Draughting Pens

When I worked at Nortons, a Tracer was employed to trace all the legacy drawings. The ones that stick in my mind were the 1/2 size general arrangements of a complete motorcycle. These were drawn in ink on linen, even showed the black and red stripes on the (silver) tank, and the tread on the tyres. They were beautiful and I would love one in a frame on the wall!!

At the Admiralty, they had just moved out of the linen period into mylar (the "uniform" had only changed from a suit, white shirt, bowler hat etc a few years before I joined). The drawings were not discreet sheets, but continuous rolls, a complete system (e.g. Salt Water) on one roll which may be 50 feet long. The major GAs were amazing, imagine the side elevation of, for instance HMS Hood at a scale of 1/4" to the foot....all in ink on linen.

cheers

Bill

Here's an exercise drawn in ink on linen by my mother as an 18 year old tracer in HMS Vernon (Portsmouth) in 1936. I still have the pen and compasses she used.

I came in on the tail end of the tracing paper era, then moved on to mylar film first with ink in Rotring pens, then with pencil - Pentel film pencils with plastic leads, N (erasable) or P (Permanent). I still have them squirreled away at the back of my desk drawer.

George

I believe old linen was much sought after for model aeroplane coverings back in the days of dope before heat shrink plastic like Solarfilm.

The old bow pens and thicker Rotrings can still have a use in lining out model locomotives. At least until someone works out how to shove a 5 in Britannia through a laser printer.

When we moved to CAD circuit layouts we were no longer allowed to identify layouts with our initials and had to de-personalise with file numbers.

What a fantastic keepsake!

Is it a trigger horn off of a sea mine?

Googled this a bit - mines used chemical triggers, so is it a torpedo fuse?

Neil

Edited By Neil Wyatt on 23/05/2016 19:15:38

I would have thought that linen was a bit heavy for model aircraft? I vaguely recall using tissue paper and cellulose dope on balsa wood model aircraft, before transitioning to heat shrink. Full size aircraft were traditionally covered in Irish linen, with madapolam, a lighter cotton fabric, used to cover plywood. Gliders, with lower wing loadings, used madapolam for unsupported areas, such as wings, as well as supported areas. It's a real faff covering aircraft with the older fabrics, and takes considerable time. However, an advantage is that you get high, entirely legally, on the dope.

This is one of three drawings I have on my walls in the hall:

It was drawn by my grandfather in March 1908, in Indian ink and watercolour wash on card. Gawd knows what you did if you made a boo-boo.

Andrew

That's an unusual engine Andrew, would be a good subject for a model

Looks like the very thick piston rod runs through a guide at the top and the collar on teh rod drives the crank but I can't see what provision there is for the sideways movement of the pin as it rotates?

J

Georgineer, that is a work of Art!

Great drawing, I bet Anthony Mount would enjoy a good look at that!

Actually it looks like a twisty.

My dad used to cover his RC models with light fabric.

I seem to recall about hearing well-washed draughting linen being used.

Neil

Edited By Neil Wyatt on 23/05/2016 21:45:16

Edited By Neil Wyatt on 23/05/2016 21:46:21

A tale from the Water Co. drawing office. A lady was employed as a tracer, she spent a week tracing a wiring diagram for a pumping station onto linen. She had made a beautiful job of it and just had to do the lettering. In those days we used Uno pens and stencils. Those of you who have used Uno pens will understand this trauma. Her Uno pen tipped over and spilled ink over her drawing. It was wonderful to see how everyone rallied round. Those who had expertise at erasing the ink went to work and the drawing was saved. It was not perfect but it served its purpose.

Those of you who use CAD do not know how easy it is these days.

I used to do the rounds of the local haberdasheries, looking for the most psychedelic nylon cloth that I could find to cover my control line combat models... It used to take longer to dope shrink the cloth than to reduce the aeroplane to "pieces of eighth" in the inevitable mid-air.

To get (almost) back on topic, my mum used to trace when she was a girl. One of the problems she recalls was sweating on hot days: any moisture on the linen & that tracing was scrap.

Neil - It is indeed the horn of a mine, though I know nothing more about it than that.

DrDave - There must be some mistake. I was given to understand that horses sweat, men perspire, and ladies glow.

George

My Mother, having brought up five of us, re-discovered her creative roots and took up Batik printing. In her case she was interested in drawing pictures of birds, animals, landscapes in Batik.

She discovered that the beautiful quality linen resulting from washing draughting cloth made a superb material to carry the wax resist, and took the dye reliably and with an excellent resolution so she could get the detail she wanted.

IIRC she washed quite a lot of this linen, having been given a roll of it by an interested neighbour who no longer had a use for it. Washing out the conditioner (gelatin?) was easy enough, but she found that the only easily available solvent for removing the wax resist after each stage of the dying procedure was petrol. Needless to say Father, who smoked heavily, was not allowed in the kitchen on those days!

I still have my Father's collection of Graphos pens, if they are of interest to anyone as historic memorabilia please PM me and we can discuss further.

Regards to all

Simon

This drawing reminded me of something I read somewhere, and the strange workings of my memory finally retrieved it this morning as being from Norman Friedman's "Naval Weapons of World War One".

It's a Hydrostatic Switch from a mine, not a horn. It's main purpose is to activate the mine after it's been laid.

This type of mine is anchored to the seabed by a kind of winch and cable arrangement that sets the operating depth. This could be as deep as 100m to catch submarines, but more usually would be just too deep to be set off by passing fishing boats. Mines do not float on the surface.

In storage the top of the switch is sealed with a soluble pad. The mine is safe until this pad has been slowly dissolved by seawater, by which time the mine layer should be well away. The outer top cap is pulled off just before the mine is dropped into the sea.

Once the pad has dissolved seawater can enter the innards of the switch to press on the diaphragm. At operating depth the piston is pushed sufficient against the spring to make an electrical connection between the two lower bolts. This brings a battery into the firing circuit and activates the mine. After that bumping a horn will set it off.

A secondary purpose of the switch is to make the mine less dangerous should it accidentally come adrift. Randomly drifting mines are dangerous to everyone. If the cable breaks the mine floats to the surface. With luck removing pressure from the piston will disconnect the battery, making the mine "safe". I say "with luck" because after several months in the water corrosion or sea-life might have jambed the mechanism.

Friedman reproduces a drawing on Page 361 of a complete British EC II mine that includes one of these devices. On the drawing it's labelled "Hyd Switch Mark III" .

The drawing in the book isn't as good as that traced by Georgineer's mum. Well done her!

Cheers

Dave

Andrew - you must have pondered the design for many hours over the years! I'm assuming that the connection between the pin and the disk on the piston rod must be either spherical or at least capable of accommodating 2 axes of rotation. Was it his own design? Do you know if it was ever built? Perhaps somebody ought to have a go at a making a detail design and then building it....

Interesting that the "plan" view is actually a sort of perspective / slightly isometric view. And the views show shadows. Somewhere between a technical drawing and a rendered view!

Murray

I think Neil may have it right when he says its a "Twisty" one, there is no sign of valve gear and the "crank" could be harlf a bevel gear with the other half driven by the shaft comming out the top of the cylinder which point to a turbine of some sort.

I don't think the plan is iso or perspective but it does show draft angle on the main castings.

Indeed it would make an interesting project, maybe andrew could provide a few close ups and also share the other two engines

Thanks Dave, I assumed what must be the soluble pad was a rubber buffer.

Pleased that I figured out the basic operation though!

Neil

I'm a sucker for buying old technical books and trying to work out exactly what some of the drawings mean. Sometimes it's like doing a cryptic crossword!

I'm having a bit of fun in this thread decoding Andrew Johnston's Vertical Steam Engine. It looks as if a pin driven by the piston runs without lubrication in a circular groove: surely that would have caused trouble! It also seems that the valve gear is meant to be driven by a belt, which is peculiar too. (Not that I know anything about the subject!)

I guess the drawing is intended to give a general idea of the Engine's layout and some of the detail is missing.

Another mystery is what the designer thought the advantage of such a configuration would be? I wonder if it was ever built and what it was used for? If the brickwork is to scale it would be about 6 foot high. (The plan says it's scaled 1 1/2" to the foot but we don't know how big the paper is.)

The quality of the drawing and colouring is excellent: it must of taken a lot of practice to get that proficient. No TV or Internet back then.

Dave

I thought that the pully and belt would drive a shaft to bevel gears just above the governor as I can't see any other way it is driven

I agree on closer inspection. It's actually just shadow - but it's cast on the machinery but not the foreground which is confusing.

If you were to build it, you'd certainly need to decide if it's a reciprocating engine (my vote) or a turbine. Of course, it may have been a "naive" design that would never work. No disrespect intended but we have no idea how real it was. Hopefully Andrew knows something about it....

Ah ha! That makes sense, no problem driving a governor with a belt.

Even though I can't see any valve gear I think it reciprocates too.