Tomix track cross section dimensions

[The_Ghan]

Has anyone ever measured the cross sectional dimensions of Tomix Fine Track. 

 

The sort of info I'm after is rail and balast profiles.  If no one has done it, what tools do I need to accurately measure these things? 

 

The reason I ask is I'm thinking of modelling the parts in either Google Sketchup or Autodesk 123D - both of these products are free.  The idea being that we can share the library here.  We could even share complete track plans in full 3D - free.  Ultimately, we should be able to each design J-track modules that link together ... then build these modules and ship them all to the same place ... for some big exhibition or something.

 

I also have a separate plan to model them in Revit ... but only because that's what we use at work.

 

Any thoughts?

 

Cheers

 

The_Ghan

[inobu]

Ghan,

 

You need a digital caliper

 

It will give you all the number you need to build it in a CAD program.

 

You will laugh again when the geometry comes into play. You will think "Ahhh yes that's a plane and I need a tangent to get that track to line up". Why didn't they explain it like this.......lol

 

I bring up geometry because you will need to make the track ballast outline pieces into wire frames for the CAD. This is where the numbers on the Unitrack comes into play. I'm sure Fine Track has the same numbering or similar format.

 

 

Here is the layout for Unitack and how the radii part numbers are derived.

 

From 0 to 718mm outward with a second line 15 degree apart you will create a R718-15 this is center track

 

You have to build this profile for the tracks in your CAD and you will be good to go.

 

Inobu 

[bill937ca]

Tomix has the same geometry layout, but I can`t find it online.  Its in their catalog.

[The_Ghan]

Thanks guys,

 

I have access to all the geometry.  It's cross-sectional measurements I'm after.

 

Cheers

 

The_Ghan

[inobu]

The cross sectional is the first part. The second step is getting the "geometry into the cad so you can maintain the standard radii. Being off 1 degree will throw everything out of whack. We are just looking down the road.

 

Inobu

[inobu]

Ghan,

 

I kinda had the same thought in mind hence I posted the quick answers.

 

[smg id=1485]

 

If you look to the left you can see the track radii layout. I just focused on the ballast width the rail will automatically fall into place. I even added the part number on the pieces.

 

Inobu

 

I used the image I posted as the template to get the track geometry.

[The_Ghan]

Hey inobu,

 

What software are you using to draw that image?

 

The geometry just doesn't worry me at all.  Geometry is my thing, and as an Architect with 20 years experience (even longer using AutoCAD), I think I'll be OK on that front.  Personally, it will be an interesting way for me to test out the capabilities of Google Sketchup and Autodesk 123D.

 

But I do get your point, with which I agree: even the smallest error in the geometry will result in an error which will be compounded each time the part is used.  That said, I've already had this discussion with the AnyRail people, when questioning the accuracy of their parts, who raised the following points:

 

1. Around a simple loop of track there is usually about 5mm of play.  Thus, in some instances where track is planned at odd angles a loop may not actually close in the CAD drawing but it will still work at a practical level;

 

2. With specific regard to Tomix, it "appears" that the Tomix curved points are not quite as geometrically correct as described.  I discovered this when actually laying track with curved points - it didn't match the AnyRail drawings.  I then substituted the curved points for a R315 and a R280 curve and couldn't get those to match with the curved points either.

 

Now, since you're looking down the road, I might also point out that Sketchup and 123D are 3D modelling packages.  This means that when you rotate a piece of track in 3D to obtain, say, a 4% grade, the length of the track in plan will become shorter - something that I notice doesn't happen in AnyRail.  I hope that makes sense.

 

Cheers

 

The_Ghan

[inobu]

Yes you are right on it. I have come to understand that Anyrail or any other software gives you an easy and fast way of laying track for reference only. As you pointed out the play in the joiners creates the deviation which kinda nullifies the precision that the CAD delivers. That variance can be reduced by change the connection tolerance in the program but it still has the factor of the actual track that induces the variance.

 

That's why is just focused on the ballast width and opened it .25 mm. My thought is the ballast has no deviation .

 

Oh, I use Rhino 4.

 

Inobu

 

 

   

[inobu]

I forgot..........the run and rise alters the lengths as you noted. It is even an issue in the CAD as the change in elevation caused the track to intersect as it cannot bend.

 

Inobu   

[The_Ghan]

I forgot..........the run and rise alters the lengths as you noted. It is even an issue in the CAD as the change in elevation caused the track to intersect as it cannot bend.

 

Inobu   

 

Hmm ... an interesting problem.  The junction at the top of a ramp would be at the base of the balast.  Ie: there would be a gap in the rails.  The junction at the bottom of a ramp would be at the top of the balast and there would be no gaps in the rails.

 

While this is true with pre-balasted track, other track CAN be bent.  I'll think about how best to do this.  In Revit, I think I can design a part that will flex.  I doubt these free products offer such an option.

 

Cheers

 

The_Ghan