New brass Milwaukee Bipolar EP-2 clinic- part 2

[Pizzaparty]

Great work Ron!

Do you think that over time as the mechanical parts age they will run differently? I assume there’s enough “slop” in the drive train that it wouldn’t be a huge issue.

Side note - these big EP-2 engines are just ripe for some one to 3d print up a chassis. It was done with the the little joe so I can imagine that this is possible

[u18b]

Great work Ron!

Do you think that over time as the mechanical parts age they will run differently? I assume there’s enough “slop” in the drive train that it wouldn’t be a huge issue.

Side note - these big EP-2 engines are just ripe for some one to 3d print up a chassis. It was done with the the little joe so I can imagine that this is possible

Thank you.

As to wear.... yes some, like anything else.   The most wear is from the main gear  tower gear on the truck and the worm- both of which can be replaced.    But I don't think it's a problem.

In these locos (mine and the NJ version from 1983) the bigger risk is Zamac rot.  The main truck frame on the four axle truck is Zamac.    The worst rot was in the Kumata Alcos- they are terrible.   The EP-2s are not that bad, but the truck frame may slightly curve-- and this will change the running characteristics including cogging.

At some point in this process, I plan to make a mold of a truck frame so that I can make some back up castings in the future- just in case I have one that rots really bad.
So far this is not a problem, but I'm going to plan ahead for worst case problem.

As to plastic,  I know that @draskouasshat had begun drawing and printing early drafts of the shells for the streamlined (post 1953) version.  It was looking pretty good! 
But I think he stopped for a while.  Maybe he will post a response.

A mechanism with a four axle truck would still be a big obstacle.   Weight might also be an issue (all brass being heavier than mostly plastic).

[u18b]

Pizza party.
Here is a pretty extreme example of truck frame problems.   This is from a repair I did many years ago on an NJ Custom Brass EP-2.  These are now 40 years old.

You can see that the frame has warped downward.  I placed the truck on a straight edge.  But this is fixable.



If someone has an old EP-2 that is no longer running well, this is where I would start the inspection.

[draskouasshat]

Thank you.

As to wear.... yes some, like anything else.   The most wear is from the main gear  tower gear on the truck and the worm- both of which can be replaced.    But I don't think it's a problem.

In these locos (mine and the NJ version from 1983) the bigger risk is Zamac rot.  The main truck frame on the four axle truck is Zamac.    The worst rot was in the Kumata Alcos- they are terrible.   The EP-2s are not that bad, but the truck frame may slightly curve-- and this will change the running characteristics including cogging.

At some point in this process, I plan to make a mold of a truck frame so that I can make some back up castings in the future- just in case I have one that rots really bad.
So far this is not a problem, but I'm going to plan ahead for worst case problem.

As to plastic,  I know that @draskouasshat had begun drawing and printing early drafts of the shells for the streamlined (post 1953) version.  It was looking pretty good! 
But I think he stopped for a while.  Maybe he will post a response.

A mechanism with a four axle truck would still be a big obstacle.   Weight might also be an issue (all brass being heavier than mostly plastic).

The EP-2 project is still around but i havent messed with it much. Finding suitable mechanism parts is the biggest holdup as i havent moved to the "engineering a new mechanism" part of the cad drawing yet.

Drasko

[u18b]

This is a little bit of a long post on the challenges of prototype modeling.   My goal has been to make EP-2s with road number accurate details.

For those who follow this thread, you know I share my thinking, planning, attempts, failures, and successes.  This is about details which came from new research.

I’m now moving forward with the very challenging modeling of E-1 in what I call the Experimental scheme.

This was the first colorful (non-black) EP-2.   My challenge stems from the fact that I can only identify FOUR photos of this locomotive- and only one of them is good quality.    This forces me to sometimes make educated guesses.

I have posted on multiple forums asking for help and no one has responded.   Maybe those are the only photos out there (though I doubt it).

So let me walk you through my struggles with reference to details.

1.  The horns.

Black EP-2s started out with a steam whistle under a dome (I assume for a resonance effect).

As in here.   I have determined the steam whistle is under that dome between the bell and the cab.  You can see the air hose going to it.




But I have seen no photo to date of any non-black EP-2 with a whistle.  So evidence suggests that when they were shopped for a new colorful paint job, a few changes were made.    The whistles were removed….. and single chime horns were added.

Some had two horns installed, one on each end.  And there are some patterns for placement.

(remember that the A cab has the relatively clean roof and the B cab has all the coils.)

So I now look at photos of E-1 in the Experimental scheme and I can see no horns at all.

I covered this in an earlier post and I’ve decided to place one horn on the A cab.  This photo shows no horn, but that may be the base of the horn behind the light.   Even though I have no photo evidence of a horn, I can’t imagine they sent this loco out without one (this an educated guess).

[u18b]

2.  Headlight placement

Earlier in this thread, I described how I discovered that the headlight usually sticks out, but sometimes does not.    And that photo above is an example of the latter.  The headlight on the right side does NOT stick out.

OK, great.  Hard detail to capture, but I made the change on my model.  In fact, I recently finished building E-1 in the cigar scheme- and note how the headlight on the left overhangs the nose with a support brace.





And I modeled this properly.   One horn and a recessed light on the A end.  The B light overhanging.







The prompt for this posting came when doing more research.   I have spent countless hours looking for photos of EP-2s over the years.     Every 6 months or so, I go on another all-out search using various search terms.

I did that last week and discovered some new photos I had not seen.   And that’s what got me.   I found a couple of photos of E-1 in black and saw something new.

Here is the shot that caught my eye.  Notice B cab is on the right….. and the headlight is recessed on the B cab!





And here is an even stranger view.   The headlight is recessed…. And has three bulbs (all other black have one bulb).





This now made me go BACK and study the Experimental scheme shots.   This is the only shot that shows the B end.  And when I study it- even though it is fuzzy….. clearly, that B headlight does not hang out  with supports, but is recessed.




So I must conclude that E-1 had TWO recessed lights while in the black and experimental scheme.  However, when they shopped it and painted it in the cigar scheme, they moved the B light outward.

So I’m glad I caught this now.

Thus I spent modeling time this week pulling the stock headlight off the B end, kitbashing the light, and remounting it recessed.  So now, on this model,  A and B both have recessed light.

(this is a lot of work)

[u18b]

3. Light bulbs

And now what about light bulbs?
I have no photos of the B end in the experimental scheme,  So I must guess… 

All on the B end…  Here is a shot of E-1 in black paint, 3 bulbs.



A shot in the later cigar scheme with one bulb.




And a shot of cigar scheme and four bulbs.




And here is the A end in my target scheme with one bulb.




So my choices are:
A and B with 1 bulb.
A with 1 bulb, and B with 3 or 4.

So I choose A and B with 1 bulb.

[u18b]

4.  Grab irons

Well, we’re not finished, because research has opened my eyes to something else I wish I had seen a long time ago.    Kumata modeled a grab iron on the boiler room.




But I noticed:  no grab iron here.




No grab iron here.




But here….. this is what the Kumata engineers saw….
Without thinking, it COULD be a grab iron.

But look closer.   It’s not a grab iron.   It’s a drain pipe that goes between the two Es all the way down to the bottom edge of the wall.  This is probably a pressure relief drain for the boiler.




This one is the most unusual with two pipes- one wrapping around the herald!




So I’m not sure what I’ll do at this point.  There is a hole for a grab in the brass wall.  Can it be covered up?   I have a testbed boiler room and I may experiment with different looks.

[u18b]

An important posting over the next day or so about another revision I’m making.

Well, I successfully solved a vexing problem I’ve had  for a long time-- not only with the EP-2, but also with almost ALL Kumata locomotives.

It has to do with the gearbox / truck retaining pin interface.

There is a slot in the bottom of the gearbox.  The truck goes into the box and then a headless screw goes into the slot and through the truck to retain it.   This photo is from a Trainmaster.



Well, the concern is the slop (or excess play) in this interface- which you can clearly see in that photo.  Edit:  That gap from the bottom of the headless retaining screw to the bottom of the slot is 22 mil.

Now look at the headless retaining screw.  It has two diameters.  The slot in the gearbox must be large enough for the wide portion where  the main truck gear rides.  The smaller portion touches the slot of the gearbox and transmits electricity toward the motor.



A caliper shows that there is a 14 mil difference between the fat portion and the skinny portion.

Added to the size of the slot, that means that the truck can float up and down by 22 mil.   This has implications for gear mesh.   

I’m not able to accurately measure the depth of gear teeth, but I can tell you what my eyes see. 

I use the screw under the motor to adjust the height of the motor and thus the gear mesh.  I set the screw so that the teeth on the truck gear show a tiny bit of daylight between the gear and the worm to avoid a bind.

When I make this adjustment, I PRESS the truck upward tightly and look through the sight hole I created.



But note…. From that setting…. the truck can now drop down 22 mil.
When that happens, the gear mesh goes to the other extreme and the teeth barely touch.

I’ve had situations where I thought I had the gear mesh set properly, but when running, had the gear “ratchet” where the gears pass each other and no longer mesh.    That’s how LITTLE room there is for error.

Further, there are a variety teeth.

Kumata employs at least two different teeth lengths.  As you can see in this photo.



Also, I showed a long time ago that I like to use modified Atlas/Kato U25B gears.  Because they are Delryn, they are quieter.  But I found they wear too fast- and I think this gap is part of the problem since the tips of the U25B gear wear.



After thinning, it works very well as a replacement.



So…… what to do?

One solution I have tried is to BEND the bottom of the gearbox to narrow the gap.  I did this early in my Kumata experimentation.



This does improved the gear mesh slightly by forcing the headless screw upward (on straight track!).  But there are a few problems.

1.  I’m obviously scared I’ll break the brace (after all, this is Zamac).  I always hold my breath when I ping the bottom of the brace.

2.  It makes installing the headless screw retainer hard because the fat part needs that space.  On locos where I have bent the bottom edge of the gearbox slot, I had to twist the truck to the side for more room.

3.  Will it last?  Have I damaged the integrity of the Zamac and caused it to prematurely fail one day?

So I stopped doing it- but have still looked for ways to solve this.

[u18b]

So all of that was to explain the problem.
Here now is the solution I came up with.

My first attempt at improvement was to glue a piece of brass pick-up strip (like from an Atlas SD50) in the slot.  That strip is 8 mil.  and  there is not much slop left.

Here is a shot of what I did.  It’s hard to see the glue applied on the top side of the stripe.     



And it worked!

The EP-2 cab ran great.  But I just didn’t like this solution.   The glue will get brittle one day and will eventually fail.  This does not seem like a lasting solution.   This is especially problematic for someone else’s loco who may not be able to repair when the failure comes.

I needed a way to keep the strip in place without glue.

[peteski]

Ron, what you did will likely eliminate possibility of the truck being able swing from side to side. That might be detrimental to the locos overall running quality, and power pickup on imperfect track.  If you examine any N scale loco (plastic or brass), the truck to chassis fit is a little loose allowing for the trucks to swing.  I think that in your quest you're trying to be too perfect in the worm to worm-gear mesh.

[u18b]

Pete, Good observation.  You are correct in that some play is needed, but it's not as bad as you're thinking.  My goal is not zero play.

First, that photo just above is a bit deceiving.  It's purpose is to show the spacer glued into position.  Unfortunately it appears from this angle that there is no play- and that's not the case.

Second, your post caused me to realize I was not as precise as I easily could have been.

I just measured the slot itself in the gearbox.   So here are the precise measurements:
Slot is 73 mil.
headless screw fat portion- 65 mil.
headless screw tips - 51 mil.

So since the tips ride in the slot, then the actual gap is 22 mil (not 14 mil- I made corrections in the text above).

So my point is- there is still a gap- just a smaller gap.

[u18b]

So here is what I’m doing now.

I take 16 mill brass strip.




Since I’m repeatedly cutting pieces off, I make sure the end is pretty square.





I then drill two holes toward the outside.  The holes need for a 1.4mm screw to pass through. 
Here is a template I used (NOTE: this procedure had problems- which I’ll discuss in a future post).




I then  taped that to the brass strip.




And use a fine awl to mark the hole.  (The hole must be relatively high on the gearbox.)





I drill the holes for M1.4 screws.

Then lay that on top of a gearbox half.  I line up the edge of the brass with the top edge of the slot as shown.   Now I can use a Sharpie marker to mark the holes on the gearbox.






Now I can drill and tap the gearbox for M1.4 screws.




I then enlarge the holes so that I can move the plate and more precisely position it.  A diamond dental bit is good for opening holes.



The plate is screwed into position- lining it up with edge of the slot.



I then cut and test fit a piece of pickup strip from a bigger Atlas loco, like a GP38/40SD50/60.  For example, the strips for a VO-1000 are more petite and not as helpful.  These strips are 5.5 mil- which is a little thinner that my first attempt with glue.

These bigger loco strips are perfect because they are slightly wider than the gearbox- so that if the inside edge is flush, then they stick out to the outside.  This is good because it gives me a soldering spot.

I clean it for soldering and apply flux to the brass edges of the plate.








Now the really tricky part.  I place the strip in place, hold it with tweezers and solder it in place.

It was terribly hard to hold in place.  But I finally found some tweezers that were the exact thickness of the resulting hole.    I wedged them in place.

 Notice I have not cut the brass plate short yet.  Keeping it long helps hold it all during the hot soldering process.

By the way, I turn my iron up to max- which is about 480+ degrees.   The gearbox will act as a heat sink which mist be overcome.



Once cool, I remove the plate and clean up the excess solder.  I also draw a line for cutting.




This is the back side.




But wait- I still need to open up the gear mesh sight hole, so I reinstall the plate.



And trace the hole with a marker.






This half is finished.   This is a great use for these M1.4 steel screws I found on ebay.   Their extra large heads help grip tight.



I repeated the procedure for the other side of the gearbox, reassembled the Cab and took it for a test run.  And the adaptation worked.  It ran wonderfully because the gear mesh was retained at an ideal spot.   I was surprised to note that even ran quieter- which was an indication that the excess play was allowing the truck to rattle a bit.

[peteski]

Sounds like you did consider that some sideways play is needed for reliable operation.
I had a good chuckle at you ending up using those large head screws so "nothing can ever move".  Like me, you like to grossly over-engineer things. Nothing's wrong with that! 

In this instance, simply gluing those brass plates using J-B Weld  epoxy or even CA glue would have been more than sufficient (since the glued area is large, and the load is minuscule), but why not make it better by using couple of screws!  I love it!  I would have likely glued *AND* screwed.   

[nkalanaga]

"grossly over-engineer things" pretty well describes GE's electrics from the early 20th century, so it's in keeping with the prototype.