Wednesday, June 17, 2020

AHM Krauss Maffei ML-4000 HO scale locomotive

AHM Krauss Maffei ML-4000 HO scale locomotive

Total Rebuild

After doing the Tenshodo SD24, I finally gained the skills necessary to revisit the AHM Krauss Maffei ML-4000 project that I started about 5 years ago.

When I started the project I found it simple to disassemble and strip all the paint.  The motor is a vertical shaft with a worm that goes down to a set of brass gears inside the rear truck.  Power is picked up from 2 axles on one side in the from, which is the right side and by a single axle on one side in the back.  The way this thing is able to work at all is because of the very heavy weight blocks.  It does run quite smooth in fact.  There are 2 traction tires in the rear.

The trucks are quite detailed with a single piece sideframe and screw on bottom cover.  This is the problem.  There is only 1 wire coming up from the center and to add power pickup was beyond my skill at that time.

Fast forward to the Tenshodo.  I had begun using the Tichy phosphor bronze wire to get more pickup out of the Bachmann and Life-Like trucks which lead to figuring out a way to do the same with the Tenshodo.  That's when I remembered the Krauss Maffei.  Could this method be adapted.  On the front truck, it was simple and a couple quarter inch holes in the frame floor gave plenty of clearance for turning.

Now for the rear truck.  There is a problem in that the motor just floats freely and is held in place with a spring clip.  The floor of the frame has a steel plate which is another obstacle.  Even if those two items are overcome,  2 wheels have traction tires and there is a serious clearance issue with the steel plate and motor in the way.  So let's see what we can do....

Wednesday, June 3, 2020

Bachmann pancake motor GP50 and Life-Like pancake motor GP38-2 Multiple Unit Build

Bachmann High Nose GP50 pancake motor
Life-Like High Nose GP38-2 pancake motor
Multiple Unit Build

I've got these 2 locomotives that I found at train shows.  They both have the infamous and notorious pancake motors.  A few years ago I airbrushed them with Rustoleum Gloss Red Enamel.  The paint jobs are actually pretty good, but did take weeks to fully cure.  I also put the decals on and number boards.  Then they sat in the junk pile for about 5 years.

I got the idea that I could use a 2 pin connector and make a connection between the two locomotives so that they would share power.  The reason is that they have plastic front wheels with traction tire and only get power from the rear truck.  Yes I could have replaced the wheels and made it all-wheel pickup, but I've lately been trying to think of ways to improve the original system without investing into replacement parts.

I rebuilt the motors to better than new performance.  In fact, the motors, despite being damaged and beat up, have come back to life in the most amazing way.  I've always believed in the pancake motor concept because it's proven itself in slot car racing.  The motors in DVD and CD-ROM drives are pancake motors with a better enclosure and more modern cores, but they are still pancake motors.  I'll probably be using one of those motors from an old DVD drive on a Bachmann steam engine that I've got sitting in the deadline.

So the concept of this operation is to make a PC board that collects power from the pickup truck.  Then power is routed to the motor.  But, a set of wires with a 2 pin quick connector will also be on that PC board.  The male connector will be on the outside of one of the locomotives and the female with a bit of the wire leads will be on the other.  When connected, the 2 locomotives will be sharing power pickup from 2 trucks instead of 1 truck each.

So let's see where this takes us....

Clean the wheels, polish them and paint the ends if you're going to do that now.  Clean any paint off the part that touches the rail.  Coat the back and tread area with Oxgard - it will stay greasy for a couple weeks then turn to a film.

Wipe a paper thin layer of red lithium high temp brake grease - which you get at any auto parts store in a little tub that will last decades - into the sockets that hold the axles.  No more than a paper thin layer and no excess.

You will lay the wheels into the centerpiece after the wipers are installed - but do not put the side frames on.  When you get to the phosphor bronze wire step, carefully set it upright without the sideframes on and with the wheels in place.

Rebuilding the power pickup trucks is one of the more difficult challenges.  The idea is to keep the copper wipers exactly as they are built.  They need to be cleaned with new black and red 32 awg silicone wire soldered to them.  Then they must be coated with Oxgard.  The new leads are threaded through the existing holes like usual.  But, before doing any of that we need to make a modification for the new parts we're going to make.  Look carefully at the truck and you will see a small hole where the wire gets threaded into the center so it can go up through the frame.  You will need to take a 1/16" drill bit and make a second hole that mirrors the one on the other side.  You will be drilling 2 holes, 1 on each side so that when you are done you will have holes that match.  This is super simple but hard to describe, there will be pictures later.  Look at the truck and see the holes that it came with are drilled near the axle socket.  You will make 2 new holes in the same way near the other socket - like a mirror.

Now you can install the copper wipers and thread the wire - red on one side, black on the other.  This wire goes through the hole that was factory made - right hand hole when you are looking at it laying on its side.

You will need a tube of phosphor bronze wire for the next step.  My goto wire for this is .0125 phosphor bronze from Tichy.  You will need to cut 2 pieces that are long enough to span the tops of the wheels on each side, but not so long that the sideframe can't be put back on.  Lay this piece on top of the wheels and mark a spot just to the right of the hole we drilled earlier.  Now tin this spot with solder and solder a red wire to one piece and a black wire to the other.

Next thread the wires through the holes we made - make sure the red is on the red side and the black is on the black side.  You can't do this wrong because the center piece of the truck will fit either way, it's totally the same.  Just get all the wires of one color on the same sides.

Pull the electric wire tight enough to keep the bronze wire touching the tops of the wheels.  At this point you will probably need a drop of super glue to hold the electric wire tight.  When you have everything they way you like it, put the side frames back on.

The pancake motor rebuild went very well.  With all the parts cleaned in the ultrasonic cleaner using Mean Green, the parts looked good.  The core was inspected and polished.  The motor housings were thoroughly cleaned in the ultrasonic.  Oxgard was applied to all the parts that needed it, but especially the screws that hold the housing and the brush covers.  these screws tend to rust over time.  The brush covers were polished and coated with Oxgard.  It's important not to get Oxgard on the actual brushes because it can cause them to become soft.  Better is to use powdered graphite inside the brush sockets to keep everything dry and free moving.  Once assembled and lubed carefully with red lithium grease the testing could begin.

The red lithium gets a little stiff when cold so it helps to warm things up.  Once in use, you would never believe how smooth a pancake motor can be.  Also, the sound changed.  The motor now sounds acceptable.  The annoying high whine is much less than before.  It sounds best at about 50% power.  Extra weight needed to be added at strategic points to help keep the wheels from picking points due to light weight.  The plastic pizza cutter wheels will reveal many track flaws.  Cheap switches that have rivets holding the points will get picked frequently.  At first I thought it might be a wheel gauge problem, but after checking and rechecking, I noticed that the locomotives had no problem on my hand laid switches.  The problem appeared on a couple switches where I used the cheapest snap switches where the rivet is not perfect.  I fixed a couple of these, but I marked them for replacement with my hand laid switches.

On the GP50 I put the socket on the rear pilot.  When I wired it I kept the red wires on the right and the black wires on the left.  This means that one of the locomotives needs to have the red and black reversed on the M.U. cable only.  So on the GP38-2 I put a solder pad on the rear pilot and brought the wires through.  This means that if I want to remove the shell I must unsolder the connections.  On the GP50, I put a disconnect on the inside so I can remove the shell.  One thing about the 2 pin connectors is that I shaved the off the teeth that hold the connection in place.  The reason for this is that the connectors are extremely difficult to disconnect in small spaces.  They are not likely to come apart so removing the locking teeth is no problem.  Also in the event of some failure of couplers the locomotives will just disconnect instead of dragging themselves by the wires.

The performance of the lash-up is off the charts fantastic.  Super slow, no stalls, excellent for switching ops. I would classify this as a huge success.  I'll add pictures pretty quick and do a youtube video of the performance.

So.... my U36Bs....  this is what I'm going to do to them.  I've pushed individual locomotive performance to the max, but with multiple units sharing power we have excellent performance.  The operating reliability is so far as good as anything else and will certainly get DCC.  BQ23-7s are another bunch that will get this treatment.  The bonus is that locomotives can be swapped around.  The AHM FM C-Liner project is now a total go - that will be a B unit with the cable on each end and the A units each with a socket.

Saturday, May 23, 2020

Brass Tenshodo SD24 Total Rebuild

Rebuilding a brass Tenshodo SD24

Part 1

The HO scale SD24 brass diesel locomotive by Tenshodo is a difficult beast to tame.  The goal of this project is to rebuild it and keep as much of the original mechanism as possible - but not the motor.  This locomotive is going to be powered by a rare earth super strong magnet 24 volt motor.

There are 3 mechanical challenges to overcome.  First is the linkage from the motor to the gear tower.  The original design uses a rubber hose.  This is a totally sound concept and the original hose can be replaced by a slightly more flexible silicone hose.  The silicone hose is very cheap and a single roll will probably last a lifetime.  The shaft on the gear tower is one size bigger that the shaft on the motor, but the hose does not have a problem with that.  If you have a locomotive with a worn out hose, the size I used has an outside diameter of 4mm and inside of 1mm.  I also tried a hose with 3mm outside diameter and found it to be too flexible, but still usable.  There is another option and that is to use standard splines and couplings like those found in an Athearn blue box locomotive.  The motor has a much smaller shaft than the Athearn, but since I can 3D print these parts that shouldn't be a problem.  We'll see if it's necessary after everything else is mechanically sound.

The second challenge is the power pickup.  The trucks pickup power from one side only - and then only from 2 of the 3 axles.  The middle axle floats and doesn't contribute to the pickup all the time.  It's not a dead axle, but it's not normally load bearing in order to prevent skidding type derailments.  With little to no weight on it most of the time it shouldn't be considered a reliable source of power, but....  The first upgrade that I am trying is the phosphor bronze wire trick.  If I can use a piece of phosphor bronze wire that wipes the top of all 3 wheels and then use a wire to my power collection board the reliability will improve dramatically.  If that works, it may be possible do it to the insulated side wheels giving me power pickup from all wheels - that would be huge.

Challenge 3 is the drive shaft connecting the 2 trucks on the underside.  This shaft tends to disconnect frequently.  I have successfully test a small silicone hose sleeve on the end that gives the trouble.  This seems to work so far, but the locomotive has yet to complete the obstacle course of tight switches and curves that I setup.  The goal here is to negotiate 18" radius curves and #4 crossovers without derailing.

The first step in the whole procedure is to make sure the trucks have reliable movement.  Gear binding seems to be a serious problem.  One of the worm gears needed sharpening on the drive shaft on the front truck so far, but is still suspect.  One of the axle gears had broken loose.  A single drop of super glue fixed that gear in place very tight, but now we have to see if the tolerance between axle and worm will mesh....

Several hours later.... the binding gear problem was solved.  The gear in question was examined much more closelier, yes closelier.  The gear was split.  To remove it the axle was heated with the big soldering gun and the insulated wheel comes right off.  My first thought was to replace it.  I found a plastic replacement that I could have used if I put one on each geared axle in both trucks.  Like I've said many times, shaft sizes and gears are not special.  When a gear is cut, it's cut using a tool that is a standard size.  The gear cutting set is like a machinist drill bit set in that the sizes are all indexed.  This is why you can almost always find a matching gear to anything that needs it, as long as you know where to look.  For now, I've just removed the old gear and someday I'll run across another wheelset that I can replace that axle.  Unless this project turns out to be much better than expected - then I'll replace all 4 gears from my plastic replacements.

Tomorrow's job will be seeing how smooth I can get it to run before I add the extra power pickup.

The phosphor bronze wire totally did the job.  The multimeter shows full voltage through the wires.  Now that power available, we can test it.  On the road test first we checked to see if the hoses used on the drive shafts both topside and underneath would hold.  The good news is that they work so well that they will be retained.  The hoses have done an excellent job.  The crossover test was successful and without difficulty we went over a large crossover that has long unpowered frogs.  We were able to make several times without derailing or stalling.  Next we tried a string of #4 switches that are from a mix of manufacturers.  Rail is brass, yellow brass, steel, nickel silver and we made it through without stalls or derailments.  Then we moved on to the 18" radius test and that was no problem.  Feeling extra brave, we went through a spaghetti bowl of very sharp turnouts and then down to the 15" radius that crosses open space over a concrete floor.  We went through the 15" with some grinding sounds, but stayed on the track both fast and slow.  I'm calling this rebuild a success so far.

Really digging into the locomotive and its inner workings has helped me step up my game to a new level.  For a couple of years I've considered this SD24 a piece of junk - and for good reason.  I haven't been able to find any good comments from people who have them or any stories of rebuilding them.  I know they are out there and hope this story will bring out other information.  Now that the locomotive is in very good working condition I can move into paint and decals.  I have something exciting in mind....

Now time for some pictures....

And that's a wrap.