I’m building a couple of HO modules and have the luxury of laying out some large radius curves. I need anywhere from 90" to 110" radius. The 90’ seems easy enough, rip a piece of 8’ plywood, however, I’m looking for ideas so I can collapse this tool and store it for future use. I have a couple of ideas, such as three 4’ strips with a short pivot strip connecting them (that ways all 3 pieces will still lay flat) versus connecting each to pivot on the end of the previous one. I also know the string method but I find it to be somewhat of a hassle as I lay out a center line and one inch over and one inch under to get a 2" wide sub roadbed.
I used a trammel where I could but found it cumbersome in a lot of situations. So I took a large appliance box and drew various arcs on them,cut them out and used them. I cut the big pieces into lengths and lay them end to end if I need to.
The two samples in the photo have a 31 inch radius on the inside and 32inch radius on the outside. I generally just eyeballed my track laying and used these pieces of cardboard to make sure I didn’t go under my minimum radius. I have some larger curves on my layout but just put the track down where I thought it looked best. As long as it didn’t go under my minimum radius who cares what the radius was. I think a layout looks a lot better if there isn’t fixed radius curves everywhere.
I don’t know how often you think that you will using this tool to make 110 inch radii. Doesn’t seem to me that you would be putting it together and taking it apart every other day. So, if it were me, I think I’d simplify the project by eliminating the pivoting feature. Then you can get a couple yardsticks, overlap them a couple inches on the ends, and bolt them together. MicroMark sells a set of trammel points that will slip on a yard stick: http://www.micromark.com/YARDSTICK-COMPASS,6560.html
I would take a couple olf pieces of wood about 6 ft long and screw them together with a foot overlap. Drill a hole near one end for a pencil with a side hole for a screw to keep it tight. Then drill a series of holes for the pivot point for whatever radii you need. Take the two pieces apart for storage.
That sounds like a good idea, once I break it down, I could bolt the two 6’ pieces back to back for easier storage.
To the others, I may make templates but I would still need the trammel in the first place to to get accurate curves to cut. I also stated that I prefer not to go the string route, it would work but initial alignment is a little tougher. And while I may not use this every other day, I don’t want to find a place to stash a 12’ long tool, hence why I want it to either fold or break down.
maxman, thanks for the link for the micro-mark clamp on trammel points.
Take a hint from a carpenter’s folding ruler. connect the two (or three…) sections with a pivot (bolt with two nuts torqued against each other) and a locking bolt to hold each joint in the straight position.
My trammel (solid, designed for curves under one meter) has four holes for each radius I use. Two are 25mm off the centerline, the outer edges of the roadbed (which I carve out of thin foam.) The other two are offset 14mm (four scale feet) and delineate the end-of-tie lines. No centerline - I anchor my flex track with grey latex caulk, so a centerline wouldn’t do me much good.
Inidentally, I use the small holes marked with the radius as the main pivot (around a wire nail.) The hole at the end of the trammel is larger, designed to fit a pencil. That way, the overhang is at the center of the arc, not somewhere out where it might meet interference beyond the track line.
I also have several arcs of thin plywood cut to the inner tie end radius of my most-used curves. Where structure or aisleways get in the way of trammel-swinging those templates are invaluable.
Years ago I have made and heavy duty trammel whith an aluminium tube, a fixed turned pin in one end and a travelling pin which give me the radius, but I think it’s going to far. I am a crafstman in wrought iron and have the access of soldering and some big machine to build this kind of trammel.
If the center of the radius track is out the benchwork use a temporarely piece of wood screwed to the module in the axis of the radius, which allow you to put the center of the track; you can also use a tripod of a camera to make “a center” of your radius.
I am in the way to expand my railroad and will go to an another approach.
I first lay the turnouts in place where they need to go.
I temporarely connect the turnouts whith a thin piece of pine wood holding it whith temporary nuts.
The thin piece of wood pine is very flexible and follow a much “fluid road” to connect the turnouts; the track flow togheter much better.
You can change the place of a turnouts if needed; when happy whith the track countours, drawn a stencil line along the pine and lay your flextrack as usual.
This is very easy to do, but the result is a very realistic flow of the track; much better, easements to curves are natural whith this method; it’s allow also the train to better run through the track.
Take a look at this blog; this well know modeler use this simple technique (see pics of it) whith an amazing results. www.aorailroad.com
Thanks for the addiitonal inputs. For this project I can lay the the subroadbed on th floor so I don’t need a tripod. For my home layout (just waiting to finish out the room first) I will use the template and the flexible wood methods as the curves will be a bit more standard size, 30" min.
For my previous HO layout (1993-2008) and the current one now under construction, I did as “Batman” indicated but used 1/8 inch paneling instead of cardboard, cutting them out on a bandsaw. I started at 18 inches, and cut the templates in 1 inch increments (1 inch wide) up to 36 inch radii. Believe me, they have worked out really well!
I also made a trammel from a metal yardstick, with the “pinhole” at the one inch mark. This worked out great for certain situations - and the only thing you have to keep in mind is that the yardstick numbers will be one inch larger that the curve you are drawing (as your pinhole is at one inch, not “zero”)
I use a length of aluminum carpet transition trim. Comes in 12 foot lengths. But heck, I buy the stuff by the gross for work. I drill holes at the required radii and mark them and my center hole for later use. The trim is 1 1/2 inches wide and has an angle’d side that I place down so it will swing the ark easily. In a pinch, I’ve also used metal stud to swing an arc. The track comes in 10 foot lengths.
