Hood Examples

On the left we have my MicroMimesis GP7-ish high-hood cab with the first draft of a high-hood to go with it. Note that the hood is 1.21″ wide per earlier discussion. The front deck is .625″ (30″ full-scale) wide.

On the right we have the Atlas U23B cab. The opening in the front of the cab is 1.52″ wide. The short hood shown was made to fit that width. The frame/chassis is an earlier version lacking the piece across the front as I did with the frame on the left.

A look under the hood (heh)

On the left you can see I added a piece across the front to strengthen the frame/chassis and act as the lower half of the high-hood.

On the right is the earlier version frame/chassis without the added piece. Notice that the mechanism runs right up against the end. Adding the piece would lengthen the short-hood by that amount.

View from the back

A quick look at the two designs from the rear. I just extended the draft short-hood to create the long hood for the far engine. Closer you can see the large opening in the back of the cab. This 1.52″ width of course was for the original standard gauge hood. To use this cab the opening would have to be closed up or the long hood would have to taper back to the 1.21″ width.

Hood V11

The nomenclature I use is mostly so I can ‘sorta-kinda’ keep track .. nothing more than that so if that nomenclature jumps around and makes little sense .. that the ‘why’ of it.

Case in point is this iteration. This is a high-hood version of the front/short hood. In the view of the inside you can just see a .. call it a ‘bracket’ which is U-shaped. That will contain a threaded insert. Behind that (actually in the front of the inside of the hood) you can just see a block with a hole. This is for a 1/16″ brass guide pin. The way it is supposed to work is that you place the hood on the frame so the pins fit into matching holes in the frame and then a 2-56 screw is inserted from below to secure everything. The slight recess is to fit around a projection on the cab to hold that in place.

Here’s a look at the concept. Up top is the socket for the threaded insert. The difference between making the socket for a FDM and a MSLA printer is that with the FDM printer you want an interference fit so heating the insert (brass) basically melts or welds it in place. A MSLA printer is different and the socket needs to be just large enough the insert can be inserted into the socket with glue such as an epoxy. The 2-56 screw inserted from below will be completely hidden.

1 thought on “Long and Short Hoods”

  1. I dropped one of the earlier frames and the corner of the .. front .. pilot? I am using just a standard PLA to prototype and it is somewhat brittle (arguably .. if I had dropped a regular HO body to the floor the styrene would have been damaged also)> I see where I can purchase PLA+ (plus) which is at least twice as strong. Has anyone used one of the *plus* ..aka .. stronger PLA filaments?

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