In the current issue of The Missing Conversation, Tony Sissons shares how he uses a camera as a double check on the accuracy of his modeling. Let’s face it, the camera doesn’t lie as my own photos show.

Air intake cover

I scratchbuilt this quarter-inch scale inertial filter hatch for a diesel project I plan to nibble away at for the rest of my life. I had to laminate different thicknesses of styrene to get the finished dimension. I also punched 0.010″ rivets around the base (they barely show up here) and build the grill for the air intake opening out of brass wire. I don’t recall the size used. I’m guessing 0.012″ or similar. Yes I drilled all 14 of those holes with the drill press. That was fun (not).

I milled the opening on the drill press too and those trim strips cover a multitude of sins. Now let’s look this work over in the cold light of reality.

Air intake close-up

Yuck! Now you can see all the filing/sanding fuzz from the cleanup around the outside of the grill and frame. This might not be apparent to the naked eye, especially my 58 year old naked eyes, but it would certainly show up nicely once paint and primer were applied. Leaving this stuff would make a lovely mess of things and totally ruin the model. I also have some body filler residue to clean up too. Looking further, I think those wires might be a bit too heavy. A smaller size would look better I think. Thankfully, this isn’t intended to be a finished part because now I can see lots of room to improve the work. Let’s look some more.

Air intake grill-front.

Things aren’t too bad on the front of the hatch. You might make out the rivets and the hole is for a lift ring. The two braces are off a bit from being identical, but not too bad for a practice piece. More filler residue to clean up but it’s looking better in this area. That seam between the laminations will cause trouble in the finishing stages as it will be visible. That’s why there’s body filler everywhere, to make such ugliness go away.

What is the take-away here? Scratchbuilding is a series of decisions from simple to complex. You get to take things as far you want to. Someone is certainly going to tell me that this part is commercially available, eliminating the need for so much “wasted effort” on my part.

Let me stop that line of thought dead. Scratchbuilding this part is a personal choice. I wanted to have that air intake opening in full three dimensions rather than a shallow relief but solid casting. That was choice number one. Choice number two revolved around the grill. I wanted that delicacy you’d see on the prototype and one way to get there was to scratchbuild.

Prototype air intake NS GP40

Yes, I could also drill out this area on a commercial part. That’s certainly a valid option. I didn’t have said part, so choice number three was to build it.

Now that I know the areas of weakness in this build, I can focus my attention where it is needed the most. I might be able to bring this piece up to specs, or may have to give it another attempt. Regardless, I’m better informed than before. Knowledge is power.

Regards,
Mike