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Discussion Starter #1
How do I go about knowing the radius of my flex track 3ft ho scale as I am putting down my track? Am I making sense?
Thanks!

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normally (for me) draw lines first using a home made 'compass".
Or use a piece of sectional track to draw outlines.

Cut a pizza box to the radius you want, use it as a template.
 

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Discussion Starter #3
normally (for me) draw lines first using a home made 'compass".
Or use a piece of sectional track to draw outlines.

Cut a pizza box to the radius you want, use it as a template.
We have a track plan on paper so we are going by that generally..but its all flex track...want to make sure we are not making to sharp of a radius. How do we go about knowing the radius?

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We have a track plan on paper so we are going by that generally..but its all flex track...want to make sure we are not making to sharp of a radius. How do we go about knowing the radius?

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Are you saying that your track plan doesn't give you the radius?

Dennis gave you several ways to mark that radius on your layout surface so that you have a guide to follow as you lay the track.

There are also commercial radius templates available from half a dozen companies, in metal, plastic, or wood.
 

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draw it on paper to scale. Grammar school graph paper, for example 1 square equals 2".

Put dimensions for edges of table, post it here.
We can give you a rough idea.

For example, a circle fitting in a 40" square layout will be around 18" radius.
 

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Discussion Starter #6
The plan that we are working from is on grid paper. 1ft squares pic below


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When you laid this out on grid paper did you measure with a divider or compass on a ruler before drawing the curve?

How big are the squares? Are they a half inch, three quarters of an inch, one inch?
 

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So, it is 13' wide 22' long.
Curves seem to be 24" radius. No problem using flex track.
 

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Discussion Starter #9
I think u are correct..found some note from my buddy who did the track plan using software an it states 24" radius. Should of dug deeper in my notes!

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Radius is measured to the center of the track, [usually where the holes are] ,not inside or outside, just a fyi
 

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I would make a 24" radius cardboard template, then use it while laying the track to make sure you don't put any sharper radius kinks in the real track. Also don't forget about easements into and out of curves! and especially any vertical easements! Get the sub road bed correct, correcting the actual track later is frustrating!
 

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Make yourself a trammel out of a 40" length of lath or strapping. You drill a hole at one end for a short screw's tip to act as a centerpoint, or pivot. Then, starting at, say, 10", you drill a hole every inch outward toward the far tip big enough to hold a pencil's tip. Use a marker to label each hole for ease of reference.

This way, you won't have to carefully carve a template for curves that are 18" radius, 20" radius, 22" radius, 24' radius, and so on, about two or three hours worth and many losable templates. You just have the one trammel that you hang on a nail, always handy, via one of the several pencil holes you drilled.
 

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Make yourself a trammel out of a 40" length of lath or strapping. You drill a hole at one end for a short screw's tip to act as a centerpoint, or pivot. Then, starting at, say, 10", you drill a hole every inch outward toward the far tip big enough to hold a pencil's tip. Use a marker to label each hole for ease of reference.

This way, you won't have to carefully carve a template for curves that are 18" radius, 20" radius, 22" radius, 24' radius, and so on, about two or three hours worth and many losable templates. You just have the one trammel that you hang on a nail, always handy, via one of the several pencil holes you drilled.
I've done the same thing with a cheap yardstick. Just allow for a slight offset because the hole at the fixed end won't be exactly at the "zero" measurement. If you don't want to destroy the yardstick, you can purchase clip-on trammel points. One has a point, the other a clamp for a pencil.
 

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Discussion Starter #14
I've done the same thing with a cheap yardstick. Just allow for a slight offset because the hole at the fixed end won't be exactly at the "zero" measurement. If you don't want to destroy the yardstick, you can purchase clip-on trammel points. One has a point, the other a clamp for a pencil.
That's exactly what I ordered on Amazon today. 2 Trammel clamps. Thanks all for the help!

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I drew my track plan on 11 x 17" graph paper old school and used a compass and scale rule.



To do it in full scale, you make a trammel out of a yard stick or similar but longer and use it to draw out radii on plywood and cut it with a jigsaw/sabre saw to install on the benchwork.

I am planning some radii as much as 42 inches, so I found a piece of wood at Home Depot that was similar to a yard stick only it's 48 inches long. That allows me to draw radii that are larger than 36".
 

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Discussion Starter #16
I drew my track plan on 11 x 17" graph paper old school and used a compass and scale rule.







To do it in full scale, you make a trammel out of a yard stick or similar but longer and use it to draw out radii on plywood and cut it with a jigsaw/sabre saw to install on the benchwork.
Very nice! Great idea!

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