Making The Adapter Plate For The Electric Victa Mower Conversion

 Making The Adapter Plate For The Electric Victa Mower Conversion

Blue Adapter Plate which attached Electric Motor to Crank Case.

Blue Adapter Plate which attached Electric Motor to Crank Case.

The previous article discussed the first attempt at making a coupler which helped in transmitting power from Electric Motor to crankshaft which ultimately drives the blades. In order for the coupler to stay in the correct position, the coupler must stay on the shaft of the Electric Motor and more importantly, the Electric Motor must be held in position. This means the Electric Motor must be held in position like a frame or chassis or in this case the mower base. In this case, the Electric Motor was going to be attached to the crankcase of the original Victa engine via an adapter plate, just like how Electric Motors are attached to the transmission via an adapter plate on Electric Car Conversions.

What is an adapter plate?

An adapter plate is a plate that allows two objects that on their own would not nicely bolt together to be bolted together.

How was the adapter plate made?

How to Make Adapter Plate Template

Making adapter plate template using a plastic sheet which is sort of transparent.

Making adapter plate template using a plastic sheet which was sort of transparent.

As part of my preparations for making the adapter plate, a template was first constructed. In fact, I ended up making two templates as I make many mistakes with the first template. The material I used was a sort of transparent plastic material cut out from an old container. The good thing about a sort of transparent sheet of plastic is that you can see where holes have to be marked out and what needs to be cut out.

The sheets of plastic I started with were originally cut to a size of around 8″ by 8″ (200mm by 200mm). With the recoil starter removed from the engine, the plastic sheet was placed on it. Various things were marked such as:

  • mounting holes to mount the adapter plate onto the engine – actually, these mounting holes were made first, then bolted to the crankcase.
  • crankshaft center – here a big cross was marked out to assist with centering of the Electric Motor.
  • an opening to allow access for the coupler.
  • then things were trimmed.

The Electric Motor was put on the template and mounting holes were marked out. There was a bit of guess work involved as trying to line up the Electric Motor shaft axis with the axis of the crankshaft was difficult.

The first time this template was made, things were not accurate and not all the holes lined up, so the process was repeated more accurately.

Work in progress when developing the adapter plate template.

Work in progress when developing the adapter plate template.

On the second attempt, the plastic adapter plate template was bolted to the crankcase of the gasoline motor and the Electric Motor (with the coupler engaged to the crankshaft) was eventually mounted to the plastic adapter plate template. Why eventually? Well, the conrod was interfering with the coupler so the piston and conrod were removed and the special bolt (which held the conrod in place and acted like a journal) on the crankshaft was put back on. Power was applied to the motor and the blades were spinning, allowing grass to be cut. However, there was a lot of flex in the plastic adapter plate template so as expected and planned, a stiffer one had to be made.

How To Make The Adapter Plate With Limited Resources

Using adapter plate template to mark out what needs to be drilled and cut in the sheet metal adapter plate.

Using adapter plate template to mark out what needs to be drilled and cut in the sheet metal adapter plate.

A piece of scrap steel sheet metal of approximately 1/16″ (just over 1mm) thickness was used. Initially, it was cut up to approximately 8″ by 8″ (200mm by 200mm). The template was placed on the sheet metal and the holes and outline were drawn. Drilling the bolt holes was straight forward. Cutting the big hole to allow the coupler to go through was not as straight forward. In the ideal world, one would have used a hole saw of the appropriate size, but a hole saw kit with various sizes would have cost $130. Initially, I thought I could cut the big hole with a jigsaw, but I quickly learned that it is very difficult to do curves with a jigsaw. I ended up drilling holes at various points and cut into the sheet metal from hole to hole, sort of like joining the dots.

I tried putting the adapter plate onto the crankcase, only to find that more material needed to be trimmed. With the plastic template, it flexed around certain protruding bits, but this did not work the metal adapter plate so some things had to be trimmed by drilling and cutting with jigjaw.

 Using the Adapter Plate

The adapter plate worked and for a while I was able to mow the grass, only to later come across problems with the coupler, which will be discussed in a separate post. However, the concept of the adapter plate as often used in Electric Car Conversions worked in this case.

This is Al Bunzel signing out.

 

Making The Coupler For The Electric Victa Mower Conversion

Making The Coupler For The Electric Victa Mower Conversion (1st Attempt)

Coupler attached to Electric Motor shaft.

Coupler attached to Electric Motor shaft.

The previous post discussed the Electric Motor for this Electric Victa Mower Conversion. However, rotational power had to be somehow transferred to the blades and in this case, an attempt at using a coupler was done. This first attempt was later met with problems and these problems are discussed in future posts.

What is a coupler?

Arrow points to special bolt on crankshaft which the coupler would engage with.

Arrow points to special bolt on crankshaft which the coupler would engage with.

In the context of the Electric Victa Mower Conversion, a coupler is a device that joins two moving parts so they move together. The intended implementation was to have the coupler attached to the shaft of the Electric Motor which would engage a special bolt in the crankshaft of the old gas engine.

Couplers are not typically used in Electric Motorcycles/Scooters or Electric Bicycles, but are often used in Electric Car Conversions where it is usually between the Electric Motor shaft and transmission. Couplers used in Electric Car Conversions look very different to the one used in this Electric Mower Conversion.

What material did I use for this coupler?

C channel aluminum (or U channel depending on how you look at it)

C channel aluminum (or U channel depending on how you look at it)

U channel aluminum (or C channel, depending on how you look at it).

U channel aluminum (or C channel, depending on how you look at it).

The coupler was made from a piece of aluminum C channel (or U channel depending on which way you look at it). The material was fairly easy to work with, but being relatively soft compared to the pulley, it meant that later on, it would be a problem, especially, when the key way started to wear out prematurely. Prior to working with it, I did not check what material it was and assumed it was steel, although I did wonder why it was light and soft and would not rust like steel.

Hint: Carefully select and check your materials and components before working with it.

How did I make the coupler?

Loosening nut with breaker bar and socket with pulley held in with a vice to stop it rotating.

Loosening nut with breaker bar and socket with pulley held in with a vice to stop it rotating.

The Electric Motor originally had a pulley on it so that was removed by holding pulley (with motor still attached) in a vice, holding the motor to stop it turning, then undoing the nut. The professional way would have been to use a rattle gun – no vice would have been required, but I don’t have any air tools or an air compressor, hence, resorted to using a vice. The pulley was removed using a pulley removal tool.

With the pulley removed, it was easy to work out what size hole would need to be drilled into the coupler.

A length of C channel was cut measuring around three inches. A hole was drilled in the middle that would match the diameter of the Electric Motor output shaft. A key way was filed to accommodate the key on the Electric Motor shaft. It took three attempts to get it right as the first two attempts were filed to big meaning that there was unacceptable play.

First attempt at making coupler, before being trimmed and put on motor.

First attempt at making coupler, before being trimmed and put on motor.

At the time, I did not work out how to best measure where the other hole which engaged into the special bolt of the crankshaft should go, so I ended up guessing and drilled two holes around one inch (center to center) from the original hole. Due to my lack of accurate measuring (more like guess work), the holes were made oval by drilling a smaller hole next to the holes and filing them with around file, resulting in oval holes. This compensated for things not lining up correctly. Later on, I worked out how to measure things more accurately.

How the coupler was used?

The coupler was attached to the shaft and the nut tightened against it. However, the coupler could only be really tested when used in the mower and for that to happen, the adapter plate between the Electric Motor and crankcase of the Victa engine had to be fabricated. After the adapter plate was made and the motor attached to the mower, it was tested and there were several problems found with the coupler.

This is Al Bunzel signing out.

P.S. Please check out the next article about how the adapter plate for this Electric Mower Conversion was made.

Electric Victa Mower Conversion Build Thread-The Electric Motor

Electric Victa Mower Conversion Build Thread-The Electric Motor

The Electric Motor selected for Victa Da Stinka Electric Mower Conversion.

The Electric Motor selected for Victa Electric Mower Conversion.

Whether you are doing an Electric Car Conversion, Electric Bike Conversion or an Electric Mower Conversion like this one, the Electric Motor is one of the major components of the conversion. The Electric Motor is the heart. The previous post discussed the fate of the 2 stroke engine and this post discusses the requirements of the electric motor for this electric conversion, what motor was selected and how it was evaluated.

What features and requirements was I looking for in an Electric Motor for Vikta Da Stinka Electric Mower Conversion?

The requirements and features I was looking for in an electric motor for this Electric Mower Conversion were:

  • Power and Torque – 3hp was my preference so that I could easily cut long grass, but anything over 1 hp would have been sufficient. I had read in Issue 105 of ReNew magazine of a similar electric mower conversion where they successfully used a 500 watt (0.7hp) electric motor.
  • A physical size that was no bigger than the original 2 stroke stinker it will sit on.
  • As cheap as possible – I wanted the whole project to cost under USD $400. Any more than that, then it is not economically viable as one could buy a decent battery powered Stihl Electric Mower for that price.
  • That the motor could be mounted on the motor face which would permit it to be bolted into an adapter plate.
  • The motor could rotate in an anti-clockwise direction.
  • A shaft where a coupler could be attached.
  • Something that would easily run without complex electronics. This limited choices to simple brushed DC motors.

What Electric Motor did I end up using?

After putting the word out there that I was looking to convert a mower to electric, I was given a Hitachi GSB107-06 Starter Generator rated at 12V 0.9HP. This motor was previously used as a starter motor and alternator for a gas engine and are often found on Yamaha Golf Carts. What is interesting is that there appears to be a set of terminals, used for starting and there are a pair of thin wires which I assume is used for the generator/alternator component. For this Electric Mower Conversion, the generator component will not be used as there is no other mechanical or rotational energy source to move the motor.

Armature Terminals of Hitachi GSB107-06 with red wire connecting A2 to F1.

Armature Terminals of Hitachi GSB107-06 with red wire connecting A2 to F1.

F1 Terminal of Hitachi GSB107-06 with red wire connecting F1 to A2.

F1 Terminal of Hitachi GSB107-06 with red wire connecting F1 to A2.

F2 Terminal and DF wires of Hitachi GSB107-06

F2 Terminal and DF wires of Hitachi GSB107-06

 

Although I did not pull the Starter Generator apart, it appeared to me that the starter part of the motor was a series wound brushed DC motor, especially with labels such as F1,F2,A1 and A2 stamped next to terminals and the external cable that connected A2 to F1. Although, I did not open up this motor, I have often found with motors that F1 & F2 typically denote the ends of the field windings whilst A1 & A2 typically denote the ends of the armature. There was also a DF terminal with two wires coming out from it. Typically, that is the dynamo field for charging purposes, but this wire was not required for this Electric Mower Conversion.

 How did I check this Electric Motor?

Once, I got possession of the Hitachi GSB107-06, before doing any work on it, I checked to see that the shaft would rotate when power was applied. Using a 12 volt battery and jumper leads, power was applied to A1 and F2. Since, it behaved like a series wound brushed motor, it did not matter what polarity was applied to those two terminals. Looking at the motor from the output side (where the pulley normally went), the shaft rotated anti-clockwise which meant that looking at the motor from the rear casing, it rotated clockwise. This meant that when connected to the mower in the method I was envisioning, it would rotate in the correct direction. (Note: To change the direction the shaft rotates, remove cable connecting A2 to F1 and instead connect A1 to F2 and apply power to A2 and F1.)

I was not able to measure the speed of the Hitachi GSB107-06, but without using a motor speed controller, I had to watch that the motor did not speed up with no load, otherwise there could have been a risk of it self distructing – something to watch for when using series wound motors with no load.

I was satisfied that the Hitachi GSB107-06 could be used for this Electric Mower Conversion so the next step was to work out how to mount this Electric Motor to the mower and make a coupler for it.

This is Al Bunzel signing out.

P.S. Please check out how I attempted to make a motor coupler for this motor.

 

Electric Victa Mower Conversion Build Thread-Dealing With The 2 Stroke Stinka

Electric Victa Mower Conversion Build Thread-Dealing With The 2 Stroke Stinka

What decisions were made regarding the fate of the 2 stroke engine?

Left: Electric Motor. Right: Victa The Stinka with fuel tank removed.

Left: Electric Motor. Right: Victa with fuel tank removed.

 

The previous introduction post discussed why do an Electric Mower Conversion, the requirements of the Electric Mower, basic parts list and tools list. This post will discuss how we deal with the 2 stroke stinka engine and the basic design decisions that are being made. The advantages and disadvantages of the design decisions are outlined.

Most people who do EV conversions or Electric Conversions tend to remove the smelly gas engine to make way for a clean electric motor. This is a sensible approach so why would I keep most of the Stinking gas engine in my Electric Mower Conversion? The reasons why I intend to keep the engine block and crankshaft are:

  1. I’m not sure what strain the mower blades will have on the electric motor so I have two choices. One is to add another support bearing to the electric motor, but that is tricky for me. The other option is to utilize the existing bearing of the gas motor and bolt the electric motor to the crank case via an adapter plate.
  2. No need to take the blades off during this conversion.

What stayed and what got removed on the Stinka 2 stroke engine?

Obviously, I won’t be keeping everything on the Stinka 2 stroke engine. I don’t intend on making this a hybrid lawn mower, but rather a full electric mower. However, I plan on utilizing some of the gas engine components, but the incomplete gas engine will not be used to power the mower. Items removed from the gas engine were:

  • Recoil starter and cover.
  • Fuel tank.
  • Cylinder head.
  • Air filter and air cleaner hose.
  • Piston and conrod – although, originally I had thoughts of not removing these parts because
  1. it would have helped with maintaining balance.
  2. there would have been no need to remove the bolt on the crankshaft which held the conrod in place, especially when you don’t have the special Victa tool to remove that bolt.

Items that stayed on the gas engine were:

  • Engine block.
  • Crank shaft.

The advantage of keeping the existing, but incomplete gas motor were:

  • Protection of electric motor should the mower blade strike a rock since the gas motor bearing will be the first bearing to take the shock.
  • Easy conversion process.
  • This method has been successfully done before as published in ReNew magazine.

What are the disadvantages of keeping the existing gas motor?

There are several disadvantages of keeping the existing (but incomplete) gas motor such as:

  • Extra weight.
  • Space wasted which means where does one locate the batteries?

So now that the basic design decisions have been discussed, the next few posts will discuss the implementation and build processes of this Electric Mower Conversion.

This is Al Bunzel signing out.

P.S. Please check out the next article regarding the requirements, selection and evaluation of the electric motor used.

Electric Victa Mower Conversion Build Thread-Introduction

Electric Victa Mower Conversion Build Thread-Introduction

 

Electric Mower Conversion In Progress

Electric Mower Conversion In Progress – working out adapter plate.

 

Why do an Electric Mower conversion?

You may be wonder why I would want an electric mower, let alone bother converting a Victa 2 stroke mower to electric considering you can buy a decent electric mower at a reasonable price. Several reasons why I wanted an Electric Mower were:

  1. No need to worry about fuel. With a gas mower, every time I want to use it, I have to ensure I have enough gasoline and if I don’t I have to go the gas station and get some which results in wasted time traveling to and from the gas station.
  2. No need to worry about mixing 2 stroke fuel, changing air filters or spark plugs.
  3. No starting issues. I found gas mowers often had starting issues due to various reasons.
  4. Less things to go wrong with Electric compared to gas powered mowers.
  5. Less noise to put up with since electric motors are inherently more quiet than their gas equivalents.

The reasons why I did not go out and buy an electric mower from the shops were:

  1. To reuse a mower base where the only thing wrong was the gas engine.
  2. I wanted the ability to be able to service and repair my own mower and not be locked into a propriety system.
  3. I read in Renew Magazine several years ago about how someone converted a Victa Mower to electric & thought it was a good idea to do something similar.
  4. Because I can.

Requirements

The requirements of this Electric Mower were:

  • Be able to cut a quarter of an acre of grass within 4 hours.
  • Use an existing mower base (in this case a base from a Victa mower).
  • Battery operated so I don’t have to be plugged into a power point.
  • US$200 budget (excluding batteries).

 Parts List

The following was a rough list of parts which I believed I would require:

  • Mower base with blades and wheels – in this case, a Victa 2 stroke mower base was used.
  • An electric motor – in this case a Hitachi GSB-107-06 12V 0.9HP motor was selected. It will be interesting to see if this motor is capable of doing the job as per the above requirements.
  • Batteries – most likely selection will be Lithium Iron Phosphate (LiFePO4) cells.
  • Contactors.
  • Various cables and wires.
  • Possibly a motor controller if variable speeds are desired.
  • U-Channel to make a coupler.
  • Steel plate for making an adapter plate to mount the electric motor.

Tools List

  • Spanner or wrench set.
  • Socket set.
  • Screw driver set.
  • Hacksaw.
  • Angle grinder with cutting blade and grinding blade.
  • Marker.
  • Jigsaw with cutting blade that cuts metal.
  • Drill machine.
  • Drill press.
  • Drill bits of various sizes.
  • Center punch.
  • Hammer.
  • Transparent plastic that holds its shape – used for making a template for the motor adapter plate.

The next post discusses how the 2 stroke stinka (the gas engine) is dealt with along with design decisions and the advantages and disadvantage of the decisions. The subsequent posts will discuss the build process and the various issues faced.

This is Al Bunzel signing out

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