Boosted output from an amplified Mike...

Discussion in 'The Academy' started by doctorwayne, Apr 15, 2006.

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  1. doctorwayne

    doctorwayne Active Member

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    ...or to put it another way: how to boost the pulling power of the Athearn Mikado and improve its over-all performance. If this subject is of interest to you, please read through before starting: while not particularily difficult, it involves working with lead, so if you're uncomfortable with this, save your time. The gain is dependent upon addition of lead.
    The first step is to disassemble the locomotive, making notes and/or sketches as required, to aid in re-assembly. First, disengage the boiler braces from the sides of the smokebox, then remove and discard the long screw that goes up through the cylinder block. Disengage the lower ends of the cab handrails, and then, using a small flat screwdriver, carefully spread, from the inside, the bottom front corners of the cab, and lift off the cab. Next, squeeze the lower rear end of the boiler between your thumb and forefinger, in order to disengage the tabs that protrude through the firebox, then lift. Continue lifting the rear of the boiler until it is high enough to clear the top of the motor (this is a tight fit). Now slide the boiler forward until it clears the front of the main boiler weight, and set aside. To remove the weight/motor/idler gear unit, remove the screws from both sides of the boiler weight (above the lead driver), and the screws from the motor terminals (bottom rear area of the motor). Lift off the entire assembly, feeding the "pigtail" through the slot at the rear (the small circuit board on the end of the pigtail must be removed to obtain enough clearance).
    [​IMG]

    Now, slide the running board/lower boiler assembly to the rear, until the protrusion on the chassis is clear of the slot in the lower cab backplate. Lift off, and set aside, taking care to not lose the screws.
    To disassemble the weight, remove the three screws (and nuts) as shown in the photo below. Don't lose the plastic spacers from between the halves of the weight. Carefully separate the two parts of the weight: the motor and driveline should stay together with one side or the other.
    [​IMG]

    If you are using DCC, or want working lights but don't wish to rewire them, skip this step. I feel that the "pigtail" adversely affects the tracking qualities of the tender, so I remove it. To do so, strip the heat shink tubing from the wires and cut the Red and Black wires near the circuit board. Unsolder the Grey wire from the upper motor terminal and replace it with the bare end of the shortened Black wire. Repeat this operation, using the shortened Red wire to replace the Orange wire on the lower motor terminal. On re-assembly, the brass terminal connectors on the other ends of these wires will be screwed on at the rear of the motor as before, Red on the right (engineer's side), Black on the left (fireman's side).
    Mark the top of the motor, and note the placement of the worm bearings and the idler gearbox. Remove the motor/flywheel/worm/bearings as a unit and set aside. Remove the idler gearbox. Wipe the stripped-down weight halves of excess grease and oil.

    Using a suitable square, and working on the inside face of each half weight,project a line from the forward face of the gearbox protrusion up to the top edge of the weight, then carry this line onto the outer surface of the weight.
    [​IMG]

    Using a suitable straightedge, line it up with the top edge of the two bearing retainer slots machined into the casting. Scribe or mark a line from the previously scribed vertical line, forward to the end of the flat surface. The arrows on the photo indicate the bearing slots.
    [​IMG]

    Scribe another vertical line mid-way between the hole for the front screw/spacer/nut and the square depression machined into the bottom of the weight, which accepts the mounting protrusion that extends upward from the chassis. This line represents the first cut, which will remove the shaded area in the photo.
    [​IMG]
  2. doctorwayne

    doctorwayne Active Member

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    Using a hacksaw, make the first cut, removing the front of both halves of the weight. Next, cut along the two lines to remove the shaded area, then clean up all cuts with a mill file.
    [​IMG]

    The next photo shows two modified halves at the top, with two unmodified half-weights below.
    [​IMG]

    I removed, using the same techniques, an additional small amount from the stock weights, as shown by the shaded area.
    [​IMG]

    The stripped-down stock weight weighed 5 1/4 ounces, while our cut-down version tips the scales at 3 1/2 ounces, a net loss of 1 3/4 ounces.

    Now we need to make new weights. I use old wheel balancing weights, obtained free from a local tire shop. Using a suitable metal container and a propane torch, you can melt the wheel weights, which will allow the steel clips and dirt and impurities to float to the surface of the molten lead, where they can be removed. First though, we need to make some moulds. I used .015" sheet aluminum (scrap aluminum siding will also work: make sure that the painted side faces out).
    [​IMG]

    These are simple tubes, held together with soft steel wire. The inserts (one per tube) are to provide a rough profile of the "step" required to nest this casting into the end of the modified stock casting. Cut the curved end to match the diameter of the tube: the other end is pinched over, as shown on the upright mould to the right side of the photo. To pour the weights, the moulds should be standing, as shown, on a metal sheet.
    When handling the lead, do not eat, smoke, pick your nose, or in any other way ingest lead residue from your hands. Always wash your hands thoroughly after handling lead and don't leave it where children or pets can come in contact with it. I always wear a two-stage respirator when melting and pouring the lead, although workers that I spoke with at a lead casting factory assured me that no harmful fumes are released when lead reaches its melting temperature. At higher temperatures, lead vapours are released and are very harmful to breathe. (I worked in a steel mill where we occasionally rolled a grade of steel with a high lead content: breathing protection was required, as the rolling temperature was 2350 degrees Fahrenheit, and the sweetish smell of the lead vapours was everywhere).
    When the lead is molten, and the impurities have been removed, gently pour it into the upright mould. I hold the mould with a pair of channel locks to prevent tipping. Make sure that you have enough lead to fill the mould in one pour. If some slops, or if you accidently overfill the mould, don't worry: you can go back after the mould is filled and play the torch flame over the offending mess and it will soften and drop off. Make sure that the lead has cooled (this takes more than a couple of minutes) before removing the mould. The insert may need to be removed from the casting with pliers if there was leakage between it and the mould.
    Now you need a coarse file to shape the rough casting: any will work, but I've found that the type used in autobody work is the fastest. Clamp the rough casting in a vise for this. You need to shape the back end of the lead so that it mates with the front end of the modified stock weight, and adjust the diameter so that the assembled pieces will fit into the plastic boiler casting. File and fit until satisfactory, then thoroughly clean the stock weights with soap and water to remove all grease, oil, and filings. Reassemble the motor/drivetrain assembly back into the modified weight, paying attention that the depressions on the edges of the plastic bearing retainers face to either side, with the protruding nubs oriented vertically, so as to be trapped between the halves of the weight. The plastic spacer with the smaller flange installs between the halves of the weight at the upper rear of the motor.
    I also cast small lead weights that go on top of the frame just behind the cylinder casting and another that fits into the cylinder itself. These, as well as the large lead weight, are insulated from the frame with electrician's tape.
    [​IMG]
  3. doctorwayne

    doctorwayne Active Member

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    Also shown in the photo above are the new air tanks: these are pieces of brass tubing, filled with lead, and fitted with brass mounting bands.
    The first step is to remove the plastic air tanks. I used a utility knife for this, as the mounting lugs cast onto the boiler shell are fairly heavy.
    [​IMG]
  4. doctorwayne

    doctorwayne Active Member

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    Next, we need to remove the cooling coils, complete with their mounting pins, from the air tanks. Some of the ones on my locos simply pulled out, while others required that the tank be carved away from them. This photo doesn't show it very clearly, but the knife is used to remove a wedge of material from the air tank, with the mounting pin in its middle, then the excess material is trimmed away from the pin.
    [​IMG]
  5. doctorwayne

    doctorwayne Active Member

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    Some of the cooling coil mounting pins fit into bosses cast on the underside of the running boards. We need to remove part of these in order for the new air tanks to sit snug against the underside of the running boards and we also need to retain part of these bosses for re-attaching the cooling coils. In the photo below, the chisel blade is cutting down along the curve of the boiler, while the other blade is cutting on an angle towards it. The piece between the two blades is to be removed, then the back end of the remaining piece carefully trimmed until the new air tank will lie flat on the underside of the running board.
    [​IMG]
  6. doctorwayne

    doctorwayne Active Member

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    Below is a view of the new air tanks, ready for installation. I used brass wire, inserted into holes drilled in the back of the tanks, as mounting pins, pushed into appropriate holes drilled in the boiler, along with some epoxy where the running board meets the boiler. The slots, cut into the two front air tanks (using a cut-off disc in a Dremel tool), are for the cooling coil mounting pins that were cut free from the tanks earlier. The mounting boss that was trimmed in the previous step can be seen to the left of the brass tank on the right: the mounting pin of the cooling coil will be epoxied into it.
    [​IMG]

    [​IMG]
  7. doctorwayne

    doctorwayne Active Member

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    The balance of the loco work involves reassembly and, if you wish, detailing, paint, etc. I also modified the tenders to pick up current, using trucks from the Bachmann Consolidation. To use these trucks, the mounting bolsters on the Athearn tender need to be cut down enough so that proper coupler height is maintained. I set mine up so that the rear truck picks up from the right rail and feeds to the right (Red) terminal on the motor, while the front truck picks up from the left rail and feeds to the left (Black) terminal on the motor. If you've retained the pigtail and circuit board, you'll need to figure out where to connect the wires, which may make separation of the tender from the loco difficult. I used a two conductor mini plug between the loco and tender, which works well for my unlit, DC powered locos.
    [​IMG]
  8. doctorwayne

    doctorwayne Active Member

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    The stock Athearn Mikado, loco only, weighs 12.5 oz., balanced at the rear of the third driver. The modified Mike weighs 16.75 oz., balanced at the mid-point of the driver wheelbase. I have removed the overly strong spring fron the trailing truck, as this tends to shift the balance point too far forward. I may experiment with the spring reinstalled, with more weight added inside the cab. As it stands, the added weight, along with the shift forward of the balance point, has greatly increased the pulling power of these locos. I operate them as pairs: two will handle a 13 car coal train (100 oz. weight) up the 2.5% ruling grade on the subdivision or will pull a 24 car merchandise train up the same hill. The grade is laid out on a 34" radius "S" curve, with the distance between the curves shorter even than the length of the 13 car train, so the effect of the grade is compounded by the curves.
    Here are a couple of builder's photos.
    [​IMG]

    [​IMG]
  9. doctorwayne

    doctorwayne Active Member

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    And another of two of them in service at Lowbanks.
    [​IMG]
  10. doctorwayne

    doctorwayne Active Member

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    And finally, a shot of the 636 at speed, near Airline Junction, on the Grand Valley.
    [​IMG]
  11. doctorwayne

    doctorwayne Active Member

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    I hope that some of you have found the foregoing to be of some use or interest. Your questions and comments are welcomed.


    Wayne
  12. MasonJar

    MasonJar It's not rocket surgery

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    Wayne...

    Nice work. Very good how-to. When I get around to it, can I move this to "The Academy"?

    Andrew
  13. MilesWestern

    MilesWestern Active Member

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    Dr. Wayne, were you inspired by my pic of the TrainMaster at speed? ;)
  14. doctorwayne

    doctorwayne Active Member

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    You're right Miles, your picture was the inspiration for my photo: that's the only one of about twenty that was even recognizable.
    Andrew, thanks for the vote of confidence, but I think that those first ten pictures are linked from Photobucket. It's my intention to put all of the photos in the Gallery, and then link them to the thread, but I'm really busy doing a renovation right now, so trains are sorta on the back burner for a while. To be quite honest, I'm not sure that it would be worth the effort for you anyway, as this isn't what you'd call a high traffic thread. I think that the use of lead has put a lot of people off, coupled with the fact that this isn't a one evening project.

    Wayne
  15. MasonJar

    MasonJar It's not rocket surgery

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    Interesting about the lead and the apparent lack of vapour at low melting temps. I think you are wise to use a mask anyway! Have you heard of or used a product called "Temp-Lo"? It is a dense, low melting point metal that is supposed to be safer. I think Trainclown inquired about it some time ago. I am sure it is not as cheap as the wheel balance weights...!

    There are all levels of experience here at The Gauge. I would not count your excellent how-to out. I think it is a worthy addition to The Academy.

    Andrew
  16. Art67

    Art67 Member

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    Excellant "how-to" tutorial. I will certainly refer to it if I ever get to that level of super detailing my steamers. The Photo of the train racing down the main is fantastic as well. Thanks for sharing.

    Stuart
  17. modelsof1900

    modelsof1900 Member

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    Hi Wayne,

    an excellent step by step modeling! Your work changing good models to very spezific steam locos is remarkable! Congratulations! :thumb: :thumb: :thumb:

    Bernhard
  18. doctorwayne

    doctorwayne Active Member

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    Just a bump to let any interested parties know that the photos from this thread are now all available for viewing in the Gallery.

    Wayne
  19. steamhead

    steamhead Active Member

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    Hi,

    Great tutorial & great results!! This gives me some ideas I might want to try on a B'mann SY 2-8-2 that can barely pull a small consist (4-5 cars) up a 2% grade without slipping its wheels! Looks like this loco is destined to run only on my "Plywood Flats".

    Gus (LC&P).
  20. MasonJar

    MasonJar It's not rocket surgery

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    This thread was moved to The Academy 09 Nov 2006. Some posts may have been edited for clarity.

    The thread is now locked. If you have any questions about the information presented here, please post them in General Talk with a link to this thread.

    Andrew
    'The Academy' Moderator
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