Sunday, July 5, 2020

Building a Garden Tractor Out of Wood - Trying to Power the Wheels

About to build a drive train


The last time I worked on the tractor, I had mounted the engine to the tractor. Now I was faced with the prospect of attaching the engine to the rear wheels so that the tractor could actually move under its own power.

As I mentioned at the start of the build, I wanted to keep all the moving parts of the tractor's drive train as far away from my limbs as possible, My idea was to use the vertical drive of the lawnmower engine to connect it to the rear wheels with a drive belt that would have a 90-degree twist to a secondary set of pulleys that in turn would be connected to the rear wheels. 

I got the idea for this arrangement from a set of plans for a wooden go-kart that has its wheels powered via that type of arrangement.

I'm not entirely sure how successful I will with this since I am not entirely sure how the belt will stay on the pulleys with that severe of a twist, but I am willing to give it a try. 

To start the build, I first gathered up the various parts that I needed to make the drivetrain. 

This included 2 pulleys (one to connect to the engine drive belt and the other to connect to the drive belt for the rear wheels). The pulleys were of different sizes in order to adjust the overall speed of the tractor.  The pulleys also had a 5/8 inch opening in the middle to accept a shaft of that size. 

Obviously, I also got a length of 5/8 inch threaded rod.   

I also gathered two bearings with a 5/8 inch inner shaft diameter and a couple of mounts for the bearings. 

I also gathered up a handful of nuts, bolts, and washers.  

Pulleys, Bearings and Rod
Ready to get going

The only thing that I did not have on hand was a pulley to attach to the drive shaft of the lawnmower engine.

While I could have simply gone out and bought a pulley to fit the driveshaft, I did have the adaptor from the lawnmower that was used to connect the mower blades to the engine. The adaptor did have a couple of mounting points on it that I could use to mount something to the engine.

When I looked at the original plans for the tractor, I did notice that they did utilize what appeared to be wooden pulleys as part of the drive train for the tractor, so I was actually pretty curious about the feasibility of using wood for that sort of function. Since the blade adaptor looked like a really nice mounting point, I figured that I would make the engine pulley out of wood and attach it to the blade adaptor.

Mower blade adapter

To make the engine pulley, I took a 2-inch thick piece of pine and cut it into a 7" X 7" square, trimmed off of the corners of it, and mounted it on my lathe.

7 X 7 pine
Ready to turn on the lathe

Using a bowl gouge I then turned the block into a circle with a diameter of about 6 inches.

Turning the pulley
A perfect circle

Next, I cut a half-inch deep groove on the edge of the circle to allow for a place for the belt to sit on the pulley

Cutting a belt groove
Groove cut into the pulley

Finally, I smoothed one side of the pulley in order to remove any "wobble" potential when the pulley was spinning, and I marked the center of the pulley with the gouge. 

Smoothing out the pulley and marking the center
Center marked

In order to attach the pulley to the engine, I needed to have access to the center bolt that attaches the blade adaptor to the engine's driveshaft. To attach the adaptor I would also need to use a socket wrench to tighten the bolt.

To accommodate this and to allow access for a socket wrench, I drilled a 3/4 inch hole through the center of the pulley at the mark that I had carved with my gouge.

Drilling a hole
Center hole drilled

To attach the pulley to the blade adaptor, I inserted the bolt used to attach the adaptor to the drive shaft into the adaptor and I center the adaptor on top of the pulley, using the bolt to center the adaptor.

Getting ready to attach the adapter
Bolt in the center hole
Adapter centered on the pulley

Using an awl I then marked the location of the mounting holes for the adaptor on the pulley and drilled 1/4 inch holes into the pulley at those locations.

Marking locations for bolt holes
Locations marked
Drilling holes

Using a couple of 3-inch long 1/4 inch bolts I then attached the blade adaptor to the pulley

Bolting the adapter to the pulley
Adapter attached to the pulley
Tightening down the bolts
Adapter attached
Adapter attached

After that, I attached the whole assembly to the engine's driveshaft.

With the engine pulley installed, I switched my attention over to the intermediate pulley section that will serve as a gear reduction section between the engine and the rear wheels. 

I inserted the 2 pulleys onto the 5/8 threaded rod and did a test fit for the position on where I wanted to locate the pulleys on the tractor. 

I wanted to make sure that the belt for the rear wheels had a little bit of slack since I wanted to use that section of the drive train to start and stop the tractor with the use of an idler pulley which would be used to increase and decrease the belt tension. 

Doing a test fit of the pulleys
Figuring where to install the pulleys
Making sure there is some slack in the drive belt

Once I determined the location I then measured the distance between the engine pulley and the pulley I intended to use for the gear reduction and grabbed a belt that size from the local hardware store.

Belt going from the engine pulley

Next, I installed wooden hanger brackets at the location that I wanted to install the pulleys and drilled a 5/8 hole into the brackets to install the threaded rod (I positioned the pulley where I wanted to to be and used a pencil to mark the location for the hole).

Installing hanger brackets
Marking the hole location

I then drilled a 5/8 hole into hanger brackets and gave the brackets some additional reinforcement

Drilling the hole into the hanger bracket
Reinforcements added

I then installed the pulley and rod into the hanger brackets and attached the belt to both pulleys, as outlined in the instructions that I got from the go-kart plans that I had

Test fit of the pulley assembly

Giving the engine a couple of spins, unfortunately, confirmed my worst fears.  The belt just simply could not stay on the pulleys.

While there was more than plenty of tension on the belt, it would not remain one more than a couple of turns of the engine.

I tried a few different approaches to try and solve for this issue, including making the pulley on the engine a lot smaller in order to make the belt as close in line as possible between the top and bottom of the pulley in the rod.

When that failed, I tried to create a guide around the engine pulley to also try and keep the belt as centered as possible, however, I kept finding that the belt still had a tendency to pop off the pulley.

The belt couldn't stay on the pulleys

At this point, I had to admit defeat on this approach and come up with a new plan.

So while this wasn't a success, I did actually learn some things in the process, and I was actually pretty impressed on the potential of having a belt pulley made from wood.

But I now need to plot what the next course of action I should take, but based on what I have learned I do have some ideas on what to do next.

Back to the drawing board. 😀

Sunday, June 28, 2020

Building a Garden Tractor Out of Wood - Mounting the Engine

Installing an engine

In my last post, I had just acquired an engine for my tractor, thanks to an old lawn mower that I managed to score to free.

Now that I had my engine, it was time to install it in my tractor.

I started the process by setting the engine on top of the tractor's chassis. The idea was to position the engine as close to the front of the tractor as possible.

However, as the plans had indicated that the engine was to be surrounded by a hood, including a front grill and a dashboard, I also needed to make sure that the engine was not too far ahead, which would prevent proper air circulation around the engine.


Sunday, June 21, 2020

Building a Garden Tractor Out of Wood - Sourcing an Engine

Getting an engine for my tractor

Now that my garden tractor is now able to roll around on its own wheels, I really needed to get an engine sourced for it before I can go any further.

In the original 1941 magazine article, the tractor was powered by what was referred to as a "utility motor" with no further specification on what type of motor that it was, or what type of horsepower that it needed to have.

Looking at the diagram in the magazine, it appeared that the motor in question was the fairly typical small engine of that era that you would find in your finer lawn mowers and garden tillers.

With small engines, there are two basic configurations, regardless of how many cylinders or how much horsepower it may have. A small engine could be configured to have a horizontal drive shaft (ie, the engine provides power to drive things from the side of the engine) or a vertical drive shaft (power is being provided from the bottom of the engine).

Looking at the magazine article, the tractor was originally designed to be powered by a horizontal engine. These are the type of engines that you would find powering things like snowblowers and wood chippers.

Since I was a bit squeamish about having moving parts that close to my limbs, I determined that I really wanted to have the drive train for the tractor contained within the relative safety of the chassis.

To accomplish this, I really wanted an engine that was configured for a vertical drive, with the power from the engine being delivered from underneath the engine.

Those sorts of engines are pretty easy to find since they are what you find in virtually every gas-powered push mower that is made today.

Traditionally the engine that powers these mowers come in around the 3 horsepower range (I think that would be more than plenty enough power for my tractor), and since it's coming around to springtime around here, there a many used mowers for sale for very cheap as people "upgrade" their equipment for the upcoming mowing season. 

Luckily, I came across a mower that was free to a "good" home with a 3.5 hp Tecumseh gas engine.

A couple of quick pulls with the starter cord proved that the engine was still in good shape.  I loaded the mower into the back of my truck and headed home.

The mower was a bit of a dusty, oily mess, but after a quick pressure wash, it definitely looked a lot better and was now prepped for surgery.

Ready for disassembly

On initial inspection, the engine seemed to be attached to the deck of the mower with just three bolts, with the starter cord, throttle controls, and a deadman switch (which shuts the mower off when it is released) attached to the mower's handle. 

Flipping the mower on its side revealed the business end of the machine with its rotating blade that was directly attached to the drive shaft of the engine. 

Obviously, the first thing that needs to happen is to remove the blade from the engine. 

Business end of the mower

The blade is attached to the engine with an (in this case) fairly standard 5/8 inch bolt. 

The trick is that if you just simply try to remove the blade with a socket wrench, all that you will be doing is manually turning over the engine. 

To prevent this, I needed to prevent the blade from spinning when I tried to loosen the bolt off of the engine shaft. I accomplished this by wedging a 1/2 inch board between the mower blade and the inside of the mower deck, which prevented the blade from moving. 

Blade immobilized with a wood board

With the blade immobilized, the blade was easily removed with the socket wrench.

With the blade out of the way, I could easily see the 3 bolts that were securing the engine to the mower deck.

Using a 1/2 inch socket, the bolts were removed and the engine was simply lifted off of the mower deck.

Blade removed
Bolts attaching the motor
Removing the bolts
Engine free from the deck

While the engine was off the deck it still wasn't completely free from the mower - the pull cord, throttle, and deadman switches were still attached to the mower handle.

In the case of this mower, they were attached to the handle via some 1/4 inch bolts which were dealt with thanks to some more help of the socket wrench.

I made sure to keep the throttle and deadman controls attached to the cables after removing them from the handle since I do plan to use them on the tractor.

Started cord on the handle
Throttle and deadman controls
Removing the controls

And with that, I now had a powerplant for my tractor.

Engine is now removed

Now that I had my engine, the next hurdle was to install it on the tractor. 

Sunday, June 14, 2020

Building a Garden Tractor Out of Wood Update - Getting Things Rolling


Starting to get things rolling

A few weeks back I embarked on building a small garden tractor based on plans that I had found in a copy of Mechanix Illustrated from 1941.  The unique thing about this tractor was that it was built completely out of wood. 

I managed to put together the chassis for the tractor, so the next step would be to attempt to put some wheels on to create a rolling chassis. 

Sunday, June 7, 2020

Making Custom A/V Patch Cords - A Quick Project

Transferring some old video tapes

Last weekend I was doing a bit of deep cleaning in the shed when I stumbled across a box of old VHS tapes.

Its been at least a good 20 years since I last played a VHS tape, so I was a bit mystified as to why I would be holding onto a box full of these things.  Since the intent was cleaning out the shed, these tapes now had a long-overdue date with the recycling bin.

But before I sent them on their way, I felt that it might not be a bad idea to at least take a quick look at the contents of the tapes. If there were some treasured memory stored on them, I should probably rescue them before they were permanently lost.