# Build a Beam Track Radius Compass..



## ED-RRR (Jun 4, 2015)

irishfreight said:


> "Grand plans"
> For most of the corners I'd like to curve then, I know they should fan out but how to create the curve correctly?
> Has anyone got any tips on how its done? Thinking of a large piece of cardboard and a piece of string and a pencil.... :dunno:


You will require a beam compass for an "accurate" radius measurement !!

There are many "expensive" ($'s) beam compass's..
Why not build your own beam compass !!
There are many different home made beam compass's from advanced to simple basic compass's..
You will only require a good Beam Track Radius Compass for your usage..
A cheap sloppy built compass can/will result with "faulty" markings..

(#1) Basic
Taking a yard/meter stick and drilling holes into it..
There is "no" fine radius adjustment..
The pencil is "not" correctly secured 90' degree and can/will move during layout..








(#2) Very Advanced
Building this custom made unit (x1 solid pc.) requires "special skills" in carpentry..
Has fine radius adjustment..
The pencil is correctly secured 90' degree and will not move during layout..








===============================================

This Project:

(#3) Advanced (Simplified)
I have taken the (#2) Very Advanced version and "simplified" it so anyone can build it..
No special carpentry skills will be required..

Special Notes:
The required compass pencil and compass center point bolt must be the "same" size..
The design of this Beam Compass is based open this..

Hardware Required:

Blue Arrows = (x2) yard/meter sticks..
Yard Stick Thickness = About 1/4" (.250")..
Hardware = 1/4-20 bolt (.250").. 
Required Pencil = .270" across (x2) flats.. 
= Recommend the (x6) sided pencil for much better clamping..
= Mush easier to modify for this for this Beam Compass..

Green Circle = (x2) permanently clamped locations using screws and nuts..
(x2) 10-32 screws x 1" long..
(x2) 10-32 nuts..
Drill = 13/64" (.203")

Red Circle = (x1) permanently clamped end using a screw, wing nut (x2) washers and a pencil..
(x1) 1/4"-20 Bolt x 1 1/4" (1.25”) long.. 
(x1) 1/4"-20 Wing Nut..
(x2) 1/4" I.D. Washers..
Drill = 17/64" (.265")

Black Circle = (x1) adjustable moveable clamped end using a screw, wing nut, (x2) washers and a nut.. 
(x1) 1/4"-20 Bolt x 2 1/2" (2.50”) long (100%) threaded length..
(x1) 1/4"-20 Wing Nut..
(x1) 1/4"-20 Acorn Nut (has internal nylon thread locking)..
(x2) 1/4" I.D. Washers..







(#4) Custom Bolt
Black Circle = (x1) adjustable moveable clamped end using a screw, wing nut, (x2) washers and a nut.. 
This center point locator is "custom" made..
Require a "bolt" that has a very "long" thread..
Hack saw "off" the head of the screw..
Insert the threaded stud into an electric drill and do "not" over tighten the drill chuck damaging the threads.. 
While the drill is turning, slowly "file" a center locating point where the screw head was located..







(#5) Compass Frames (x2)
You will "Not" require the full length of a 36" (3' Feet) long = 72" (6' Foot) Dia.
Also if the compass frame is "too" large, marking out the required radius may become difficult.. 
Also note that a "large" track radius's takes up much more layout space !!
Never go "Under" the "Minimum" track radius for your required "Scale".. 

Special Notes:
Will "Not" be using the "Original" markings on the yard stick because this could/will cause "errors"..
Shorten the "length" of the (x2) yard sticks by cutting "off" the ends that have a --> "Hole" at the ends..







(#6) Compass Frame (Assembly #1)
--> The (x2) shims to be added should be the "same" thickness as the Dia. of scriber bolt..
- use the remaining excess yard stick material "thickness" to start with..
- cut and insert a (x1") inch long spacer, between the (x2) compass frames at (x1) extreme end..
- cut and insert a (x1") inch long spacer, between the (x2) compass frames at the pencil end..
--> allow for the (x1") inch gap at the pencil end..

Shim Testing Procedure:
- Temporarily place the (x2) shims and clamp into place..
- Check to see how the center point bolt slides inside the locating slot..
- It should move freely for easy and accurate settings..
- You may be required to add more thin shim like layer cardboard (cereal box)..

Wood glue and clamp the (x2) spacers into place and allow the glue to dry..
Remove the (x2) clamps..
Spray paint "everything" black in color to cover up the "existing" numbers on the (x2) yard sticks.. 
This will also make it look more professional..







(#7) Compass Frame (Assembly #2)
(x2) permanently clamped locations..
Drill = 13/64" (.203")
Drill the (x2) required clearance holes and permanently clamp with screws and nuts..







(#8) Compass Frame (Assembly #3)
Allow for clamping clearance for the pencil to fit when drilling the clearance holes.. 
Drill = 17/64" (.265")
Drill required through clearance hole to clamp the pencil into place..







(#9) Compass Pencil (Assembly #3)
Beam Compass internal slot = 1/4" (.250")..
Pencil = .270" across (x2) flats.. 
Recommend the (x6) sided pencil for much better clamping..
Slowly file down (x2) sides of the pencil till it fits into the slot = 1/4" (.250")..







===============================================

Assemble everything together
......


----------



## ED-RRR (Jun 4, 2015)

*Using a Beam Track Radius Compass..*

Special Notes:
I have worked with [CAD/CAM], building the Colt M16, F15, F18, plus..
I also had a very advanced 3D [CAD/CAM] model train software program that I did not use.. 
Some individuals like to use a 3D [CAD] model train software program to design their model train layout..
-BUT-
Now comes the hard part..
The images from the CAD "computer" must now be "accurately" transferred to the model train layout..
You must know verify your computer [CAD] dimensions to an actual [POD] proof of diemensions..

Fact:
Very accurate layout lines will be required for a correct functional operating model train layout..
When using preset "curved track" this is "not" a problem..
When using "flex track" the track must be 100% [Tangent] 90' degrees to the center line of the radius..








Hardware:
I would recommend using:
- a "large" [Flat] carpenters metal square to locate the (x2) required "center lines"..








- also smaller [Flat] plastic drafting tools..







......


----------

