Author Topic: Bachmann 44 tonner - making it better  (Read 6469 times)

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peteski

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Bachmann 44 tonner - making it better
« on: April 10, 2014, 05:13:00 AM »
+2
Friend of mine bough one of those locos to be used as a switched for an industry on his DCC layout.  it is not a bad model but he wasn't happy with the factory DCC decoder. He couldn't tune the speed range to his satisfaction. He likes Digitrax decoders, so I offered to retrofit it with a DZ125 decoder.  Since I had the loco apart anyways, I also made few other modifications to make it run better.

The locomotive was extremely over-lubricated. Grease was everywhere!  I took the trucks fully apart and degreased all the parts (including the frame halves). I also examined the electrical contacts in the truck frames. They were not springy enough to keep in good contact with the loco's frame.  My first modification was to make them more springy.  I accomplished that by grinding them to be narrower. I also cut slots in the pickups to elongate the contact strips. By making them narrower and longer, they were much more flexible.  I then bent them until they were in good contact with the frame at all times.


44t_pickups01.jpg

The truck on the left has the modified contact strip. Right one is unmodified.

Couple of hints on how to grind these strips down without ruining the truck:

1. I use a cutoff wheel in a Dremel tool, but for precise grinding (like needed here) I do not use a full-diameter wheel.  When I use cutoff wheels for larger and less precise jobs, I let them wear out to couple of smaller diameters (like 2/3, 1/2 and even smaller), then I save them for use later (like for this job).  Here I used a cutoff wheel of about 2/3 of original diameter here.

2. When grinding, do it at reduced speed for better control and less heating (and possibly melting plastic).  Grind very lightly (not much pressure), and make sure to grind in a direction or rotation which will not kick up the thin metal strip.  In this example, I held the Dremel on the left side of the truck as it shown in the photo above. 

To thin the right side of the finger I used the inner surface (one on the Dremel tool's side) as a grinding wheel. To thin the left side of the metal finger I would have used the opposite side of the cutoff wheel (facing to the outside). After thinning, I ground the slots extending the length of the finger by gently using the outside edge of the cutoff wheel.  Don't apply too much pressure so the metal pickup piece does not heat up and melt the gear case.


Next were the frame halves. I sanded and polished the metal areas which will be in contact with the truck's pickup strips.  I find that this produces a more reliable contact - better than just burnishing these areas.  Plus, the polishing compound seems to prevent further oxidation.


44t_pickups02.jpg

Next was the decoder conversion. I like clean installs, so I designed and etched a printed circuit board to replace the factory installed decoder.  It will hold the DZ125, new warm-white LEDs, the over-current protector for the motor, and the current limiting resistors for the LEDs.  I originally thought of eliminating the over-current protector (the yellow disc), but if Bachmann bothered to use it to protect the small motor, I didn't want to take any chances either. 


44t_dcc01.jpg


44t_dcc02.jpg

This is the new DCC board next to the original Bachmann decoder. It is amazing how many components there are on the very basic Bachmann decoder, and how large it is compared to the DZ125 (which has much more advanced capabilities).

Here is the new decoder attached (by the original screws) the the frame.  I had to file down the screw posts on the frame slightly to give me enough clearance for the decoder and the LEDs.


44t_dcc03.jpg

The last item I wanted to change was the coupler.  Not only is the Bachmann pseudo-McHenry "boxing glove" coupler ugly and large, it is also a bit stiff when coupling and uncoupling (which is what this loco constantly does on the layout).

I figured out a way to retrofit it with the offset shank (2001?) MT coupler.  I could have used a Z scale coupler, but for the sake of reliable coupling I used the N scale coupler.

First, I cut off the post inside the coupler box. Then I enlarged the hole until the post in the Bachmann shell fit inside the hole.  I also had to enlarge the coupler opening in the pilot to be able to install the MT coupler box. I just had to trim the sides of the opening.


44t_coupler01.jpg

I then carefully assembled the coupler and the spring in the coupler box. This was a bit of a pain, but I finally managed.


44t_coupler02.jpg

I then installed the coupler box cover and fastened it using the original Bachmann coupler screw.  The only problem is that because the Bachmann's coupler post doesn't extend all the way to the new coupler box cover, the cover can shift a bit to the front and back.  This messes up the coupler centering.  I aligned the top and bottom part of the MT coupler box, then using a soldering iron, I welded the box halves together. That way they will stay aligned.

While it is still a bit large and sticks out a bit far, it looks better than the Bachmann coupler, and it will also work smoother.


44t_coupler03.jpg

My friend told me that the loco now runs better than ever.  :)
« Last Edit: December 15, 2018, 02:58:17 PM by peteski »
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Chris333

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Re: Bachmann 44 tonner - making it better
« Reply #1 on: April 10, 2014, 05:50:19 AM »
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"making it better"  I thought you were gonna norrow the hood  :D

peteski

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Re: Bachmann 44 tonner - making it better
« Reply #2 on: April 10, 2014, 05:55:09 AM »
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"making it better"  I thought you were gonna norrow the hood  :D

That's funny Chris!  :)  I didn't say "more prototypical"  :P
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reinhardtjh

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Re: Bachmann 44 tonner - making it better
« Reply #3 on: April 10, 2014, 10:03:22 AM »
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Neat job on that PC board, Peteski.  I've been looking into that for other DCC conversions also but I don't have the stuff to make my own boards.  Yet.
John H. Reinhardt
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C855B

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Re: Bachmann 44 tonner - making it better
« Reply #4 on: April 10, 2014, 10:09:55 AM »
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... It is amazing how many components there are on the very basic Bachmann decoder ...

Don't forget most of that junk on the top of the board is for RFI suppression to meet Euro appliance guidelines. Chokes and high-value caps don't miniaturize well. :|
...mike

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Ed Kapuscinski

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Re: Bachmann 44 tonner - making it better
« Reply #5 on: April 10, 2014, 10:56:05 AM »
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Pretty awesome.

I really dig the hand-drawn circuit board, and how effective it is in this situation.

Denver Road Doug

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Re: Bachmann 44 tonner - making it better
« Reply #6 on: April 10, 2014, 11:10:30 AM »
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Pretty awesome.

I really dig the hand-drawn circuit board, and how effective it is in this situation.

+1
NOTE: I'm no longer active on this forum.   If you need to contact me, use the e-mail address (or visit the website link) attached to this username.  Thanks.

dnhouston

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Re: Bachmann 44 tonner - making it better
« Reply #7 on: April 10, 2014, 11:20:36 AM »
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Nice work Peteski.  Any chance you'd be willing to create and sell some of those replacement boards preassembled?
David

JMaurer1

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Re: Bachmann 44 tonner - making it better
« Reply #8 on: April 10, 2014, 11:22:42 AM »
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What he said
Sacramento Valley NTrak

rschaffter

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Re: Bachmann 44 tonner - making it better
« Reply #9 on: April 10, 2014, 11:49:43 AM »
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Nice job, Pete!  :)
Cheers,
Rod Schaffter

mmagliaro

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Re: Bachmann 44 tonner - making it better
« Reply #10 on: April 10, 2014, 07:03:29 PM »
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Very nice work.   Did you use one of those ink pens to draw out your PC board?  I haven't done that since
the 1970s, but it sure is handy for small one-shot boards like this.   Looks very neat.

What do you use to polish the metal?  I really like the look of those contact surfaces.  That would be a great
thing to try on the undersides of some Kato diesels and other engines that depend on truck frames rubbing
on the split frame to make contact.


up1950s

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Re: Bachmann 44 tonner - making it better
« Reply #11 on: April 10, 2014, 07:32:22 PM »
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Also like the PC board . I have MM etch stuff , 5 years old at least , some day maybe i'll read up and use it when I get an itch to etch but when is still sketchy .

OldEastRR

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Re: Bachmann 44 tonner - making it better
« Reply #12 on: April 10, 2014, 07:58:03 PM »
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So now you can see thru the cab?

jmlaboda

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Re: Bachmann 44 tonner - making it better
« Reply #13 on: April 11, 2014, 02:44:12 AM »
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Can't wait to build a 65-tonner from the 44T and 70T models...


wm3798

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Re: Bachmann 44 tonner - making it better
« Reply #14 on: April 11, 2014, 09:00:19 AM »
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I like that conversion.  I've got one sitting on my desk waiting for me to build a switching layout, and what little I've run it I find quite frustrating.  Jackrabbit starts, very little slow speed control, and dull headlamps.

I'll be the third to ask about having a board printed...

And yeah, the Bachmann decoder looks like it's built with vacuum tubes and snap relays... :facepalm:

Lee
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Lee Weldon www.wmrywesternlines.net