Need Help Determining Track Radius

[modelrailroadrookie]

Hi All,

I'm trying to purchase track for my first layout and I'm having some difficulty determining what track radius I should use. I'd like to lay a second track on the outside of the oval track that came with the train set I bought, the Bachmann DCC Digital Commander, however I'm not sure what radius will fit around it.

I tried determining the radius of the track I currently have by building a circle and then measuring across but it doesn't seem to measure out to any radius that is currently sold by Bachmann. The radius turns out to be 19" (my initial estimate without measuring was 18" but I measured several times both halfway across as well as across the entire circle and always get 19" for the radius and 38" for the diameter).

Any ideas? Thanks for your help.

[the Bach-man]

Dear Rookie,
Radius is measured to the track center, so you have 18" radius. 22" radius will make a concentric outer circle.
Have fun!
the Bach-man

[modelrailroadrookie]

Hi All,

I'm trying to purchase track for my first layout and I'm having some difficulty determining what track radius I should use. I'd like to lay a second track on the outside of the oval track that came with the train set I bought, the Bachmann DCC Digital Commander, however I'm not sure what radius will fit around it.

I tried determining the radius of the track I currently have by building a circle and then measuring across but it doesn't seem to measure out to any radius that is currently sold by Bachmann. The radius turns out to be 19" (my initial estimate without measuring was 18" but I measured several times both halfway across as well as across the entire circle and always get 19" for the radius and 38" for the diameter).

Any ideas? Thanks for your help.

I forgot to mention (although it's probably obvious since I bought a set) that I'm using EZ Track. From some rough measurements, I believe a 22" radius will be able to wrap around my current track but I figured I'd check with the experts before buying anything.

By the way, I'm still confused over why the radius on my current track measured out to 19". Seems odd.

[lmackattack]

track radius is measured from the center of the track. it sounds like you have 18" is this the EZ track ? If so how many sections makes a 1/4 circle? if its 4 sections I believe thats 18"

Trent

[modelrailroadrookie]

track radius is measured from the center of the track. it sounds like you have 18" is this the EZ track ? If so how many sections makes a 1/4 circle? if its 4 sections I believe thats 18"

Trent

Yes, this is EZ track and I think you're right about it being 18". Four pieces make up 1/4 of the circle. I think my measuring must be off somewhere but I tried it several times and never get exactly 18" (usually between 18.5 and 19). Perhaps I'm not supposed to include the outer part of the roadbed in the measurement?

Also, will a 22" radius work around this?

Thanks for your help.

[lmackattack]

 no just use the center of the rails at the center point for the measurement. if you had a full circle of track it would be 36" from the center of the rails n once side to the center of the rails on the other. 18" is the halfway point. 22" will work around the 18" I think you need 5-6 sections of the 22" to make a1/4 circle?

[modelrailroadrookie]

no just use the center of the rails at the center point for the measurement. if you had a full circle of track it would be 36" from the center of the rails n once side to the center of the rails on the other. 18" is the halfway point. 22" will work around the 18" I think you need 5-6 sections of the 22" to make a1/4 circle?

That explains it all. It's certainly 18" when I measure from the center of the track. Thanks again for your help.

[Yampa Bob]

18" radius track has a divergent angle of 30 degrees, takes 6 to make a 1/2 circle, 22" has a divergent angle of 22.5 degrees, takes 8 to make a 1/2 circle.

[Joe Satnik]

Dear Attack,

Outer Diameter of track is twice radius plus a track bed width

D = 2R +tbw

For Ho EZ-track the track bed width is very close to 2".

15"R HO EZ-Track is 12 sections per circle, or 30 degrees each section.

18"R is the same.

22"R is 16 sections per circle, or 22.5 degrees each section. 

26"R, 28"R, 33.25"R, and 35.5"R sections are 20 sections per circle, or 18 degrees each. 

Hope this helps.

Sincerely,

Joe Satnik

Edit: spelling