Installing Cannon Fans on a Kato Shell

This article focuses on Kato HO Scale shells, however the technique doubles for Athearn Blue box, or any model with cast on fans.

Kato, and Athearn in their earlier models (some current RTR and Roundhouse too) used a fan on diesel locomotive that was cast on to the model in the shell molding process.  While these are often well detailed, they cannot match the detail and scale fidelity of Cannon & Co see through fans.

I drill out the fans on any unit I'm replacing fans on with a Step Drill.  This step drill came from Harbor Freight, however a much better set is available on Amazon here.  Specifically you need the 1/8"-3/4" size, which is the largest in the set.  Sometimes I use a small 1/8" drill but to core each fan, but that is nor necessary.  Start your hole with a "T" pin, directly in the center of the fan.

Mark the Step Drill with a black sharpie at the 5/8" step.  You'll need to drill to the 9/16" step, which is one step smaller.  By marking the 5/8" step, it serves as a reminder as you drill to stop before that step.  You could mark the 9/16" but then you would be drilling until you lined step disappears, so I recommend the next step up!

Chuck you step drill into a power drill, and begin drilling the hole out, making sure to remain centered in the fan housing.  I routinely stop after each step clears through the shell, and using the fan rings as a guide, I can tell if the hole is still roughly centered.

Once you are to the 1/2" to 9/16" step, you will work slower, double checking to make sure it is perfectly centered in the old fan housing.  Once the 9/16" step clears the shell, the step we marked before drilling, 5/8" will conveniently carve off most, if not all of the remaining fan housing from the top of the shell.

Clean up and remaining fan housing walls, and flash created by the drilling on the inside of the shell, with a sharp new #11 Xacto blade

Assemble the Cannon & Co fans per manufacturer instructions.  Make sure to use fans appropriate for your prototype, Dave at Cannon & Co will aid you if you're unsure.  Test fit your fan by gently placing it in the hole it will be installed in.  If it does not fit, gradually clean up and widen the hole with a round jewelers file, until the fan fits with no friction, but snug.  I use Plastruct Plastic Weld to secure the fan to the shell.

As you can see, the rear most fan housing on my model is shorter.  I need to thin down the top ring as this particular unit, WC #6001, had a low profile radiator fan installed on the rear most position, at some time during servicing.

I hope this article helps you see how easy it really is to replace these cast on fans.  Total time invested is under 1 hour for me, but possibly 2 hours for a first time user of this technique.  I can remove 5 fans from and SD40 in about 15-20 minutes, on a good charge on my drill (longer if I need to recharge it!).

Thanks for reading, and let us know on the forums if there's more you'd like to see!

© 2018, 2019, Josh Baakko,