My Milwaukee Union Station kit will be sitting on a concourse/foundation/platform with several tunnel portals of several different widths due to the trackage spacing.
What draftsman or woodworking tool would one use to draw oblong/oval curves? A French Curve? Is there a template made soley for drawing curves for ovals?
Thanks,
Jim
Hi,
I’ve used a number of French Curves (Lane Tech HS - 1962 Chicago) in two years of drafting, but the biggest ones I’ve seen won’t help you out.
I suspect your oval curves are really easements of sort. In my experience there are two ways to do this:
Get a piece of 3 ft. flex track and tack down one end at the beginning of the curve, and form the track to fit what you want. Pin it in place and put pen dots at track center all the length of the track. Remove the flex track and “connect the dots”.
A less desirable way is simply freehand efforts. So get a pencil and a big eraser and go to it.
Hi, sorry, maybe I didn’t write my original post clearly enough…
It’s the tunnel portal top curves I’m looking to draw. The trackage is all laid, but because of the odd spacing(s) each portal will be of a different width (some not so standard) and I want to be sure to draw them properly.
A strip wood batten is a good and simple idea. I suppose if the legs are equal distance apart the top curve has to be even as well, right?
Any other ideas or tools? Sorry if I confused you guys.
Thanks, Jim
I could easily describe the mechanical drafting procedures required to draw an ellipse (oblong curved shape), but that would only confuse you. It would be simpler to go to Michael’s Crafts, Staples or Office Depot and see if they have an ellipse arc template (plastic) in stock. Better yet, if you have a blueprint supply store or art store that sells drafting equipment in your area, that is another place or two to look for such a template. Also easier (sort of): (assuming you are wanting a small (HO/N) sized shape; use google images to find a set of drawn ellipses, click on that picture so it goes larger, save the image as a jpg on your desktop, then either make copies and find which arc is what you want, or enlarge/reduce by 5-10% at a time to see if larger/smaller arcs will serve your purpose. Isolate the final desired arc, make some copies, trace over the area you want to cut or build with and you have your first arc. Repeat process as needed for various other elliptical arcs. Remember- these arcs are either shallower and wider, or taller and narrower, as per the varying distances between the horizontal (major axis) and the vertical (minor axis) of the ellipse. Back to the template- you can get one and draw arcs as desired, then just enlarge/reduce the shapes to suit. Drawing the right sized ellipse then becomes a brief trial and error process. Cedarwoodron
Thank you Cedarwoodron. That’s very helpful. The copying/reducing idea is another good one. I’ll check out the templates (now that I know what they’re called) and figure out the best way to proceed.
Jim
You can draw a perfect ellipse by driving two nails into a board, putting a loop of string around both pins and, keeping the string tight, running a pencil around the loop while allowing the string to move freely. Since you said there are several different lengths of arch, you would have to reposition the pins and re-size the string for each size.
To find the necessary dimensions go to
http://www.1728.org/ellipse,htm
The ellipse calculator will need the major axis (length of arch span) and minor axis (2X height of arch) and prefers doing business in whole numbers or decimals. I suggest converting the dimensions to metric units.
Chuck (Modeling Central Japan in September, 1964 - with one parabolic arch)
Wow! Who knew there were so many ways to draw an oval/arch! Thanks for the ideas and variety of methods.
Jim
A flexible curve drafting tool. Here’s an example: http://www.amazon.com/18-Flexible-Curve-Drafting-Tool/dp/B001DT3HCK
If you want a half round top, using a compass draw a circle the size of the width of tunnel and draw two parallel lines one from each side of circle. For a flatter top using the center, vertical line of this oval use the compass to draw a much larger circle across the top.
Cost is minimal. [tup]
Lee
Paint, a free utility that comes with Windows, has an oval-drawing tool. You can use that to create a picture and print it. If you have Microsoft Word, you can import the drawing into a Word document and easily re-scale it to get what you want.
Looks like i’ve started something that’ll be useful to a lot of folks here. Unless I’m the only one with such weird track spacings ;-
Jim
Jim,
I’m not sure you need an elipse. IIRC, from some old Frank Ellison artlcles and other sources that railroad tunnels were based on a “Two Radius Arc” for single track and a “Three Radius Arc” for double track. The basic idea is to have vertical walls rising at clearance on each side, a radius whose center is the center of the track at rail level joining those vertical walls and the junction of those surfaces radiused with an approriate radius. Vertical walls, curved roof and cove corners in other words. That’s probably as clear as mud, I wish I could just draw it.
Lou
If you have Excel or something similar on your computer you can usually draw a circle or elipse. This can be stretched to your span and arch height. Print, cut out, and trace, and voila, there it is.
In Excel in the home command bar, it is insert, shapes, and select the circle shape. If you hold the shift key down you will get a circle, if you don’t you will get an elipse.
By the way, in these days of CAD, most “drafting” supply stores, if they even exist any more, don’t carry much in the line of templates since no one uses them anymore. I’m in the business and can’t even tell you the last time I saw someone using a triangle or French curve. I certainly don’t even know where mine are. Even basic things like scales are getting rare. The new guys don’t even know what they are. They all went the way of the slide rule and Smoley’s Tables.