Best Of The TP56/TP70 Kitbash thread N scale

[u18b]

Ron, just for kicks can you install those zener diodes just to test how it changes the speed?

David

They would have to be pretty tiny ones.

And I wouldn't even know what to buy.

Would they go back to back.  Solder the ends together,   and then insert them between a motor pole and a wire (say the gray wire)?

[u18b]

Ok, I'll join the party....
My shells arrived today. Being in Germany, they are printed in the Netherlands.

Welcome!

I look forward to seeing yours!

[u18b]

When you look at this photo..... you notice that huge gap under the cab.
And because that gap is so big, the sanding hose really stands out.

So I figured I needed some.




I made this side a little too snug.  But looks good.  I'm using .008 guitar string (much tougher than brass wire- but harder to work with and form too!).

I soldered these wires directly to the brass frame.

(ignore the fuzz, ignore the fuzz.  Don't look at the fuzz    )




The front was a bit more challenging.  On the green unit (above), the hose runs down from the nose in FRONT of the fuel tank and then goes under.

The black unit has the front hoses going down BEHIND the fuel tank.




I don't have an I-beam frame to hide the source of the hose, so I decided to mount it in the fuel tank itself in the middle where it would not be seen.

[u18b]

I sent the following email to the address on the Tractive Power website.
Hope to hear back from someone.

-------------------------

 Hi,

I am a modeler and enjoying building a model of your TP56/TP70.


What an amazing switcher!


I have some questions and would love to correspond with someone from the company who can provide clarifications.


Here are my questions and information if you could please confirm or correct.


It appears to me that you have made three of these.


1. The first one made, or demonstrator, was black and numbered 5601. It appears shorter than the other two. It appears the fuel tank is mounted in the engine compartment.   Sold to

Parish & Heimbecker Ltd. I saw this referred to once as a TP1, but I'm thinking that must not be correct.  Your blueprints obviously call it a TP56.



2. The next was the green one. A TP56 sold/leased to Curry Rail.


3. And then there is the black one. Is this a TP70? Except for the headlight, it looks identical to the green one. This one appears to be leased.


Have you made any more? Or plan to?


And lastly, we have attempted to model your TP56/70.  I'm building the black one, others are building the green. But we had to guess on some of the dimensions. The dimensions you published seem to be for the demo unit maybe.


Here is a photo of my model in progress.





Do you have some kind of blueprints or plans beyond the ones on the website? As I said before, the first demo unit appears to be a bit shorter. So more accurate drawings for the green TP56 or black TP70 would be helpful.



If you want to do some reading on the creation of this model, it may be found at a modeling discussion board called The Railwire:

https://www.therailwire.net/forum/index.php?topic=42126.0


We are a group of modelers that enjoy getting things as accurate as possible- thus my reaching out to you.


Once again, you do amazing work.


Thank you for your time.

I genuinely hope to hear from someone.


Best wishes.


Ron Bearden

[mmagliaro]

They would have to be pretty tiny ones.

And I wouldn't even know what to buy.

Would they go back to back.  Solder the ends together,   and then insert them between a motor pole and a wire (say the gray wire)?

Correct, if we are both interpreted "back to back" correctly.  End-to-end is probably a better term.  And yes, then you just put them in-line in one of the motor leads.
end-to-end like this:



The part should be a 5.1v zener.  The forward conducting zener will drop 0.7v and the reverse conducting one will drop 5.1, for a total of 5.8, so with a 12v decoder output maximum, that gets you 12-5.8 = 6.2, pretty darn close to a maximum of 6.    Power... 5.1 x 0.1 = about 1/2 watt. 
So this depends on your maximum current.  If your motor draws under 100 mA, you can use 1/2 watt zeners (let's be safe... if it draws under 80 mA, you can use 1/2 watt zeners.).    You probably don't want anything bigger because a  1 watt zener will make a lot of heat - enough to melt plastic.

Here's a surface mount option:
http://www.mouser.com/ProductDetail/Vishay-Semiconductors/MMSZ5231C-E3-08/?qs=sGAEpiMZZMtQ8nqTKtFS%2fGqv07jO8JlbzeNSDEwA1us%3d

Here's a conventional lead option:
http://www.mouser.com/ProductDetail/Central-Semiconductor/1N751A-TR/?qs=sGAEpiMZZMtQ8nqTKtFS%2fDCq3ePMRaeFizzIF3dHYJ8%3d

But since you have a decoder in there, you have already programmed it so that the highest speed step is at 6 volts, right?  If you did that, there is no purpose for adding the zener diodes.

dcutting:
Remember that zener diodes are not going to magically allow this engine to run any slower than its present mechanical capabilities.  All they do is protect the motor from being driven with too high a voltge (which could burn it out).

[mmagliaro]

And by the way, Ron...

This has been a wonderful bit of modeling and engineering.  Nice work!

[peteski]

But since you have a decoder in there, you have already programmed it so that the highest speed step is at 6 volts, right?  If you did that, there is no purpose for adding the zener diodes.

dcutting:
Remember that zener diodes are not going to magically allow this engine to run any slower than its present mechanical capabilities.  All they do is protect the motor from being driven with too high a voltge (which could burn it out).

Max, the anal part of my brain is still worried that even at "6 Volts DCC" the 6V motor actually receives 50% duty cycle square-wave 12V pulses.

[up1950s]

delete

[mmagliaro]

Max, the anal part of my brain is still worried that even at "6 Volts DCC" the 6V motor actually receives 50% duty cycle square-wave 12V pulses.

Yeeeeaaaahhhh...... I hear you on that.   I admit I am on thin electromagnetic ice here, but my thinking goes like this.
What really fries a motor is the heat in the motor windings, which is a function of the current draw.  (For anyone
following this motor diatribe along, this is a key point.  It really helps to stop focusing on the voltage and instead think about current draw and heat dissipation when it comes to motor overloads.)

If the average voltage is never above 6, the average current (and heat) could never be higher than the windings can stand.   There is always a time factor involved in overload conditions.  The winding wire can burn only if it is subjected to enough current for a long enough time.  If the motor isn't heating up, my gut tells me we are not forcing the windings to dissipate more heat than they can stand, even at the widest PWM pulses.  If the temperature of the winding wire isn't rising, it's not going to burn out.

What would I do if it were my engine?  I have to admit that since I'm not 100% sure of my above theory,
I'd put the zeners in unless there was simply no way I could make them fit.  They are cheap insurance.

[up1950s]

Max, the anal part of my brain is still worried that even at "6 Volts DCC" the 6V motor actually receives 50% duty cycle square-wave 12V pulses.

duty cycle

[u18b]

I obviously have not heard back from the company yet.....

But I have figured out a bit on my own.

When you first encounter something new, your brain is in info overload.  But over time, you begin to sort things out and notice things.

That's what I've done, and will share here.


We start with the TP56 Demo Unit

It has no visible fuel tank.  Notice there is one access door under the cab, placed forward.
Be sure and note the first and second stanchion are placed close together.




Here it is first being built.  This is a helpful pic.




You can see in that photo a couple of things.
1.  This TP56 has some kind of collision posts on either side of the rear cab door (not present on the others).
2.  On this side there is a small access door under the cab.
3.  The fuel tank is actually inside the engine compartment next to the engine.  You can see the tank there on the far side of the CAT engine.  Thus fuel must be added on the right side of the switcher.

And so in this photo, knowing where to look, you can see a little access door for fuel- just like on your car.   It is not marked, but that MUST be what that little door is for.




Now, this view shows a couple of things.



When the demo first built, there were no number boards.

Also, it has ditch lights.
And huge lift rings above the ditchlights.
Notice also the lower rear windows are smaller.
And there is a drop step.

Here is the same loco, but now it has number boards.
And notice the road number....



#5601 is not a co-incidence.
It is a TP56, and this is the first one.

Having understood all this, the drawing now makes sense- and why the numbers did not come out as we expected.

Study the plans and you will see:
No fuel tank, huge lift rings, ditchlights, small left access door under the cab and number boards.

So these drawings are for the DEMO model, not the other two.




You can also see that the info below would appear to apply to the Demo unit.
Note rated at 80 tons.




TP70  #0002

Now this photo is helpful for info.




The one in the background is black and #0002 and is nearing completion.   So that means the one in the foreground is the green one.

That means the black one was build second and the green third.   The road number 0002 is also a clue.

This news spot from Railway Gazzette (info probably released by TPC) says TP70 was second and weighs 91 tons.   The blurb also mentions a demonstrator.... but then has a picture of the green one (that was a source of confusion).  So I think the picture is wrong).

http://www.railwaygazette.com/news/traction-rolling-stock/single-view/view/tier-4-industrial-shunting-locomotive.html

But then I found a brochure from Tractive Power Corp itself which clearly shows number 0002 as a TP70.

http://www.tractivepowercorp.com/wp-content/uploads/2017/01/TP70_012017_Brochure.pdf


So let's look at the TP70.


This shot shows that the headlight on unit #2 is recessed in the nose just like on the Demo.



And it one has no ditchlights, and no drop step.




The TP70 has an external fuel tank.    And the access doors are bigger and double.




This shot clearly shows that the first and second stanchion are further apart than the demo- thus confirming the extra length.
Note the A/C is pretty close to the horn.




TP56 is unit number 3.  It is the green one.

We know the green one is a TP56 because it says so on the cab!

Externally, it appears identical to the TP70 with only one exception- the headlight.

Here is a side-on shot that also shows 1 and 2 (from the cab) stanchions farther apart like the TP70.




But this shot clearly shows the headlight is surface mounted on the nose.
A minor detail, but still a difference.




And lastly, here are 4 views for painting purposes.
Note the A/C unit is mounted off center in the roof shot.
Also, the walkway top surface is gray.
(have not found any high shots of the TP70).











Happy Modelling!

[u18b]

Also, as for the fantastic job David did....

He did an early drawing of the demo unit (David I hope you saved the file in case someone wants to build that one).
If you add it to the line, I would call it TP56 Demo.
It was not my first choice just because that tiny fuel tank looks cool.
But someone might want it for the ditchlights.

Also, it is a pretty minor detail, but the shell I got from David is technically a TP70- only going by the headlight.

Not sure if it is worth it to make another whole TP56 shell just for the non-recessed headlight.

To David:

If you ever do tinker with the drawing, there are a couple of minor things I would add/change.

1.  Dimples for the windshield wipers on the front.   You added dimples for the rear (thanks), but the two big front windows need them as well and also the small right window in front of the engineer.

2.  Add dimples to the side of the walkway.  It can be a bit tricky to know where to start drilling.
I'll provide some side on shots of my model, but you can probably use some side on shots of the prototype.

3.  Dimples on the top surface of the walkway for the pilot stanchions on the ends.  I moved mine back from the edge just a tiny bit so that the drill bit would go THROUGH the shell just behind the inside surface of the pilot.   To go more forward means you will be drilling into the pilot all the way.  My way, I could add glue on the underside to help hold the stanchion.

4.  Make the brake stand wider.   It's a minor detail, but I see from photos that the brake stand is visually about as wide as the tool box opposite.

5.  Make the walkway with no cut out at the cab.  Just my 2 cents having worked with this.   The B-HDA material is a bit flexible.  And the walkway is pretty thin right there.   It would be more rigid with no cut-out.   Now, I have a weight sitting there, but a smaller weight could be glued inside the cab.   You would lose a few grams of weight, but not that much.

6.  Since the shapeways product bows and curves slightly- and this is a known issue..... the greatest casualty is the steps.  Why not adapt and make the steps a little longer.  If someone amazingly gets an unwarped shell, they can file the steps down very easily.  We're talking 1 or 2 mm would make a difference.


This is such a great model.

Thanks for helping to make this happen.

[u18b]

Correct, if we are both interpreted "back to back" correctly.  End-to-end is probably a better term.  And yes, then you just put them in-line in one of the motor leads.
end-to-end like this:



The part should be a 5.1v zener.  The forward conducting zener will drop 0.7v and the reverse conducting one will drop 5.1, for a total of 5.8, so with a 12v decoder output maximum, that gets you 12-5.8 = 6.2, pretty darn close to a maximum of 6.    Power... 5.1 x 0.1 = about 1/2 watt. 
So this depends on your maximum current.  If your motor draws under 100 mA, you can use 1/2 watt zeners (let's be safe... if it draws under 80 mA, you can use 1/2 watt zeners.).    You probably don't want anything bigger because a  1 watt zener will make a lot of heat - enough to melt plastic.

Here's a surface mount option:
http://www.mouser.com/ProductDetail/Vishay-Semiconductors/MMSZ5231C-E3-08/?qs=sGAEpiMZZMtQ8nqTKtFS%2fGqv07jO8JlbzeNSDEwA1us%3d

Here's a conventional lead option:
http://www.mouser.com/ProductDetail/Central-Semiconductor/1N751A-TR/?qs=sGAEpiMZZMtQ8nqTKtFS%2fDCq3ePMRaeFizzIF3dHYJ8%3d

But since you have a decoder in there, you have already programmed it so that the highest speed step is at 6 volts, right?  If you did that, there is no purpose for adding the zener diodes.

dcutting:
Remember that zener diodes are not going to magically allow this engine to run any slower than its present mechanical capabilities.  All they do is protect the motor from being driven with too high a voltge (which could burn it out).

Glad you had that drawing.   I was thinking side by side and reversed.  Your drawing helps.

So let me make sure I understand what is being argued.

This is a pager motor.
Limited to 6 volts.

But the decoder will send out 12 v pulses just like a throttle-- regardless of what I set Vmin and Vmax.

So adding these will protect the tiny motor better.

And after they are installed, adjust Vmin, Vmax etc.

Right?   

[u18b]

And by the way, Ron...

This has been a wonderful bit of modeling and engineering.  Nice work!

Thanks Max.

[u18b]

My package came from Kato today.
Got my F40PH Metra A/C unit  (thanks again Jane!)

But I also ordered some HTCR trucks.

If some of you are wanting to build one of these critters, but the lack of HTC trucks is holding you back.....
And you're willing to make a slight foobie with different trucks....

I can confirm that the HTCR (radial) trucks are identical to the sd40-2 Mid HTC trucks- except for the sideframes.

These would be a good choice because they are visually close to the HTC trucks.

The only problem I noted was....

The HTC truck is perfect because it is flat all the way across.

The HTCR truck is not.  I has one high spot in the middle.  Study the photo below.  What Kato did was make the brake cylinder more 3D.  So you could take an Xacto knife and trim the plastic just in front of the pickup that sticks up.

In my case, I stole two trucks from my BN SD40-2 mid.   These trucks are now under it and it runs happily (and looks kind of cool-- I might keep it this way!     ).



So if the truck is the only thing holding you back..... Kato is out of the HTC trucks and will not be re-running them any time soon (Got that in Orlando).

But they DO have these trucks in.

929321R trucks.  HTCR phase 2 truck.
For the SD70M revised and the SD70ACe.

http://search.cartserver.com/search/search.cgi?cartid=s-1078&keywords=NSD70MREV&maxhits=100&go=List+Parts&bool=AND&bool=AND

And they have more than one color (different part numbers though).