LMR: The Booth 2nd Class Carriage

[What About The Bee]

In 1830, Henry Booth authored An Account of the Liverpool and Manchester Railway.  In that authoritative tome, there is a plate showing rolling stock for the LMR.

One thing must be properly understood.  Booth was an officer of the company and therefore, the portrayals are trustworthy.  Perhaps they are a bit stylized by the artist.  Perhaps just in process for the LMR at time of publication.  Perhaps already on the LMR. Yet as real as any portrayal can be.

In the top right hand corner, is the Booth 1st class Curtain Carriage, of R30090.  We have discussed that, extensively.   Top center is the Lacy and Allen 1st class carriage¹.  Top left is the Wellington Glass Carriage, also a 1st class carriage. Lower row, right, is the topic of this post.  The lower row, center, a sheep wagon and the lower row, right, is for cattle.  

There is no roof.  There are no curtains.  Indeed, there are no walls.  Just some bench seating, bent wrought iron hand rails and open backrests.  I will assert that this is a 2nd class carriage, based on the accomodations.  To the modern eye, this seems wildly unsafe, yet the 16 mph speed limit² may cause a rider to relax their grip.

We have no written account of this carriage.  Further, the illustration does not appear elsewhere.  But the illustration is in an authoritative source.  The carriage must have existed.  Therefore, I have modeled it in FreeCAD.

Shapeways states that the model can be printed for a reasonable sum.  In a previous post, I theorized that ganging a bunch of items results in less expense overall.  This has been confirmed, with a bunch submitted and in process.   3x cattle, 1x pig, 1x Ackermann 2nd no canopy and 1x Ackermann 2nd with canopy.  6 carriages/waggons are in process at Shapeways. 

Unfortunately, this means that the Booth 2nd class carriage must wait for the next round.  Who knows what will go with it?! 🤷‍♂️

Bee

¹ This will definitely be covered in a later post and is also certainly on my list of items to model.
² Measured by elapsed time.  It was expected that express trains of 1830 would take 2 hours to go from Manchester to Liverpool, or visa versa.  31 miles divided by 16 mph yields 1 hour 56 minutes.  There was a brief stop at Parkside to take on fuel and water.  Enginemen were fined for early arrival at destination, indicating excessive speed.

[What About The Bee]

Ha!

The Booth 1st Class Curtain Carriage is top left, the Wellington 1st Glass Carriage is top right.  I have it reversed above.

Futher, on the lower row, the 2nd class carriage in question is on the left, not the right.

You would think I could tell my left from right.  Doh!

A pity I cannot edit these errors, perhaps a moderator could fix that.  If one of you lads wouldn't mind?  Thanks in advance

Bee

Edited March 13 by What About The Bee
Because I cannot tell left from right, apparently.

[What About The Bee]

Once I reach a milestone in CAD, I like to study the imagery, to spot the differences between what I have designed, and what I was attempting to model.  That is, does my sketch resemble the prototype?

The Booth 1830 2nd Class Carriage is no exception.

The first thing I noticed was that the openings for passengers to step through have rounded bottoms, while I have modeled it as square apertures.  This should be relatively easy to fix.

Another is the weight of the wrought iron handrails.  They are a scale 2⅜", which is quite a heavy bar.  They should be smaller in diameter.  Yet, at a true 0.8 mm (0.031"), they will be extremely fragile in 3D print.  I wonder if I should go with copper wire?  Probably so.

And then I come to the black semicircles.  I have no idea what these might be and perhaps someone would venture a guess.

To aid in the identification, I placed the Booth 1830 2nd Class carriage next to the Stephenson 2nd carriage.  I sized the depth of the seats to be as close to identical as possible, reasoning that anatomically, a second class seat will be the same.  I then aligned the top of the seats, vertically, yellow line.  Notice that the rail aligns.  The tops of the open seats are roughly the same height as the peak of the Stephenson carriage.

Here is what I do NOT think the black semicircles are.  The floor.  The green line is the floor, extended from the Stephenson 2nd to the Booth 1830 2nd.   Anatomically, a seat is a seat, independent of carriage. The green line is quite close to the base of the aperture.  Meaning the opening isn't a trip step, the base of the opening aligns to the green line fairly well given the crude Booth sketch.  Yet, if they are the floor, they are entirely too high.  

So if they do not represent the floor of the 'compartments', what do you think the black semicircles are??

Bee

Edited March 14 by What About The Bee

[What About The Bee]

Also, my seat backs have an extra bar at the bottom.  

It should be two cross members and three uprights.  I have three cross members and three uprights.

Its the little things like this that make a model pop.

Bee

[LTSR_NSE]

42 minutes ago, What About The Bee said:

And then I come to the black semicircles.  I have no idea what these might be and perhaps someone would venture a guess.

To aid in the identification, I placed the Booth 1830 2nd Class carriage next to the Stephenson 2nd carriage.  I sized the depth of the seats to be as close to identical as possible, reasoning that anatomically, a second class seat will be the same.  I then aligned the top of the seats, vertically, yellow line.  Notice that the rail aligns.  The tops of the open seats are roughly the same height as the peak of the Stephenson carriage.

Here is what I do NOT think the black semicircles are.  The floor.  The green line is the floor, extended from the Stephenson 2nd to the Booth 1830 2nd.   Anatomically, a seat is a seat, independent of carriage. The green line is quite close to the base of the aperture.  Meaning the opening isn't a trip step, the base of the opening aligns to the green line fairly well given the crude Booth sketch.  Yet, if they are the floor, they are entirely too high.  

So if they do not represent the floor of the 'compartments', what do you think the black semicircles are??

Bee

Considering the carriage lacks doors, possibly something akin to a plinth/skirting board? (a small effort towards preventing walking sticks/umbrellas/etc. making a bid for freedom as carriage goes around curves?)
However since the benches don’t appear to have a similar edge/lip perhaps not?!

[What About The Bee]

Earlier, I asked what the black semicircles were.  I think I can answer my own question now.

Firstly, I was wrong.  The black semicircles appear to be the floor.  The floor is just drawn very poorly in Booth.

On to the model. First, I added the round bottom portals.  As expected this raised lip would create a tripping hazard.  My OO passengers could trip on this lip and do a header from a high above the rails.  

The floor surface needs to be elevated above the bottom of the round bottom portal, eliminating the trip hazard.  Booth shows full carriages sides, we cannot see the ends of the floor planks in his plate.  Therefore, I increased the thickness of the floor and set the floor planks inboard of the shell of the carriage.  This immediately presented as the black semicircles.  Unmistakable.

Version 1.0 is just for comparison to the latest version, V1.5.  

Minor points.  
1) Booth does not show individual cubby holes for each passenger under the seats, just one large volume.  My error.  The dividers were removed.  
2) The seat backs are now the proper form.  Only two cross members, not three.
3) I spent hours chasing an arithmetic error, arranging the seats and armrests to be symmetric and with uniform leg room.  It may not have been visible in production, but it was there nonetheless.  

Still to go is how to do the armrests.  I thought to print them in metal.  It was ridiculously priced.  They will be insanely fragile in plastic.  I'm still leaning towards wire, but I will need a reliable method to form them.

More to come

Bee

[LTSR_NSE]

33 minutes ago, What About The Bee said:

Still to go is how to do the armrests.  I thought to print them in metal.  It was ridiculously priced.  They will be insanely fragile in plastic.  I'm still leaning towards wire, but I will need a reliable method to form them.

More to come

Bee

Possibly you could 3D print a mo(u)ld or jig of the correct design into which you can lay/bend/solder the wire together?

Thereby allowing uniform production results!

[What About The Bee]

I decided to go with @LTSR_NSE's recommendation for the armrests. I did some thinking about using etched copper or brass.  Wire will simply look better.  So off we go.

Bending jigs are tricky.  There are many pitfalls in the design of such jigs.

First, let's take a peek at the result.  That is, what does the Booth 2nd Class Carriage look like with the new armrests?

I will be using 26 AWG wire.  This results in a scale 1.2" armrest.  You may observe how the armrest enters the base of the seat and crosses the back rest, in the detail insets of image 1.  I think this looks very nice!  Compare to the drawing in Booth, earlier in this thread.

The side panels have been let in and the seats now have rounded edges, just slightly overhanging the shell.  I tried to give an impression of intended colors, blue shell, brown seats, brown floor and black arm rests.  That is, seats cannot be painted, the paint wears too quickly.  Similarly the floor.  Yet the shell could be painted, and since this is a 2nd class carriage, blue it is.  Wrought iron, black.

So how to make the armrests?

In image 2, the neutral axis of the bends is shown in green on the left, with the wire armrest in that path on the right.  Bending always occurs at the neutral axis, material at lesser radius in compression, material at greater radius in tension.

The path around the backrest is particularly tricky, as the two bends meet at a point of tangency.  There is a terrific amount of arithmetic and geometry going on, everywhere.  Get one value wrong, and the jig will not function!

So with the path established, we can make the bend.  To bend material, we apply a force greater than yield, a function of Youngs modulus of elasticity and the cross sectional moment of inertia of the material being bent. A 3D printed jig, by itself, will simply fracture under those applied forces. 

As such, the wire is bent around commercially available brass rod.  The sizes are imperial, because I live in the US, where materials are commonly imperial.  Yet FreeCAD is metric.  So lots of translation and weird numbers.  Sorry about that.

Making the jig

In the top left, the arm rest is shown bent around the brass rods.  To hold the brass rods in place, they will be glued into a handle, purple.  I need to wrap the wire around the brass rods in a plane, perpendicular to the major axes of the brass rod.  The red anvil is added to serve as the reference plane for the wire.  The red anvil may be slid on and off the brass rods.  

On the bottom left, the wire is added.  Note the wire is anchored into the side of the red anvil, made slightly transparent to make the anchor path easier to see.

An important feature of the red anvil is the slight step, which prevents the wire from moving towards the center as it is wrapped.  You will see the step in the lower right of image 3.

But wait, there's more!

In order to insure that the wire sits flat on the red anvil, the green press can be pressed on and off.  One end is flat, but the other end of the green sliding press also has a step.  This step prevents the wire from moving away from the center.   You may just make out the step on the lower left of image 4, outside of the wire.

On the lower right of image 4, the step heights are shown.  The step height is just under the diameter of the wire, yellow circle.  When the green press is pushed towards the red anvil, the top and bottom of the wire touches them first, and is therefore firmly made planar.  The press and anvil never actually touch.  The side to side of the step walls is slightly bigger than the wire, but forces the wire to be in the rectangular channel

You may think of the rectangular channel as something which follows the bend path.  

In practice, the flat side of the green press will be used incrementally, as each bend is made.  When all bends are in place, the step side will be applied, insuring the armrest conforms to specification, in all directions, to within a few thousandths of an inch, in all directions along the path.

The red anvil and green press are then slid off of the brass rods.  A few snips and the wire armrest is set free, ready to be glued into the seat.

Whew!  But why do the armrests have this shape?

This bending jig design took an extraordinary amount of time to CAD.  During that time, I pondered, why?  Why does it have that shape?  

When putting the artful touches on the blue carriage shell, I thought to myself, that's odd.  What do the passengers hold on to as they climb up?  Where are the ubiquitous vertical bars next to the round apertures?  There are none.

My though is that the arm rest takes all these twists and turns so as to provide multiple hand grips to passengers.  The floor is ~3 feet 6 inches (1.075 meters) above the railhead.  The base of the seat is another 18 inches, or so.  This places the armrest just at or above eye height. As a passenger climbs, the horizontal parts of the armrest serve as the cross members of a ladder!  The curves can also be used as grips.  Quite convenient and clever, actually!

Finishing up

The bending jig will be more expensive than the first 3D carriage print.  But the bending jig will be robust enough for 100s of uses, amortizing my cost over multiple carriages.  It will also permit me to experiment with other 26 AWG wire materials.  I intend dead soft copper at first, but may go to steel, due to the higher tensile strength.  

Yeah, bending jigs are tricky!

Bee

Edited March 21 by What About The Bee