Rick H, Kelly M, Katy and I got pressed into service this past weekend to make grate hangers, prep and install the grates in the 40 while Mark P was way up in Canada playing!
Mark decided to go with the "Field tested" grates that we have in Jim's 40! No sense messing with something that works... at least not for now! These same grates have also found there way into a lot of 80 Case boilers.
Rick and I built the set that are in Jim's 40 quite a few years ago, so this was round 2 for us! It was fun to build another set with him... this time we had something to copy!
It the first two photos, Katy and Ted Mandt take turns cleaning up the holes, all 966 of them!!! in the 7 grates. The holes are cast to end up 1/2", but the process leaves behind a lot of undesirable material so they are drilled out to 9/16 to clean them up and make a smooth surface for the air to travel through.
The holes in the grates are cone shaped, so the air is actually accelerated as it us drawn through the grates with the draft. Ingenious design, and very effective!
Rick and I teamed up laying out and drilling the holes in the grate hangers. We started with 1/2" holes, then 1", and I think we ended up with something around 2-1/2" holes. The two hangers were welded together so we only had to lay it out and drill it once. 
In this picture it looks like we are at the 1" step. We really were busy... we just got to sit for about 3 minutes while the drill press auto fed through the 2" thick material (2-1" pieces) and then we would have to re-set the work and drill the next hole.
After the holes were drilled we cut out the tops of the holes with the band saw to form the "U" shaped cradle for the grates to set in. I then cut the two pieces apart and in the picture below Rick cuts the final shape into each hanger.
While Rick was doing that, Kelly M (not pictured, sorry Kelly) were drilling holes in the rocker arms in the 7 grates. While only 3 of them will be hooked up to rock, 3 more of them will be bolted solid with these arms to keep them level.
A finished grate hanger bracket ready to go into the boiler!
The 4" long pieces welded to each end are by design. The hanger supports are narrower than the firebox to miss the rivets in the corners, but the hangers have to be closer to the outsides of the firebox to make room for the grates. The design is very similar, and were patterned after the original grate hangers.