Coarse Scale was once considered the usual standard for 0 gauge modelling and dates back to the days when track was laid in sections on the floor, or as garden layouts. In both instances, the necessity for rolling stock to cope with poor quality track regarding alignment and level, meant that wheels had to have deep flanges and wide treads simply to stay on the track. Although once popular, it is now becoming a minority standard, having been eclipsed by Finescale. It is also the area of 0 gauge modelling that is the least standardised, with several manufacturers having entered the market in recent years with retro style models, using wheels that differ significantly from, and are not compatible with, the Guild Coarse Scale standard.

The first draft of a standard, listed as Coarse was published by the British Railway Modelling Standards Bureau in 1941. Before that date, apart from track gauge, there were no generally adopted standards in railway modelling in the UK. The first 'O Standard' (now known as Coarsescale or Coarse Standard), was developed from existing commercially available O gauge track and wheelsets. Since it was readily available, vast quantities were produced and much is still in existence and use. The track gauge used is 32mm.

There are, and have been in the past, many large and extensive Coarsescale layouts, many of them outdoors, and Coarsescale has proved very reliable, with very intensive operating systems. However, these layouts were built around the Guild Coarsescale standard, generally, with hand-built trackwork, locomotives and rolling stock, all built to the one standard. In recent years, there has been a large upsurge in interest in ‘O’ gauge vintage style modelling. This is mainly due to a number of manufacturers coming on the scene, mass producing locomotives and rolling stock specifically for this market, to a very good, robust standard at competitive prices. However, there has been much variation in the wheel profiles, (with little similarity to the Guild Coarsescale standards), between the individual manufacturers products, and, also between specific models produced by these manufacturers, to the extent that readily available off the shelf reasonably accurate trackwork, to suit the extreme cases is hard to come by, and tinplate or handmade trackwork is usually resorted to. The Guild Coarsescale standards are provided for by various parts suppliers, with wheels for locomotives and rolling stock available. Non Guild standard Coarsescale rolling stock wheels particularly, can be replaced to provide a consistent Coarsescale standard, but unfortunately replacing locomotive wheels can be a lot more complicated.

• The deeper flange and wider wheel tread ensures that wheels are more tolerant of bad track.
• Can generally accommodate tighter radius curves.
• Ready to run equipment is generally very robust and attractively priced.

• No common wheel profile on ready to run equipment.
• No reasonably accurate ready to run trackwork is available to accommodate all the different wheel profiles.
• Excessive clearances are required on track and pointwork to allow for over scale wheel flanges and under scale wheel ‘back to back’ dimensions.
• Wheel ‘back to back’ size is less than scale, which may necessitate altered dimensions for loco frames and some distortion of bodywork.
• Kits with inside frames may require modification to accommodate Coarsescale wheelsets