Assembling the parts

In order to get to where I'd like to get with this project, I spent some time (and some money) ordering in the parts I could find from various sources - Details by Eric, Walthers, and Litchfield Station.

With the decoder, I also ordered a small, small speaker. I'm going to try and not put the speaker in the cab, so hopefully this one will work.

With the arrival yesterday of the decoder and speaker from Litchfield Station, I can now start moving forward, as despite having the detail parts for a while, I want to get the mechanics up and running solidy before working on the exterior.

I'll be following this!

Great to hear Scarpia!  I've been waiting for you to post this for a while.  I'm planning on taking on the same project, but as I've never attempted an install myself I'm going to follow your progress to hopefully pick up a few pointers before I try and fail miserably due to my inexperience do the installtion myself. 

Looking forward to it!

~Rich

EDIT:  Sorry for the reply in the middle of your post (was caught up in the excitement).  I'll delete it if you feel it breaks up the look of the post.  Just drop me a private message or post it on the thread.  No hurt feelings, I promise.

Testing

Just a quick caveat - I'm spanking new at this, so if you see me make a stupid mistake or overlook something, let me know! 

 I hadn't tested the loco yet, so once the body was off, I hooked it up to a DC power pack and a piece of test track.

Not surprisingly, it worked fine, but I felt better testing it at least this little amount.

Disassembly

With that working, it's time to take it apart. From my research, I know that this machine needs to have the electrical motor isolated from the frame, so disassembling everything is required.

I started by cutting the truck power feeds close to the copper power strip.

Next up was unscrewing the single top screw, and removing the copper power strip and top weight.

Flipping the model, There is one metal screw that holds the motor to the bottom of the frame. The screw is right behind the front truck, as you can see here from the location of the screwdriver (apologies for the blurry picture).

Here's the motor assembly. The black screw as shown is one that needs to be replaced with a nylon screw, I'm headed to the local hardware store this afternoon.

and the empty frame. Additional isolation (electrical insulation) will also be needed between the frame and the motor.

And the completely disassembled model. Note the motor is out, as well as the drive shafts (I didn't want to loose them).

That's it for the moment, until I can find a replacement nylon screw.

until I can find a

Which, is apparently impossible in my local area. Anyone know a good source for small fiddly bitz like this?

Never ordered from them, so not vouching but just in case

Google says contact these guys:

http://www.microfasteners.com/catalog/products/NYL.cfm

FYI, I’m looking to do the EXACT same project as you, so if you order a few extras I’ll go in with you if you’re interested.

~rb

Kadee screws

Scarpia,

The screws you are searching for might  be closer than you think - you might have some packages of Kadee couplers wich have 2-56 nylon screws. Just shorten them and use them. I think I did on my old Atlas S4.

TCS also mention this on one of their decoder installation webpage for a S2.

Yep, I keep a supply of Kadee nylon screws on hand ...

Yep, I keep a supply of Kadee nylon screws on hand for just such a purpose. They're easy to cut to length and the 2-56 size is common enough that they often do the trick nicely.

I read where some one else

I read where some one else did the exact same engine and to kill two birds with one stone he used a layer of Silicon sealant as both the attachment and the insulator.

First you wrap the motor in saran wrap then apply the silicon to the main frame work and then set the saran wrapped motor into the silicone in the exact position it needs to be in. don't worry about the excess silicon that oozes out but don't over do it with the silicon. Set everything in a safe place and let the silicon dry for at least 24 hours. After the 24 hour period has passed cut the saran wrap and remove the motor and then clean any excess silicone off of the frame and remove the excess saran wrap with an X-Acto knife. you now have an electrically isolated custom made engine mount.

Next re-coat the silicon with a lite layer of fresh silicon approximately 1/16 inch thick or less and set the motor into the fresh silicon making sure to keep the silicon out of any moving parts. now once again set the engine frame and motor aside to dry make sure every thing as far as drive shafts are installed and aligned. Now wait for another 24 hours and your engine is now electrically Isolated as well as reattached to the frame and other than the Body and hooking up the wires and DCC your ready to go.

I was really impressed with this way of installing and isolating the motor from the frame because I have a number of engines that need to be switched to DCC . I plan to do this procedure for all 17 engines I want to convert to DCC and I have a number of the can conversion motors ready as well as some motors that all I need do is Isolate the motor from the frame and add the DCC components Good luck cant wait to see your finished product.

Dan

What month are you modeling in 1956?

 7917 was renumbered to 8093 in June, 1956!

Seriously, looking forward to seeing how you handle this conversion, since I want to do an "as-built" 7918. 

Marty

Newbie Comment

So here's a newbie comment - I still don't  fully understand these screw sizes. What, exactly, does a 2/56 screw mean? (I know the 2 part, and am guessing the 56 is a measurement of length, or is it thread count?)

Thanks for that info. I called Atlas yesterday, and got no response on the actual size of the screw (mine measues as a "1" by the way per the guage at the hardware store) and now I'll have to look to see if I have a nylon one from Kadee - off hand I think I don't.

KnuT, thanks for that link. I never thought to check the TCS pages - doh!  I've been using this one as reference, I'll add the TCS one to my list.

Dan, that's an interesting idea. I'll think about it, but I may just go with electrical tape, and add the screw as I get closer being completed. I'm going to put it together first, do a road check, than pull it apart for detailing and paint, so wel'll see. That idea seems sound, but you'd definatly want to make sure the motor sits properly the first time you "cast" the mount. I'd also worry that there isn't enough space between the frame and the motor in this model, but I may be mistaken.

Marty, I don't have my book with me here, so I'll have to get back to you. Here's the modified picture that I am working from (Central Vermont & Grand Trunk Diesel Locomotives (1940-1975), Liljestrand, Robert A. & Sweetland, David R. Page 6. No Publisher or Publication date or ISBN available).  If my memory is correct this was early 1956, prior to the renumbering, but a bit after the picture you put up from Jim Macfarlane.

You've got it!

Yes that's right, number of threads per inch.

Edit: As you have no doubt already ascertained, the first number is an expression of the screw size, (diameter).  The diameter can be roughly calculated with the following equations.

for screw size #0 and larger, D = .060" + (# X .013)

for screw sizes smaller than #0, D = .060" - (#zerosize X .013")

Lichtfield Station installations webpage

Scarpia,

Your welcome, and thank you for the good tip of your reference. My Alco S is also a Santa Fe model.

An other great site for decoder installations is MRH sponsor Lichtfield station. Bruce has also a solution for this loco. Keep in mind the issues with termal shutdown he experienced, and how he solved that.

BTW, I used a Digitrax DZ125 decoder in my old non-sound loco, manufactured by Roco. I hope that Soundtraxx one day will make a drop in decoder for these Atlas Alco Switchers, and for the LikeLike P2K EMD switchers.

Good Write Up

Good write up and detail on how to do it. Great showing the pictures of all the parts and pices.  Pictures worth 10000 words.

Firing up the soldering iron

This weekend has been a bust so far, from a weather point of view, but that also meant I was able to spend some time on this project.  Yesterday, I started in.

After reviewing the articles of other's work on this, I decided to dump the top weight in it's entireity, and instead make a two part shelf to keep the wires and decoder out of the moving bits. I used half brass, and half styrene, the brass is for the decoder (per Litchfield Station), the plastic for the speaker and wires. Here's the two shelf pieces

and a top view

da big oops!

With the shelf assembled, I started in on preparing the existing wiriing. Well, while trying to strip the end of the wire of one of the truck feeds, I pulled the wire right off. Doh!

And I soldered in two new (long) wires. I wish I had both red and black, but in this guage this was all I had on hand.

Wiring up!

With the trucks repaired, I took a look at isolating the motor.  I first had two layers of electrical tape in the well on the frame where the motor sits, but there is so little clearance that the motor would not seat properly.  There certainly isn't enough room on this model for silicon.

I broke out the multimeter, and was surpised to find that the frame really isn't that conductive.

And with that in place, I was able to tape the bottom of the motor.

Testing

I assembled the entire model, and took it out. The sound is very weak, in part no doubt to that small speaker (which does, just, fit under the hood). I don't know how to change that other than to put the speaker in the cab, which is something I don't really want to do.

Before I begin on lights, I do want to get the sound better, so stay tuned!

Video Sample

Here's a video sample of where we're at right now.

Speaker baffle?

Scarpia,

One thing I don't see is a speaker baffle - is there something (which is needed) isolating the front of the speaker from the back?

There isn't one currently

No speaker baffle, currently. I was under the impression that one isn't necessarily needed if the speaker uses the entire body as  its enclosure. Am I mistaken? Is one needed to seperate sound waves?

Adding one will be even more challanging, due to the space in here

Baffle needed? Probably

Unless the body of the locomotive completely surrounds the speaker isolating the air in front of the speaker from the air in back (which I'd find difficult to believe, at least for the curved ends), then you need a baffle of some sort. 

Otherwise it's always going to sound anemic.

Check the measurements of your current speaker against these:

http://www.railmasterhobbies.com/Speakers.htm

That's right

Without a baffle the sound waves produced at the back of the speaker cone will cancel out low end frequencies coming from the front of the cone.  If the speaker was large enough to cup in your hand, you should notice a difference just from doing that, IMO.

Another order incoming...

Ok, another order incoming from Litchfield. Speaker enclosure, some other speakers (I have other models to do), wire, Kapton tape, etc.

I'll tear down what I've done so far (I have to anyway, as the bad wire I used for the truck leads has already busted off)

If they mail quickly, I should have it by the weekend, so stay tuned.