TT Scale Archbar Trucks?

Re: TT Scale Archbar Trucks?

Postby Bernd » Sat Oct 17, 2015 7:23 pm

Got more accomplished on the archbar trucks. After cutting out 5 pairs of bolsters I started to work on the fixture to bend the bolsters to the proper size.

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With the pocket milled out on the Sherline CNC, the part need just a bit of clean up to fit in the pocket.

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The part is held down with a machinist clamp so it doesn't move and the ends are bent over to a 90° angle.

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Both sides have been bent over.

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Nice even and equal bends on both ends.

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The holes in the side are drilled out by hand so they are snug fit on the plastic nub that sticks out on the truck side frame.

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The bolster could be narrower. The wheels are a little lose in the journal boxes. That's also do to the tapered hole being bigger than the TT scale axle. It's acceptable for now. I need to get the log buggy built and some track down to test the trucks rolling capability. More to come.

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Re: TT Scale Archbar Trucks?

Postby Bernd » Sat Oct 17, 2015 8:08 pm

I was playing around with a second truck after I narrowed the fixture to bring the truck sides together a bit more. I then touched the soldering iron to the plastic nubs to secure the bolster but not enough to restrict the whole truck from flexing. That's a piece of .040" styrene the back wheel is on. Notice how the ruck flexes.

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The truck is still a little tight. I need to pen the holes a bit so it flexes easier.

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Re: TT Scale Archbar Trucks?

Postby ConducTTor » Sun Oct 18, 2015 12:20 am

:thumbup:
What people think: "liberals/conservatives are ruining my country"
What the powerful know: divide and conquer
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Re: TT Scale Archbar Trucks?

Postby Bernd » Sat Nov 14, 2015 10:46 pm

Finally have the last of the three jig's properly made for building my archbar disconnects.

I made a fixture for making the U channel that'll mount on the truck bolster. You can't buy this channel as it's custom made for the truck.

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Re: TT Scale Archbar Trucks?

Postby Bernd » Sun Nov 15, 2015 4:43 pm

To make the U channel I made a two part die for forming. The U channel is made from a piece of .015" thick annealed brass .308" wide by .900" long. It's bent into a U channel aprox. .188 wide by .060" thick.

First I needed to accurately cut a piece of brass .308" wide. I made a jig to hold .015" thick sheet brass so I could cut it in the milling machine with a slitting blade .0315" thick. The jig is milled to have a step in it .010" deep by .308 down from the top. The picture illustrates how the brass sheet is held in the vise for cutting. The clamp is used to hold it together for purpose of photographing.

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The pieces are then put in the die for further shaping. The female part of the die holds the brass piece. The male part of the die is guided by 3/16" dowel pins for a perfect fit when the dies come together.

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These are the two dies and one fixture used so far in shaping the parts needed for the log disconnect.

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Next will be the truck bolster pads and the log bunk. I don't think I'll need any fixtures for those.

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Re: TT Scale Archbar Trucks?

Postby Bernd » Wed Nov 25, 2015 9:17 pm

Al was kind to send me a Christoph log car to see what I could do about using it as a master. The interesting part was the archbar trucks that came with the kit. I compared them with the one's I made using Precision Scale Products HOn3 archbar side frames. The comparison is quite good. Christoph side frame top, Precision Scale bottom.

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Since I can't legally use the PS trucks for a master I'm going to try and see if I can make copies of Christophs side frames in resin. I'm also contemplating of trying metal spin casting using low temp metals. I've always wanted to try lost wax casting also. This may be a down the road project.

I also have done a bit of research on log cars and discovered that the Grasse River Railroad was a logging company located in northeastern part of New York state. I have several Keystone Locomotive works HO scale log buggy kits. The Christoph are close in appearance to the Keystone ones.

Keystone on left. Christoph on right. Top side

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Bottom side.

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Other than being different scales they represent log cars used on eastern logging lines. The Keystone represents the log buggy that a Barnhart loader ran on rail spiked to the top of the log car. The Christoph one represents more of the standard log car used in lumber hauling. Disconnects were used more in the northwest logging lines due to larger trees. The eastern style log buggies were used for hauling hard wood lumber of trees that were no larger than 3 feet in diameter. So it looks like I'll be using the two versions of log cars. I've got a bit of design work ahead of me.

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Re: TT Scale Archbar Trucks?

Postby j p » Thu Nov 26, 2015 5:57 am

Bernd, if you want to try lost wax casting, check this:
https://www.etsy.com/uk/listing/98385243/microfoundry-lost-wax-casting-system-for?ref=shop_home_active_2

It is made in UK. I am not sure if you'd make an exception from your "US only" approach. The price is not in EUR. (350 GBP)
I am happy with it.

Have you got any idea where to get the springs for the trucks?
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Re: TT Scale Archbar Trucks?

Postby Bernd » Thu Nov 26, 2015 10:24 am

j p wrote:Bernd, if you want to try lost wax casting, check this:
https://www.etsy.com/uk/listing/98385243/microfoundry-lost-wax-casting-system-for?ref=shop_home_active_2

It is made in UK. I am not sure if you'd make an exception from your "US only" approach. The price is not in EUR. (350 GBP)
I am happy with it.

Have you got any idea where to get the springs for the trucks?


Very nice small system. DIY approach would be to use fire brick, small SS container and a butane torch. Much cheaper.

I see the springs are smaller than what is available from Kadee. I'd say wind your own using .005" phosphor bronze wire. I've done it using .010" PB wire and had good success.

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Re: TT Scale Archbar Trucks?

Postby Bernd » Fri Nov 27, 2015 7:23 pm

The metal logs that came with the car are in poor shape due to zinc contamination. They are starting to crumble. So Mother Nature to the rescue. I'm always on the look out for natural flora. I discovered that golden rod makes for nice tree trunks.

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The log buggy with the metal logs.

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The log buggy with the golden rod. The nice part is Mother Nature already painted them for me. 8-)

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Here is a comparison between the golden rod and metal logs. Can you tell which are the metal one's? :wtf:

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Well, how do you think they stack up to each other? (pun intended)

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Re: TT Scale Archbar Trucks?

Postby tomvanhoy » Fri Nov 27, 2015 9:45 pm

They look good, wondering though what the diameter is?
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