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Mid-Cornwall Lines - 1950s Western Region in 00


St Enodoc
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2 hours ago, FarrMan said:

I would suggest a bit of drafting tape (or masking tape) either side would reduce unwanted breakout and give a better grip to the point of the bit. Too fast a drill speed and you will melt the perspex, so a slower speed would be preferable. If it is a large hole that you need, start with a small bit and gradually work up to final size. 

Hope it works OK for you.

 

Lloyd

I'd definitely go for taping as acrylic does have an inclination to split/shatter when being drilled (although that might be doen to either cheap Hobbycraft acryliceor my hamfisted drilling or even a combination of the two).  

I've wondered about using a glass/tile drill bit instead of a twist drill but have never tried so I don't know if it's a sensible aternative

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7 minutes ago, The Stationmaster said:

I'd definitely go for taping as acrylic does have an inclination to split/shatter when being drilled (although that might be doen to either cheap Hobbycraft acryliceor my hamfisted drilling or even a combination of the two).  

I've wondered about using a glass/tile drill bit instead of a twist drill but have never tried so I don't know if it's a sensible aternative

I don't mind if it cracks but if a corner splits off or the sheet shatters I'll go to Plan B, which is 4mm MDF...

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16 minutes ago, St Enodoc said:

I don't mind if it cracks but if a corner splits off or the sheet shatters I'll go to Plan B, which is 4mm MDF...

 

Hi John - for once something I have a (very) little experience with.

I did spend nearly a year in a plastic fabrication co, and might just remember

a little of the techniques.

 

1) Acrylic sheet does not like heat, so keep your drill bit cooled, by dipping in water, frequently.

 

2) Drilling is also inclined to chatter, which in turn causes stress fractures. These in turn can lead

    fractures later. Where I worked new drill bits were treated with a file, to rempve the sharp edge

   on the tip.  Slow drill speed, with an "old" bit, should achieve similar results. (and don't push too hard).

 

All the best

TONY

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3 hours ago, FarrMan said:

I would suggest a bit of drafting tape (or masking tape) either side would reduce unwanted breakout and give a better grip to the point of the bit. Too fast a drill speed and you will melt the perspex, so a slower speed would be preferable. If it is a large hole that you need, start with a small bit and gradually work up to final size. 

Hope it works OK for you.

 

Lloyd

Not sure about acrylic, but perspex is best done with a sharp knife along the line of cut and then bend it over a rigid edge. It just snaps off along the line.  Use knife firmly, as you want to do a bit more than just score the surface. If you have a wee bit spare, you could try it and see. If you need to use a saw, then I would think as fine a tooth saw as you can get. Again to avoid getting it too hot, do it in short stages, or cool the blade frequently.

 

Talking of avoiding undue heat reminds me of a story I heard about a contractor cutting up an old underground petrol tank (i.e. BIG). He should have been using a hand saw, but chose to use a power saw instead. The Petroleum Officer was just around the corner when he heard the explosion. The contractor went up to an altitude of 15 feet - he went up white and came down black! His first words to the Petroleum Officer were 'Does this mean that I am taken off the list of approved contractors?'

 

Lloyd

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56 minutes ago, St Enodoc said:

I don't mind if it cracks but if a corner splits off or the sheet shatters I'll go to Plan B, which is 4mm MDF...

When using MDF, remember that the saw dust can be carcinogenic. Best done outside if possible, with suitable respiratory protection.

 

Lloyd

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16 minutes ago, FarrMan said:

When using MDF, remember that the saw dust can be carcinogenic. Best done outside if possible, with suitable respiratory protection.

 

Lloyd

 

Absolutely, I use one of these when I'm cutting anything, also sanding etc.

 

air_stealth_main_2.jpg.8f28d46a3312cfd26c62c4f405409720.jpg

Edited by Tim Dubya
Photo, + they do a smaller size for little heads.
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11 hours ago, ianathompson said:

I would sooner settle for sloppiness than the need to call every train past a signal at danger!

I’m sure you would, and I’m equally sure S&T wouldn’t because sloppiness becomes failed locking much sooner.  :-)

Speed of getting it working to your satisfaction is what matters.  Interesting that it took a couple of shifts before it seized up.

Paul.

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2 hours ago, 5BarVT said:

 Interesting that it took a couple of shifts before it seized up.

 

Quite agree with this comment.

As a relief I was not working the box in question when the work was done.

It was, I was assured, properly tested and signed off as 'in order'.

Presumably the temperature changed significantly during the interim.

 

Ian T

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2 hours ago, 5BarVT said:

I’m sure you would, and I’m equally sure S&T wouldn’t because sloppiness becomes failed locking much sooner.  :-)

Speed of getting it working to your satisfaction is what matters.  Interesting that it took a couple of shifts before it seized up.

Paul.

When the Nantgarw bran ch from Taffs Well was singled back in the 1970s we had a lot of problems with the FPLs on the new facing crossover at Taffs Well because of the S&Ts difficulty in getting them adjusted.  It took a couple of weeks, with some occasional strong words on my part to get it to the Signalmen's (and my) liking because it inevitably became a very hard pull to get the FPL bolts to engage.  The reality is that sometimes these things can happen and it can take time for new work to bed-in and get the adjustment right and while it might mean hard pulling that's a lot better than dealing with sloppiness somewhere in the mechanism (i've encountered some of that too and I know which I prefer).

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56 minutes ago, aardvark said:

Hope you're keeping your head above water down there.

 

Yes, 200m above sea level so if we flood others have far bigger problems...

 

Fires are a greater risk for us. A couple of years ago, if the Gospers Mountain fire had jumped the Hawkesbury River we might have been in trouble.

Edited by St Enodoc
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2 hours ago, St Enodoc said:

Yes, 200m above sea level so if we flood others have far bigger problems...

 

I did think, after posting, that as a grand sweeping generalisation, we model railway tragics are probably not of a socio-economic demographic that would make us likely to be victims of flooding, i.e. we live in better houses that aren't on flood plains.

 

Having written that, I remind myself that nothing is normal any more.

 

Also, I hear that there's a bit of rain about, and roofs sometimes leak, even new ones.

 

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On 03/07/2022 at 17:35, St Enodoc said:

I'd like to have been able to say that the mechanical work is now complete and before I fitted the locking bar springs I thought it was. However, once the springs were fitted two levers refused to move. I'll have to take the springs off and work out why.

I've had a quick look and I think that I can do two things. The first is to increase the gap between the spring retainer plates and the frame, which will give the conditional locking bars more room to move, as the springs are almost fully compressed in both positions at the moment. The other is to ease the square notches on tappets 4 and 27 where they engage with locking bar D, by filing a slight bevel on their edges.

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1 hour ago, St Enodoc said:

I think that I can do two things.

Oh, I am sure you can do more than two things.

The question is, can you do two (or more) things at the same time?

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3 hours ago, Regularity said:

Oh, I am sure you can do more than two things.

The question is, can you do two (or more) things at the same time?

You'd be surprised.

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Only a short session today after fitting a new seal to the bottom of the workshop door, where some water had seeped in during the wild wind and very heavy rain we had last week.

 

I did have time to open up the interlocking and ease all the square notches by filing a slight bevel on each corner. All the levers now work when they should, although some are a little, erm, "notchy". More importantly, nearly all the levers don't work when they're not supposed to (the true meaning of verification). One is free when it should be locked but I don't think it will affect operation, so other than going through the charts and tables to see if there's an obvious reason I'm going to leave it all alone.

 

No photos today but I might take a couple tomorrow, before and after I've lubricated the interlocking, which will indeed mark the end of the mechanical work.

Edited by St Enodoc
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2 hours ago, St Enodoc said:

One is free when it should be locked

Details, details!!!

Unless its in the conditional locking the converse should also be free when it should be locked.

I thought about asking what the travel on the tappets is when you mentioned your filing error on 17 (modratec) to see if that would free up something irregularly but having looked at the locks spreadsheet for the both ways locks it looks like the travel is two locking bars.  If I’m right, that means your false notch on IJ moves to JK which doesn’t exist so won’t release anything irregularly.  I was puzzled by what looked like a pin on IJ at the notch in 17 but further inspection indicates it’s the ‘down’ pin for the lock on 18.

Thank you for the fun mental exercise provided!

Paul.

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2 hours ago, 5BarVT said:

Details, details!!!

Unless its in the conditional locking the converse should also be free when it should be locked.

I thought about asking what the travel on the tappets is when you mentioned your filing error on 17 (modratec) to see if that would free up something irregularly but having looked at the locks spreadsheet for the both ways locks it looks like the travel is two locking bars.  If I’m right, that means your false notch on IJ moves to JK which doesn’t exist so won’t release anything irregularly.  I was puzzled by what looked like a pin on IJ at the notch in 17 but further inspection indicates it’s the ‘down’ pin for the lock on 18.

Thank you for the fun mental exercise provided!

Paul.

Thanks Paul. That's correct regarding the travel. Each locking bar is approx 4.5mm wide and the lever throw is approx 9mm. I can't remember which lever seems to be wrong - its twenty-something - but everything's out in the workshop at the moment. When I've had a closer look and a think I'll follow up with you separately.

Edited by St Enodoc
speling
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On 29/06/2022 at 12:31, St Enodoc said:

I've now restored all my images on this topic back to the start of June 2021. Once I'd got into the routine, it was quite therapeutic. In fact, in a way, I'm sorry it's finished (no I'm not, don't be ridiculous).

I  was hoping some server fixer-upper wizardry would do that. Are you *quite* sure we need to do it ourselves? *Shudders at the thought of going back to Feb 2018 on my thread*

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13 hours ago, Martin S-C said:

I  was hoping some server fixer-upper wizardry would do that. Are you *quite* sure we need to do it ourselves? *Shudders at the thought of going back to Feb 2018 on my thread*

Unfortunately, I think I'm right. As I understand it, all images posted between June 2021 and March 2022 inclusive are gone and will need to be restored by the posters concerned. Images from May 2021 and earlier will be restored automatically, although that process seems to be extremely slow at the moment.

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