It sure is nice to finally start!!! In fact, yesterday, I finished the open grid! Maybe this week, I can get some legs underneath it.... The simpler the tables, the better. I am no math major.... 1.5"--will that be enough to have a short 'guardrail' to protect for derailments from going on the floor? With 89' cars, I need to have space for overhang. Since I have to maintain my 2% grade, (2.5% would be way steep, especially on the tightest helix loops) I can moderate the mainline grade to allow for the helix to remain at not more than 2%. If Crescent has to level out, that's fine. If the mainline will be too tall at the end of the modeled mainline, I can flatten it to 1% for a few feet here and there to compensate. My most current trackplan is at work, I think... I have a general idea where things go, but that doesn't help you, does it? I'll attach a rudimentary one.... I'll have to redo a new one! I'm not sure what you're asking for here, as I can adjust trackage into the helix area as necessary to keep the helix simple. The 6-8" thing--I can rough-scenic a short portion, but I'm not sure it is necessary, as tunnels 1 and 19, (or 23, or whatever) will be the exits to staging/helix. As for rough scenicking portions of the helix, I dunno yet. The dimension of the loop ends is 42" wide, 28" wide at the narrow end, and 6' long. The narrow end is 29" long. The wide end is 42" wide for 29.5 inches, before the 45* angle back to 28" wide. Absolute minimum radius is 16". Beyond that, it gets mighty tough to run autoracks, and passenger cars with body-mounted MT 1015's. Since the South Draw loop has scenery, and underneath it, staging return loop, center access is again a good idea. I will likely make that a wide curve as well. Both end loop modules will be identical.
Hemi: Here is my latest version of the Spiral Helix detail for your track plan. This is a 4-loop helix (if you count the loops within the helix and about 1/2 the length of the tangents where tracks enter or leave the helix). The grade throughout the helix is 2%, so each of the loops rises about 2 inches. The smallest radius within the helix is close to 16.5 inches, and the largest is 20 inches. The width of the helix ramp is only 1.0 inches. I had hoped to have the ramp 1.25 or 1.5 inches wide, but overhead clearances were too tight on the lower tangents entering the helix from Plain and from staging, plus these ramp widths yielded minimum radii of 15.875 and 14.75 inches, respectively (possibly leading to poorer reliability with some longer equipment). This narrower (1 inch) ramp provides a rise within the helix of about 9 inches. With an additional inch entering the helix from staging and an extra inch while exiting the helix toward Crescent, total rise between the lowest point (Staging) and the summit at Crescent about 4 to 6 feet from the helix will be about 10 or 11 inches. Plain will be at about 3.5 inches elevation. Note: The elevations given in the picture are approximations!! Actual clearance and elevation after construction will probably vary. Critical clearance points include: 1. where the tracks to/from Plain cross under a loop and out of the helix, 2. where the tracks are closest to the edge along the opening between the benchwork into the middle of the layout, 3. where the track is closest to the back edge or backdrop on the back of the helix. The middle half of the top loop is shifted about 4 inches away from the next smaller loop so track on the largest loop may be sceniced. In effect, there will be about 5 to 6 more feet of mainline on which to put tunnels teeth: a late Christmas bonus!) I noticed you posted about putting a guard on the inside of the loops to prevent the “big plunge”. The 1 inch wide ramp (and for such long cars, maybe even the 1.5 inch wide ramp) will, indeed, be too narrow to have a guard on the 3 top loops, but it would be quite easy to cut the bottom/smallest ramp wider. If you plan on using the helix base and supports as pictured in my helix album, then cut the access hole as small as you are comfortable with (thus making the bottom loop ramp very wide but still positioning the track centerline at the radii indicated on the drawing). Put your guard around the edge of the access hole. Depending on how you position the access hole, you may have a narrow ledge with 2 inches of depth inside the track all the way around the bottom loop. Or, if you shift the opening an inch or two to one side (I would suggest toward the front so you have a slightly shorter distance to duck under when you come inside the helix for maintenance), you may have a 3 inch wide ledge on one side and 1 inch ledge on the other…it’s easier to set tools on the wider ledge. It is possible to run trains directly from staging to Plain to Crescent to staging, or from staging to Crescent to Plain to staging. Trains completing either of these runs will be following a point (staging)-to-loop-and-back-to-point track configuration. To complete the run will require traveling over the lower part of the helix both out and back, but trains will NOT be going through any sceniced portion of the layout twice. (I'm considering the staging, Plain, and Crescent levels to be separate scenes in the layout, even though they may be on the same section of 28" shelving.) It is also possible to run trains in a continuous loop from Plain to Crescent to Plain to Crescent, etc, without needing to make any changes in turnouts after setting them for a continuous loop. On this continuous loop, the trains never go down to the staging level. As I recall, staging is configured as a returning loop, but unless you install some fancy circuitry to detect train direction and switch turnouts automatically, you will only be able to use the staging reverse loop as part of a continuous grand loop if you change certain turnouts yourself each time the train makes one grand loop. This grand loop could start in Plain, go to Crescent, take the helix down to staging, take the staging reverse loop around, and climb back up the helix as far as Plain in order to start the grand loop again. The 3 helix turnouts at Plain will need to be aligned each time the train enters the helix—once going down the helix and bypassing Plain, and once going up and entering Plain. I’ll put together some tables showing the 32 specific heights needed for each of the 4 loops on the 8 supports. All elevation values within the helix will be affected by how much rise you want to make before entering the helix. My drawing shows 1 inch, but you will need to make the executive decision about how far along the stem of the U the level yard ends and where the slope up to the helix begins. If the slope starts 4 to 5 feet from the center of the helix, then elevation values within the helix will be pretty close to what was indicated in my drawing. Starting the slope closer or farther away will reduce or increase the elevation, accordingly.
Dave, I was awake in the wee-hours of the morning dreaming up ways to work this helix--how much run is required to cut a loop from the helix? The 1" roadbed, well, seems tight. If I lengthen the helix module a foot or so, and make a spiral/OVAL helix, would the extra run with a 6-12" extra run each lap be enough to cut a loop from the helix? If it would give the necessary run to avoid increasing the grade past 2.5% *2.25-2.5% would be permissable if needed, if we cut the top loop, and ovaled the helix*, the loop roadbed would be wider, and possibly still allow the top loop scenicking... Just thinking aloud. If my ideas are out of left field, I'll go back to bed, and look at it again later! Wow, that's a neat plan! I am unsure if turnouts in the middle of a helix is advisable? Then again, is there a way around it? I don't see much of a way. Here's a quick idea of what I had in mind. I am also unsure if my loop module matches your dimensions. Will that affect helix clearances? Would engineering the helix first be wise? Build the helix, and fine-tune it, then adjust as necessary to connect to the layout... Just thinking aloud..
I did some quick calculations, and I came up with an extra 18" length to make my 9" height goal with one less loop....
In other news, since I am too exhausted to work on the layout, I'll just report that I have legs under one leg of the 'U'. I leveled it a bit, and tossed some track, and roadbed on it to simulate staging. I did the same, with more elvation for Plainview, and another mockup of Crescent's elevation, near the helix. At 9", the scenic separation looks great! maybe this weekend, I put legs under the other end, and the middle, level it all out, and start installing staging roadbed... Hmmm.....
Hemi: Some additional comments... The tangents in and out of the helix should be made with different panels, not part of the panel used for the helix loops. Plan ahead on how you will cut your access hole on the INSIDE of the loops to give yourself your ledge, but make sure you also consider how the loops will intersect with the tangents on the OUTSIDE of the loops, in particular, the tangent that comes along the front edge of the shelf before going to Plain. The line of intersection will probably have to be curved to match the outside edge of the loop where the tangent track goes from loop panel (subroadbed) to tangent panel (subroadbed). For the 2 tangents going to Plain, think ahead on how you want to activate the turnouts in the helix. If you are going to mount Tortoises underneath, you will want to prepare the holes and mount the tortoises before you drop the helix ramps/loops onto the supports. The Tortoise in the back will be especially difficult to mount once the helix ramps are on the supports. I mounted mine with sealing adhesive where I couldn't reach to use screws. It's a pain in the caboose to do this after track is down, but do-able as long as the loops are not secured to the supports. If (like I did) you secure the ramps to the supports with a wood screw driven through the middle of the ramp into the top edge of the support, and the middle of the ramp is where your track will be positioned, then it is CRITICAL that you mount your Tortoises before you install the ramps and especially before you install the track. Otherwise, you will have to pull up your track to remove the screws to give yourself space to reach in and position the Tortoises (Been there. Done that). This task is do-able, but a hassle, nonetheless. Regarding the extra 6 to 8 inches outside the helix for scenery... I personally like the idea (A LOT!) of putting scenery on the outside portions of the top/last loop of the helix. If you have the scenery drop down a few inches in front of the tracks (toward the aisles), and rise a few inches to eye level along and behind the tracks (but absolutely NOT above the other loops), then you will create gorgeous view blocks to hide the helix from a casual observer, but with a step onto a stool, you can watch your trains in the helix (if you're worried). Where the track runs close to the narrow aisle between the ends of the U, put the view block in front of the loop, maybe as a tunnel (that can be easily removed for maintenance). If you decide against scenery around the helix (hmm..did I mention that I think scenery outside your helix is a great idea??? :teeth: ), you could make the helix an oval shape with all curves being the same, but an extra 5 to 7 inches on each side in the straight portions of the oval. This will yield an extra 30 to 42 inches of run through the helix and, thus, an extra .6 to .84 inches of elevation. I drew up my detail of your helix a few days ago when I couldn't get on to TB, so I didn't read about the dimensions on the helix benchwork until yesterday. I think the view block (jagged line) I drew in the corner next to staging is directly over the frame you built for benchwork. This is not problematic, as the center of the helix could be moved away from staging/Plain/Crescent to ensure clearance or a little more area to be sceniced in staging/Plain/Crescent. (Just don't move it so far that you won't be able to put scenery on the outside of the helix...Please?mg: ) Here's a pic of how I put scenery up to the edge of one of my helixes.(Did I mention...Ok...I guess I've belabored it enough.:embarassed: ) That handsome fellow working the Scrap Yard Job at my 12-30-06 operating session is me. I’ve used Styrofoam to form 2 inch hills covered with trees around the edge of the helix. The tree-covered hillside serves as a view block for the helix. From the normal viewing height, you can’t see into the helix. Only when stepping onto a stool (like when taking a picture or watching a train in the helix) can an operator see into the helix. The cardboard strip in the lower left represents a mock-up for the highway overpass that will disguise where trains pass under the bridge, off the layout and into the helix. You have indicated you will be using your tunnel portals to move between your helix and the sceniced part of the layout, in much the same way I’ve used the bridge.
Hemi: I wrote the "additional comments" post a day or two ago and posted it today without addressing your concerns about the 1" wide ramps. Sorry. Here goes... As far as using the oval shape to increase the length of the loop, that's do-able, but wider ramps affect the radius of each loop too. Going to 1.25 inch wide ramps will reduce the minimum radius to 15.5 inches. One quarter turn around that first loop the radius will have increased to (15.5 + 1.25/4) 15.81 inches, half way around to 16.15 and all the way around (start of the 2nd loop) the radius will be 16.5. If this pushes the minimum radius envelope too far, then let's remove the inner loop. This will increase the minimum radius to 16.5 inches. I think you'll have 353 inches of length in the remaining loops which should lift your track about 7.06 inches. [Note: the following numbers are to be considered "ball park" only. I need to tweak my Excel worksheets for the wider ramps.] I'm not sure where you're coming up with the 6 to 12 inches on a side for the oval...I think you're giving yourself 5 feet from the end of the shelving to the exits to/from staging, Plain, and Crescent, and my drawing only gave 4 feet. We want to make up about 102 inches lost when we removed the tightest loop, and we'll have 2 sides to each of our 3 loops, so 102/6 = 17" on an oval side to gain 9 inches through the helix. Hmmm, way longer than your "6 to 12 inches" of available length.:sad: If we figure 6 times 6" on an oval side, then we'll recoup about 36 inches of length and will rise about (353 + 36)* .02 = 7.78 inches through the 3 loops of an oval spiral helix. If we figure 6 times 9" on an oval side, then we'll recoup about 54 inches of length and will rise about (353 + 54)* .02 = 8.14 inches through the oval helix. If we figure 6 times 12" on an oval side, then we'll recoup about 72 inches of length and will rise about (353 + 72)* .02 = 8.5 inches through the oval helix. I'm still anticipating rising 1 inch between staging and 4 feet to the bottom of the helix, and 1 inch between the top of the helix and 4 feet to Crescent. Plain will be at roughly 2.5 inches (but I'll have to study my drawings and warm up my calculator before I can give you a more accurate elevation). The oval helix will shorten up the level areas of all 3 "decks" by 6, 9, 12, or 17 inches. Executive Decision #Umpteen-eleventy: How far are you willing to shorten tracks in staging, Plain, or Crescent to gain back the height at Crescent? This is exciting!! You must be thrilled to finally get some benchwork up and track down.
Dave, I did the math, and came up with 18" added to the helix to make up the lost loop. Are you suggesting, I start the 2% in staging, and run 4' before I reach the helix? Once again, I think building the helix first, and adjusting the tracks to the modeled layout to match seems a good idea. I still haven't settled on a helix design yet!
Hemi: Make several copies of this spreadsheet and play with the various values in the orange cells. Notice how other #s get calculated. Please be careful with the other cells because the formulas aren't locked...if you change a formula by mistake everything will get thrown off. (That's why I suggest making several copies. Maybe someone out there in TB land knows how to lock formulas in some Excel cells without preventing inputting new values in other cells.)
Dave By default all cells in a worksheet are locked. To lock all cells you need to turn on worksheet protection. This however will now not allow any changes to the values in any cells, To allow changes to the selected cell in the worksheet you need to format the cells involved. For each cell or range of cells simply select the format cells option, an option box will appear. Select the protection tab and notice that the locked check box is checked, click that to remove the check. Do this for each cell you want users to have the ability to change values. Now under tools on the menu select protection and activate worksheet protection, you can add a password or not as you wish. Hope this helps
Oh, Dave, that is COOL! I found that ramp width of 1 1/4" will suit me better, and stay within my givens & druthers. The sheet even tells me exactly how high my helix supports need to be at every level, for 8 supports! Wow! I think I may add a sheet of plywood in the helix area, and level it, that way my helix stays constant, and not dips with the undulations of the not-exactly-level benchwork grid. Will 3/8 or 1/2" be sturdy enough to stay level? Heck, I may start to build this helix this weekend! Of course, I'll have to take the extra height into consideration. OK, Dave, how do I draw this out? I assume I draw a complete circle at my first radius, as the track centerline, then draw another circle at the next radius, and so forth. Or have got that wrong? I seem to recall you said somewhere how to draw the helix? (the blog is down, so I cannot check there). I wanna get this rollin'!
More progress! Since the helix module seems a bit flimsy in the loop area, I added another leg, and it sure helped shore it up better. I also re-arranged the lights, and found I need at least 4 more shop lights to get the amount of light I desire. I also noted that since moving the shop lights around, my modeling desk is in the dark.. OOps! The layout is now in its permanent location, next is leveling it all up, and installing legs on the other modules, and attaching it all together.
Very nearly.. My modeling bench is behind the fence, along with a bazillion tiny tools, parts, and pieces that my little engineer would LOVE to get his paws on.... The fence has been moved to the other side of the layout after that pic was taken. I got some 1/2" ply that would work well for this. The helix itself will be cut from 3/4" plywood. Not OSB. The roadbed for the entire layout will be 3/4" plywood stock. The only stuff I bought was the 2 shets used for the open grid. All rescued from the wood recycling pile! Amazing what you can get for FREE!
Hemi: How do you plan to secure the track to the plywood? Do you plan to use the frame as the fascia? Or will you be hanging the fascia board on the edge of the plywood subroadbed? Along the 28" shelf it shouldn't matter either way, but if you have some latitude to use the plywood to hang the fascia, it might be possible to gain a few inches beyond the outside end of the helix shelf and on the 19" diagonal near the staging level.
Hemi: While you're drawing lines on plywood, I'll work on drawing some on paper (probably later today). I'll try to draw out what I meant about where the cut lines will be for the ramp edge and for the tangents.
Legs are under the whole layout, 14 in all. The benchwork is in its final position, and the 2 sides of the 'U' are connected. Next step: leveling the works: I mocked up the positions of staging, Plainview and Crescent (although I should have labeled it Tunnel 21 or somethign a bit further west of Crescent):
