This design is for a Hornby/lima model with a co-co wheel arrangement using a CD-Rom type Motor to replace the existing Ringfield motor.
These designs are for a CD-Rom motor that has a 24.4mm diameter and has a depth of about 9mm, various holes have been added to the design to accommodate pre or non-wired motors. I have also added a cable management loop to feed cables through. You will also likely need to buy a drive gear to attach to the shaft of the motor, you may need to trim 1-1.5mm of the end of this gear. You will need to source a Drive Gear like
https://amzn.to/3WYUboV *(Amazon) *you will need to match the shaft diameter and external diameter and the amount of teeth required.
Note 1: With Co-Co wheel arrangements you will need to sourse a CD-Rom type motor with a minimal depth as the middle wheel is likely to interfer with the motor. To achive this I used a 9mm deep motors from aliexpress.com. https://a.aliexpress.com/_mtGe6WMNote 2: If the housing of the motor is made of metal you will need to insulate between housing and the motor, this can easily be done with some sticky plastic or a spacer on the edge of the motor that comes in contact with the housing. Personnally I would enlarged the hole to 8mm so the motor woukd sit better in the housing with some sticky plastic to insulate.Note 3: Motors that are less than 12v rating, then it might be worth researching installing something between DCC decoder or track pickups and the motor to reduce voltage getting to the motor and limit the chance of burning out the motor.
I have also done a design for Bo-Bo wheel arrangemnt which enables you to use a deeper motor of about 12.5mm.This model has been designed to be printed on a resin 3d printer. The example in the photos has been printed on a AnyCubic Photon M3 Resin 3D printer and used on a old Lima Class 47 bogie. A customer has also managed to print this on a FDM printer and installed it in a loco sucessfully (See Photos).
The main resins I use for printing can be found with my affiliated links below.I use AnyCubic Water Washable Resin for most of my items but use AnyCubic ABS Like Resin for anything that needs to be stronger and tougher.
AnyCubic ABS like Resin https://amzn.to/3yRjgu4 (Amazon)AnyCubic Water Washable Resin https://amzn.to/3T3MgFY (Amazon)
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If you would like a particular item that isn't listed here you can request for me to do a project for you via cgtrader.com. Please be realistic.