My first stab at HO table top design… feedback welcome before I do track layout

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William Burg said:
This is not something you're going to be able to build in HO scale using anything but streetcars. Keep in mind that, with the size of those blobs, your outer radius will be 12-14" at most, and an inner radius has to be at least 2-3" inside the other loop to avoid having the trains bash into each other (ordinarily it's less than that, but the sharper the curve, the more cars will stick out into the middle of the curve) so the inner turning radius will be between 9 and 11 inches in radius. That's also a lot of diamond crossings, on curved tracks with a 9"-12" radius, which nobody makes commercially--and trust me, scratchbuilding and handlaying traction-sharp diamond crossings is high-level wizardry even for a skilled and experienced model railroader. Also, putting them on sharp curves is begging for derailments. Re elevation changes: there's no way these tracks will be going up and over each other (not that it would be possible anyhow, unless the entire train consists of flatcars, including the locomotive.) Model trains can handle maybe a 4-5% grade, with good trackwork and not on sharp curves, and you need enough room to get things up to a higher grade, which you do not have here.

Also, assuming that you have soldering and brass fabrication skills necessary to build those meticulously detailed diamond crossings, your grandkids will bash trains into each other at the crossings constantly, since there is nothing stopping them from running into each other.

Model railroaders are, ideally, a supportive bunch, and the moderators of forums really try to encourage people to use positive feedback, rather than criticism. But I don't see how you are going to be able to get where you want to be with HO scale--and yes, I recognize that you don't want to go to N scale, I'm likely a bit younger than you and N scale is too small for my eyes and hands too. But there might not be a way to get what you want, without some changes in your expectations, and a willingness to plan a layout before you start building.
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I had a 19" radius (38" diameter) life-like power-loc circle set up in those bubbles for testing my new Athearn locomotives and it worked just fine with the 'regular size' rolling stock and two different locomotives (a steamer and a diesel)

So I believe I'll be alright

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William Burg said:
When buying your motive power and rolling stock, keep in mind that if the blobs at either end are 30" and 28" wide, the widest radius your curves will have is 12"-14", so you're going to be limited to very small one or two truck engines (if diesel) or 0-4-0 or 0-6-0 steam (if steam), and 40' or shorter cars. And while you can reach the back corner of the room, can you perform detail work (applying scenery, painting, filling holes, soldering feeders, rerailing a derailed locomotive) at that distance? Also note that when trains come out of each blob, in the foreground they will immediately curve sharply in the other direction--model railroaders call this an "S-curve" which causes derailments because the bodies of the cars are no longer parallel to each other, meaning one or the other car (typically the lighter one) gets pulled off the track. And all of the above assumes operation at slow speeds--which is a speed that kids do not want to run trains at. And if you decide what I'm saying is bunk and buy yourself a modern diesel with six-wheel trucks, or a big steam engine, good luck even getting it to sit on the track, let alone running it.

Of course, there is another option--pick up a couple of streetcars! They're intended to run on even sharper curves than these, and don't have to pull trains of cars. For a single-truck Birney or even a two-truck Brill or PCC streetcar, 12" radius is comfortably broad--and some operate on curves as tight as 6-8" radius.

It's easy to hand-draw loops on a template and assume everything will work out all right. In practice, it's always a far better idea to either draw a detailed schematic, one you can measure, or use free track planning software to map out what you want--or even just grab a bunch of Snap-Track and stick it together on the floor or on a tabletop so you can see for yourself what will fit in the space you want, and what won't fit. Because it seems like what you want is not going to fit where you want it, unless you are willing to change some of your expectations.

How easy is it to drill through that 1/4" bathroom wallboard? Keep in mind that you'll want to put holes through it for power leads, and controls for turnouts, unless you were planning on leaning over to control them manually (which is fine, but again, it's always better to plan for these things in advance than just start knitting a parachute on your way out of the burning airplane.)
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Here’s the dimensions … blobs are 44” diameter…

Hence the test runs I did with 38” diameter circle of Life-like power-loc ‘snap track’ worked well

The John’s Manville GoBoard is incredibly easy to drill though… it’s the lightest, yet strongest and easiest material to work with I’ve ever encountered. I encourage anyone to take a look at it next time you are in the lumber store / Lowe’s, Menards, etc

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I still don't see any return track. Loops (on the blobs) don't prove anything. Of course those will work.

Do you want to find out now that you can't connect the two blobs, or later when it's too late? :)
 
I have a boatload of life-lock track and 75’ of flex track

I’ll be doing some testing of my design by laying out some of that track on the table soon

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Will be exciting to see what I find out
 
What you will find:
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Your loop exit follows the yellow arrow. To do that, it has to clear the blob corner next to the arrow. That forces you to drastically reduce the blob radius (as you actually show). In reality, the exit angle from the blob follows the green arrow. In that case, you have almost a 90 degree turn to make, to be parallel to the wall (which you must be, to prepare for the rear return loop). The same problem exists on the other blob.

It's desirable to leave "easements" or adjusting sections between major track features. In your case, not only do the easements not exist, they are actually negative (leading to impossible geometry).

Also, both solutions to a cross over have issues. If you have a level crossover, the angle is strictly limited to the angles available in your sectional track catalog. If you have an over-under, you have severe grade issues, you will have constant derailments and/or running problems or difficult track assembly.
 
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RetiredinIowa said:
Here’s the dimensions … blobs are 44” diameter…

Hence the test runs I did with 38” diameter circle of Life-like power-loc ‘snap track’ worked well

The John’s Manville GoBoard is incredibly easy to drill though… it’s the lightest, yet strongest and easiest material to work with I’ve ever encountered. I encourage anyone to take a look at it next time you are in the lumber store / Lowe’s, Menards, etc

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Ok, must have misread your earlier statement of dimensions--you are still likely to run into problems, but only slightly less severe, and the inner loop will be about 16" radius. Also note that grades basically increase the sharpness of a curve (you're curving in 2 dimensions instead of 1) and make it harder to keep track level (or superelevated, if you lay things out that way). The way you have things laid out means less straight track and more S-curves, which as mentioned above, is more of a challenge than just having sharp curves, and that's before you get into grade changes.

The equipment you posted are basically 40-foot cars, a diesel with 2-axle trucks and a 2-6-0, which are still in the "small" category (they will run on 19" radius HO curves), and will likely manage 15" curves all right--they're about the largest things I run on my layout, which also has 15" radius curves and a 12" curve on an industrial spur. So if you stick to that size of rolling stock you're likely to be okay--until you hit those S-curves.
 
All great feedback and considerations! Thank you all!

I’ll start doing some test layouts tomorrow and see what I find on curves, s-curves, etc etc

I ordered a boatload of riser supports for the Power-Loc track from eBay (to help with potential overpass crossing and also ordered some foam riser kits I’ll need for the flex track)

trial and error in my future :)
 
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Marlin39 said:
You've done the hard part.....laid track without any derailment or electrical issues. 👍
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The second track will be a huge challenge of course with some elevation to cross tracks etc

But I'm up for it (I think) :)

Might be a mix of flex track on cork road bed plus some of this power-loc track (I have adapter pieces)

We shall see
 


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