Flared Tender Sides

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Flared Tender Sides

This topic has 11 replies, 6 voices, and was last updated 31 August 2017 at 22:52 by Clive Brown 1.

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29 August 2017 at 12:01 #314413
Clive Brown 1
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@clivebrown1
Hi,

I'm starting to build the tender for the 5" gauge Princess of Wales. A problem that's occupying my thoughts is how to make the side and rear sheets for the tender, which have curved flares along the top edges. The curvature is about 1" radius. I'm intending to use 16g brass and I don't fancy my chances of producing an even curve along a 21" length. Not to mention the awkward rear corner joint .

One idea has been to cut lengths from a 2" diameter tube and attach by soldering, reinforced by the brackets for the coal-rails, but I'm open to suggestions.

Any advice would be gratefully received.

Clive
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29 August 2017 at 12:01 #30628
Clive Brown 1
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@clivebrown1
29 August 2017 at 12:44 #314417
Phil H1
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@philh196021
Clive,

This might not be too helpful – I have never done this kind of brass bashing before. However, I have seen the split tube solution written up somewhere else. I think it might have been an LSBC design for a similar 3 1/2" gauge tender. The unhelpful bit is that he proposed both solutions i.e., bending the sheet over a bar or the method you have suggested.

Phil H
29 August 2017 at 14:12 #314423
Paul Lousick
Participant
@paullousick59116
I had a similar problem making the spectacle plate for my traction engine. Plate used was 5mm thick and corners cut out of a 20mm pipe elbow. The radius of the straight edges made the same as the radius of the elbow. The pipe elbow was tack welded to a plate and mounted on a rotary table and machined to size on the mill.

2 days making the brake press and 10 minutes to bend the plate. (Took about 10 tonne to bend 5mm thick x 220mm long plate).

Fabrication welded and finished product after grinding and painting.

Paul
29 August 2017 at 14:27 #314426
duncan webster 1
Participant
@duncanwebster1
Many years ago I tried this on the tender for a 15"g loco, steel obviously. The tube opened up like a banana when slit. I'd advise trying it on a short bit and if you get the same problem anneal the tube before splitting.

Paul's method look good to me. With 16g brass you might get away with a jury rig made from round bar, angle and lots of G clamps. Again try it on a short bit to get the radius of the bar right, it will spring back unless you've annealed the whole sheet. For the back corner on my 5"g tender I turned a sort of trumpet end shape, quartered it and soldered it in
30 August 2017 at 11:34 #314523
julian atkins
Participant
@julianatkins58923
Hi Clive,

Do not under any circumstances anneal the brass sheet.

I would suggest making up an internal former out of standard kitchen work top with a radiused edge. The brass is then sandwiched between this and another piece of kitchen top or steel which is then clamped on top but exposing the length to be shaped over the lower kitchen top.

The brass must be very securely fixed so that it cannot slip.

The exposed brass is then slowly beaten to shape.

This is the set up I have used which is rather Heath Robinson-ish. I ought to have added something better to secure the brass as it did slip. However this really is my kitchen work top and drilling it was out of the question!

I have used the same sort of set up for GWR tender bodies and bunkers and pannier tanks. There is something to be said for having material greater than the height of the tender sides as the bend is more easily formed. Then trim back to the required height.

I presume you know there are 2 types of tender drawing for PoW ? Do you have copies of ME for 1971?

When you get to the valve gear it can be significantly improved by increasing the suspension offset on the expansion links.

Cheers,

Julian
30 August 2017 at 13:23 #314543
Phil H1
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@philh196021
Julian,

Is the bend visibly uniform at both ends? I can imagine a nice uniform radius all the way along the bend but maybe a slight distortion (maybe a slight upturning) at both ends i.e., is extra attention required at the ends or do you trim the sheet to length after the bending operation to clean the ends up?

PS: I hope you did that when everybody else was out of the house.

Phil H
30 August 2017 at 22:04 #314633
julian atkins
Participant
@julianatkins58923
Hi Phil,

I know exactly what you mean.

Just a bit of extra dressing required with my Thor hammer using the copper face on the ends.

Cheers,

Julian
30 August 2017 at 22:08 #314634
Clive Brown 1
Participant
@clivebrown1
Thanks for your responses. Some tips and encouragement there, I'm now inclined to try Julian's method. I was shying away from too much experimentation on expensive pieces of brass!

Should have said, I'm building the 6 wheel tender, I like the look of it better than the 8 wheel monster and I did think ithat there was less work in it. However Martin Evans only drew frames, wheels, axles and a side elevation so there's quite a bit of puzzling out to do. I've taken some photos of the example in York, so that's some help.

I'm working from the Evans "words and music", 1971 onwards. Unfortunately, he seems to have had a tendency for mostly describing the easy bits, leaving the harder parts to the reader

Question re valve gear:- I've made all the bits but later heard that it could be improved without knowing any details. I take it that the offset refered to is the 3/64" dimension shown on the expansion link drawing. What figure should that be increased to?

Clive B.
31 August 2017 at 10:24 #314672
David Taylor
Participant
@davidtaylor63402
When I made my 6 wheel tender with flared top I used a steel bar with the desired radius welded to a flat plate of steel as the former. To do this you'd sit the bar and the plate on a flat surface and weld them such that the plate was sort of tangential to the bar.

The brass was sat upon this, situated so the start of the bend was where the bar joined the plate.

Another flat sheet laid on top of the brass, and everything clamp together. A bit like Julian's solution.

I did anneal the brass. I think I did that when it was already clamped between the two sheets of steel.

Then just tap the brass over the former. Luckily it worked well – I would have been upset after drilling all the rivet holes if I messed up!

The join at the rear corners was tricky, I just kept filing until I had a reasonable fit. I did mess up the rear plate of the tender and had to make another.

Sorry I don't have a photo of it, I borrowed the steel bits off a club member.
31 August 2017 at 11:22 #314677
julian atkins
Participant
@julianatkins58923
Hi Clive,

Yes, the offset is the 3/64" you refer to. It was a guess by Martin Evans. He never understood the niceties of Stephensons valve gear. The correct figure for the suspension offset is 0.223".

This much larger amount is due to using launch type expansion links with direct drive and outside admission.

Don't follow Martin Evans' description of how to set the valve gear. You will need negative lead in full gear so that the lead is not excessive when the gear is notched up.

Cheers,

Julian
31 August 2017 at 22:52 #314769
Clive Brown 1
Participant
@clivebrown1
Thanks for further info. Comments on valve gear duly noted. Fortunately, the changes don't seem to need too much re-working, so the job will be put on the to-do list.

Clive B.
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