06/06/07
| ADAPTING ATHEARN GP SIDE FRAMES TO YOUR ATLAS GP GEAR BOXES USING DETAILS WEST ADAPTOR PLATES |
To make a long story short, this project came about when Andy Harman wanted to find a way to put Athearn
blomberg side frames on his Atlas GP locomotives. I told him I could find a way to do this so he sent me all
the parts I requested. In a weekends worth of time, I had the conversion designed and implemented. About a
year or two later I offered the design to Details West and they took it on.
The parts offered by Details West are as follows:
AP-355 Adaptor Plate to Convert Atlas Gearbox to Athearn's Blomberg Sideframe
AP-356 Adaptor Plate & Blomberg Sideframes to Convert Atlas Gearbox to Athearn's
AP-355 is just a pack of adaptor plates and AP-356 is the adaptor plates with the side frames included.
I thought it might be a good thing to put up a "HOW TO" page on how to make the conversion. I want to show
you all how easy it really is. So with all this said, let me begin!
Before you disassemble your Atlas truck, make note of how the gear case rides on the axle gear. This is very
important.
Looking at the photo below, the top side frame is the Athearn blomberg without any details added and the
bottom is from Atlas as it comes on the model. What you should notice first is how much heavier the Athearn
side frame looks. It carries the look of more weight and thus makes your model look heavier on the rails.
There is more depth to the Athearn frame. The Athearn side frame is the standard that no other model
manufacturer has come close to duplicating and how old is it????????
blomberg side frames on his Atlas GP locomotives. I told him I could find a way to do this so he sent me all
the parts I requested. In a weekends worth of time, I had the conversion designed and implemented. About a
year or two later I offered the design to Details West and they took it on.
The parts offered by Details West are as follows:
AP-355 Adaptor Plate to Convert Atlas Gearbox to Athearn's Blomberg Sideframe
AP-356 Adaptor Plate & Blomberg Sideframes to Convert Atlas Gearbox to Athearn's
AP-355 is just a pack of adaptor plates and AP-356 is the adaptor plates with the side frames included.
I thought it might be a good thing to put up a "HOW TO" page on how to make the conversion. I want to show
you all how easy it really is. So with all this said, let me begin!
Before you disassemble your Atlas truck, make note of how the gear case rides on the axle gear. This is very
important.
Looking at the photo below, the top side frame is the Athearn blomberg without any details added and the
bottom is from Atlas as it comes on the model. What you should notice first is how much heavier the Athearn
side frame looks. It carries the look of more weight and thus makes your model look heavier on the rails.
There is more depth to the Athearn frame. The Athearn side frame is the standard that no other model
manufacturer has come close to duplicating and how old is it????????
Below is a photo of all the parts required to make the conversion. Missing of course is the power pickup
strips. Sorry, I forgot to add them to the photo. Remember, if you use AP-356 then you do not need the pack of
Athearn side frames.
strips. Sorry, I forgot to add them to the photo. Remember, if you use AP-356 then you do not need the pack of
Athearn side frames.
Here we have the back of an Athearn side frame. What needs to be done is to have all the protrusions
cleaned off down to the flat surface of the side frame. The surface marked "A" is the flat surface I am referring
to.
cleaned off down to the flat surface of the side frame. The surface marked "A" is the flat surface I am referring
to.
A
A
In this photo of the same side frame, you can see that all the protrusions have been cleaned off and sanded.
Do this to all four side frames. Take care to make sure you do not cut or sand the surface uneven.
DO NOT cut the shelf at the top all the way off. Leave a small sliver of it overhanging the back of the side
frame.
DO NOT glue your adaptor plates on yet. I will tell you when it is time for that.
Do this to all four side frames. Take care to make sure you do not cut or sand the surface uneven.
DO NOT cut the shelf at the top all the way off. Leave a small sliver of it overhanging the back of the side
frame.
DO NOT glue your adaptor plates on yet. I will tell you when it is time for that.
Next you want to get the power pickup strips prepared. Here you need to clean off all the parts that stick out.
Grind off the nubs that the axle goes through and cut off the tab that the wire connects to. What you end up
with is what you see in the lower photo of the power pickup strip. When you are done, make sure you clean up
the axle holes. The notch you see at the top of the pick up strip where the wire clip connected to is for
soldering a wire to. Do this to all four pick up strips.
Grind off the nubs that the axle goes through and cut off the tab that the wire connects to. What you end up
with is what you see in the lower photo of the power pickup strip. When you are done, make sure you clean up
the axle holes. The notch you see at the top of the pick up strip where the wire clip connected to is for
soldering a wire to. Do this to all four pick up strips.
Here you now see the wire soldered in place and the adaptor plate fitted. It is important that the wire clears
the adaptor plate. Solder your pickup wires to all four of the strips. VERY IMPORTANT, make sure you know
what side your soldering your wire to so it is on the inside of the adaptor plate and not between the side
frame and the adaptor plate.
the adaptor plate. Solder your pickup wires to all four of the strips. VERY IMPORTANT, make sure you know
what side your soldering your wire to so it is on the inside of the adaptor plate and not between the side
frame and the adaptor plate.
Now it is time to modify all the gear tower pin support holes. You will have three pin support holes on each
side of the gear tower. The outer holes are the side frame support holes. The center hole is the power pickup
strip pivot hole. Start by cutting the two outer holes down to the flat shoulder as shown in the photo above.
Use a sharp razor and SLICE the pin support off. DO NOT USE NIPPERS. You will crush and most likely split
the delrin. Use a rocking motion with your razor blade using the flat shoulder as a support till it slices through
the delrin.
side of the gear tower. The outer holes are the side frame support holes. The center hole is the power pickup
strip pivot hole. Start by cutting the two outer holes down to the flat shoulder as shown in the photo above.
Use a sharp razor and SLICE the pin support off. DO NOT USE NIPPERS. You will crush and most likely split
the delrin. Use a rocking motion with your razor blade using the flat shoulder as a support till it slices through
the delrin.
Next you are going to cut the center pin support down even with the two outer supports. To do this, place the
razor flat on one of the outer pin support holes as a reference surface. Then contact the bade with the center
pin support.
razor flat on one of the outer pin support holes as a reference surface. Then contact the bade with the center
pin support.
Now with a little bit of pressure on the blade, rock the razor over till it slightly sits on the other pin support
shoulder. The razor should now be supported by both of the outer pin support shoulders and just barely
cutting into the center pin support.
shoulder. The razor should now be supported by both of the outer pin support shoulders and just barely
cutting into the center pin support.
Now that you have started the cut into the center support, you can rock the blade from shoulder to shoulder
apply pressure on the center pin support. The razor will start cutting deeper into the pin support. Take care
that when you rock the blade, that it is even with the two shoulder surfaces. This will ensure you cut the center
pin support even with the two outer supports.
apply pressure on the center pin support. The razor will start cutting deeper into the pin support. Take care
that when you rock the blade, that it is even with the two shoulder surfaces. This will ensure you cut the center
pin support even with the two outer supports.
And now the blades cuts through the center support and rests comfortably on the two outer supports. Go
ahead and cut all the way through the center pin support.
ahead and cut all the way through the center pin support.
When you are finished, all your pin supports should be the same length as shown above.
Next you need to take another 0.040" of the center pin support. This is very easy to do. Just measure in 0.040"
on the center pin support and slice it off with your razor blade. Try to make the cut even, but it is not critical. If it
is slightly uneven, do not fret. Cutting this center pin support deeper is to give clearance for the power pickup
strip.
On the left is an unmodified gear box.
With the pin supports cut on the gear box, it is time to test fit your adaptor plates. You will find they are VERY
snug in the holes. I found them to be to snug and if I ever had to pull the side frames off, the adaptor plates
would probably stay on the gear tower and the side frames would pull free from them. I took a 0.084" drill bit
and reamed out the holes. The fit is still snug, but not that much. I find the fit to be perfect.
Now install the plates into the gear case. Then slip the side frames on them. Hold them snuggly in place with
your fingers and look at them from the end. I found mine to angle in at the bottom. They were not straight up
and down.
on the center pin support and slice it off with your razor blade. Try to make the cut even, but it is not critical. If it
is slightly uneven, do not fret. Cutting this center pin support deeper is to give clearance for the power pickup
strip.
On the left is an unmodified gear box.
With the pin supports cut on the gear box, it is time to test fit your adaptor plates. You will find they are VERY
snug in the holes. I found them to be to snug and if I ever had to pull the side frames off, the adaptor plates
would probably stay on the gear tower and the side frames would pull free from them. I took a 0.084" drill bit
and reamed out the holes. The fit is still snug, but not that much. I find the fit to be perfect.
Now install the plates into the gear case. Then slip the side frames on them. Hold them snuggly in place with
your fingers and look at them from the end. I found mine to angle in at the bottom. They were not straight up
and down.
To fix the angle of the side frame, place the adaptor as shown in the photo above and firmly press down on
the pins. This will slightly bend them up. Test fit it all again and repeat if necessary till you are satisfied with
the angle of the side frame making sure it is parallel with the gear case. This is important because if the side
frames angle in at the bottom, you are likely to have the frame rub the wheels.
Once you are satisfied with the side frame angle, then you can glue the adaptor plates to the back of the side
frames. The block on the adaptor plate fits into the rectangular depression on the back side of the side frame.
Do two side frames at a time. Once you have two done, insert them into the gear case and make sure that the
bottom of the side frames all sit flat against your table If there is any unevenness to them, press them down
hard until it all sits flat. You do not want them uneven. Once both side frames are even, then you know they
are squared up with the gear case. Now you can do the same to the other truck.
I used cyanopoxy to glue the plates to the frame. My frames did not come out even and I had to man handle
them to tweak them so they were even across the bottom. I heard the slight creaking noise in the white metal
plates, but now all is the way it is supposed to be.
the pins. This will slightly bend them up. Test fit it all again and repeat if necessary till you are satisfied with
the angle of the side frame making sure it is parallel with the gear case. This is important because if the side
frames angle in at the bottom, you are likely to have the frame rub the wheels.
Once you are satisfied with the side frame angle, then you can glue the adaptor plates to the back of the side
frames. The block on the adaptor plate fits into the rectangular depression on the back side of the side frame.
Do two side frames at a time. Once you have two done, insert them into the gear case and make sure that the
bottom of the side frames all sit flat against your table If there is any unevenness to them, press them down
hard until it all sits flat. You do not want them uneven. Once both side frames are even, then you know they
are squared up with the gear case. Now you can do the same to the other truck.
I used cyanopoxy to glue the plates to the frame. My frames did not come out even and I had to man handle
them to tweak them so they were even across the bottom. I heard the slight creaking noise in the white metal
plates, but now all is the way it is supposed to be.
Now you need to make a very simple tool. You need to take about 0.042" off each side of the axle gear. Make
a block of styrene that is 0.180" thick and drill a 0.120" diameter hole through it.
a block of styrene that is 0.180" thick and drill a 0.120" diameter hole through it.
Stick your axle gear through the hole as shown above.
And slice off the tip of the axle gear that sticks out. Again, I urge you to use a razor blade here. These gears
are VERY easy to split. Do this to both sides of the axle gears.
After you have done this to all the axle gears, go back and chamfer the inside of the hole that the wheel axle
goes into. This will remove any burrs and help lessen the chance of you splitting the axle gear when inserting
the wheel axle. It is important to make sure there are no burrs or stray pieces of delrin in the hole.
are VERY easy to split. Do this to both sides of the axle gears.
After you have done this to all the axle gears, go back and chamfer the inside of the hole that the wheel axle
goes into. This will remove any burrs and help lessen the chance of you splitting the axle gear when inserting
the wheel axle. It is important to make sure there are no burrs or stray pieces of delrin in the hole.
Next I nipped off the axle tips on the outside of the wheel and ground the face smooth. You do not need these
axle tips anymore and they will interfere with the new side frames. After that I washed all the wheels to
remove any oil or grease and prepped them for painting.
Now you have all the major modification done. If you are not going to paint anything, You can reassemble the
trucks by following the steps below. If you are going to paint the wheels and trucks, I suggest you do that now
before proceeding to the next assembly steps.
axle tips anymore and they will interfere with the new side frames. After that I washed all the wheels to
remove any oil or grease and prepped them for painting.
Now you have all the major modification done. If you are not going to paint anything, You can reassemble the
trucks by following the steps below. If you are going to paint the wheels and trucks, I suggest you do that now
before proceeding to the next assembly steps.
Now you can assemble the trucks. The pick up strip goes on the inside of the wheel now. This is what allows
this conversion to happen. Take two wheels, one axle gear and two pickup strips. It is very important you
know which way your pickup strips go. They are not mirror images of each other.
VERY IMPORTANT: When inserting the wheel axles into the axle gear, DO NOT just push them in. Turn the
wheel as you insert the wheel axle into the axle gear. This will help slide them in and reduce any risk of
splitting the gear.
this conversion to happen. Take two wheels, one axle gear and two pickup strips. It is very important you
know which way your pickup strips go. They are not mirror images of each other.
VERY IMPORTANT: When inserting the wheel axles into the axle gear, DO NOT just push them in. Turn the
wheel as you insert the wheel axle into the axle gear. This will help slide them in and reduce any risk of
splitting the gear.
Notice how the pickup strip tabs are offset. This is determined by the adaptor plate. You will notice on the
adaptor plate there is a shelf with a break in it. The pick up strip tab fits into this break. So when assembling
the wheel sets, make sure you know which way the tab needs to be in order to fit properly into the adaptor
plate. Now gage your wheels. Only do one end here.
adaptor plate there is a shelf with a break in it. The pick up strip tab fits into this break. So when assembling
the wheel sets, make sure you know which way the tab needs to be in order to fit properly into the adaptor
plate. Now gage your wheels. Only do one end here.
Now fit that assembly into your gear case as shown in the photo above. The pickup strip center hole should
line up with the center pin support in the gear case. The pickup strip should sit on top of the two outer pin
supports.
line up with the center pin support in the gear case. The pickup strip should sit on top of the two outer pin
supports.
Now drop in an axle gear and thread the wheel axle through the pick up strip and while turning the wheel,
insert it into the axle gear.
insert it into the axle gear.
Now do the same to the other side. Thread the wheel axle through the pick up strip and while turning the
wheel, insert it into the axle gear. Now you can use your NMRA gage and set the wheel flanges to the proper
width.
wheel, insert it into the axle gear. Now you can use your NMRA gage and set the wheel flanges to the proper
width.
With the wheel sets assembled and gaged, you should have what you see above.
Just another view from the bottom of the assembled wheel sets in the gear case.
One more minor cutting modification that needs to be done. You see the four rectangular locking tabs labeled
"A". At the top of them there is an angle. You need to cut these off just below that angle in order for this bottom
clip to fit back snuggly onto the gear case.
What I do, is to cut first at the angle. Then just nip a little at a time until when I fit this part back onto the gear
case, the four locking tabs click into place properly.
"A". At the top of them there is an angle. You need to cut these off just below that angle in order for this bottom
clip to fit back snuggly onto the gear case.
What I do, is to cut first at the angle. Then just nip a little at a time until when I fit this part back onto the gear
case, the four locking tabs click into place properly.
A
A
A
A
Here is how it should all look inside the side frames. Notice how the power pick up strip is under the shelf on
the adaptor plate. Remember at the beginning when I said to take note of how the gear case rides on the axle
gears. If the gear case does not ride on the axle gear, you will get a front to back rocking motion in the truck.
The shelf on the adaptor plates helps to keep this from happening.
When I put this truck together, I had a slight unevenness to the truck meaning that not all four wheels touched
the rail. To correct this, I put the truck on my table and pressed firmly down on JUST the gear case. This
helped to level out all the pins and now all four wheels touch at the same time. Basically by pressing down on
the gear case, I once again I forcefully trued it all up. The gear case is not 100% square so there is going ot
be a need for some slight tweaking.
the adaptor plate. Remember at the beginning when I said to take note of how the gear case rides on the axle
gears. If the gear case does not ride on the axle gear, you will get a front to back rocking motion in the truck.
The shelf on the adaptor plates helps to keep this from happening.
When I put this truck together, I had a slight unevenness to the truck meaning that not all four wheels touched
the rail. To correct this, I put the truck on my table and pressed firmly down on JUST the gear case. This
helped to level out all the pins and now all four wheels touch at the same time. Basically by pressing down on
the gear case, I once again I forcefully trued it all up. The gear case is not 100% square so there is going ot
be a need for some slight tweaking.
AND, this is what the truck looks like on a finished model.
I hope this little "HOW TO" is helpful for when you want to make this conversion. It is very easy and you should
be able to get it all done in an evenings modeling session. If you have any questions at all, please feel free to
email me.
I hope this little "HOW TO" is helpful for when you want to make this conversion. It is very easy and you should
be able to get it all done in an evenings modeling session. If you have any questions at all, please feel free to
email me.