Help!!! Track Geometry Failure (Resolved)

[Railbob]

Hi everyone,

I’m at a loss as to what has happened with my layout, I preflexed the track to take out the known geometry issues and I pre laid out the track and everything fitted correctly. Well as you can see on the photo it doesn’t fit 😡 All the joints are neat and with no gaps. Does anyone know what I’ve done wrong?

Railbob

[taunmarc88]

What curve is that top left inner radius? It doesn’t look right at all.

[Moccasin]

With my settrack (which goes down, comes up and goes down again as my baseboard is my dining table), the only way to make it work is with gaps in places. The track isn’t perfect by any means. My locos, even my new 08, cope with the slight gaps with no complaint.

I think you might have to take the curves up and adjust to fit.

As @taunmarc says, that curve on the left doesn't look quite right.

Hope you can tweak the layout slightly to get everything to fit.

[Robc058]

Where is your layout?

Mine is in the loft and the weather is suddenly much warmer.

I have not finished cork underlay yet so I expect to take much of the track up and relay it. I have already started this so my oval is no longer complete and in any case I want to add 2 X straights.

Is it possible you have some expansion in the track in a warmer environment?

[Railbob]

Taunmarc, the top inner left is a T8004 2nd radius curve, which is the correct one for the layout, I’ve followed the layout marked on the Easterner box and according to Hornby the inner track should be T8004 2nd radius. The outer track is having a similar problem but not as bad.

Railbob

[Railbob]

Robc,

The layout is in the house and doesn’t suffer from any extremes of temperature, hopefully 🤞. I’m thinking that I’ll try and lift the track off of the cork, finish off the cork and reglue it back down 👍

Railbob

[taunmarc88]

When I laid some loops, I had a similar issue but nothing like this bad. I pinned the track down lightly and then drew around it on the cork. I would not recommend glueing the cork before the track. As the geometry changed by the time I got to putting the track on the now glued cork. I have since taken it all up as it was all in reverse to how I wanted it and it has left an absolute mess! Perhaps next time I would pin the track through the cork and then try to glue underneath the track.

[Rallymatt]

Bob, I know this sounds like a real pain but it might just be worth checking the curves again, there seem to be a few deviations where the centre to centre of each line vary (it’s hard to tell on a photo) sometimes the error is earlier in the curve but the effect is felt at the last part. Hopefully it’s not all glued down! 😁

[taunmarc88]

As Rallymatt says, the joins should align on both loops, that’s how I sorted mine out. There were a few gaps in the track but as I understand it this allows flexibility in the warmer months.

[96RAF]

You have the radius dimensions so just draw it out on the boards and match the track pieces to the drawing.

A simple radius compass can be made with a strip of wood or other material with a centre pivot and various radius holes drilled for a pencil or marker pen.

If you draw it right then the track centres will be correct and the points will match up.

[Railbob]

Hi everyone,

I think I’ve found the issue, what should be the distance between the track i.e. the 6’ in railway terminology? I have on the bottom straight a consistent 28mm but by the time you get to the 2nd and 3rd radius curves it’s down to 25mm at the centre of the curve. This is what appears to be the problem, so it looks like a lifting of the curve to bring them out to 28mm if that’s correct?

Railbob

[Railbob]

Taunmarc,

Just checked the joints on your suggestion and some don’t align as they should. I think I’ve gone for too tight on the joints leaving no room for expansion so I’m going to lift and relay with a bit more tolerance on the joints, hopefully that will allow me a bit more flexibility on the track.

Thanks everyone for your advice so far 👍

Railbob

[Fishmanoz]

It’s easy to tell what the distance between track radii should be - the difference in radius of R2/R3/R4. You’ll find this to be 43mm measured centre to centre. This is also the spacing made by crossover points or a point plus R6 curve back to parallel.

As the total width of track plus sleepers is a touch under 20mm, this leaves a gap of 23mm+ between them.

If you start from the bottom right at your crossover points, the R2 and R3 loops plus the R4 external siding all start at the same place horizontally on your board so should all track together around the RH end curves and finish at the same place (all equidistant from the RH edge of your board) except the R4 siding of course.

The R4 siding should turn 90 degrees with its 3 R4 curves and end up parallel to the edge of the board, not angled in as shown in your photo. You will need to move the entire layout to the left to fit in the parallel siding at the end of this siding.

[ntpntpntp]

Always draw out the centrelines using the stated radius measurements for the pieces and the parallel spacing. I would never rely on the track being 100% correct just by plugging it together.

It is easy to create radius templates and parallel spacing templates from card (or maybe consider the West Hill Wagon Works products mentioned in the latest TT:120 magazine?)

[Railbob]

Fishmanoz,

Thanks, I’ve checked my distances and found the following, the distance between the points, straights and R6 curve are correct at 43mm, it’s on the curves where things start to move out of alignment. I think I have enough wiggle room on the track underlay to lift and refix without too much grief. I suppose that the tiny difference in rail length add up to quite a bit overall and I should have allowed some gaps to allow for wiggle room. I’m learning a lot about track laying 😂

Railbob

[Railbob]

Hi everyone,

It’s amazing what a very sharp chisel can do without damaging the track, everything is lining up better and you can see it aligns better with my original markings 😀👍

[Hobby11]

The outer curve on the left doesn't look right, it shouldn't go in towards the inner track at the top left. Push it back out until the end of the outer curve is parallel with the end of the curve on the inner track. One other thing which I'm not sure if it's been suggested is to check that all the curves in each oval are actually the same radius, there isn't much difference and an R2 in amongst the R3s or vice versa can give you the problems you are seeing.

[Railbob]

Hi Hobby,

I haven’t fixed the outer loop yet so I’ve got plenty of leeway left. As for your other very pertinent and good about how closely the radius of curves can resemble others, I left the labels on until I glued them into place for the exact reason you mentioned .

Railbob

[96RAF]

Do these TT track pieces like the OO track pieces not have the SKU moulded into the underside of the sleepers. Having to rely upon sticky labels seems bit of a gamble.

[Rallymatt]

Rob, the radius and part number is moulded into the sleeper base but it’s not the easiest thing to read.

[RB51]

Agreed Rallymatt, tiny shallow print image. Not easy when the old peepers are getting on a bit. R-

[RB51]

If you are struggling you will find on P.27 of the Spring Club magazine there are some track laying templates available from

https://westhillwagonworks.com/layout-accessories/545-tt120-track-guide-templates-large-set.html

There are three options

1. Templates Large Set
2. Templates Straight Set
3. 43 cm Track Centre Spacers

R-

[Fishmanoz]

Two things on the inner loop top left:

• there are kinks at the last 2 joins, the curvature is not smooth
• where you have concentric loops of R2 and R3, the joins should match each other around the entire loop. Or if you put an edge at right angles to one loop at the join, it should meet the join on the other loop. This doesn’t appear to be the case with the left joins of the middle top left curves.

My conclusion - you have a wrong radius curve in there somewhere. Or at the least, some of the curves aren’t fully de-stressed to the correct radius.

[Railbob]

Fishmanoz,

I see what you mean but it’s okay the track is not properly joined and is sitting proud on the outside rail, I haven’t yet glued it down as I’m going to redo the underlay into the correct shape 🤞

Railbob

[Railbob]

Hi ,

This is the current situation on the layout, I’ll be working on it tonight 😀 If things don’t go well you’ll never hear from me again 😂😂😂😂

Railbob