Mid-Cornwall Lines - 1950s Western Region in 00

[St Enodoc]

1 hour ago, The Fatadder said:

Looking very good, one day I must replace ,my basic control panel with a leaver frame.   Every time I see it on the mid Cornwall lines I want my own!

I'm very lucky, Rich, in that the Modratec system lets me do what I have wanted to do for about the last 45 years but was never able to due to my lack of skill a) to design the interlocking (the Modratec SigScribe4 program does that for you) and b) make the frame (the Modratec system means you only need very basic skills, the hard and clever bits having been done for you). I've another one on order for St Enodoc and once the signalling arrangements for Pentowan and Treloggan Junction are finalised I'll order the third and final frame. They're not cheap but I consider them excellent value for money.

 

Usual disclaimer, although I have to add that over the years Harold, a fellow BRMA member, has become a good friend too.

[Barry O]

did someone mention a Shack?????

 

 

Like this one Airfix built??

 

 

Baz

[St Enodoc]

Having slept on it, and had another look today, I think I can use the self-adhesive labels after all. Instead of pressing them down direct on their surface, I can press the labels down with the hard rubber roller using an intermediary, rather like burnishing dry print transfers through a sheet of paper after you've applied them. The solution to the "crease" problem should be to cut the lever lead labels into two parts and fix the top and front separately with a slight overlap. I'll print some new copies and try this next weekend.

 

The rest of today's time was taken up by uncoupler magnets. I'd worked out a while ago how many (14) I need for Porthmellyn Road and roughly where they need to go. Last year I recovered 15 from the fiddle yard area of the old St Enodoc layout, so I tested them today and found that 14 of them were good (the 15th had gone short circuit somehow, so I'll rewind the bobbin another time).

 

The magnets are made from thin enamelled copper wire wound on to metal sewing machine bobbins. These will fixed to the layout from below, using 6mm set screws that are cut off at sleeper height and act as an armature as well as holding the coils in place.

 

Here are a couple of photos from when I was building the old layout that should explain this more clearly:

 

 

I worked out the exact locations where I wanted the magnets to go, taking into account fouling points, point motors, baseboard framing, signal location and so on, then drilled the holes for all 14. Drilling 5.5mm holes means that the screws cut their own threads in the plywood and the whole thing ends up quite secure.

 

I'll control the uncouplers with momentary toggle switches on a mimic panel next to the lever frame. This panel will also house rotary switches for the three hand points that are wired up temporarily at the moment. Once the magnets are in place I'll build the panel using white-faced MDF as usual. All this might not happen for a few weeks as I'm still waiting for an order of switches and black-and-white wire.

 

As I'll be using dc power I might add freewheel diodes across the coils to minimise arcing - what does the team think?

 

 

Edited July 18, 2023 by St Enodoc
images restored

[5BarVT]

1 hour ago, St Enodoc said:

As I'll be using dc power I might add freewheel diodes across the coils to minimise arcing - what does the team think?

Depends how frequently you want to replace the toggle switches!

Don’t know the internals of toggle switches very well, but I doubt they have much of a wiping (cleaning) action, so I think a freewheel diode is essential.

How much current does your coil draw?  Gut feel is that the diode needs to be rated for at least that current to stand the initial surge. (L of a current mate!)

Paul.

[St Enodoc]

7 minutes ago, 5BarVT said:

Depends how frequently you want to replace the toggle switches!

Don’t know the internals of toggle switches very well, but I doubt they have much of a wiping (cleaning) action, so I think a freewheel diode is essential.

How much current does your coil draw?  Gut feel is that the diode needs to be rated for at least that current to stand the initial surge. (L of a current mate!)

Paul.

Thanks Paul. That's exactly my reason for asking. I used to work these coils off cheap push-buttons but that wasn't really a good idea.

 

The coils have a resistance of about 16 - 17ohm. Last time I ran them off a 12Vdc supply but this time I might increase that to 24, so about 1.5A maximum. The alternative is to run them off ac but I think they would buzz a bit, which woudl be irritating.

 

I know some people use a timer circuit to stop the coils staying on but I haven't tried that.

[5BarVT]

Two different issues here. 

Timer is to stop the coils overheating and burning out: 24V 1.5A = 36W you’ll soon feel that!  Still needs a diode to protect against back emf.

At 1.5A I’d be tempted to go for a 1N5401 or equivalent (3A rated) rather than a 1A 1N4001.

Paul.

[St Enodoc]

19 minutes ago, 5BarVT said:

Two different issues here. 

Timer is to stop the coils overheating and burning out: 24V 1.5A = 36W you’ll soon feel that!  Still needs a diode to protect against back emf.

At 1.5A I’d be tempted to go for a 1N5401 or equivalent (3A rated) rather than a 1A 1N4001.

Paul.

Yes I realise they are different problems. I'm not going to bother with the timer for now. I hope the diodes will be enough to stop the switch contacts welding up. Thanks for the details of the diode type. I should have some of those buried somewhere in my electrical bits box.

[Barry O]

sprung switches seem to work well. 

could this be of use?

Baz

[Michael Edge]

What's the wire you are using? I've long since run out of the magnets we used to buy and I've been using coils from old half dead point motors recently.

[St Enodoc]

20 minutes ago, Michael Edge said:

What's the wire you are using? I've long since run out of the magnets we used to buy and I've been using coils from old half dead point motors recently.

34 swg enamelled copper wire, Mike.

 

I'm going to try H&M coils when I run out of recovered sewing machine bobbin coils. What voltage do you run them at?

 

You're probably talking about the old Whistons coils. They were somewhat more meaty as I recall.

[St Enodoc]

29 minutes ago, Barry O said:

sprung switches seem to work well. 

could this be of use?

Baz

Pretty much the same Baz, but only two position On-(On) (if I've ordered the right ones...). They're coming from Element 14, which used to be Farnells. About the same price too.

[Michael Edge]

8 hours ago, St Enodoc said:

34 swg enamelled copper wire, Mike.

 

I'm going to try H&M coils when I run out of recovered sewing machine bobbin coils. What voltage do you run them at?

 

You're probably talking about the old Whistons coils. They were somewhat more meaty as I recall.

I think mine are on something like 23v but they are OK on 15v. Going through Barry's wagons in the last few weeks I've found a lot more non-magnetic stainless steel wire droppers - fortunately I still have a decent supply of the iron wire we used to make the old club couplings out of, this makes a big difference in operation. We ought to get the Morris brothers to 3D print some bobbins.

I've used sprung switches in the fiddle yard, they should be more reliable than a lot of the push buttons I've used - some of them fail to contact but worse still some weld themselves shut.

 

[St Enodoc]

1 hour ago, Michael Edge said:

I think mine are on something like 23v but they are OK on 15v.

Thanks Mike, that's good. I can run them from the same supply as my existing ones in that case.

 

1 hour ago, Michael Edge said:

the iron wire we used to make the old club couplings out of

Ha, ha, I've got a couple of yards somewhere too. I knew it would come in useful one day. All I've got to do is find it...

 

1 hour ago, Michael Edge said:

3D print some bobbins.

Make sure they are heat resistant. I made my first few magnets with plastic bobbins. Big mistake - not only did they distort when the coil warmed up but sometimes if I wound them too tightly they'd just snap. Now I only use metal ones.

 

1 hour ago, Michael Edge said:

I've used sprung switches in the fiddle yard, they should be more reliable than a lot of the push buttons I've used - some of them fail to contact but worse still some weld themselves shut

Yes, that's why I'm changing to sprung switches! The buttons are OK for low current work like my DCC route setting but no good for higher currents, especially dc. I've also had some buttons physically fall to bits.

[innocentman]

10 hours ago, St Enodoc said:

Make sure they are heat resistant. I made my first few magnets with plastic bobbins. Big mistake - not only did they distort when the coil warmed up but sometimes if I wound them too tightly they'd just snap. Now I only use metal ones.

 

 

The 3D FDM printing process is thermal and relies on a thermo-setting plastic, typically ABS or PLA. Other materials are available but all print at around 180 -230 degrees C. More than happy to print a few bobbins for experimentation purposes.

 

Although I have to wonder how long you are keeping the magnet on for it melt. Sound we need some experimentation, left and right hand rule stuff to a maximise the magnetic pulling force while minimising current flow

 

Regards

 

One half of the Morris Brothers

 

 

Edited April 20, 2020 by innocentman
Typo

[St Enodoc]

1 hour ago, innocentman said:

 

The 3D FDM printing process is thermal and relies on a thermo-setting plastic, typically ABS or PLA. Other materials are available but all print at around 180 -230 degrees C. More than happy to print a few bobbins for experimentation purposes.

 

Although I have to wonder how long you are keeping the magnet on for it melt. Sound we need some experimentation, left and right hand rule stuff to a maximise the magnetic pulling force while minimising current flow

 

Regards

 

On half of the Morris Brothers

 

 

That sounds good Fred. The melting magnets happened when the push-button contacts welded up (see above). I didn't calculate the true magnetic flux but when I was deciding what gauge of wire to use I used "ampere-turns" as a comparator.

 

I wind the coils using the time-honoured method of chucking them in a hand brace that I turn slowly while feeding the wire on. If I'm careful, I can get about 800 turns of 34swg wire on to the bobbin.  That gives a resistance of about 16 - 17ohm (see above) and with a 12Vdc supply a current of about 0.8A, so about 650 ampere-turns. If I use 32swg wire the corresponding values are 600 turns, 7.5ohm, 1.6A and 950 ampere-turns. I've also got some values for 36swg wire somewhere but I can't find them!

 

Broadly, if you use thinner wire the resistance goes up faster than the number of turns, so the pulling power goes down.

 

As I wanted to keep the current below 1A at 12Vdc I decided to standardise on the 34swg version. It has enough pull but with experience I think upping the voltage to 24Vdc and hence the current to about 1.5A will still be acceptable and will double the pulling power and so help with "sticky" couplings (which too many of mine are).

Edited April 20, 2020 by St Enodoc
Typo

[innocentman]

34 minutes ago, St Enodoc said:

That sounds good Fred. The melting magnets happened when the push-button contacts welded up (see above). I didn't calculate the true magnetic flux but when I was deciding what gauge of wire to use I used "ampere-turns" as a comparator.

 

I wind the coils using the time-honoured method of chucking them in a hand brace that I turn slowly while feeding the wire on. If I'm careful, I can get about 800 turns of 34swg wire on to the bobbin.  That gives a resistance of about 16 - 17ohm (see above) and with a 12Vdc supply a current of about 0.8A, so about 650 ampere-turns. If I use 32swg wire the corresponding values are 950 turns, 7.5ohm, 1.6A and 950 ampere-turns. I've also got some values for 36swg wire somewhere but I can't find them!

 

Broadly, if you use thinner wire the resistance goes up faster than the number of turns, so the pulling power goes down.

 

As I wanted to keep the current below 1A at 12Vdc I decided to standardise on the 34swg version. It has enough pull but with experience I think upping the voltage to 24Vdc and hence the current to about 1.5A will still be acceptable and will double the pulling power and so help with "sticky" couplings (which too many of mine are).

I think I need a laboratory!

 

I will dig my old uni text books out and refresh my memory on how to find the best compromise between number of turns, resistance, current, armature length etc

 

[St Enodoc]

11 minutes ago, innocentman said:

I think I need a laboratory!

 

I will dig my old uni text books out and refresh my memory on how to find the best compromise between number of turns, resistance, current, armature length etc

 

Thanks! The armature length is fixed, of course, by the thickness of the bobbin and of the baseboard.

 

Typo in my last post by the way. 32swg wire means 600 turns, not 950. That should make more sense. Original post edited too.

Edited April 20, 2020 by St Enodoc

[Michael Edge]

I think a 3D printed bobbin will be fine, they should only be on for a few seconds at at a time.

The Whistons ones melt when the current is left on, quite a few of mine are partly melted because of switch contacts welding up but still work. Once or twice they have been on the point of setting the layout on fire - the LMRS has form for this of course....

[St Enodoc]

Some rotary switches for the hand points and sprung toggle switches for the uncouplers arrived today, so I should be able to make some good progress this weekend. The panel will go next to the lever frame on the left side. I just need to sort out exactly how I will mount it on the layout. A bit of trial and (not too much) error is called for.

Edited April 22, 2020 by St Enodoc

[St Enodoc]

For a change I did some more on the C65 tonight - the first coat of crimson on one side.

 

The lower panel wasn't too bad, as I could brush freehand up to the line where the old lining was and the new lining will go. The cantrail band was harder as there wasn't anything there before and I couldn't get the Tamiya masking  to sit very flat above the tops of the windows and doors. I much prefer to get the basic colours done before all the detailing bits go on but that wasn't an option with this model. Anyway, it's done now and I will tidy it up when it's dry, but not hard, using a cocktail stick. I think I'll need to put two coats on each side so that's another three sessions' work.

[St Enodoc]

Today is ANZAC Day, the 105th anniversary of the landings at Gallipoli in 1915 and the day on which Australians and New Zealanders remember those of our compatriots who gave their lives in armed conflicts. It's rather an odd day this year as of course there are no church services, wreath-laying ceremonies or marches. There was also no service at Anzac Cove in Turkey for the first time in many years - probably since the end of the Second World War.

 

Model railway-wise, I put the second coat of crimson on the C65 yesterday and the third this morning. That's two coats on one side and one on the other. Tomorrow morning should see that done. Then I'll tidy up the boundary between the crimson and cream, repaint the roof and touch up the black bits. After that it will be ready for lining, numbering and varnishing. By next weekend it could even be ready for service.

 

This afternoon I made the frame for the Porthmellyn Road uncoupler/hand points panel. Why did that take all afternoon I hear you ask? Well, the structure's a bit complicated. Because I want to keep the height of the panel down to the distance between the bottom of the baseboard and the bottom of the L-girders, namely 125 mm, I had to cut away some of the frame at the top and bottom to clear space for some switches. I added timber "fishplates" along the back edge of the frame and cut away the main structure to create the space. Once I was comfortable with the fit I screwed and glued the frame parts together and left them to dry.

 

As a result of locating the frame where I have, I've had to move one pair of droppers and associated feeders on No 2 Up Siding to clear the frame when it's installed.

 

No photos today - I'll take some tomorrow when I should finish the frame and get the front panel cut and fitted before the SWAG RMweb Virtual Members' Day opens.

 

 

[St Enodoc]

I put the final coat of crimson on the C65 today and then finished the frame for the uncoupler/hand points control panel. The panel hangs from two joists by a bracket arrangement that both supports it and keeps the front of the frame flush with the baseboard edge. This means that the panel face itself will be proud of the edge but flush with the future profile board when it is fitted. The frame is held in place by a magnetic catch.

 

This is what the frame looks like on its own. You can see the two cut-outs at the top and one at the bottom, with the fishplates that hold them together.

 

The brackets have a vertical part that stops the frame being pushed back too far and a horizontal part that supports the top member of the frame. There are rather a lot of screws in a small space here and you can see that on the left the the vertical part has split. I held it together with a long screw driven in from underneath. There's some packing to make sure that the frame and brackets have a nice sliding fit.

 

Here's the frame in place, showing how it rests on the two brackets and is flush at the front.

 

The last job for today was to glue the white MDF front panel to the frame, weight it with bricks and leave it to dry overnight.

Edited July 18, 2023 by St Enodoc
images restored

[manna]

G'Day Folks

 

Wot, No picture of the glue drying, looking forward to that !!

 

manna

[Barry O]

14 hours ago, St Enodoc said:

I put the final coat of crimson on the C65 today and then finished the frame for the uncoupler/hand points control panel. The panel hangs from two joists by a bracket arrangement that both supports it and keeps the front of the frame flush with the baseboard edge. This means that the panel face itself will be proud of the edge but flush with the future profile board when it is fitted. The frame is held in place by a magnetic catch.

 

This is what the frame looks like on its own. You can see the two cut-outs at the top and one at the bottom, with the fishplates that hold them together.

 

The brackets have a vertical part that stops the frame being pushed back too far and a horizontal part that supports the top member of the frame. There are rather a lot of screws in a small space here and you can see that on the left the the vertical part has split. I held it together with a long screw driven in from underneath. There's some packing to make sure that the frame and brackets have a nice sliding fit.

 

Here's the frame in place, showing how it rests on the two brackets and is flush at the front.

 

The last job for today was to glue the white MDF front panel to the frame, weight it with bricks and leave it to dry overnight.

Shackleton looks ready for build!!

Baz

[St Enodoc]

39 minutes ago, manna said:

G'Day Folks

 

Wot, No picture of the glue drying, looking forward to that !!

 

manna

Later...