General Comments

DML's IS series kits date from the 1990s and while the standard of molding does not necessarily match that of later kits such as the Tamiya offering, the DML kits provide a good basis for building a good model of the IS-1 or the various IS-2 sub-variants.  The kits are not without their issues, but these can be corrected by following the steps below and on the pages dealing with the individual kits.

Lower Hull Height

The lower hull molding on all the DML IS-1/IS-2/ISU kits is approximately 1.5mm too short from top to bottom.  The real vehicle measures approximately 750mm from the bottom of the hull to the bottom of the sponsons, which translates to 21.43mm in 1/35 scale.  The DML hull measures approximately 20mm.  With the unmodified lower hull, the top run of the tracks sits much too close to the underside of the fenders.  If you are not careful, it can be difficult if not impossible to fit the tracks after the hull is assembled.  To overcome this, follow the steps below: 

1. Increase the height of the lower hull by adding 1.5mm strips of styrene sheet along the tops of the lower hull front and sides.
2. Align the front of the upper hull (part 19) with the extended front of the lower hull tub.
   
3. Remove approximately 0.5mm from the rear of the lower hull sides so that the lower rear plate (part A8) will meet with the rear edge of the upper hull (part A19) along its upper edge.  This may require some trial and error in order to achieve the correct fit, so remove the excess plastic a little at a time and test fit continually.
   

This modification is NOT necessary if you are building the 'retooled' Cyber-Hobby JS-1/JS-2 2-in-1 kit #9108 or JSU-152 3-in-1 kit #9112.  These kits provide revised hull parts which raise the hull to the correct height.  However, they do not increase the height of the lower hull sides along their entire length, resulting in a gap that is visible behind the top run of the tracks.  This gap should be closed using strips of sheet styrene for a better appearance.

Road Wheel Diameter

The road wheels on all the IS series vehicles, from the original IS-85/IS-1 to the T-10, were 550mm in diameter.  This translates to 15.71mm in 1/35 scale.  The road wheels in the DML kits are 14.85mm in diameter; 0.86mm or 5.5% under-sized.  The difference is not overly noticeable but if you wish, you can modify the kit wheels by attaching a strip of styrene sheet around the rim of each wheel and sanding it to match the contours of the wheel, or replace the wheels with after-market items from MiniArm or Friulmodel.