Making The Adapter Plate For The Electric Victa Mower Conversion
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
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.
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
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.