Building a General Models Pacific

1) Determine how much extra clearance is needed for the drivers to rotate freely.

2) Insert thin washers between the plate and the frame or

3) Fabricate thin gaskets to install between the plate and the frame. Possibly use gasket material, styrene or metal (brass shim).

Just a suggestion. Not sure how either would work.

MELGAR

Hmm, I could try that. Is the plate normally supposed to clamp down on the driver bearings or should it clamp down on the frame or something else?

From your description, I assumed the plate would lay flat against the frame. How much additional clearance do you think you need? You could experiment by adding some layers of paper (one at a time) until the spacing seems correct. A picture would help.

MELGAR

Is in possible the bearings have a flat side, that should be down against the plate, while the rest is in the slot.   I built an AN 4-4-0 years ago and did not have any issues like this.  

Another solution if there is not enough height for the axles is to file the top of the slot in the frame to gain a few thousandths.    And I would suggest bolting the two frame halves together and filing both sides at the same time to keep them as much the same as possible.

Doesn't look like there is a flat side to the bearings, so I don't think that's it. What I'm wondering is if the slots for the bearings in my frame aren't deep enough. I don't want to file them away until I'm sure that's the issue, though. Attached is a picture of how much the bearings stick out from the bottom.

How about several more pictures that show the situation more clearly?

MELGAR

@Johnbeere posted:

Hmm, I could try that. Is the plate normally supposed to clamp down on the driver bearings or should it clamp down on the frame or something else?

Think on the frame but looks like in your photo it's hitting the bearings.....

Yeah, it's definitely hitting the bearings on mine. Maybe someone could look at their All-Nation locomotive for me and see if it does clamp on the frame? The slots for the bearings may not be milled deep enough on my locomotive. It would be really appreciated if someone could measure how deep those slots go for them so I know for sure that's my issue.

It's hard to take pictures of this - there's not really any good angles. The last photo I posted shows the locomotive upside down, looking between the frame and plate to show how much the bearings protrude.

Please take pictures of the individual pieces looking upward from the bottom of the locomotive. I want to see the screw holes in the plate and the frame, the bearings and axles, and the slots....

MELGAR

Maybe one of these helps?

I think you may be missing some sort of spacer piece that goes between the plate and the frame. There are four holes in the mounting plate that go into the cross-members. The plate has three additional holes. For what are they used? Do the holes in the plate align with the holes in the cross-members? If the motor is mounted to the top of the plate, the plate height may be critical for proper engagement of the motor worm gear to the spur gear. It may be possible to put three washers between the plate and the cross-members. The front cross-member is at a different height and looks like it needs a longer screw. Are there drawings in the instructions?

MELGAR

Two of those additional holes are for the motor, though I'm not sure what the smallest one is for, it's threaded. That's part of what confuses me, the instructions don't show any spacers. Here's a photo of the instructions.

I was just about to post that same photo; I'm sure someone will be able to weigh in and help you with this.

Mark in Oregon

I can disassemble an A-N frame and look.  I am inclined to think that your bearings need a flat spot on the bottom.

That would be really appreciated if you can confirm that.

Something is not right. Is the frame assembled perfectly square? Do the bearings fit snugly or tightly into the frame slots? They should not be free to rotate within the frame. Your original complaint was that installing the plate caused the drivers to bind, even without fully tightening the screws. It's hard to believe that slight tightening of the four mounting screws squeezed the bearings enough to cause binding. Are there spacers in the kit?

MELGAR

As suggested by Bob2, a flat spot on the bearings (trapping them inside the plate) will keep them from rotating. That is necessary.

MELGAR

Yes, the frame is as perfectly square as I could get it - in my troubleshooting I held a straight edge to both sides and got it as close to square as possible. The bearings are a loose fit in the frame, until the plate is lightly tightened on. All the axles spin freely in their bearings - with the plate removed, and rotating the wheels by hand, the bearings aren't turning. The kit did come with two sets of two different kinds of spacers - I'm not sure what they're for, but since they're not shown or specified to be used for this purpose, I don't think they're to be used here.

My thought of what is actually happening is that the bearings might be twisting a little in the frame when the plate is tightened on them.

There are no flat spots on my bearings, so I'm inclined to think that that is probably my issue. Before I go filing away at my bearings, though, a photo proving that that's what needs to be done would be really appreciated.

It's possible that spacers go between the cross members and the plate to introduce a gap between the plate and the frame. (The longer spacer might go onto the front cross-member.) The other possibility would be to have a flat spot on the bearings. You would have to be certain before you file the bearings that you would not have to file so deeply into the bearings that you get to the axle bores.

MELGAR

Of course - I'd be careful to not file them too far.

Here's a photo of those spacers - they're all the same thickness, but the inner diameter on both is different - doesn't really seem like they're meant for this.

One more comment. In the sketch, the front bearing is shown within the frame slot but it does not show a flat spot on the bearing, and it seems to show the round bearing entirely within the frame slot. That would allow the plate to seat directly onto the frame.

MELGAR

Yeah, it does seem to show it entirely in the slot. It's possible that the slots on mine aren't milled deep enough? That was one of my first thoughts, but it seems improbable for it to be that screwed up.

The slots and cross-member positions on your model look just like the drawing. Another possibility is that the outside diameter of the bearings is too large and needs to be turned down on a lathe.

MELGAR

Do you have a dial calipers that you can use to measure the depth of each slot (all 6)? If so, is the measurement the same for all 6? If you sight down the frame, or put a straight edge on the bearings, are they all at the same height/depth? If only 2 axles are binding, that suggests they are not all seated to the same depth in the frame.

Chris

LVHR

They all appear to be at the same depth - Owing to my theory that the bearings are getting slightly out of line when they're pressed on by the plate, it's probably just luck that the first driver spins freely. Hopefully someone with one of these old locomotives can report back to me with what's different about my locomotive. I'm fairly confident flat spots on the bearings will fix it, but I want to be really sure that that's what needs to be done before I do that.

If you introduce flat spots onto the bearings, be sure that you don't have to remove so much material that you penetrate into the axle bores. From the pictures, I'm not sure the bearings have sufficient material. Will look for what's doing on this tomorrow.

MELGAR

Of course, I'll be very careful. Looking at them myself, it looks like I do have plenty of material to work with. They have a smaller diameter section in the middle, and a larger diameter section on the ends. I think if I file just far enough to where the file starts touching the smaller diameter, I'll be okay.

@Johnbeere posted:

...They have a smaller diameter section in the middle, and a larger diameter section on the ends. I think if I file just far enough to where the file starts touching the smaller diameter, I'll be okay.

If you're referring to the outside diameter of the middle bearing section (end-middle-end), that should be OK. There might be some way of mounting the bearings on a rod or between the jaws of a vice (with protection from the jaws) so that you can get an aligned flat surface with the file. The better way to do this would be at a machine shop but may not be necessary.

MELGAR

Gee, my instruction sheet (which you also have) doesn't say anything about needing to flatten any bearings: my advice would be to hold off (if you can) and wait for "bob2" or someone else with an example to weigh in here...material needlessly removed cannot be replaced.

Mark in Oregon

When I built this All Nation model back in 1970, I had the same problem.  The drive bearings have  an external groove  which allows them to fit into the frame slot.  Two had a snug fit, so I made sure they were both on the same axle. I then filed both sides of the axle slot in the frame slightly, until the bearings were a slip-in fit.

When putting on the retainer plate, I found that it touched the rims of all four driver bearings but did not touch the frame by a few thousanths of an inch.  So I filed the rims of each bearing until they matched the frame's bottom edge. Not much had to be removed, but it allowed the retainer plate to firmly fit on the frame with no binding of the drivers.  I did not want to file the axle bearing  slots deeper, as that would lower the locomotive closer to the rails and possible cause the pilot to touch on uneven track or beginning to climb a grade.

Fitting the worm to properly mesh with the main driver's gear required some fussy fitting of shims under the heavy brass mount to get it just right.   A half century later, it still runs great!  I sold it in 2018. Here it is at its new home.

S. Islander

Two things that occur to me.   First in the photo of the mech with bottom plate off, it looks to me that there are flat spots on some of the bearings.    Maybe this is an optical (obstacle) illusion?

The second thing is it looks like the side  rods are already attached to the drivers.    The bind may be in the rods not the bearings.     I have a friend who has one of these and I asked him about it.   He said his base plate does not fit tight to the frame either, but his drivers turn freely.    He did not think tightening the base plate could deform the bearings easily.    So my suggestion is to remove the side rods and try installing the drivers and see if they turn freely.    then add side rods one at a time and see which one binds, if it is a rod bind. 

The other idea mentioned above is that the bearings do not slide all the way up into the frame because the flange  way on the bearings is too narrow.   That may be something to look at also.

Went back and talked to my buddy who has some experience with these AN and GMC models and he says it really sounds like rod bind.   An opinion from someone with experience who is offering it without seeing it.   Certainly worth a look.

I have never built one these models.  However looking at your pictures and instructions sheet, I am wondering if the bearings are backwards.  It looks like in your top view picture the part of the bearing outside the frame is thinner and not as high.  The instructions show a large diameter on the outside of frame.   I am an expert, but from the pictures the part of bearing outside the frame looks smaller.   Good luck. 

Thanks for all the help. Good to hear I'm not the only one who has had a similar issue to this, and that filing the bearings fixed it - going to hold off on filing them until I'm sure that's what I want to do.

Since the wheels were binding before I installed the rods, I don't think the rods are an issue. Plus, it all rolls very smoothly with the plate removed.

Looking at the bearings, both ends look like they're the same diameter, and I'm confident that there are no flat spots on any of them.

@mecmt posted:

It looks like in your top view picture the part of the bearing outside the frame is thinner and not as high..... from the pictures the part of bearing outside the frame looks smaller.

Good observation. From the picture, that appears to be correct. Try reversing the bearings - inside to outside.

MELGAR

I think it's just an optical illusion. I've just checked with calipers on both ends of the bearings - same diameter.

I built several 4-6-2 and 4-6-0...like everybody else on this site.  I remember filing flat spots on the bushings to get the clearence.  I have a couple brass engines where I space the retaining plate away from the frame.

Thanks for the input, sounds like filing them might be my best bet. I'll probably wait for another day or so before I go ahead with it in case someone comes up with a better solution.

In the mean time, does anyone have instructions for the boiler and tender? I only have the instructions for the mechanism.

I'm also missing three parts so far - the two "piston rod bushings", part 1382, and one of the screws that attach the eccentric rod to the eccentric (I've currently got a different screw in place of it, but having the correct screw would be very nice). If anyone has a parts locomotive, I would really appreciate buying those parts off you.