TT Trackwork

Re: TT Trackwork

Postby ConnRiver » Mon Oct 27, 2014 8:54 am

Bernd, I think you could be right on target about reducing three foot sections to one foot to match smaller machines. Central Valley produces its flex ties in 12-inch strips, I believe, that can be mechanically linked and glued together (anyone here use this track, is this correct?)

The injection molding machine I'm copying is pneumatically powered, a sort of semi-auto operation. Once the drawings are finished, I'm going to explore enlarging the machine a bit, factoring in pressure (tons force) and air cylinder capacity/availability, and so on. Would hope to accommodate 50 foot rolling stock.

Devcon (a pourable metal epoxy product) is said to create molds capable of tens of thousands of injection molded reproductions. So there's that hope. At this point, with the CNC mill and Devcon, I'm not worried about creating molds. I might be living in a fool's paradise, though :-)

Donnell, I've hemmed and hawed about contacting Micro-Engineering. I'm not sure why. It might be that I'm wary of relying on outside sources for production, the lack of control involved. I have learned key information from the ME video though, which is further amplified by the information contained in the industry books. I have a decent, basic understanding of the processes involved, probably more so than what ME might be willing to share.

I was excited to explore the Central Valley Web site but cooled a bit when I understood that the tabs on each tie have to be forced over the flanges of each rail. This appears to be a time-consuming necessity. Is this assumption correct?

> Again, going back to the PCB idea, Cloverhouse offers .075" PCB tie strips in TT-scale. So, making a fixture should be easy, and can be done without a CNC machine, although cutting a fixture on a machine would be so much nicer! <

It would be simple, I'd think, to cut a 12-inch fixture from hard plastic (I've got some 1/4-inch ABS that might do the job), just cut PCB tie pockets at whatever spacing one might wish. Might work for an interim fix?

A chief character flaw of mine (maybe others here suffer from the same malady?) is beginning a project but failing to finish it. I have some downtime at my day job and am using my laptop to finish CAD drawing a TT scale NE-5 caboose (yeah, not of universal appeal, but I had the project information at hand). At home, I'm working on the Gordon Odegard eight-part series detailing the scratchbuilding of an HO USRA 2-8-2 Mikado steam locomotive; I'm creating the drawings in TT scale. Figure I can learn a lot about fabrication, including gearing and power train, from this project.

I want to finish these two projects - NE-5 and Mikado - and then focus solely on the injection molding machine.

I could mill the PCB fixture pretty quickly, though. Anyone interested in these? Maybe others here with machines would care to tackle this, too? Any thoughts?

Such a track fixture should only hold PCB ties, correct? The wood ties used to fill out the roadbed might not be the same thickness as the PCB ties, therefore should be glued to the sub-roadbed and sanded as needed, I'm guessing? But, if this sanding step is necessary, is the fixture an advantage? If the wood ties have to be individually placed and glued, might as well place the PCB ties individually, too, and then solder rail to the PCB ties?

-Brian

Brian Chapman
Cedar Rapids, Iowa / USA
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Re: TT Trackwork

Postby Tom Dempsey » Mon Oct 27, 2014 11:50 am

Traditionally, in scales smaller than S, the PCB ties "float" and the area between them and the roadbed is filled in with ballast. Works just like a 1:1 railroad. For a tangent stretch, one PCB tie is recommended every fifth tie to maintain gauge, you can probably stretch this for N and TT. In the heavier scales, a shim can be placed under the PCB ties if there is a concern, although with normal wood tie spacing I can't see how the normally code 100 or larger rail would deflect sufficiently to cause a problem. The Canter P:48 plastic flextrack was produced in 9 inch lengths so the 3 ft length is not some sort of requirement, just what ME and Atlas turn out. Since they're the big dogs in that regard, that's what you're used to seeing. But it's flextrack folks, make it any length that works for you, the customer will cut it to the length they need.
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Re: TT Trackwork

Postby sd80mac » Mon Oct 27, 2014 2:48 pm

Tom Dempsey wrote:Traditionally, in scales smaller than S, the PCB ties "float" and the area between them and the roadbed is filled in with ballast. Works just like a 1:1 railroad. For a tangent stretch, one PCB tie is recommended every fifth tie to maintain gauge, you can probably stretch this for N and TT. In the heavier scales, a shim can be placed under the PCB ties if there is a concern, although with normal wood tie spacing I can't see how the normally code 100 or larger rail would deflect sufficiently to cause a problem. The Canter P:48 plastic flextrack was produced in 9 inch lengths so the 3 ft length is not some sort of requirement, just what ME and Atlas turn out. Since they're the big dogs in that regard, that's what you're used to seeing. But it's flextrack folks, make it any length that works for you, the customer will cut it to the length they need.


Hi Tom,

Regarding PCB material, Cloverhouse's website states that "One package of ten 12" long PC tie strips sheared to a scale 9" width (.075" actual) from .062 board. For use with scale 7" x 9" wood ties." This will yield 141 standard 8'6" ties. Using a typical prototype tie spacing of 21", and soldering one PCB tie every ten ties (roughly one tie every 2" or 6 ties per foot), one pack of Cloverhouse PCB ties will be enough to lay at least 20' of track. If you decide to go one PCB tie every fifth tie, then one package of CH PCB tie strip material will yield about 10' of track.

One thing to note about CH wood ties is that are actually 0.004" shorter than their PCB tie material. From CH, "Finish cut unstained sugar pine ties milled to a scale 7" x 9" x 8'6", actual size is .058" x .075" x .85", packaged in lots of 1000 in a plastic bag. This is sufficient for approximately one-third scale mile of track." The wood tie height should not pose a "floating tie" issue as the wood ties could theoretically be slid into place under fixated PCB track sections.

So, one bag of CH wood ties, and one package of CH PCB tie material would be enough material to lay 20' of track for $21.45, plus the cost of rail, solder, flux, etc. In all, still a relatively low cost.

Donnell
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Re: TT Trackwork

Postby sd80mac » Mon Oct 27, 2014 5:22 pm

ConnRiver wrote:Bernd, I think you could be right on target about reducing three foot sections to one foot to match smaller machines. Central Valley produces its flex ties in 12-inch strips, I believe, that can be mechanically linked and glued together (anyone here use this track, is this correct?)

The injection molding machine I'm copying is pneumatically powered, a sort of semi-auto operation. Once the drawings are finished, I'm going to explore enlarging the machine a bit, factoring in pressure (tons force) and air cylinder capacity/availability, and so on. Would hope to accommodate 50 foot rolling stock.

Devcon (a pourable metal epoxy product) is said to create molds capable of tens of thousands of injection molded reproductions. So there's that hope. At this point, with the CNC mill and Devcon, I'm not worried about creating molds. I might be living in a fool's paradise, though :-)

Donnell, I've hemmed and hawed about contacting Micro-Engineering. I'm not sure why. It might be that I'm wary of relying on outside sources for production, the lack of control involved. I have learned key information from the ME video though, which is further amplified by the information contained in the industry books. I have a decent, basic understanding of the processes involved, probably more so than what ME might be willing to share.

I was excited to explore the Central Valley Web site but cooled a bit when I understood that the tabs on each tie have to be forced over the flanges of each rail. This appears to be a time-consuming necessity. Is this assumption correct?

> Again, going back to the PCB idea, Cloverhouse offers .075" PCB tie strips in TT-scale. So, making a fixture should be easy, and can be done without a CNC machine, although cutting a fixture on a machine would be so much nicer! <

It would be simple, I'd think, to cut a 12-inch fixture from hard plastic (I've got some 1/4-inch ABS that might do the job), just cut PCB tie pockets at whatever spacing one might wish. Might work for an interim fix?

A chief character flaw of mine (maybe others here suffer from the same malady?) is beginning a project but failing to finish it. I have some downtime at my day job and am using my laptop to finish CAD drawing a TT scale NE-5 caboose (yeah, not of universal appeal, but I had the project information at hand). At home, I'm working on the Gordon Odegard eight-part series detailing the scratchbuilding of an HO USRA 2-8-2 Mikado steam locomotive; I'm creating the drawings in TT scale. Figure I can learn a lot about fabrication, including gearing and power train, from this project.

I want to finish these two projects - NE-5 and Mikado - and then focus solely on the injection molding machine.

I could mill the PCB fixture pretty quickly, though. Anyone interested in these? Maybe others here with machines would care to tackle this, too? Any thoughts?

Such a track fixture should only hold PCB ties, correct? The wood ties used to fill out the roadbed might not be the same thickness as the PCB ties, therefore should be glued to the sub-roadbed and sanded as needed, I'm guessing? But, if this sanding step is necessary, is the fixture an advantage? If the wood ties have to be individually placed and glued, might as well place the PCB ties individually, too, and then solder rail to the PCB ties?

-Brian

Brian Chapman
Cedar Rapids, Iowa / USA


Hello Brian and Bernd,

Molds for the benchtop machine that Bernd posted are limited to just over 3" in length. Though this is small, you could still take advantage of its potential and create short tie strips with alternating half-height ties with indexing pins just like Central Valley did with its tie strips. Given the $10,000 cost for ME to manufacture TT-scale track, I'd easily much rather go with the benchtop machine and develop and adapt a process to fit its current abilities. In time, I would try to see if it was possible to increase the length of the mold frames, or even cut longer solid molds to use in the machine.

Donnell
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Re: TT Trackwork

Postby CSD » Tue Oct 28, 2014 1:53 pm

I have found this discussion interesting, but I have a question regarding practicality.

I want to lay fine scale track tomorrow. What do I do?
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Re: TT Trackwork

Postby areibel » Tue Oct 28, 2014 3:10 pm

Switch to HO? :twisted:
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Re: TT Trackwork

Postby krokodil » Tue Oct 28, 2014 3:33 pm

Cut the ties from basswood, rolled the rails from brass or copper wire and nailed them to the ties..... :-)
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Re: TT Trackwork

Postby CSD » Tue Oct 28, 2014 4:43 pm

krokodil wrote:Cut the ties from basswood, rolled the rails from brass or copper wire and nailed them to the ties..... :-)


Okay, I could do that. But, why not just use available code 40 or code 55 rail from Micro Engineering or some other manufacturer?
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Re: TT Trackwork

Postby sd80mac » Tue Oct 28, 2014 4:48 pm

CSD wrote:I have found this discussion interesting, but I have a question regarding practicality.

I want to lay fine scale track tomorrow. What do I do?


In all practicality, I would use parts and pieces from Clover House, Micro Engineering, and Proto 87 Stores. Along with that, I would use a handful of homemade fixtures and gauges to help shape and align rail, and build the track structure according to NMRA S-3.1 TT-fine specifications. Still being practical, I would probably forego the some of fine detail, concentrating more on the overall picture. I would most likely solder skeletal sections of the track together for strength, consistency, and speed. Then, I would fill in the gaps with wood ties and paint and weather everything to match.

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Re: TT Trackwork

Postby ConducTTor » Tue Oct 28, 2014 5:28 pm

CSD wrote:I have found this discussion interesting, but I have a question regarding practicality.

I want to lay fine scale track tomorrow. What do I do?


I hope this question is a joke. But in case it's not:
Take the switches and gap masters from your own inventory, get ties from Clover House and rail from Micro Engineering and start laying.

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