An Alco C-855B Chassis For N Scale

In last week’s post I said I was going to share with you the test fitting of the N Scale Alco C-855B body onto the modified chassis and that’s exactly what this week’s post will be about.

The C-855B is basically a C-855 without a cab. It’s exactly the same length and all the trucks and parts are in the same place.  However, as there is no wide cab this section at the front end of the chassis will need to be modified.

The donor chassis is from a Con-Cor U50 or Turbine and has been extended using my 3D printed stainless steel parts. You can read more about that here.

The rear of the chassis doesn’t need any modifications. The front needs to be cut to resemble the rear.

In the image below you can see the top section of the extended chassis.  I’ve also started to modify it by cutting off the front right lug which used to fit inside the cab area.

C-855B Chassis 1

In this close up you can see I’ve cut it so it tapers in very slightly from the side of the chassis.  This helps with the fit.

C-855B Chassis 2

Repeating the same cut on the left hand side will finish off the top section.  To make these cuts I simply used a cutting disc in a Dremel-style tool.

C-855B Chassis 3

The bottom section will require a bit more work.  Again you can see in the image below I’ve already done the right hand side and I am working in the left. To get the cuts in the right place I fixed the top and bottom halves of the chassis together and marked the bottom with a pencil.  The cuts should line through vertically.

C-855B Chassis 4

Using the cutting disk I cut along the top of the chassis following the same line as I did with the top section which was marked in pencil.  You only need to go down as far as the lower flat area.  Then, cutting horizontally, I came in from the side.

C-855B Chassis 5

When you are almost through it should look something like this.

C-855B Chassis 6

Once the unwanted section has been cut out the area can be cleaned with a file.

C-855B Chassis 7

The last section to remove is part of the front.   Again I marked the cut line with a pencil after fixing the two halves together and then used the cutting disk to slice in from the top.

C-855B Chassis 9

The last cut comes in horizontally to remove the unwanted section.

C-855B Chassis 10

The chassis is then assembled and is ready for a test fit.

C-855B Chassis 11

I found that my chassis was about 0.5mm too long for the shell; this might be caused by a slight shrinkage in the 3D print when it first cooled or too much glue between the chassis extenders and the original bits.  The shell should be a nice fit and shouldnt need to be forced. This was easily fixed by cutting a thin slice off the front as you can see below.

C-855B Chassis 12

The shell and fuel tank then fitted perfectly over the chassis.

C-855B Chassis 13

It’s important to make sure the chassis is fitted in the correct way round.  Both the chassis extender parts have arrows which point forwards and on the C-855B the front is the plainer of the two ends.  In the photo below this is on the left.

C-855B Chassis 14

All that is left to do now is to have it painted, fit the last bits of brass and add a DCC chip and it will be ready to join its C-855 companions to complete the trio.

C-855B Chassis 15

This has been a fun project to work on even though it has taken a long time.  I’m looking forward to seeing all three working hard uphill on the layout ‘Somewhere West’.