11/18.2011
| Coupler Pocket/ Draft Gear Box to fit Atlas Alco C424/ C425 Model |
Back in October, Andy Harman was discussing the N&W C425 he was working on. He was commenting on how he
would like to build new coupler pockets for it because the Atlas version of the Alco coupler pocket was severely
lacking. He wanted to replace it with something that looked right. Unfortunately for Alco modelers, detail parts are
scarce. Not a lot of attention has been given to Alco. Lucky for Andy, I have been playing around with getting some
parts made with the 3D printing process. A fellow Dlister, Luther Brefo volunteered to get me the dimensional
information I needed and within about a month I had the parts in hand.
There are positives and negatives to 3D printing. The positive is if you can design in 3D, you can get parts that are
not available. The negative is that the parts need some work to clean them up. They come with printing lines on
them. The lines are easy to clean up, but it is a time consuming task. I feel it is worth the effort for getting parts that
are not commercially available. If I am to offer this as a detail part, you must understand what needs to be done so
you know what you are in for.
The parts come with an oily/ waxy film on them. I soak the parts over night in a 50/50 mixture of Simple Green
industrial degreaser and Dawn dish washing liquid. You can also use a product called Bestine which is a rubber
cement thinner. I picked up a can at my local Michaels craft store. I have not used it though. The 50/50 mixture
seems to work well. After I remove the parts from the degreasing mixture, I wash them in warm soapy water with a
soft tooth brush. The parts will dry with a white chalky film on them. This film is what you have to clean off as well as
the printing lines. Enough blabbering here. I will explain more with the photos.
would like to build new coupler pockets for it because the Atlas version of the Alco coupler pocket was severely
lacking. He wanted to replace it with something that looked right. Unfortunately for Alco modelers, detail parts are
scarce. Not a lot of attention has been given to Alco. Lucky for Andy, I have been playing around with getting some
parts made with the 3D printing process. A fellow Dlister, Luther Brefo volunteered to get me the dimensional
information I needed and within about a month I had the parts in hand.
There are positives and negatives to 3D printing. The positive is if you can design in 3D, you can get parts that are
not available. The negative is that the parts need some work to clean them up. They come with printing lines on
them. The lines are easy to clean up, but it is a time consuming task. I feel it is worth the effort for getting parts that
are not commercially available. If I am to offer this as a detail part, you must understand what needs to be done so
you know what you are in for.
The parts come with an oily/ waxy film on them. I soak the parts over night in a 50/50 mixture of Simple Green
industrial degreaser and Dawn dish washing liquid. You can also use a product called Bestine which is a rubber
cement thinner. I picked up a can at my local Michaels craft store. I have not used it though. The 50/50 mixture
seems to work well. After I remove the parts from the degreasing mixture, I wash them in warm soapy water with a
soft tooth brush. The parts will dry with a white chalky film on them. This film is what you have to clean off as well as
the printing lines. Enough blabbering here. I will explain more with the photos.
On the left is the part after being degreased and washed. You can see how white and chalky the surface looks. As
you can see there are two part. The body and the lid. If you look closely at the face of the part on the left, you will
see the printing lines as well as on the inside of the lid. On certain surfaces that will not be seen, it is really not
necessary to remove the printing lines.
After working with 3D printed parts for a few months now, I have become more familiar with their characteristics and
what needs to be done to clean them up. For instance with this part. When I first received them, I test fit them into
the Atlas frame. They did not fit. The body was to wide. BUT, after I cleaned up the printing lines the body fit
perfectly into the frame. I have noticed that the printing lines add thickness to the original size of the part. When I
remove the printing lines, the surface thickness is exactly what I designed it to. Removing the printing lines is like a
dentist removing plaque. I scrape at it with a sharp #11 blade until the surface is smooth. At this point the printing
lines are gone as well as the chalky white surface. The part on the right has been cleaned and one additional step
of being grit blasted. Grit blasting really gives the surface a nice finish for painting. Total, it probably took me about
a half hour to clean the one part. I still think it is worth the effort. The part looks great installed.
you can see there are two part. The body and the lid. If you look closely at the face of the part on the left, you will
see the printing lines as well as on the inside of the lid. On certain surfaces that will not be seen, it is really not
necessary to remove the printing lines.
After working with 3D printed parts for a few months now, I have become more familiar with their characteristics and
what needs to be done to clean them up. For instance with this part. When I first received them, I test fit them into
the Atlas frame. They did not fit. The body was to wide. BUT, after I cleaned up the printing lines the body fit
perfectly into the frame. I have noticed that the printing lines add thickness to the original size of the part. When I
remove the printing lines, the surface thickness is exactly what I designed it to. Removing the printing lines is like a
dentist removing plaque. I scrape at it with a sharp #11 blade until the surface is smooth. At this point the printing
lines are gone as well as the chalky white surface. The part on the right has been cleaned and one additional step
of being grit blasted. Grit blasting really gives the surface a nice finish for painting. Total, it probably took me about
a half hour to clean the one part. I still think it is worth the effort. The part looks great installed.
This is just to show you the bottom of each part and you can see the inside cavity to the pocket body. The part is
designed to use the existing Atlas pin screw and fit perfectly the Atlas frame.
designed to use the existing Atlas pin screw and fit perfectly the Atlas frame.
This is showing how the lid fits into the body. It is a nice snug fit.
Here you can see how the Atlas pin screw fits into the recess in the coupler pocket lid.
A side view showing the coupler pad. The block is sitting on a 0.012" angle iron. The minimum thickness for this 3D
process is 0.012". That is not an industry standard. There is a place in Raleigh, NC that has a minimum wall
thickness of 0.007". You are going to pay dearly for that too.
process is 0.012". That is not an industry standard. There is a place in Raleigh, NC that has a minimum wall
thickness of 0.007". You are going to pay dearly for that too.
I am showing the couplers because I made the coupler pocket opening to scale or near scale. The Sergent coupler
on the left you have to remove about 0.015" off each side. The Kadee coupler is the whisker type and you have to
make the sides straight. You will notice the whiskers are gone. The prototype does not use a self centering coupler.
If I am going to offer these as a part, I am going to make a different version for the Sergent coupler because with this
version, the coupler sticks out to far. I will make it so the coupler sticks out the correct distance to the pulling face.
This will make the modeler have to fill the pin screw hole and drill a new one.
on the left you have to remove about 0.015" off each side. The Kadee coupler is the whisker type and you have to
make the sides straight. You will notice the whiskers are gone. The prototype does not use a self centering coupler.
If I am going to offer these as a part, I am going to make a different version for the Sergent coupler because with this
version, the coupler sticks out to far. I will make it so the coupler sticks out the correct distance to the pulling face.
This will make the modeler have to fill the pin screw hole and drill a new one.
Now you will get to see what it all looks like installed. Here you can see it fits perfectly into the Atlas frame and lines
up with the screw hole.
up with the screw hole.
Here you can see the height is right. If need be there is enough room inside the pocket to put a 0.005 to 0.010 shim
under the coupler. The Sergent coupler height gage was built dead on center with the Kadee coupler height gage.
The Sergent coupler in this pocket is dead even with the height gage.
under the coupler. The Sergent coupler height gage was built dead on center with the Kadee coupler height gage.
The Sergent coupler in this pocket is dead even with the height gage.
This design turned out as planned. The coupler pocket is snug up against the pilot face. I am sure Andy will be very
happy with his model using this coupler pocket. As yo can see, the Kadee sticks out a bit far as well, but this pocket
is setup to be a direct OEM bolt in. You will have to do some pilot plate modification to fit this in, but doing so will also
make your pilot look more prototypical.
If there is an out cry in demand for this, I will offer it up in both this form and for the Sergent coupler.
happy with his model using this coupler pocket. As yo can see, the Kadee sticks out a bit far as well, but this pocket
is setup to be a direct OEM bolt in. You will have to do some pilot plate modification to fit this in, but doing so will also
make your pilot look more prototypical.
If there is an out cry in demand for this, I will offer it up in both this form and for the Sergent coupler.
