I guess I'll start this with the seagraves radiator rehab.
I had the opportunity to work on a 1923 Seagraves firetruck, The radiator was beyond repair and to recore it with the original style honeycomb core would have cost over 6000.00. I proposed to the Gilroy historical society to gut the old core and install a newer readily available radiator from a newer truck. The idea was was that the original external appearance be as if it was original, but it would be just a facade. The firetruck had been in use from 1923 until sometime in the '50's, so it was an important part of Gilroys history.
I made a flush arbor that would hold a 3" X .045" slitting saw. Turning the screw in the middle causes the arbor to expand into the saw's center hole. The idea was to not rip through the core material as it is only .005" thick. The slitting saw with it's fine teeth,( 180 teeth, I think), worked very well. It was run slow, about 170 rpm in a climb cut.
In the last pic you can see the construction of the old core. This is not a true honeycomb. The little channel for the water is created by runnung the strip brass through a crimper and assembling it row upon row so the ends could be pinched closed at the front and rear and pool soldered. (early form of wave soldering) There was actually 2 type of crimps, the one that was paired up to create the channel ,and the crimp size that made the connecting cooling fin. There were some little bumps in the crimp also that were there to create turbulence in the water tube. The minds that came up with this stuff in the teens and twenties were truly great.
Man am I glad that mill had a power feed. each pass took 15 minutes. any faster and the core would shread up. The finished cut was very uniform and had very few burrs. The final thickness was about 1/2" All together that radiator was on my mill for over a week, actual set up ,tooling and machine time was over 24 hours.
All told, I removed 58 pounds of brass from that radiator core. It filled up a 33 gallon trash bin. I got 59.00 dollars for it at the recyclers. Mikey had a beer with lunch that day.
With the core removed , I could deburr the screen. I made a tool out of an old wood drill that had a tapered square shank. Fitting this in each of the 1768 holes to make sure they were open was a tedious task. Now the shell is ready to fit the radiator and make some braces. I did not get a pic of the radiator as I recieved it. It was a HD 4 row radiator for a mid 70'0 ford pickup with a 460.