yielded up several stones of varying sizes and makes an attractive border for my dirt pile.

Dirt pile?  What dirt pile?

So, if you're considering this project for your parking needs, you can save yourself some money by doing some things yourself.  While the Bobcat rental and gravel was expensive, having a parking spot made for me could have run into the low thousands depending on the contractor you have chosen.  

Having a truck to tow the Bobcat on its trailer 10 miles too and from the rental place saved me $115 on delivery.  But it also ate up a lot of gas in the F250's V10, did a number on my brake pads (I could smell them on the way back into town) and gave me a chiropractic exam as the combined mass of the trailer and Bobcat S150 fought with the truck all the way to and from the store.  That was probably the most unnerving part of the whole experience.  Driving the Bobcat was a piece of cake and saved me a lot of time and effort.  If you have a big job to do, make it smaller by renting or borrowing some big tools.  :-)