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Resin Cast Tie Strips Track and electrical/DCC
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MRH Author 5,632 posts Bernd MRH Author 5,632 posts
Bernd

Being interested in TT scale also I've discovered that the scale doesn't enjoy many products that are available to both N and HO sale, especially track components. If they are available the they quite costly or need to be imported from Europe. So you are either left with a product that doesn't quite look North American, or you will need to hand lay all the track. A couple of track producing companies were approached to see if they would make flex track in TT scale. The cost was quite prohibitive for an individual to undertake, plus, not being a very popular scale, a product would probably not sell the amount needed to make up the cost of manufacture.

I decided to see if there was something viable that an individual could do for themselves to help make track laying faster and less work intensive.

Mike Rose gave me the idea of using Taskboard to do tie strips. I tried that. Didn't work so good, not that the product would have been not workable, but the cost of having a local laser shop do the cutting. They didn't want to do it. I finally figured out why. The amount of linear travel a laser has to do to cut all those ties out is quite large. Ties up a lot of laser time and is cost prohibitive.

So I searched for another solution. Why not cast the tie strips in resin? So in the last month or so I worked to see if that idea had traction.

Here are the results of that experiment.

Using Double Cad (free CAD software) I drew up a section of track. Converted it to CNC language the Sherline CNC mill works with and milled a piece acrylic plastic to make a master mold.

An acrylic piece bolted to the table.

[ResTrack1]

Milling the tie profile.

[ResTrack2]

The end result. This was a test piece. A newer design was made later. It had several flaws as can be seen on the far left side. Plus the depth was not quite what it needed to be.

[ResTrack3]

Tie plates being added to the first side.

[ResTrack4]

A closer view. Clear acrylic is hard to photograph.

[ResTrack5]

Adding the tie plates to the second side.

[ResTrack6]

The finished master.

[ResTrack7]

I wondered if casting a turnout using resin casting might work so I drew up a TT scale #6 turnout and milled out the tie strip. Tie plates still need to be added.

[ResTrack9]

On the straight tie strip section master I added some side and ends and poured the rubber. Looking at the top of the mold.

[ResTrack11]

Bottom view showing the tie plates.

[ResTrack12]

The master rubber mold.

[ResTrack13]

And a track section cast.

[ResTrack14]

At this point the resin casting is still quite soft. The flash helps keep it aligned until the casting gets harder. That will be in a day or so. I can then remove the flash. I'll be able to then either glue the rail down with Pliobond, drill holes in the tie plates for micro spikes or cut out every 5th or so tie and added a copper tie to solder the rail to.

Be back in a day or so with the finial answer.

Bernd

New York, Vermont & Northern Rwy. - Route of the Black Diamonds - NCSWIC
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Neil Erickson NeilEr Moderator 5,800 posts
Neil Erickson NeilEr

Ingenious!

Bernd:

Is the acrylic brittle? When drilling for spike it seems that you may need to be very careful but I love the whole idea. My mill does not have the CNC attachment but clearly you have mastered that. Worth a second look at the cost. 

I am anxious to see the turnout as it would lend itself to curved situations as well. The tie plates should also help keep things in gauge when laying rail beside looking great. Had you considered simply cutting PC board for the entire switch instead of a casting master? The cad work is nearly done!

Neil Erickson, Hawaii

 

Neil Erickson, Hawai’i 

My Blogs
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casenundra Regular poster 367 posts
casenundra

DIY

It's a wonder what you can do when caught between a rock and a hard place.  What will you do for curves?

Can you bend the cast resin before it hardens?

 

Rich S.

Home of the Here N There RR (N) (under construction)

One of these days I'll be able to run some trains!

Now on Facebook for whatever that's worth.
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JimBrown Regular poster 113 posts
JimBrown

PC board ties

Would it be possible to put the PCB ties in the mold prior to pouring the resin?

...jim
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Bernd MRH Author 5,632 posts
Bernd

Resin Cast Track

Neil,

Is the acrylic brittle? When drilling for spike it seems that you may need to be very careful but I love the whole idea. My mill does not have the CNC attachment but clearly you have mastered that. Worth a second look at the cost. 

I am anxious to see the turnout as it would lend itself to curved situations as well. The tie plates should also help keep things in gauge when laying rail beside looking great. Had you considered simply cutting PC board for the entire switch instead of a casting master? The cad work is nearly done!

The acrylic is used to make the master rubber mold. No drilling holes in the acrylic. Also something like this can be made manually. You do not need a CNC mill to do this. Using styrene one could make a master to make a rubber mold. A bit of work I agree, but then when nothing else is available what do you do? It will take a bit of work to get something.

I've included a picture at the end of a curved section of tie strip, I removed the flash to allow it to bend. The same can be done for the turnout.

Reread the paragraph were I stated about cutting the Taskboard. It takes a while even with CNC machining, especially a table top mill such as the Sherline, to mill a section of track. Consider you will be using a cutter of approximately .039" in diameter. The wrong feed and speed and you will break a costly carbide tool. Casting is much faster in making multiples of something for the modeler. It took over two hours to cut the master into the acrylic sheet. The tie strip is only 9" long. In two hours with multiple rubber molds I could cast more sections than could be cut on a CNC mill in any material.

@rich,

Can you bend the cast resin before it hardens?

It's quite bendable. At the end I show piece fresh out f the mold with the flash cut off and bent to 12" radius. I've got another section that I'm going to try this after it has a couple of days to cure fully.

@JIM,

Would it be possible to put the PCB ties in the mold prior to pouring the resin?

I hadn't considered it but looks like something to look in to.

Here's a section nailed to a piece of MDF, wrong material to nail wouldn't you know it, at a 12" radius.

[ResTrack16]

NOTE: The Kingstone Model Works logo in the corner of my pictures is not a business for those of you who are thinking I'm using this as a product promotion. I wouldn't have put this idea out in the public domain if I had wanted to produce a product.  Perhaps somebody my want to actually try producing this and selling it on the market. I'm doing this solely for my enjoyment of model railroading.

As I was rereading my post I came up with another way to do this. You guys using Sketchup could make a master. Have Shapeways do the master for you and then use that to make a rubber mold. So who's going to give that a try?

More to come as I experiment some more.

Bernd

New York, Vermont & Northern Rwy. - Route of the Black Diamonds - NCSWIC
Reply 0
Yaron Bandell ybandell Prolific poster 1,556 posts
Yaron Bandell ybandell

pcb ties in resin

Instead of trying to add pcb ties to the mold before adding the resin, I would include special ties in the master that are only the height difference of the normal tie height and the PCB tie. That way you could simply pour resin as usual, and after it comes from the mold you can glue on the PCB ties in the proper spots. This would, at least in HO scale, help those people whose PCB ties are slightly less high than their regular ties. 

Bernd, I love the projects you come up with and how you document them such that it shows everyone, with a bit of planning and gathering of the materials, that they could do your projects them self and gain modelling skills.

-Yaron.
Susquehanna Bridge Build | My Personal Website | Capitol Free-mo
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ctxmf74 Super User 15,990 posts
ctxmf74

"Instead of trying to add pcb

Quote:

"Instead of trying to add pcb ties to the mold before adding the resin"

It's a simple matter to glue PC board ties down to roadbed then fill in between them with dummy wooded ties so making a mold seems a bit round about way to get track unless one was making track to sell?  I found TT scale track laid with code 70 rail and a kadee spiker the fastest way to get track laid but PC board ties with code 55 rail looked a bit better for scale height. Most folks would probably be better off going with the PC board ties and gluing them down method since it doesn't require any special tools and is quite easy to master. ... .DaveB

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Graeme Nitz OKGraeme Prolific poster 1,695 posts
Graeme Nitz OKGraeme

Unfortunately you made a mistake

Unfortunately you made a mistake that nearly all manufacturers do in that you have the "connectors" between ties on alternate sides. This means when you curve the strip instead of the ties fanning out into a series ov "V" shapes you get ties in series of "W" shapes. The connectors should all be under one rail.

This is not a criticism of your work you have done a great job but it bugs me to see ties on sharp radii with the ties all higgledy piggledy!!

Graeme Nitz

An Aussie living in Owasso OK

K NO W Trains

K NO W Fun

 

There are 10 types of people in this world,

Those that understand Binary and those that Don't!
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Bernd MRH Author 5,632 posts
Bernd

Connectors

Graeme,

Yes, I did notice that. Time for an engineering change. Thanks.

Bernd

New York, Vermont & Northern Rwy. - Route of the Black Diamonds - NCSWIC
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