Help on Radius's

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Serjt-Dave
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Help on Radius's

Postby Serjt-Dave » Mon Feb 26, 2018 3:46 pm

Hi All. Not having ever built a layout before I need some help and advise please. The templot that was done for me has to be altered so the track runs round my room. So basically the ends of the plan have to curve round to go around to end up creating a continuous circuit. The width of my room is just under 12', so I'm thinking about 4' radius curves. This I hope will give a short straight section before the next curve to take it down the other side of the room. Looking at the first image you can see where the Templot ends and where I've laid some flexi-track to create the curve. I took a tape measure and measured out 4' from the end of the track on the Templot. Turning the tape measure 90 degrees to mark where the curve ends. I then curved the flexi-track around to fit within those two points using the measure to help create the curve. Does this look about right? I know I'm not being precise but it's just to get an idea. At the other end of the Templot it gets a little more tricky as there are more tracks and points involved. I'm thinking of shifting the whole plan back a bit, the first point so that point will be the start of the curve. I'm hoping this will give me a bit more room to curve the other end of the plan without having to alter too much of the track work at that end. As it's a junction I still have to try and create separation between the mainline and branchline. Any help will be much appreciated.

Dave
1 Layout.jpg
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2 Layout.jpg

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grovenor-2685
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Re: Help on Radius's

Postby grovenor-2685 » Mon Feb 26, 2018 6:15 pm

Four foot radius should be fine, but it is a very good idea to include transitions. And laying by eye its quite easy to get tight spots that only show up in running later.
Templot has made life much easier for this, just draw out your curve in templot and put in transitions at each end. Rather than a straight between the two corners just extend the transitions to meet up.
The hardest part of the process is sticking the prints together accurately :)
Regards

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PeteT
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Re: Help on Radius's

Postby PeteT » Mon Feb 26, 2018 6:43 pm

+1.

I would add that a tighter minimum radius allowing for a decent transition would be far preferable to a gentler minimum radius but harsh straight-curve interface.

Armchair Modeller
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Re: Help on Radius's

Postby Armchair Modeller » Mon Feb 26, 2018 7:02 pm

grovenor-2685 wrote:The hardest part of the process is sticking the prints together accurately :)
Regards


If laying direct on the baseboard (or a sub-base), then drawing an accurate grid on the baseboard helps tremendously. Easier and more accurate to line the templates up with the baseboard grid than with each other. That way you also hopefully eliminate any cumulative errors.

John Palmer
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Re: Help on Radius's

Postby John Palmer » Tue Feb 27, 2018 2:19 pm

Dave, I think the pictures you've posted may show the Templot plan I originally developed as overlaid on the OS plan, which I subsequently adapted to suit your cellar dimensions. Now you have a substantially greater area to play with, so I've taken the original drawing and adapted it to fit your 24' X 12' shed.

The attachments are the output of the sketchboard in .pdf format and the box file. I have added a baseboard shape having 23' X 11' dimensions and taken the layout to the extremities of these dimensions on the basis that this then leaves you with something approaching a 6" 'boundary strip' at the ends, which hopefully accounts for any reduction in available interior space due to insulation, etc.

The storage roads are intended to be nothing more than representative, particularly since I have not taken up the full available width.

All this is done quickly and in very rough and ready form in an attempt to see what compromises are required. I found it necessary to shorten the platform quite a bit, but that's not normally going to be a problem, given the length of most trains on the Branch. I tried to achieve maximum separation of the original SCR line to Highbridge from the alignment of the Bridgwater Railway, and think it may be difficult to get a significantly better result than this without making further compromises elsewhere. Minimum radius on the Bridgwater line is 47.6" and the adjacent siding 45.5"; I think there is nothing tighter. I emphasize that I have not done any dummy vehicle clearance tests but have opened out the adjacent track centres to 156" as a temporary expedient where it is likely to matter. Additional between-track spacing may well be required, given the tightness of some curves.

If this is any help, look on it as nothing more than a work in progress or as a launchpad for you to adapt in Templot as you see fit.
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edington_jc_2018_02_27_1335_43.box
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martin goodall
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Re: Help on Radius's

Postby martin goodall » Tue Feb 27, 2018 7:59 pm

In my experience, there is no ‘minimum’ radius for P4 track, provided your rolling stock is suitable to run round your ruling radius, or is adjusted so that it will do so.

My Crichel Down layout, which was originally had Peco Streamline 00 Gauge track and points was rebuilt in P4 to exactly the same geometry, which involved curves of only 2-foot radius. In those days, I was using only P4 wheels, but had no difficulty in eliminating any problems with the performance of rolling stock on the layout, although I certainly wasn’t trying to run a ‘Pacific’ round those curves. I found that provided a loco had plenty of side-play on the middle axle, it would happily negotiate the 2-ft curves. Purely for the sake of appearance, only short wheelbase carriages and wagons were used on the layout, although a bogie coach, when I tried it, out also ran perfectly smoothly.

On the Burford Branch, the curve on the main line as it leaves the station gradually decreases to 3-foot radius, and the carriage siding (being on the inside of that curve) has an even sharper radius, yet I have never encountered any problems attributable to the curvature of the track. But all the stock has been built or adapted to cope with this curvature. Problems are only likely to be encountered with locos where no allowance has been made for the curvature that they may encounter on a particular layout.

So, this is why I say that there is really no ‘minimum’ radius for P4, although if you have room for 4-foot radius curves, then they would no doubt be preferable to anything sharper in curvature, if only in appearance.

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grovenor-2685
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Re: Help on Radius's

Postby grovenor-2685 » Tue Feb 27, 2018 9:06 pm

Note that if you are going to do any propelling then you need to take note of this http://www.norgrove.me.uk/GWRtracknotes/R1774A.pdf
Which is where transitions are essential, and you need to be careful wherever there is a reverse curve, eg crossovers.
Regards

martin goodall
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Re: Help on Radius's

Postby martin goodall » Wed Feb 28, 2018 12:20 pm

I agree with Keith about the desirability of transition curves. Although the curve on the main line at Burford is 3 feet, it is reached through a transition curve that starts off at a radius of about 8 feet, and gradually reduces to the 3-foot minimum. This is not a true transition, as I fudged it (in my accustomed manner), but its geometry is very close to what it should be if the transition had been correctly calculated.

I have two crossovers on the layout. One is the engine release crossover, which is laid on the straight, and comprises a pair of B8 turnouts. It has never given me any problem, even when a vehicle such as a horse box is occasionally propelled over it. The other crossover (at the opposite end of the run-round loop) is laid on a curve, using the 'equivalent radius' formula, which resulted in both turnouts being C10, but it involves no reverse curves, in view of the uniform flexure of the curve on which this crossover is laid.

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Serjt-Dave
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Re: Help on Radius's

Postby Serjt-Dave » Wed Feb 28, 2018 9:03 pm

Hi All, thanks for your input. A lot to absorb there. Like I said in the start of this thread I've never built a layout so on a very steep transition learning curve.

Thanks John for the Templot plan. Will print this out and see how it looks full size and in situ. I knew trying to keep the Highbridge line and the Bridgwater branch separated was going to be an issue. I was thinking of making the Bridgwater line terminating short of the fiddle yard and having just a run round loop. After all what goes down there will have to come back out the same way. I like the idea of keeping the curve through the station. My way probably would have seen the plan more in a straight line. However not over struck on loosing any length off the platforms. Anyway see what it's like when it's printed out.

Spent all day in the shed and didn't freeze to death. Started making a milk tank for the traffic to Bason Bridge creamery. A Rumney Model chassis for a David Geen kit. The chassis went together very easily.

Dave

John Palmer
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Re: Help on Radius's

Postby John Palmer » Thu Mar 01, 2018 1:27 am

Serjt-Dave wrote:However not over struck on loosing any length off the platforms.


OK, to preserve platform length so far as possible a possible solution is to move 28 Points onto the curve. I've done this on the attached boxfile using a D12; you might be more content with a shorter lead such as a C10. I reckon this would make a platform length of about 350' feasible which seems to be not far short of the prototype, but would leave the ramp immediately adjacent to the crossing. I've also inserted the traps that were omitted from my previous effort.
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Paul Townsend
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Re: Help on Radius's

Postby Paul Townsend » Thu Mar 01, 2018 7:51 am

Dave, when finalising your minimum radii don’t forget the issue of long wheelbase locos and sideplay of drivers.
Although your engines in steam won’t have a problem you must allow for the 2-8-0s to pass through.....boiler empty, rods off.
They went regularly to Highbridge Works for minor repairs and boiler washes etc but never in steam as the axle loading was too high for the S&D mainline (sic). ;)

John Palmer
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Re: Help on Radius's

Postby John Palmer » Thu Mar 01, 2018 3:35 pm

An interesting point about working the Sevens to Highbridge. According to 'Highbridge in its Heyday' the main line (as Paul rightly puts it!) was upgraded so that these engines could go to the Works at Highbridge under their own steam. The 1914 batch had to be shedded at Radstock initially as weak bridges at the approach to the sheds at Bath precluded their accommodation there, but David Milton's monograph on the class tells us these bridges were rebuilt in 1915. I have nothing to indicate that any correspondingly weak bridges on the Evercreech-Highbridge line were uprated at the same time, so when did that upgrade take place, and what bridges were affected? I note that there were a number of bridge renewals between Shapwick and Highbridge in 1929, so I would guess that it was these improvements that obviated the need for dead working of class members to Highbridge.

I decided I hadn't done a very good job of moving the points at the east end of the passing loop, so here is a modified version in which I have added platforms and separated the Bridgwater fiddle yard to make it independent. The platforms come in at 350' in length as anticipated.
edington_jc_2018_03_01_1512_33.box
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sketchboard_2018_03_01_1511_39.pdf
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Paul Townsend
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Re: Help on Radius's

Postby Paul Townsend » Thu Mar 01, 2018 3:50 pm

John Palmer wrote:An interesting point about working the Sevens to Highbridge. According to 'Highbridge in its Heyday' the main line (as Paul rightly puts it!) was upgraded so that these engines could go to the Works at Highbridge under their own steam. The 1914 batch had to be shedded at Radstock initially as weak bridges at the approach to the sheds at Bath precluded their accommodation there, but David Milton's monograph on the class tells us these bridges were rebuilt in 1915. I have nothing to indicate that any correspondingly weak bridges on the Evercreech-Highbridge line were uprated at the same time, so when did that upgrade take place, and what bridges were affected? I note that there were a number of bridge renewals between Shapwick and Highbridge in 1929, so I would guess that it was these improvements that obviated the need for dead working of class members to Highbridge.

I decided I hadn't done a very good job of moving the points at the east end of the passing loop, so here is a modified version in which I have added platforms and separated the Bridgwater fiddle yard to make it independent. The platforms come in at 350' in length as anticipated.edington_jc_2018_03_01_1512_33.boxsketchboard_2018_03_01_1511_39.pdf


Ta for added historical modern :shock: detail.

You need to remember that my mindset is fixed in 1913 as my Highbridge model is then.

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Serjt-Dave
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Re: Help on Radius's

Postby Serjt-Dave » Fri Mar 02, 2018 8:01 am

Once again John thanks very much. I had a bit of a early day yesterday so when I got home I thought I'd print out your new Templot. But for some reason my printer didn't want to play so I got on with another job. Then later in the evening I saw you've done a refined version. Phew close call there. LOL. I'll be cracking on with it today {printer willing} and will post the results.

Paul. That ain't going to happen. I'm not going to rip the rods off me 7F I like them where they are. LOL. When I do get operational. As well as running it as a branchline I'll also run it as if the line was actually a mainline just for operational interest. I will of course strengthen any bridges etc. But that's a long way off yet.

All Best

Dave

John Palmer
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Re: Help on Radius's

Postby John Palmer » Fri Mar 02, 2018 10:31 am

Dave, before you fire up that printer you might find the further revised version attached of use. On this one I have increased the track centre gap from 134" to 158" on the passing loop. This should mean that if you have a vehicle standing on either the main or the loop beyond the east platform ramps (and therefore already on the curve) it should not be an obstacle to a vehicle passing on the adjacent line. I have tested this with dummy vehicles of LMS 65' underframe dimensions, on which the centre overhang is probably a bit more than the 57' underframes that are likely to be the longest you will be using. I opted for this spacing on the basis the the prototype had the conventional six foot between running lines - this appears to be the case from examination of the fine picture in Jem Harrison's 'The Bridgwater Branch', so I tried to keep as close to this as I could given the unavoidably tight curvature.

I haven't done any other tidying of the plan, so there will also be a deal of timber shoving to be done. I suggest you give the plan a critical once-over before you spend vast amounts of paper printing it!

Incidentally, I also attempted to use a C10 for the points at the east end of the loop, but couldn't get an acceptable flow of the tracks without opening an excessive gap between the running lines on the curve. Such are the problems of trying to fit a prototype even to so generous a space as yours!
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Paul Townsend
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Dreamland

Postby Paul Townsend » Fri Mar 02, 2018 10:40 am

Last night the gale disturbed me....so I awoke early from a vivid dream:

I had cut a hole in the neighbour's side of my Highbridge shed and erected a temporary long curve through his garden to bring the Burnham line back into mine where JP's Burnham was erected.
Another hole was not needed on the other side as a convenient window allowed the main line towards Glastonbury to curve through my garden over the rhubarb and link to Dave's Edington.

Someone must build Bason Bridge in P4 :D

PS
The sun was out with slight haze and 10day forecast for still conditions and a comfy 19C

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Penrhos1920
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Re: Help on Radius's

Postby Penrhos1920 » Fri Mar 02, 2018 7:25 pm

Not only must your stock be built to run around your curves, you also need to consider coupling choices. We found out that a 37 diesel will pull wagons off the track on a 4' radius if using prototypical couplings. Use AJs or Hornby couplings and it's fine.
Getting it Alright

Penrhos Junctions near Caerphilly - Barry Rly, Rhymney Rly and A(N&SW)D&R 1920 and pseudo modern image in S4F
and
Awrhyllgwami for DEMU challenge
and
Dispelling the P4 drop in wheel myth
and
TOERAG Obergruppenführer

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Serjt-Dave
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Re: Help on Radius's

Postby Serjt-Dave » Fri Mar 02, 2018 8:23 pm

Hi Paul. That would be one hell of a link to get my layout linked to yours and John's. I live in Kent. But hey if the Biggest Little Train can do it I'm game for it as well.

Penrhos1920. Some time back I went through what couplings to use. I just don't like AJ's. I know a P4 hit squad is now on their way round to my house for saying such a thing. I also know that people have used them to a great success but for me they just don't float my boat. I've tried Dingham's but decided on Sprat and Winkles.

Now to print off a lot of paper.

Dave

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Flymo748
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Re: Help on Radius's

Postby Flymo748 » Fri Mar 02, 2018 9:07 pm

Serjt-Dave wrote:Hi Paul. That would be one hell of a link to get my layout linked to yours and John's. I live in Kent. But hey if the Biggest Little Train can do it I'm game for it as well.

Penrhos1920. Some time back I went through what couplings to use. I just don't like AJ's. I know a P4 hit squad is now on their way round to my house for saying such a thing. I also know that people have used them to a great success but for me they just don't float my boat. I've tried Dingham's but decided on Sprat and Winkles.


Nowt wrong with S&W. It's what works for me. I'll also be keeping an eye over my shoulder for the hit squad...

Cheers
Flymo
Beware of Trains - occasional modelling in progress!
www.5522models.co.uk

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Noel
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Re: Help on Radius's

Postby Noel » Fri Mar 02, 2018 9:56 pm

Penrhos1920 wrote: We found out that a 37 diesel will pull wagons off the track on a 4' radius if using prototypical couplings.


Etched links, by any chance?
Regards
Noel

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Serjt-Dave
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Re: Help on Radius's

Postby Serjt-Dave » Sun Mar 04, 2018 9:00 pm

Hi John. Got your plan all printed out and laid out in the shed. 160 sheets of paper printed out trimmed and and sellotaped together at the cost of one finger tip and a stabbed thumb.

Overall I'm very happy with the plan. It fits well and I think There's enough separation between the Highbridge and Bridgwater lines to make it look like they are going to two separate places. The only concerns I have is the potential of the size of some of the baseboards could end up being. What I mean is, the station area, where it curves towards East {Glastonbury end} it comes away from the wall and would end up being about 4' wide at it's widest point. Not a major issue really unless it would ever needed to be moved. Options are to straighten the station layout to bring it closer to the wall, but then loose some of the character of the station layout. Or not having the baseboard going to the wall to keep baseboard width the same. Or to hell with it and have better depth for more scenery behind the station, which will also mean I'll be able to the the Railway Inn {now the Tom Mogg} featured. The same thing occurs at the Junction end of the station. Where the two line move apart from each other and then curve around the room, it could end up with some chunky baseboards. I think These concerns can be overcome with some clear thinking on how the wood working will be done creating the baseboards. As I'm writing this I have more or less made up my mind to keep the plan as is and how the baseboards can be made. Anyway here are some images of most of the Templot laid out. Let me know what you think. The 16 Ton Min Wagons are just holding the plan together where I didn't want to join them up
Attachments
1I.jpg
1H.jpg
1G.jpg
1F.jpg
1E.jpg
1D.jpg
1C.jpg
1B.jpg
1 A.jpg

John Palmer
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Re: Help on Radius's

Postby John Palmer » Mon Mar 05, 2018 2:32 am

Dave, I'm relieved to see how well that fits, and agree that the separation between the Bridgwater and Highbridge lines does suggest the divergence of routes, probably as well as can be expected. I remain concerned by the east end, and wonder how content you are with the prospect of making a 1 : 12 vee for the loop points there. In case you had reservations about this I have been playing around with the alignment of the curve on the approach to that turnout and believe it would be feasible to fit a C10 there, but at the cost of a 40.2” return curve on the branch track from such a turnout, which may be too tight for your liking. There may be some scope for further re-working of the east end of the layout, but at the moment I'm a bit stuck because of a problem I am experiencing in Templot when manipulating a curve.

Baseboards: I had rather assumed that you would be obliged to think in terms of boards that were either curved to match the curvature of the track or segmented to follow that curvature. If you don't have to contemplate the layout ever being moved then the only major constraint upon the form the boards take is your own constructional skills.

I can't see clearly whether your door opens inwards or outwards. If inwards then presumably you will need some form of lift out arrangement for one of the boards. (I carefully sidestepped that problem by specifying outwards opening doors.

John Palmer
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Re: Help on Radius's

Postby John Palmer » Mon Mar 05, 2018 11:43 am

Having surmounted with Martin Wynne's almost instant help the problem I was having with curves, I've attached a further revision of the Templot drawing. This one incorporates various easements, but the main difference is that I managed to fit a C10 into the plan as the points at the east end of the loop whilst keeping the minimum radius of the return curve to 45.5". I think this is about the best I can do. I have also eased the traverse through 26 points from the main to the bay, and done some timber shoving which I think eliminates most if not all the conflicts.
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Serjt-Dave
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Re: Help on Radius's

Postby Serjt-Dave » Mon Mar 05, 2018 3:38 pm

Wow John. I owe you a beer and a knee trembler for all your help with my layout. Thank you very much.

If your new plan doesn't change the overall size of the plan. I'll use the current one as a guide to make design and make the baseboards and this new plan for the actual track bed. What I plan to do now is to lay the plan onto some lining paper to work out the size of each baseboard and then construction can start on the baseboards. Yay!

Are you attending Scale North in April?

Dave

bevis
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Re: Help on Radius's

Postby bevis » Mon Mar 05, 2018 3:43 pm

Hi Dave,
I've been watching this interesting thread develop and noted your concern about the width of the station baseboard. Could it be two parallel boards, one purely scenic, behind the station? It's a bit unusual as an idea but in terms of weight and movability it might help.
Regards,
Bevis


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