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Fitting detachable etched brake gear to loco chassis


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I an rebuilding an etched chassis for a Craftsman SR T1 for a friend, I would like to make the brake gear detachable and have noticed some use micro tube and would like to source some advice/tips on doing so

 

I have bought some nickel silver wire and some brass micro bore tube from Hobby Holidays, the thinking about N/S wire rather than brass is it is stronger

 

Two initial questions

 

1   how long should the wire extend from the side frames

2   what length should the tube be between the frames and brake blocks

 

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I set the length of my tube from the face of the frame so that the brake blocks line up with the outer face of the wheels.

This may vary as to side play of the wheels relating to the minimum  radius curve the loco is built to negotiate.

 

Gordon A

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13 hours ago, hayfield said:

Two initial questions

 

1   how long should the wire extend from the side frames

2   what length should the tube be between the frames and brake blocks

 

 

This will depend on how far the wheels are from the frames and the thickness of the wheels.  Presumably the wire will go through the holes that would be there for fixed brake gear, so the accuracy here is less critical

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17 hours ago, hayfield said:

 

I an rebuilding an etched chassis for a Craftsman SR T1 for a friend, I would like to make the brake gear detachable and have noticed some use micro tube and would like to source some advice/tips on doing so

 

I have bought some nickel silver wire and some brass micro bore tube from Hobby Holidays, the thinking about N/S wire rather than brass is it is stronger

 

Two initial questions

 

1   how long should the wire extend from the side frames

2   what length should the tube be between the frames and brake blocks

 

 

17 hours ago, Gordon A said:

I set the length of my tube from the face of the frame so that the brake blocks line up with the outer face of the wheels.

This may vary as to side play of the wheels relating to the minimum  radius curve the loco is built to negotiate.

 

Gordon A

 

 

Thanks for the replies, the length of tube I guess reading your replies  is to the outside(ish) of the wheels,

 

Next question, how long should the wire protrude from the frames please, then I assume one uses a shorter piece from the brake shoe into the tube ?

 

Just trying to think of the sequence of what is fitted when and how

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I solder the wire in to the brake hangars, not into the tube. The wire only need to protrude by about a millimetre.

When fitting the tubes to the frames I install the tubes in pairs with a piece of wire running through both tubes to better align them.

 

If you hold your wheels either side of your chosen back to back gauge you can measure the  distance between where you want to position the brake blocks. Then subtract the overall width of your frames and divide by two. That will give you the distance that the tube protrudes outwards from the frame. 

 

Using the distance between the brake hangars (Overall width of the tubes outer faces) You can make a jig from carboard to assemble the brake hangars on the lower cross bar.

 

Gordon A

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Gordon

 

Thank you, this sounds a much better sequence than the one I had thought of

 

What about where the lower crossbar is internal and connects to the mainframes, any thoughts please

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John,

 

Hopefully the little sketch shows how to fit a tube and the rods to make the brake assembly removable.

 

699063118_BRAKEHANGERS.jpg.d38bc794fe3b023139bf4586b75e9d3b.jpg

 

The short upper brake rod can then be sprung open to fit into the tubes which are soldered to the frames.

 

Dave

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4 hours ago, hayfield said:

Gordon

 

Thank you, this sounds a much better sequence than the one I had thought of

 

What about where the lower crossbar is internal and connects to the mainframes, any thoughts please

Hello John,

 

Your question has puzzled me.

What engine are you thinking of, or has Dave's drawing answered your question?

 

Gordon

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I admit that I do it the other way round with the tube on the brake hanger and the wire in the frame.  The tube I use has a 0.45mm bore to fit 'handrail wire'.  Never thought of reversing the design, might try it next time I build a chassis that needs removable brake gear.

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2 hours ago, Gordon A said:

Hello John,

 

Your question has puzzled me.

What engine are you thinking of, or has Dave's drawing answered your question?

 

Gordon

 

Gordon

 

I have a LBSCR E4 (prebuilt but someone tampered with the chassis) The brake gear connecting (or are they called pull) rods are internal, no problems for the break shoes but its where the rods connect with the chassis 

 

Dave's drawing is fine, but I guess its just the other way round

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52 minutes ago, hobbyhorse said:

My removable brake gear from a recent build, small hex bolts hold all in place using the holes in the top of the shoes.

 

Simon

IMG_5050.JPG.ce81097c134e4271ee8f4e3eed33ffae.JPG

 

Thanks for the posting, makes things very clear and Mmch tidier than my first effort,

 

Like all things I guess the first attempt usually takes forever and quite often leads to having to be redone again

 

I started off using nickelsilver wire and building it as a fixed instillation.

 

Next up I will cut the microtubes to length. Cut the brake hanger wire to the chassis, reduce the length by 1 mm. Solder the tubes in place then try and refit the brake gear

 

Thanks again to all, and hopefully it will be a help to others, please keep up the suggestions and advice

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15 hours ago, hayfield said:

 

Gordon

 

I have a LBSCR E4 (prebuilt but someone tampered with the chassis) The brake gear connecting (or are they called pull) rods are internal, no problems for the break shoes but its where the rods connect with the chassis 

 

Dave's drawing is fine, but I guess its just the other way round

 

There should be a fairly heavy cross shaft, usually under the bunker on tank engines that is hung below the frame.

The two pull rods are connect to this by a cam / lever on each side. 

Also connected to this shaft are the hand brake and the loco steam or air brake.

 

Gordon A

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34 minutes ago, Gordon A said:

 

There should be a fairly heavy cross shaft, usually under the bunker on tank engines that is hung below the frame.

The two pull rods are connect to this by a cam / lever on each side. 

Also connected to this shaft are the hand brake and the loco steam or air brake.

 

Gordon A

 

Gordon

 

Thanks I will take my reference from an E5 chassis kit, looks similar and must be better than nothing

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I can't really add anything to the good advice offered by others, apart from saying that I also attach the tube to the frames, plus the 0.5mm or 0.45mm wire inside it and the wire then goes in the holes at the tops of the brake hangers.

 

I find that the above involves less deflection of the brake hangers from the lower transverse brake rods.

 

What I have done before is to make the 0.5mm wire a bit longer than necessary (but not so long as to make the deflection of the soldered joints excessive), make up the brake hanger and rodding assembly and then trim the excess wire with some snippers, with the brake assembly still in place. If there's still too much 0.5mm wire protruding, then remove the brake assembly and use your judgement to trim a little more off.

 

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12 hours ago, Brassey said:

The usual reason for removable brake gear is to be able to drop the wheelsets out. Is this the case?

That's correct which is useful when painting the more complex kits, also if any problems crop up with motors, pickups or anything else inside the frames. My photo shows the Nelson build which was complex with inside valve gear also fitted.

 

SimonIMG_5059.JPG.78aa5e4bede74ff0a0d5e5de23141d22.JPG

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17 minutes ago, hobbyhorse said:

That's correct which is useful when painting the more complex kits, also if any problems crop up with motors, pickups or anything else inside the frames. My photo shows the Nelson build which was complex with inside valve gear also fitted.

 

Yes. And this demonstrates that you cannot use a tube right through the frames to secure the brakes, as advocated in the diagram above, because the valve gear and motor/gearbox would be in the way.

 

Also it's a prerequisite to have some form of hornblock system to allow the wheelsets out.  And another means to hold them in.

 

All quite a lot of extra work.  I am of the school of painting the chassis before fitting the wheels.

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37 minutes ago, Brassey said:

 

Yes. And this demonstrates that you cannot use a tube right through the frames to secure the brakes, as advocated in the diagram above, because the valve gear and motor/gearbox would be in the way.

The tubes are cut on the inside faces of the frames once they're lined up and soldered in. 

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Removable brakegear is a standard feature on our kits. Wherever possible, use a full length of tube and a continuous, removable wire running through. Where there’s stuff between the frames, the hangers have short pins located into short stubs of tube and can be sprung off. 
 

Distance of hangers from frames, as Gordon says, depends on a number of variables. 
 

if you look at any of the chassis or locos on our site at www.highlevelkits.co.uk you can see how it’s done. 

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A lot of good advice above, I now tend to have a tube in the frames and short .45 wire on the hangers, mainly to make painting easier. I just use a spot of paint to secure the wire to the tube at final assembly, easily taken apart if the need arises. 

 

In this example the rear tube was soldered through , then the portion between the frames cut away to clear the gearbox. The front tube conveniently doubles up as the pivot for the compensating beam. 

 

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For 00 and Gibson wheels, I always set the distance between the backs of the brake hangers (hangars are where you keep aeroplanes) at 17.5mm, and have a wooden jig for that job. This means that the tube will also need to be 17.5, but positioning it exactly central is obviously something of a challenge. It can be made over length and then careful work done with a file and Vernier to get it central and 17.5.     

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I normally put a small spigot on the frames in the brake hanger hole. I then solder brass tube to the individual brake hangers which set the distance to the tread. The brakes sit tightly over the spigot and only need around 0.5mm of deflection to lift then over the spigot. I sometimes make the hangers bent inwards slightly to give some pre-load when assembled.

 

The trick I use for getting all the tubes the same length is to cut them slightly over length and then drill a hole into a block slightly longer than required and then file the protruding tube flush to the surface. I then use another hole exactly the right depth and put the files tube in with the smoothed end down and repeat the exercise. The tube an be removed with the tip of a small round file. This allows me to mass produce short lengths of tube with exactly the same length.
 

Others have suggested rolling the tube under a knife blade but this requires each cut to be accurately placed and the resulting part often gets catapulted to the darkest recesses of my workshop and the cut ends still need cleaning up.

 

Mark

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