This is a 4mm scale Chassis for the Lancashire and Yorkshire Railway (L&YR) Class 28 Locomotive in P4, available for WSF/BSF/FUD.
Note: This is a fixed chassis so reaming out the axle holes downwards and allowing the bushes to move freely may help things. The dummy hornblocks have 'etched' lines cut into them to aid a saw should you wish to remove these and add real brass sprung hornblocks in their place. If using a FUD chassis the chassis will be weak until the replacement hornblocks are properly installed. Chassis more readily set up for springing are being worked on as a future development.
CHASSIS INSTRUCTIONS: The chassis is designed fixed but cut outs above the axles holes and 'half etched' vertical lines are cut out to guide your saw blade should you wish to add fully sprung brass Horn-blocks from another company. 1/8th / 3mm Brass 'Top Hat' Bearings need to be joined added by simply pushing them in and gluing them in position with Super Glue.
A 1/8th Reamer or Taper Reamer may need to be rotated gently by finger pressure to get the best working clearance for the axles. If so, do it a little at a time and keep checking.
You will also need some 5' 1" wheels for the Class 28. Suitable 20mm wheels are available from several vendors.
The Brake Rodding is joined on the chassis top along with the Guard Irons at the front, these are to be cut off and glued in position relative to the brakes and wheels.
The rear spacer is sprued on the side for you to position where you want depending upon what motor and gearbox combination you use. Inbetween the frames are 2x 1mm frame thickeners as optional extras to stiffen the frames more or use them to butt up to the gearbox sides. These can also be cut to shape or partially used if needed.
Suitable coupling rods are also available in Raw Brass from this shop.
General note: Once the chassis is built and working you may need to file/shave a small amount of material from under loco body for the coupling rods due to the running plate needing to be printed thicker than a scale reality. On some models sometimes the inside edge of the splahsers need a small amount shaving away too (moreso in P4). A few passes with a brass brush in a mini drill makes this a 2 second job though.
For wheels, axles, crankpins etc
Alan Gibson is a great resource
...as is Markits
For Motors and Gearboxes, High Level are recommended.
For the L&YR Class 28 and Mogul Experiment, to allow your model to be motorised without having to hack away at the underside of the firebox or boiler as is common with many of kits depending what parts you use, a 'Roadrunner Compact +' Gearbox and a 1220 Mashima Motor from High Level will fit nicely, although it is rather small and may lack power if the trains are too long. If using this combination the gearbox sides will need to be packed width ways with plasticard or similar, these components were used in the research and development trial builds.
EDIT: Future builds have shown that a London Road Models GB4 Single stage Motor Mount (Gearbox) fits better, is cheaper and quicker to build. As with all loco kits the choice is entirely yours though.
For crank pins, hand rail rod/wire and pillars, washers, bearings and other small sundry items Mainly Trains is a good website to visit.
But of course you can use whatever suits your needs and preference best,
the above has been typed out to hopefully aid you should you be new to kit building. The advantage of these 3D printed kits is 90% of the work is done for you, both on the body and the chassis.