Turnout construction - Question here please.

Discuss the prototype and how to model it.
Terry Bendall
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Re: Turnout construction - Question here please.

Postby Terry Bendall » Sun Apr 21, 2019 9:03 am

Serjt-Dave wrote:I've now got to be a big boy and make my own 1:10 Vee jig as my EBMA one only goes up to 1:9.


The stores now sells jigs for 1 in 9, 1 in 10, 1 in 11 and 1 in 12 angles.

Martin Wynne wrote:For marking timbers, don't use a pen or pencil. Lightly stab them with a sharp point such as a centre-punch, scriber, or needle in a pin chuck.


I have always us a pencil but the use of a scriber or similar is better. Learn something new every day.

Terry Bendall

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Serjt-Dave
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Re: Turnout construction - Question here please.

Postby Serjt-Dave » Sun Apr 21, 2019 9:52 am

Hi Terry. Do you mean the jigs for filing them? If so I do have one of those. What I was thinking of is like the EBMA ones where you push the point and splice rail together to support them as you solder them.

Dave

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grovenor-2685
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Re: Turnout construction - Question here please.

Postby grovenor-2685 » Sun Apr 21, 2019 10:01 am

Dave,
That really is simple, see http://www.norgrove.me.uk/points.html.
Rgds

Julian Roberts
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Re: Turnout construction - Question here please.

Postby Julian Roberts » Mon May 06, 2019 6:48 am

I have copied this useful additional infornation from posting.php?mode=quote&f=5&p=66129
to try to keep questions on this thread.

Martin Wynne wrote:
If it helps to understand what's happening in a joggle, I have added a red line to the diagram:

Image

The red line shows the position of the stock rail for a plain set with no joggle. To make the joggle, imagine the stock rail being held along the red line, and then pushed sideways at B.

You can see that this means that when there is a joggle, there is also very slight bend in the stock rail at C. This angle is so small that it is normally ignored for construction purposes.

(For an A switch with 66" planing, and a tip of 3/8" thickness, that small angle is 1:176 = 0.3 degrees. For longer switches it is even smaller.)

If you like to use over-scale depth joggles, as many do, that angle will increase, and you might want to bear it in mind. It is more evident when there is a joggle in the straight (main-road) stock rail.

Martin.


I have to make a pair of joggled B switches with full height blades as in the straightcut blades pictures earlier on this thread. I can file the blades to a minimum sensible thickness of about 0.2mm. 3/8" blades scale out at 0.125mm.

My question is, would you increase the return length of the joggle (so move A to the left) to give the extra depth, or make a deeper joggle within the same length A to B?

PS. This question relates more to your posting on 17th Feb 2018, where you talk about the differing return lengths according to blade thicknesses, than the extra information you put above.

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Martin Wynne
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Re: Turnout construction - Question here please.

Postby Martin Wynne » Mon May 06, 2019 8:30 am

Julian Roberts wrote:I have to make a pair of joggled B switches with full height blades as in the straightcut blades pictures earlier on this thread. I can file the blades to a minimum sensible thickness of about 0.2mm. 3/8" blades scale out at 0.125mm.

Hi Julian,

You should be able to file them thinner than that at the top of the tip -- 3/8" scales to 5 thou.

The diagram you posted shows only the rail top view, or more specifically the horizontal section at the gauging line, which is 9/16" below the rail top to allow for the 1/2" corner radius on the rail. The blade tip is left much thicker below that.

Here is the view on the model rail tip (for vertical rail - if you are using inclined rail the dimensions remain the same):

straightcut_blade_tip.png
straightcut_blade_tip.png (26.71 KiB) Viewed 1322 times

The top corner radius is 1/2", so filing the rail to 3/8" thickness would initially require 75% of that radius at full height. After fitting the blade against the stock rail and fettling the rounded end, you will more likely end up with something along the green line, at 2" back from the tip.

Here's the green line in a photo:

gwr_joggled_blade_tip.jpg
gwr_joggled_blade_tip.jpg (276.3 KiB) Viewed 1322 times

Model rail section often has an incorrect top corner profile, so it's difficult to get prototype accuracy in 4mm/ft scale. In practice you clamp the blade to the stock rail, and then attack it with fine files and abrasive paper until you can run your finger along it without leaving any trace of blood. Image

cheers,

Martin.
40 years developing Templot. And counting ...

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Martin Wynne
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Re: Turnout construction - Question here please.

Postby Martin Wynne » Mon May 06, 2019 12:10 pm

p.s. to clarify that diagram -- or make it more confusing -- I have added some rail outlines:

straightcut_blade_tip_outlines.png
straightcut_blade_tip_outlines.png (16.26 KiB) Viewed 1280 times

This shows how the blade tip fits into the joggle to align the running edge with the unjoggled part of the rail.

Martin.
40 years developing Templot. And counting ...

Julian Roberts
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Re: Turnout construction - Question here please.

Postby Julian Roberts » Mon May 06, 2019 9:41 pm

Thanks Martin for your rapid reply. I have managed to lose my response.

Just briefly, you have a description of how to make undercut semi curved switches at https://www.scalefour.org/forum/viewtop ... rt=25Inbox

(In broad terms it's similar to Tony's description on the related thread to this.)

I have followed that in the past to make such a turnout. I haven't found a similar description of how to make a straghtcut switch for joggled pointwork. From your reply earlier today I get the impression it's not much different. However I found in making the undercut style that 0.2mm at the running surface was about as thin as it would go before the nickel silver started to disintegrate, which is fine for that type where the full height isn't needed all the way to the tip. Maybe steel will take more filing etc?

I think on Templot you can customize the joggle. I haven't learnt to use it. If I have a minimum 0.2mm blade at the tip, what happens to the joggle?

By the way, yes at the tip the top surface is (say around) 0.2mm, it does get thicker and has the foot of course as per your diagrams.

Julian Roberts
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Re: Turnout construction - Question here please.

Postby Julian Roberts » Tue May 07, 2019 7:15 am

Martin Wynne wrote:


For REA switches the joggle depth is 3/8" (0.375 inches) and the joggle return length is 6 inches. For older pattern straight loose-heel switches these dimensions vary, but are usually similar.
For GWR old-pattern switches the joggle depth is 3/8" (0.375 inches) and the joggle return length is 4 inches. The later GWR and BR(WR) curved flexible switches have a less severe joggle, the joggle depth is 1/4" (0.250 inches) and the joggle return length is 6 inches.

These joggle depths are barely perceptible in the smaller model scales. A 1/4" joggle is only 3 thou (0.003 inches) (0.08 mm) in 4mm/ft scale. Some modellers prefer a more pronounced joggle, and Templot provides for this with the generator > overscale joggles menu option, which creates a joggle depth of 3/4" (scale).




I am just wondering what length of joggle Templot creates for this 3/4" joggle depth (0.25mm so actually more than I had in mind)

(Measuring these tiny amounts is problematic especially on a vertically as well as horizontally tapering blade so I may well be nearer your 5 thou than I think. )

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Martin Wynne
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Re: Turnout construction - Question here please.

Postby Martin Wynne » Wed May 08, 2019 4:10 pm

Hi Julian,

In Templot you can:

switch joggles on or off for any template;

create a custom switch having any joggle dimensions of your choosing, or

use one of the pre-set GWR switches based on prototype dimensions;

select "overscale joggle depth" in the generator, which over-rides any other setting while it is in force. It doesn't change the return length or the planing length.

Bear in mind that Templot creates the template, it doesn't make the track for you. The template is a guide for construction, but you don't have to follow it if you don't want to.

The thickness dimension applies at only a single point -- the extreme tip of the blade at the top. It increases as you move down the blade or along it, so it should be possible to get it down to a few thou at the tip quite easily. Many folks create a knife edge to represent unjoggled undercut blades without too much difficulty. Perhaps you need newer or sharper files?

You might like to consider using abrasive paper instead of files (from car repair shops in various grades). Cut a small strip of it and attach it to a suitable flat instrument with double-stick tape. If you are quick you can extract a small butter knife from the kitchen, which is ideal: Image

Image

Course grade on one side, fine grade on the other. Easily replaced when clogged -- a full sheet will last you years.

Generally the difficulty with joggles is in creating the joggle in the stock rail rather than filing the blade. You might do better to create the joggle first, and only then fettle the blade to the exact thickness required to fit into it.

cheers,

Martin.
40 years developing Templot. And counting ...

JFS
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Re: Turnout construction - Question here please.

Postby JFS » Wed May 08, 2019 6:29 pm

Just to mention that joggles can be a nuisance. Although they can help keep facing movements on the rails, they are equally likely to cause trailing movements to derail - Especially if they are a tiny bit overscale (which they always are!). So if your points are facing only then fine but If they are always or mostly trailing, I would give them a miss and learn to file nice fine blades! I used them on my previous layout and a particular double slip give real trouble from this cause.

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Julian Roberts
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Re: Turnout construction - Question here please. Temporarily diverted into joggled turnout switches.

Postby Julian Roberts » Fri May 10, 2019 10:14 am

Hi Martin and Howard

Just a brief clarification.

I hate the look of overscale joggled points and haven't made any before.

I've made undercut "proper" (as I would affirm) turnouts successfully. Yes using fine sandpaper though not I confess with a swiped butterknife. (My chaotic household of artists doesn't rise to such niceties though no one would notice or mind if I did take one - if it existed!)
20190509_144456.jpg
What? No butterknife?

The blades took me longer than the rest of the turnout each time to get really 100% reliability with my own stock. But I think worth it in terms of prototypical appearance. But if a not very well suspended vehicle, or worse one without any suspension at all, derails on an undercut turnout of mine, the suspicion might be that the wheel flange is riding up the blade as the latter rises to the rail level. Anyway, my brief is to make some joggled switches , not for one of my undercut types, but for another already joggled turnout that is suspect. So this is a learning exercise for me and I am interested in how to do it with the maximum realism. Which means minimising the amount of joggle, but if I insist on a joggle that for reasons of practicality is more than prototypical, how best to disguise it. I have omitted to say this is for a colliery line, probably NCB.

I take your point haha Howard but have to say the joggles on the layout this is intended for do not give any trouble in the trailing direction.

I realize I must use my own skill and judgement to answer what is a stupid question and that, yes, I did know Templot won't actually make the point for me :idea: :D ...even if I knew how to work Templot!

Given that a REA 3/8" (0.125mm) blade has a 6" (2mm) return length joggle, a 0.2mm blade would by the same proportion have a 9.6" return length joggle: so if I manage to hit something near 3mm that will be quite accurate enough for me.

If I have any more banal questions maybe I'll transfer all this conversation to a new thread with a heading as I have put here

Tony Wilkins
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Re: Turnout construction - Question here please.

Postby Tony Wilkins » Wed May 22, 2019 3:49 pm

Julian Roberts wrote:I have followed that in the past to make such a turnout. I haven't found a similar description of how to make a straightcut switch for joggled pointwork. From your reply earlier today I get the impression it's not much different. However I found in making the undercut style that 0.2mm at the running surface was about as thin as it would go before the nickel silver started to disintegrate, which is fine for that type where the full height isn't needed all the way to the tip. Maybe steel will take more filing etc?

I think on Templot you can customize the joggle. I haven't learnt to use it. If I have a minimum 0.2mm blade at the tip, what happens to the joggle?

By the way, yes at the tip the top surface is (say around) 0.2mm, it does get thicker and has the foot of course as per your diagrams.

Hi Julian.
Not looked at this thread for a while and now catching up.
As I don't use joggles I can't really add much to this thread other than to comment that 0.2mm is about the thickness of my switch blade ends prior to putting the chamfer on the top edge. This produces a knife edge finish where it matters. If you are having problems filing nickel silver rail thinner than that, the problem will only be worse with steel rail, which has a nasty habit of suddenly collapsing under the file as it reaches a critical thinness. This situation is unrecoverable. I find N/S rather more robust and forgiving in this respect.
I note that you have started a separate thread on this topic.
Regards
Tony.

David Catton
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Re: Turnout construction - Question here please.

Postby David Catton » Wed May 22, 2019 8:51 pm

I recall that the definition of a gentleman is one who uses a butter knife when dining alone . . .

David C

JFS
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Re: Turnout construction - Question here please. Temporarily diverted into joggled turnout switches.

Postby JFS » Wed May 22, 2019 9:15 pm

Julian Roberts wrote:I take your point haha Howard but have to say the joggles on the layout this is intended for do not give any trouble in the trailing direction.


I was actually talking about the real thing - LUL has a prohibition on joggled switches which are trailed though it uses them for "A" switches used in a facing direction only (of which it has more than its fair share!). That said, I have seen a fair few derailments at exhibitions from this cause though - thankfully - mostly not on P4 layouts.

Best Wishes,

Julian Roberts
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Re: Turnout construction - Question here please.

Postby Julian Roberts » Wed May 22, 2019 9:17 pm

:D :D In PG Wodehouse land?


20190522_230412.jpg
Still no butterknife.


I wonder what he uses to eat The Gentleman's Relish ;)

Julian Roberts
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Re: Turnout construction - Question here please.

Postby Julian Roberts » Wed Jun 19, 2019 1:08 pm

Hi Tony this is from your Brimsdown thread. If you have the inclination at any point to put the soldering iron down... but I'm not wanting to interrupt progress, no hurry for reply!

Tony Wilkins wrote:
Julian Roberts wrote: I'm trying to work out if my eye is deceiving me - are some of the E switches curved on both roads?

Hi Julian. I think the answer is yes as they are all curved. That is why I had to use E switches as these were the shortest I could get away with for the minimum curvature I wanted.
Regards
Tony.


I had the idea that making straight switches is quite difficult, the more so the longer they are, particularly getting the back of the blade straight to abut the straight stockrail flush all the way along. Now you casually produce these gently curving E switches! But maybe it's quite easy to make the subtle bend by just doing so with the finished straight blade and stockrail clamped together? Come to that, on curved crossings I wonder what is the procedure?


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