Whos got suggestions on how to lay out larger radius (48"+) curves when transfering your 1" = 1’ drawings to the 1’ = 1’ actual benchwork?
I have a number of large radius curves where the pivot of the arc lays in empty space out in an aisle, etc., so I have nowhere to plant the pivot to draw the arc. Compound this with trying to incorporate easement curves and I’m having a devil of a time laying out accurate, repeateable curves.
Your thoughts and experiences would be greatly appreciated.
Jim
[:-^]
If it is possible for you to drop weighted lines (string etc.with a plumb bob or ((nut, but this is less acurate)) from where your tangent tracks are on the layout and then you can draw your radiis on the floor on craft paper. Then cut them out to use on the layout proper. If this doesn’t work, you can build up ( to layout height ) a portable table about a foot square to use as your fulcrum point. We all have done it, so don’t feel strange about it. What works – works, and what doesn’t-- to heck with it.
James 1 Verse:5
Cut your curve, or a portion of it, out of a piece of plywood or some such material (masonite, cardboard) and use it as a template.
I use templates for curves, and the “bent stick” method to layout the easments.
Nick
Jim:
I’ve not gotten to even start my benchwork yet, but have seen this discussion on other threads, and you can use either of the two suggestions mentioned. But if you want to use the method where your fulcrum is “out in space”, it seems to me the best recc. is to use a camera tripod. Elevate the base of the tripod to your benchwork height, and center at the center of your radius arc–haven’t personally had experience with this, but sure seems to make good sense.
Jim
“Off-the-drawing” radius center points was a common occurance in our all-afternoon high school vocational drafting class. This drawing could have been for a machine part or topographical map. For drafting class grading, and necessary trig calculations, 100% of the work had to be exacting because in the real world, a drawing calculation mistake could cost a business thousands of dollars. P.S.: Not to mention your employment.
We took our drawing (worksheet) to a table that was large enough to accept the straight piece (usually a yardstick) to that specific location where the center was securely placed off of the drawing. It was common practice to get another student to hold the center securely while you scribed the radius on the actual drawing.
So, I would take the preceeding suggestions given to heart as possible solutions, and; similar to using our drafting class method, if it is feasible…
[1] Place a temporary small table just off your layout area, built up to the same height as your trackage with scrapwood & possibly clamped down securely, where you can place your radius center, with a straight piece of wood and your 48" center securely placed with a long nail into the scrapwood-top of your temporary table. This would certainly be a two-person project at least at the moment you begin scribing that radius to keep everything steady.
[2] There is also another less exacting way to get your radius, all done by sight, by using a “lengthy bent stick” secured at both ends of your radius tangents where the bent stick will conform to a curve for your tracing of the center line. This is actually a lengthening of the bent stick curve tangent technique to include the entire curve.
Build an “L” shaped bracket out of 1 X 4, make the long part of the “L” about 30" and the short part equal to the side of your layout frame. Draw a center line on the back side of the long side of the “L” . Mark the pivot point at the edge of your layout and clamp the short side of the “L” to the side of your layout frame, with the lined side facing up. Then measure out the distance for your radius and set your pivot pont.
I place a photographic tripod with the mounting screw where your centre should be. The panning head can be elevated to most typical heights. Tie a length of string to the screw for the purpose of drawing your arc. You can tie a pencil at the appropriate distance from the mounting screw and draw away. Try to keep the tension on the string constant…that would be the one weakness of this measure.
One more vote for the camera tripod.
But I use a 1X2 C clamped to the tripod.
Also drill holes in the 1X2 to drop in the pencil,
Drill as many holes as needed to get different radius.
Make the curve template out of poster board. It’s easy to work with and “good enough.”
For laying out the easement, end your curve approximately 1" inside the tangential straight section, and connect the two with a curve twice the radius of the main curve. When you lay out the flex track it will smooth out the curve even more. When you’re done you’ll have a hard time telling where the straight section ended and the curve started.
Mark in Utah
Try this.
Regards,
From some of the answers you might want to ask who has used their method also.
[:-^]
Impressed with your bench work and facia Tom.
Great Job… Does your wife rent you out ???
Johnboy.
James:1 Verse:5
As a follow-up for what I call the “lengthy bent stick” earlier…
Lowes-type stores have an 8-foot item called a “Trimboard Divider” made of plastic for between $1.50 - $2.00. It is 3/4-inch wide and is used as a vertical joint between two pieces of wall paneling. The back side is flat and the front side is rounded. Greater flexibility can be had with a v-notch out of the rounded-side every foot, or as needed. A 4-foot length works well as a “bent stick” tangent tool. If you don’t like white, you can pay $1.00 more for beige.
The plastic Trimboard Divider is quite flexible, and the flat side is ideal for line-scribing a track center for the coming laying of flextrack. The 8-foot length also has the flexibility to get a template for a sweeping s-curve.
For example, on plywood or homasote, the ends are temporarily wedged between small finishing nails, and you position the middle of the curve with another finishing nail. The “plastic stick” is marked with a black Sharpie Pen every inch and with a Red Sharpie every foot on the top of the rounded-side. You then know how much roadbed and flextrack is needed.
On my next N Scale layout, I’ll be going to a foam base, and I expect that those long sewing pins will be sufficient, to replace the finishing nails, if those don’t work out with the softer foam base.
I use the same long stick with a hole at one end (for pivot point) and holes at the other end corresponding to radius distance. However, if the pivot point is out in open space (off the layout) I use a camera tripod set to the layout height, with the pivot point hole on the stick fitted over the tripod’s fitting for a camera. Hard to get super-precise, but works pretty well.
EDIT: Doh! I posted this before I saw the photo above showing exactly the same thing. Oh well, nice to know that great minds think alike! [:I]