What do you use to draw large radius curves? I considered a pin/nail and a length of string, but am concerned about being able to consistently draw the exact same arc.
Richard
Substitute stars dative or other similar piece of wood for the string. I put a nail in one end, then drilled 1/4" holes at various lengths into which I inserted a pencil.
That was supposed to be "substitute a yard stick"
Right. And if your radius is more than 35", you can just graft another wooden yardstick (or a part of one) onto the end, using plain old carpenter's wood glue.
Tom
Perfect. I will get a stars dative. Thanks for the help.
My long trammel is a cheap (69 cent!) wooden yardstick from Home Depot. The hanging hole is exactly one inch in from the end, so I have to add that inch to every radius.
When I use it, the golf pencil goes in the hole and I put a track nail in the much smaller hole drilled at the desired radius. One trick is to find the radius, then drill 2 holes. To locate them, put a flex track tie (with track nail hole) centered at the desired radius, then mark the tie end radii (which, for Atlas HO track are 14mm from the CL.) It's a lot easier to align tie ends than to try to align to a center line.
Chuck (Modeling Central Japan in September, 1964)
here is the compass i use. i can add on about 10 more 10" bars to give me dia. of up to 16 feet.
FB page of my layout *new*
https://www.facebook.com/ghglines
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thread to my layout
http://www.warcrc.net/forum/showthread.php?t=10505
pics
http://s237.photobucket.com/user/rockcrawling/library/#/user/rockcrawling/library/ho%20scale%20trains?sort=3&page=1&_suid=1388183416990004180295067414064
An electrical conduit fish wire, which is made from spring steel, forms a perfect curve, including the easements at each end.
Pin the end down on one leg of the curve, extend or retract line from the case until you get an amount that forms the curve exactly where you want it, then just trace along the wire.
The methods mentioned above do not form easements at the ends of a curve like the conduit fish wire will.
GGOOLER here is the compass i use. i can add on about 10 more 10" bars to give me dia. of up to 16 feet.
Now that is pretty cool !
Rich
Alton Junction
I used the yardstick method also, supplemented by a set of brown paper curve templates that I cut out every inch between 22" and 36". It took awhile to to mark out and cut the brown paper curves but they came in rather handy. Since my turnouts had designated positions and several were curved, it helped to have the paper cutouts to try various radii in or out of a turnout, and how that radius might vary through the curve from point A to point B (the next turnout). In several cases, a consistent radius was not best between points, including how "parallel" tracks on a curve (that needed to vary in spacing somewhat due to things at each end) would work best.
Paul
Modeling HO with a transition era UP bent
If you have access to a drillpress, drills and taps, some bar stock and rod you can make your own trammel.
regards, Peter
When I built my layout, I made a bunch of cardboard templates, each about three feet in length. Each piece was four inches wide giving me a given radius on the inside curve and outside curve (18" and 22"). I also made 19/23, 20/24 and 21/25.
With narrow benchwork and numerous outside curves, I was not able to use a string or stick from a fixed point. The templates allowed me to lay down a mixture of radii and eyeball them before actually drawing them out on the bench.
Mark.
¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ
I have a 6' long piece of thin metal 3/4" wide that I got at Tractor Supply. Probably many hardware stores may carry it too. Being 6' long should get me through most of my curves and it bends with an easement at both ends. The advantage to this over a thin strip of wood is that it won't snap. Disadvantage is that it can be over bent in a spot, giving you a bump in your curve. Just don't reef on it and it should be OK.
Good luck,
richhotrain GGOOLER here is the compass i use. i can add on about 10 more 10" bars to give me dia. of up to 16 feet. Now that is pretty cool ! Rich
Some guy's just have to have all the toys.
Brent
"All of the world's problems are the result of the difference between how we think and how the world works."
I have used/done about all of the suggestions. I made cardboard templates from 24" to 36" radius, which I made using the 'professional drafting' compass or a yardstick with holes in it I finally wound up using a scrap of masonite that I had, about 3/8" wide and 1/8 - 3/16" thick by 8 feet long. This was by far the best tool! It will make very smooth graceful curves with easments on the ends; even S curves as it is so flexible and yet keeps its rigidity in the vertical direction. I just put some nails/pins on the centerline of where the curve had to go and when it looked 'right' I transfered the curve with a fine sharpie marker. I used that line to glue my cork roadbed down and then the flex track was 'centered' on that. I did about 200+ feet of track this way and would use it again if I had to start over. Just anoher way to 'skin a cat'.
-Bob
Life is what happens while you are making other plans!
Being in civil engineering, my toys consisted of being able to design my layout using my AutoCadd (computer aided design and drafting) program at work (and home) and plotting everything fullsize with the plotter at work. Plotter can plot up to 48" wide with a length limited to the amount of paper on the roll stock. Typically the longest length was 8-10 feet. Needed to keep it managable. Broke up the base roadbed into sections, laid them out on 4'x8' layout in the computer, ie. typical plywood sheet size, in order to maximize the wood stock, plotted drawing, laid it on plywood, and cut everything out. Then assembled base roadbed sections on benchwork and risers, transfered track centerlines to base roadbed, installed cork roadbed and then track. For anything added or modified during construction I could either plot the revised design or like most of the time use what people would call vintage drafting tools, as in a beam compass, triangles, highway curves, etc. and draw it on the base roadbed, you know pencils and stuff from my old drafting days. For me it was simple enough to add curve easements (spiral curves) using the AutoCadd design software versus non-computer calculation since there are multiple tangents involved and the easement or spiral has a constant changing radius. There are formulas to calculate the easements and any point on the easement for layout. A route surveying handbook has this information in it or I'm sure it's easily searchable online.
On a more practical side, you may want to make curve templates from thin wood or a heavy cardstock since the center point of the radius of your curve you are drawing may not be on any wood or stable surface on when using a yardstick, etc. On my previous layout I used a grid system transfering the track design from a drawing to plywood sheets for the base roadbed or the table itself. Also, did some freelancing on the layout construction.
Here's a view of where I started laying out my layout on large sheets of cardboard. I used a 3' grid and transfered all my track positions to the cardboard and then made adjustments to fit. Once I had the track positions marked on the grid I used the '8 foot masonite spline tool' to make the final curves. It really is different when you layout your plan on a full size 'drawing surface' like the cardboard.
Thx to all for great tips on creating curves WITH easements.Question: Where do yo place the desired curve tool to ensure a minimum radius of say, 30", including the easements? For example, with a 180 curve, the parallel tracks would be futher than 5 feet apart, would they not?Also, how do you best create S- curves with a minimum radius that includes easements? Seems like the metal or masinite ideas would work best as I have a difficult time properly connecting twp partial circles. - but I still wouldn't know where to place it to ensure a minimum radius including the easements. Sorry - I am not a mathmatition or engineer! :)
Green Train ---
Model Railroader had a pretty thorough discussion of this subject in prehistoric days. The 1970's, I think. If you look that up, you may find the perfect answer. I'm sure a civil engineer would tell you "It's easy. Just start by......." etc. etc. etc. Well, I'm not an engineer either, so I've adopted a fairly simple solution. I start by marking accurate center lines on all my plywood subroadbed. When a straight section meets a curve, I allow for an offset of about 1/4". Then I place nails or screws along both sides of the centerline of the straight section and the adjoining curve. My longest passenger cars are about 12" long , and I have a few articulated engines, so I allow about 18" for the transition. That means no nails for 9' on the straight section and 9" on the curved in the area where they meet, for a total of 18" transition. Next, I place a long piece of lath or a similar piece of wood along the centerline, between the nails. Make sure the lath follows the curve and let it flow naturally into the straight section. Mark a centerline along the edge of the lath, remove the nails, and put down your cork or homasote ballast strips along that centerline. NO, it's not a precisely perfect spiral, but it's certainly good enough for our purposes.
I apologize, but you lost me at "when a straight section meets a curve". How do I place screws on both sides of the centerline of a curve I haven't created yet, but am trying to?The easments are "throwing me". I can make a 30" curve with the methods descibed above, but are you saying that a radius of 30" would actually be 30 1/4 with easements, and have a "bow" that is 18" longer?In other words, how many inches, or fractions thereof, do easements add to a desired radius, both in "width" and "length"? Using masonite or one of the other tools.methos mentioned seems simple enough, but how is the radius you want assured? I would imagine curves and track-laying is rudimentary to most, but I am new to the hobby and used to the sectional track (absent easements) of my childhood days. Flex-track seems quite a bit more challenging, in both normal and S-curves.If anyone can direct me to some basic books, articles, etc - I would be most appreciative because the ones I've read thus far don't explain it well.
Green Train, take a look at this explanation. There are a thousand more illustrations and explanations like it out there.
http://www.eldoradosoft.com/easements.htm
An easement is a less violent introduction to a curve for standing passengers and crewmembers. Instead of your tracks having a tangent and then a sudden onset of a curve with a fixed radius, the idea is to have the rolling stock nudge into an ever-decreasing radius until the curvature meets the needs of the engineers to reorient the track to the next tangent. However, the curve could be taken the other direction, so that side, or end, of it also needs to have an easement.
If you think about automobile driving, every turn you make is an eased curve. Your wheel is straight ahead and you are in tangential motion. You want to turn left, and you commence the turn by beginning to rotate your steering wheel to effect that turn. The first three degrees of rotation of your steering wheel chang the rate of curvature only slightly, but as you keep turning the wheel counterclockwise, the radius sharpens. The path your car takes turning left is an eased curve by definition.
To generate an eased curve, the simplest way is to let a couple of lengths of flex track do it for you. They make eased curves naturally. You join the lengths to be curved with your tangent track, and then pin the joint area so that it can't deform under strees. Then, with the joint anchored, you fashion your curve but by anchoring the far side to its joint. What falls between the two anchored ends/joints should be a close-enough approximation of an eased curve.
-Crandell
Get yourself some thing, felxible wood strips (lathe strips). Draw your nominal curve with the pivoting stick or beam compass. Draw the tangents leading away from the curve 1/4" to the outside of the resulting centerline. Pin the lathe strip on one end to follow the curve radius, and pin the other end back along the tangent. This should form a smooth gradual curve from the tangent center line to the curve center line.
Or use Atlas flex track and do what Crandell suggests - that "snaps back to straight" thing about Atlas flex track that some people hate allows it to naturally form gradual easements without all the fuss of trying to conform it to track centerlines. Some others are similar. Peco is in-between, ME, forget it, you will need to draw in the centerline with the bent stick and work the track into position.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Here is how I did mine with a strip of masonite (3/8" x 3/16" x 6'). I just laid them out on the floor for the photos. I used cardboard radius templates to mark the radius on the subroadbed/plywood and joined them to the straight section with the masonite. You can see in the closeup photo of the straight blend that it is a smooth transition using the flexibility of the masonite to form the transition curve (doesn't matter what radius it is). With radius templates you don't really need to know where the center of the radius is and therefore don't have to have a solid center place to swing a radius from.
[quote user="Green Train"] How do I place screws on both sides of the centerline of a curve I haven't created yet, but am trying to?
Oboyoboyoboy! I'll bet you're even more confused than you were before your first post! I feel for you! Nobody has given you incorrect answers, but I'm not sure the explanations have been quite clear enough. First, when laying out your track plan on your benchwork, the thing you are trying to do is to connect the various roadbed curves with straight sections. So lay out your curves first, if at all possible. I cut mine from plywood to the exact radius. Then connect them with straight sections. When you do, DON'T just run your straight track directly into the curve. Instead, run it a little bit outside the curve, as if the straight track was going to run past the curve. Picture the number 10 in your mind. The 1 is your straight track and the 0 is your perfectly round curve. Your track is offset at the point where the 1 and 0 are closest. They don't touch, but you want to connect them. In HO scale, an offset of about 1/4" to 3/8" is usually about right At the straight end, the straight track is truly straight, At the curved end, it is exactly the radius you have drawn on your curve. In between, you want the track to gradually change from straight to curve. The idea is to let the track leave the straight alignment gradually, gently easing into the curve. When you use a piece of lath or similar material such as springy masonite, you secure the lath so that it aligns with the curve. Then you let the piece find its own way to return to its natural straight condition. At the point where the curved and straight sections join, let the piece of lath find its own natural straight condition along the alignment of your straight track. That's your easement. Actually, I think you're over thinking this. It should become apparent when you get your curves established with slightly offset straight sections connecting them. I truly hope this helps.
Thx everyone! Yes, it has helped. I know what an easement is, and it's purpose - I just wasn't sure how to best create them. My hang-ups have been the off-set and the length of the easements since I need to know how close the straight track from each "side" or "end" can come before I start the curve. From what I gather, I draw out my desired radius, off-set the straight sections on each end of the radius by 1/4 inches, and roughly 18 inches before the actual radius begins. Thx for the assistance!
:G
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