Wheel profile vs. "groovy track"

Discuss park gauge trains and large scale miniature railways having track gauges from 8" to 24" gauge and designed at scales of 2" to the foot or greater - whether modeled for personal use, or purpose built for amusement park operation or private railroading.

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rkcarguy
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Wheel profile vs. "groovy track"

Post by rkcarguy » Fri Mar 09, 2018 12:46 pm

I'm using a groovy track type method for my 12" gage RR build, utilizing 3/8x1 hot roll flat bars pressed into grooves 7/16" deep in the wood ties.
IBLS wheel profiles don't have a 12" spec, only 15".

http://ibls.org/files/Standards/IBLS%20 ... 0Gauge.pdf

The problem is, the flat bar has a pretty minimal radius on the corners, while the "gage radius" on the IBLS drawing is 3/16" to 1/4". Won't this cause problems with the sharper corner of the flat bar rapidly wearing into the wheels?

Also, being I'm 12" gage, should I downsize all these dimensions a little bit?

I would think as a whole, I should maintain the angles, but maybe drop the flange width and depth to 1/4", and "gage radius" to 1/16th.
My router fixture I made for grooving the ties makes the rails 12.080" apart. I'm planning on making the wheel set gage right at 12" on the locomotive and maybe 11-15/16" on the rolling stock.

Thoughts?

Glenn Brooks
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Re: Wheel profile vs. "groovy track"

Post by Glenn Brooks » Fri Mar 09, 2018 3:29 pm

Ryan hopefully somebody with Groovy track experience can comment on your radius question. Might be a good idea as the radius helps the wheels track back towards center.

Undoubtably you will observe wear with the flat bar. However probably you won’t be running enough on the track to make an appreciable difference, at least in the short run.

In answer to your gauge question if it were me I would make the gauge 12 inch on everything. I think it would be a mistake to make more narrow gauge trucks for your rolling stock even if it is just a 1/16 or so. The gauge of the track is designed to keep the cars from oscilating side to side. More Narrow gauge cars will cause additional lateral movement with increased friction each time the wheels hit the side of the rail. Can’t see anything good coming out of that.

Glenn
Moderator - Grand Scale Forum

Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....

rkcarguy
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Re: Wheel profile vs. "groovy track"

Post by rkcarguy » Fri Mar 09, 2018 3:55 pm

My thought on the gage radius(inside corner at the flange), is that it should match that of the corner of the rail, or "point loading" will occur at the radius of the wheels resulting in rapid wear of one part or another. The 2-5/6 degree angle is what I'm understanding makes the cars track on center?

I thought your rolling stock ran a little looser than your locomotive, but if you feel .040" clearance per side is adequate I can set all my wheel sets at that. If you notice the dimensions on the 15" IBLS standards, they call the wheel gage at 14.718", leaving .282"(or .141" per side) clearance. That is with the rails being at 15" even, minimum. I am 3x tighter than that while only 20% undersize, therefore my concern.

Glenn Brooks
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Re: Wheel profile vs. "groovy track"

Post by Glenn Brooks » Fri Mar 09, 2018 4:24 pm

Ryan,

Haven’t measured all the wheel sets, but so far as I know, they are set at 12” ga exactly. As I remember, Haven’t found one less than that. Did I previously pass along different info? Can’t remember...

Yep, seems like a good idea to match the radius of the rail to the wheel as much as possible. There are some people on th forum who are very knowledgeable about wheel design. Maybe they can offer some more detail. The prototype wheel designs were a very complicated design - each measurement no doubt debated at length and mitigated a specific problem of the physics of pulling heavily loaded cars over skinny little strips of steel! Its a very interesting subject. I am sure there is much to this that I do not know.

Gpb
Moderator - Grand Scale Forum

Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....

rkcarguy
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Re: Wheel profile vs. "groovy track"

Post by rkcarguy » Fri Mar 09, 2018 4:47 pm

I recall that you had stated your rolling stock was a little undersize, not much though. What I may need to do, is add a shim to my tie router fixture such that my curves open up another .040"-.060". I think the .080" clearance would be ok for my straight sections which I am building in pre-made lengths. I am going to lay the curves "to suit" so I can work around the tree's and minimize my chances of getting in trouble (Having seen the city/state botanists require a new building have a wall moved back due to an existing tree in my line of work).

STRR
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Re: Wheel profile vs. "groovy track"

Post by STRR » Sat Mar 10, 2018 12:00 am

Ryan,

Square edges on groovy track have always been a problem. The wear you are worried about is exactly the problem many groovy track enthusiasts have to deal with. The best answer it to round the inside edge, preferably to match your flange to tread radius but anything close will be good enough. Normally, a wheel with a tapered tread will not run against the flanges but equalize somewhere between the flange and edge of the tread.

Most groovy track people grind off the inside edge of each rail. Some do it on a bench before they press the strap/rail into the ties. Others prefer to assemble the track and then grind. Several have used a flat car to lay on, belly down, with a grinder. Hanging off the car a little, over the front of the car, they can grind the rail and roll along without having to break their backs. Some use a generator on the flat car or the next car back, some use a portable gas/diesel powered welder with electrical outlets for power tools. I once considered groovy track and had thought about mounting two grinders, at different angles on a car, much like the full size rail grinders do. That way, I could just push the car down the rail and grind at the same time. If I wanted more material removed, I could move slower OR make more than one pass.

Concerning you gauge clearances. I recommend you take the 15" specs and reduce them the same percentage as your gauge. Your 12" gauge is 80% of 15" gauge so make all your specs 80% of 15" gauge specs. IF you find the measurements difficult, round up to the next increment. A LITTLE looser is better than TOO tight.

I have one big complaint with groovy track: CURVES. In any curve the gauge should expand to allow for the change in wheel geometry. I'll try to explain. If you are running down a straight section, your truck/wheel geometry is a square or rectangle. This is the measurement of the wheel contact points in relation to the rails. When you move into a curve, the geometry changes to a triangle. The inner wheel geometry changes due to the wheels being closer to the center of the radius of the curve, allowing the center of the side frame to move to inside the inner rail. Inside meaning closer to the center of the radius (not inside between the rails). Maybe outside the inner rail towards the center of the radius of the curve would be better. The outer wheel geometry changes in the same manner with the exception of the side frame moving INSIDE the outer rail. You have an effective triangle between the two outer wheels and the center of the inside side frame. This effectively widens the track of the wheels.

To counteract this widening, you need to expand the gauge in the curves. Think about a 2-10-2 locomotive. Running down the track the drivers are gauge minus clearance, WIDTH. Now, in a curve the front and rear drivers are extremely tight on the outside rail while the center drivers are tight on the inside rail. Now I think you can visualize the triangle geometry I'm talking about. In order to effectively counteract this triangle effect, you need to use a triangle track gauge.

To build a triangle track gauge; first measure the distance between the first axle and last axle in your longest fixed axle set. This is usually the front to rear drivers of a locomotive, or it could be the distance from the front axle to the rear axle on a single long truck. This will be the measurement for the bottom (wide part) of the triangle. Next, from the apex (top point) of the triangle to the bottom will be your gauge. Very simple. Your apex should be exactly center over the bottom so as to make a perfect triangle.

To use the gauge, keep the apex (top point) on the inside of the curve and the bottom (wide part of the triangle) to the outside of the curve. The triangle will automatically widen the gauge in the curves the exact correct amount to prevent binding and accelerated wear on wheels (flanges) and rail.

NOW, the trick is: How do you do this with groovy track where you make slots in the ties to affix the rails? I had envisioned cutting (routing) the inside rail slots. Then, using the triangle gauge to mark where the outside rail should be. Go back and cut (route) the outside grooves and install the rails as normal. The triangle gauge should verify the correct gauge in the curves then. One great thing about the triangle track gauge: You can use it anywhere on your track. It works just as well on straight track as it does on curves. It also hold the rail in place as you secure it to your ties IF you are NOT using groovy track as in screws, lag bolts, or spikes.

I hope I have helped here and not confused you into next week.

Good Luck,
Terry Miller

rkcarguy
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Re: Wheel profile vs. "groovy track"

Post by rkcarguy » Tue Mar 13, 2018 4:23 pm

Good points, I understand. I planning to sort of cheat, and just layout a practice section of track at my 40' min radius and see how things worked.
One thing that makes it very easy for me, is that I am using a router and running it down the sides of a block I cut to a very specific width to give me my gage for the tie grooves. It's fast, simple, easily adjustable, and a lot more finger friendly than using the table saw. I cut to length and grooved 78 ties in about 90 minutes. I can easily make another router "guide block" a little wider for the curves.

STRR
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Re: Wheel profile vs. "groovy track"

Post by STRR » Tue Mar 13, 2018 6:25 pm

I sure understand about using a router jig. If you're going to use 40' or greater radii curves, and you're NOT running any long wheelbase locomotive, you probably will NOT need to expand the gauge in the curves. 40' for standard trucks and small wheel based locos should work just fine at standard gauge. It's when you have shorter radii curves and longer wheel base locos that will bind in the short curves, then you need to give yourself a little wiggle room.

Good Luck,
Terry

rkcarguy
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Re: Wheel profile vs. "groovy track"

Post by rkcarguy » Tue Mar 13, 2018 6:47 pm

I'll do some math,testing on them and see if I need to or not. I want to build an SD-9 or an 0-6-0 later, and I'd like to not have any track issues and leave room for growth. I've drawn up my turnouts to also have a 40' radius on the diverging portion to hopefully alleviate any problems, but 40' radius for 12" gage isn't that big. I can't go any bigger though or I won't be able to loop around the detention basin and stay within the property line.

Glenn Brooks
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Re: Wheel profile vs. "groovy track"

Post by Glenn Brooks » Tue Mar 13, 2018 7:31 pm

Ryan, these always the possibility of using a turntable at one to turn the loco. Not so good for continuous operations. Also, could you bridge over the edge of the retention pond? Probably not if it’s a public ROW...
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Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....

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SteveM
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Re: Wheel profile vs. "groovy track"

Post by SteveM » Wed Mar 14, 2018 11:28 am

STRR wrote:
Sat Mar 10, 2018 12:00 am
I once considered groovy track and had thought about mounting two grinders, at different angles on a car, much like the full size rail grinders do. That way, I could just push the car down the rail and grind at the same time. If I wanted more material removed, I could move slower OR make more than one pass.
I thought about profiling a grinding wheel with the correct form for the entire top of the track (the curve on the top surface as well as the edges) and mounting that to a motor and having that ride on a flatcar towed behind something. You would need to have some kind of feeler on the track to determine that the correct depth of grinding has been achieved and stop the grinder from advancing.

Steve

rkcarguy
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Re: Wheel profile vs. "groovy track"

Post by rkcarguy » Wed Mar 14, 2018 11:20 pm

My lot is having it's natural resources assessment done next week, I've requested to be present so I can ask some questions, as far as tracks over the drainage ditches etc etc. I've got 5 acres so I have lots of options, but only a couple routes for continuous running that wouldn't need alot of truss work.
The grinder idea is certainly something I can fabricate up either before or after track laying. I'll shoot for a 1/8 radius, and try to match it on my wheels.

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