The Adapter Plate

January 2005

The Design of the Adapter Plate

The adapter plate adapts the standard transmission to the motor. The idea is to produce a general design which can be taken to a machine shop so the can fabricate the adapter. To help with the drawing, a Computer Aided Design (CAD) software package (Design CAD 3D) was used.

Here are the steps taken to design the adapter plate:

1. You can either take a digital picture of the outline of the transmission, or trace and outline. If you decide to use a camera, keep in mind that the camera angle may distort the true image size. It is good enough for sketching purposes, but if the diagram is used to drive a CNC machine, it is better to trace the outline:
   1. Trace the outline of the transmission onto paper
   2. Mark a series of grid lines onto the paper
   3. Scan the paper into the computer (multiple scans are typically required)
   4. Use photo software to stitch the images back into a large image
2. Digitize the image into the CAD software
3. Draw the drive motor in the CAD software aligning the spline
4. If your diagram needs to be extremely accurate (i.e. the diagram is used to drive a CNC machine) it is best that you accurately measure the guide pins and holes using CNC measuring machinery. See Victor's adapter plate design for how to do this.
5. Set adapter plate thickness based on separation of splines
6. Add fillets, fill and color to enhance the image

Since this diagram is not going to be used for a CNC machine, it is not required to be 100% accurate. It is primarily going to be used to discuss various options for building the adapter plate.

Double Check

A few things to double check:

• Make sure your CAD drawing is not a mirror image of the plate
• Print a full size image of the plate, paste this on cardboard and see if it approx fits the transmission
• Measure where your drive will be placed - will it hit anything obvious - such at the CV joints, drive shafts or differentials?

Adapter Plate Images

The tracing of the transmission and outline digitized into the CAD software

The specifications for the drive motor (Courtesy Metric Mind)

The actual drive

A few of designs for the adapter plate. The last design is the final design that was sent to the machinist.

Adapter Plate Construction

Here is the adapter plate after CNC cutting. It is awaiting the drive adapter plate machining.

This the the spline adapter, it adapts from the existing clutch dog to the spline on the Siemens drive. The VW clutch dog is a replacable part and is intended to be the weakest point in the system. This will ensure that the clutch dog wears out before the the splines of the tranmission or drive wear out.

Here is the finished adapter plate, and installed with the drive and transmission.