If like me you struggled with a shallow fire, a deeper fire could be your answer. Many people cut a bar off the existing grate and drop it down on the door plate and baffle. I didn't fancy destroying  the original assembly so as an experiment decided to create a whole new assembly as an alternative.

Specification

• 8mm mild steel
  
• Slots in baffle to allow more heat to lower tubes
• Straight replacement to original grate
• Roughly 50% air to bar ratio.

NOTES

There is nothing wrong with the original supplied grates which are a far superior design and construction. This was a personal project for my own locomotive rather than a commercial project. I just didn't want to cut bars and re bolt the grate lower down. 

Mild steel does not have a memory effect like stainless and is less prone to warping. It is better at conducting heat and has a higher melting point than cast iron. 

The lower grate means that you will need to rake the fire more and remove the ash below more often.

The lower grate allows for a deeper fire which can also mean far hotter temperatures. If you have a modified blower and vacuum ejector, make sure that the grate does not allow for overheating. Cherry red back plate means you are likely to melt grate bars and damage your boiler. 

Conduct a steam test before running with your new grate.