Morgan designs for mechanical underboard signal and point control - discussion - merits of wire in tube

davebradwell
Posts: 1174
Joined: Fri Jan 18, 2019 3:48 pm

Re: Morgan designs for mechanical underboard signal and point control

Postby davebradwell » Fri Jan 21, 2022 9:09 am

I didn't mean to advocate the use of wire in tube, Julian, just to show how it can be improved. My preference for a well engineered commercial product that fits together properly stands. Would suggest you have screw adjustments down there somewhere in case temperature changes at exhibitions affect operation. ChrisP has to give his mechanical system a tweak occasionally.

To take mechanicals across baseboard joints I suggest a torsion rod system.

DaveB

JFS
Posts: 813
Joined: Wed Dec 16, 2009 3:47 pm

Re: Morgan designs for mechanical underboard signal and point control

Postby JFS » Fri Jan 21, 2022 1:46 pm

davebradwell wrote: Would suggest you have screw adjustments down there somewhere in case temperature changes at exhibitions affect operation. ChrisP has to give his mechanical system a tweak occasionally.

To take mechanicals across baseboard joints I suggest a torsion rod system.

DaveB


I fully agree with Dave that some form of compensation is essential for reliability, but better if it is fully automatic.

I made up these gadgets:-

Escapement drive -2.jpg


Basically, they take the linear movement of the underbaseboard rods above the baseboard by converting it to rotation - the above basboard crank then takes over. But unlike a simple bell crank, this is an "escapement crank" which means that although the total movement of the rod is 15mm, only the centre 12mm of movement creates the actual rotation - the 2mm or so at each end does nothing. This means that upto +/- 2mm of expansion has no effect at all, so provided the rodding run is roughly compensated (ie half of it "pushes" and half of it "pulls" expansion has no effect.

Obviously, I made those myself, but I would point out that Ambis sell an equivalent device. It is a bit less elegant (IMHO!) than mine, but it is basically excellent, much underated and should be much more widely used I feel.

In passing, I note that a number of the solutions posted here only transmit the actual throw needed for the switches - ie about 1.5mm. In my method, the rods transmit 15mm reduced by the above means. This means my rods are less prone to hole-slop/backlash/hysteresis by a factor of 10!

Best Wishes,
You do not have the required permissions to view the files attached to this post.

Enigma
Posts: 533
Joined: Tue Aug 13, 2013 2:49 pm

Re: Morgan designs for mechanical underboard signal and point control - discussion - merits of wire in tube

Postby Enigma » Fri Jan 21, 2022 4:00 pm

Over a baseboard joint I have used a pair of centre pivoted short straight levers each fixed close to the b/b joint. The wires/rods to the point/signal fit into the holes at the same end and a removable 'double ended L' rod drops into the other pair of ends while the boards are attached and removed when separated.

User avatar
grovenor-2685
Forum Team
Posts: 3918
Joined: Sun Jun 29, 2008 8:02 pm

Re: Morgan designs for mechanical underboard signal and point control - discussion - merits of wire in tube

Postby grovenor-2685 » Fri Jan 21, 2022 4:14 pm

I would note that mine have worked for 25 years in my loft without any adjustment and I recently moved one set down into a bedroom where it continues to work without adjustment, maybe I'm just lucky! I do also like the Ambis PALM device but I've only used that with Servos driving it.
Regards
Keith
Grovenor Sidings

User avatar
Julian Roberts
Posts: 1389
Joined: Sat Jan 09, 2010 11:33 pm

Re: Morgan designs for mechanical underboard signal and point control - discussion - merits of wire in tube

Postby Julian Roberts » Sat Jan 22, 2022 7:01 am

Thanks again for all these helpful comments.

Above roughly what distance is some kind of compensation desirable?

As I understand the Mk2 lever frames give 6mm travel. I'd think that would be ideal for an omega loop connection to a turnout where the travel is 1.5mm? Not having made any signals ever, with 9(!) here, could I ask how much travel would be suitable for them?

Today is a one in 23 years event, the 00 gauge railway is being dismantled and collected by its new owners, so apologies for brief responses here!

davebradwell
Posts: 1174
Joined: Fri Jan 18, 2019 3:48 pm

Re: Morgan designs for mechanical underboard signal and point control - discussion - merits of wire in tube

Postby davebradwell » Sat Jan 22, 2022 9:51 am

One of the later posts reminds us of the wisdom of starting with far more throw than is needed and rather than the complex crank shown, the springy wire as used on a Tortoise would be a simpler solution. This has the added advantage of making the whole system self adjusting and most likely gets rid of any need for compensation, too. I believe there's a manual version of a Tortoise with switch included which would be just the job - Bob How described it in MRJ 237. Wire would come up under point stretcher to drive it directly - you couldn't get any simpler. The springiness of this wire does a good job holding the blade against the stock rail positively and not jut parking it close-by.

DaveB

User avatar
grovenor-2685
Forum Team
Posts: 3918
Joined: Sun Jun 29, 2008 8:02 pm

Re: Morgan designs for mechanical underboard signal and point control - discussion - merits of wire in tube

Postby grovenor-2685 » Sat Jan 22, 2022 12:41 pm

The Tortoise style spring wire drive direct to the stretcher is very easy to apply to commercial points like Peco but not so simple for hand built points where you want some realism in the point fittings, hence the Exactoscale adapter plates. The hand operated tortoise equivalents are , IIRC silly prices but there are lots of people now making servo mounts by 3D printing that do similar things and it would be easy to create one for wire in tube or rodding operation, but its the bit above board for scale use that is the tricky bit, have you tried it Dave?

Incidentally the rodding system I use with model aircraft cranks has to lose about 2/3 of the throw between lever and point, it would be possible to incorporate omega loops but there are already two areas of give in the drive so I have not found it neccesary. Firstly the vertical tube and wire arrangement through the board of the Studiolith TOUs have some spring to hold the blades against the stock, secondly any section of rodding on compression will bow slightly adding a bit more spring. These two together have proved adequate over the years to avoid any need for adjustment.
Regards
Keith
Grovenor Sidings

User avatar
Will L
Posts: 2516
Joined: Sun Jul 20, 2008 3:54 pm

Re: Morgan designs for mechanical underboard signal and point control - discussion - merits of wire in tube

Postby Will L » Sat Jan 22, 2022 12:56 pm

I think the need for an adjuster depends on how you drive the wire. Our layout used Peter Denny style sliding keys, as the electrical switch was driven from about half way along the key movement, any expansion of the wire disappeared into the spare movement either end of the key movement. The Friction in the system Martin was so worried about just keeps the point blades in the right place. I would have though an omega loop would have achieved the same effect if driven by a scale point lever. As said elsewhere, the wire movement from the leaver is much more than needed at the point and we used a crank close to the point to reduce the amount of movement. These cranks (a rectangle of brass, pivoted in one corner and with one short and one long side. Long side drilled for the wire at the corner, the sort side drilled 3 times along its length to adjust the amount of through available at the point.

davebradwell
Posts: 1174
Joined: Fri Jan 18, 2019 3:48 pm

Re: Morgan designs for mechanical underboard signal and point control - discussion - merits of wire in tube

Postby davebradwell » Sat Jan 22, 2022 1:57 pm

A slice of tube or even a loop of wire soldered to the side of a Mike Clark tiebar might be a giant boil to many but I've always thought that there's other things around more distracting. In any case most of my points are driven completely invisibly from Tortoises via a plain block that sits within the thickness of the baseboard. You don't need a slide here as the blades define the movement. It's always been a puzzle to me why anyone would want to fit bases or extra cranks and rodding to a Tortoise when it's the 'quickest to install' way of operating a point. There's a complete absence of precision in the process, too, as the bendy wire soaks up misalignments and gives that re-assuring hold of blade against stock-rail. I'll guess that the majority out there would disagree with me but that's not unusual.

If you want a challenge use the scale point rodding and I know someone who has done this with runs up to the scale maximum. Despite my predictions of doom it keeps working.

DaveB

Enigma
Posts: 533
Joined: Tue Aug 13, 2013 2:49 pm

Re: Morgan designs for mechanical underboard signal and point control - discussion - merits of wire in tube

Postby Enigma » Sat Jan 22, 2022 2:00 pm

Many years ago I described my 'Spring Thing' in S4News. This is positioned in a convenient place in the rodding and uses a Schrader car tyre valve insert (free from any car tyre fitter), 'adapted' by judicious cutting, with the spring element acting as a 'compensator. In one position (when pulled) it is in tension in the other compression (when pushed). I presume the article will still be available somewhere in the archives?

EDIT - it may not have been in S4News but in the ill-fated Modelling Railways Illustrated. A lot has happened since then - but I still have the original article and drawings in my archive!
Last edited by Enigma on Sat Jan 22, 2022 5:25 pm, edited 1 time in total.

User avatar
Julian Roberts
Posts: 1389
Joined: Sat Jan 09, 2010 11:33 pm

Re: Morgan designs for mechanical underboard signal and point control - discussion - merits of wire in tube

Postby Julian Roberts » Sat Jan 22, 2022 3:16 pm

Hoping for plenty of scope to conceal drive here

Single slip view.PNG


Tandem.PNG


20211226_171246.jpg


Piano wire attaches to stretcher bars, hopefully plenty of scope to fix up somehow to below baseboard mech
You do not have the required permissions to view the files attached to this post.

Terry Bendall
Forum Team
Posts: 2420
Joined: Sun Jul 27, 2008 7:46 am

Re: Morgan designs for mechanical underboard signal and point control - discussion - merits of wire in tube

Postby Terry Bendall » Sun Jan 23, 2022 9:23 am

davebradwell wrote:A slice of tube or even a loop of wire soldered to the side of a Mike Clark tiebar might be a giant boil to many but I've always thought that there's other things around more distracting


I have always disliked the wires soldered to the blades and passed through the baseboard to fit into tubes in some sort of sliding arrangement becasue if the wire becomes detached from the blade it is a pain to put it back. I have had it happen twice during an exhibition. I now use a Masokits streatcher bar in functonal mode with a piece of 0.45 wire soldered in place which connects to the above board crank mentioned in my last post. The cranks are close to scale size and also came from Masokits. The 0.45 wire is bent through 90 degress and passed through the hole in the crank and then bent down. The wire gives a bit of flexibility in the movement. If on the prototype the turnout would be operated by a hand lever that can be used to hide the crank, otherwise some modelled rodding or a cosmetic point motor will hide things.

Terry Bendall

User avatar
LesGros
Posts: 546
Joined: Thu Oct 08, 2009 10:05 pm

Re: Morgan designs for mechanical underboard signal and point control - discussion - merits of wire in tube

Postby LesGros » Sun Jan 23, 2022 11:15 am

Good Morning Terry,

I hope this finds you well.

:thumb Your description of the Masokits tie bars is interesting; could you post, or point us, at some images of the arrangement please.
LesG

The man who never made a mistake
never made anything useful

User avatar
Jol Wilkinson
Posts: 1113
Joined: Mon Jul 21, 2008 7:39 pm

Re: Morgan designs for mechanical underboard signal and point control - discussion - merits of wire in tube

Postby Jol Wilkinson » Sun Jan 23, 2022 2:13 pm

I also use the Mike Clarke Masokits tiebars with Tortoise/Cobalt motors. However I form a wire with a circular loop which is soldered between the rodding tabs on the tiebar. The point motor actuating wire rises through a small slot in the baseboard and ballast into the loop, trimmed off so it projects just sufficiently to do its job. The wire with the loop can be extended beyond the stock rail to actuate a crank if required.

Despite the rather daunting instructions these tiebars are easy to make up and fit. I also fitted a second Ambis tiebar which had simple etched ends with very a thin pcb centre section. With the switch rails held by the Masokits unit, these were quite easy to add. Which version of tiebar these were I don't know. The Ambis site now list a Mk6 version but only shows the Mk4 version which I have never been able to work out how to fold up.

User avatar
ianpenberth
Posts: 117
Joined: Wed Dec 29, 2010 6:25 pm

Re: Morgan designs for mechanical underboard signal and point control - discussion - merits of wire in tube

Postby ianpenberth » Sun Jan 23, 2022 4:00 pm

Jol Wilkinson wrote:I also use the Mike Clarke Masokits tiebars with Tortoise/Cobalt motors. However I form a wire with a circular loop which is soldered between the rodding tabs on the tiebar. The point motor actuating wire rises through a small slot in the baseboard and ballast into the loop, trimmed off so it projects just sufficiently to do its job.


I know of many installations of this type seeing intensive use on some large layouts, where they perform very well.

For LesGros, photo of Masokits crank installed (please ignore the extra hole in the sleeper - brain had a day off) and a section of Mike's instructions:

IMG_2409.JPG

IMG_2412.JPG
You do not have the required permissions to view the files attached to this post.
Ian
PenBits Model Railways - Diesel bogie springing and detailing

Terry Bendall
Forum Team
Posts: 2420
Joined: Sun Jul 27, 2008 7:46 am

Re: Morgan designs for mechanical underboard signal and point control - discussion - merits of wire in tube

Postby Terry Bendall » Mon Jan 24, 2022 9:07 am

LesGros wrote:Your description of the Masokits tie bars is interesting; could you post, or point us, at some images of the arrangement please.


I don't have any pictures Les so would have to get some taken. However Ian's picture shows what I do and the instructions Ian has posted show the system. I use 3mm brass rod through the baseboard running in a short length of suitable tube with the end turned down to fit the crank. I don't bother to put a flat on the end of the rod but just solder in place. This usually works but I do occasionally get a failure here but it is fairly easy to clean off any paint, apply a bit of flux and resolder the joint. The way I do things there is enough vertical movement in the 3mm rod to pull it up a bit away from the ballast and do the soldering. I use a piece of 0.45 brass wire to connect the crank to the stretcher bar.

The Masokits stretcher bars are a bit fiddly to put together but they do the job. Being rectangular in cross section they may not be suitable for some pre-Grouping layouts where I think most companies used round ones, but this is a compromise I accept in the interests of reliability.

Terry Bendall

User avatar
LesGros
Posts: 546
Joined: Thu Oct 08, 2009 10:05 pm

Re: Morgan designs for mechanical underboard signal and point control - discussion - merits of wire in tube

Postby LesGros » Mon Jan 24, 2022 10:51 am

Thanks Terry,
:thumb
LesG

The man who never made a mistake
never made anything useful

User avatar
Julian Roberts
Posts: 1389
Joined: Sat Jan 09, 2010 11:33 pm

Re: Morgan designs for mechanical underboard signal and point control - discussion - merits of wire in tube

Postby Julian Roberts » Tue Jan 25, 2022 12:30 pm

Thanks again to everyone contributing to this thread and the many very useful ideas and thoughts.

Cheers everyone :thumb


Return to “Control Concepts”

Who is online

Users browsing this forum: ClaudeBot and 0 guests