Draughting Pens

[DrDaveParticipant @drdave]

I've not seen hide or hair of my Rotring pens for many a year, but… some of these topics do bring long-lost memories back! As a post-grad student many years ago, one of my fellow students came in to the lab one day and asked me if I would clean a Rotring pen in acetone? Sound of air being sucked through teeth: certainly not. He then produced the mortal remains of the pen. A bit of metal with some molten plastic around it.

He was extremely bright, but lacking in nouse. I forget his name, but I used to call him "Isambard" because his practical abilities were the opposite of the great man.

[Bodger BrianParticipant @bodgerbrian]

Posted by John Fielding on 21/05/2016 15:34:45:

Does anybody remember Amberlith and Rubylith method of laying out pcb's with pad and tapes? I have a drawer full of pad and tapes which nobody uses these days.

I certainly do. Part of my first job at Alcan Labs in the late '70s was laying out artwork (at 2x full size) with tape and transfers, photographing the results on a large pedastal camera, developing the film & etching the PCB. It wasn't Amberlith or Rubylith though – the name of the tape manufacturer escapes me at the moment. Oh happy days….

[duncan webster 1Participant @duncanwebster1]

Posted by norman valentine on 21/05/2016 11:53:18:

Nobody has mentioned tracing linen. We used it in the Water Co. drawing office back in the 60's it was lovely stuff to use but almost impossible to correct errors. The offcuts of linen made wonderful wipes after you had washed the coating off it. I couldn't afford Rotring pens but a pen with a crossover point that was adjustable for line thickness, I think that they were called Graphos pens.

I've just Googled Graphos, that is the correct name but they weren't adjustable, 50 years on memory plays tricks!

Edited By norman valentine on 21/05/2016 11:55:56

Back in the early 70's I worked at Greenwood & Batley. Now and again we had to alter old linen drawings. What we did was abrade the surface with a fibreglass pen (sort of thing you use for cleaning PCBs) to remove the old information, snopake the area then draw on top with Rotring or spring bow. If it was more than a minor change it was quicker to redraw the whole thing. Modern snopake (water based) isn't a patch on the old stuff, so whether this would work now is anyone's guess

[roy entwistleParticipant @royentwistle24699]

I never used Rotring pens but I have still got a Thornton Drawing set, a couple of squares including an adjustable one and a set of French Curves that I had at Tech in the early 50's and I still have a couple of HB pencils without paint labeled Eagle Pencil Co   War Drawing

Roy

Edited By roy entwistle on 21/05/2016 22:49:48

[Richard ShoopParticipant @richardshoop13111]

This side of the pond it was Bishop Graphics for all our T & D projects (tape and donuts). Had to stay hard at it to get it to the industrial photographer before the donuts moved out of registration. Adhesive on the donuts was good for about 3 months if you were lucky. And very expensive.

[Danny M2ZParticipant @dannym2z]

Thanks people. I have decided to purchase the Rotring pens as they appear to have been cleaned before storage and the spare tips are still unused. Also have a small ultrasonic cleaner. I shall post a photo in a few days.

What also prompted this decision is that I happen to have scored a 300' long (x 30" wide) of Dupont Chronaflex Engineering Reproduction Film; UC-7 Tracing Film 0.007".

It was given to me because it had reached it's "Use-by" date of 2004. The surveyor who donated it explained that it was used for drawing topographical map masters and may have shrunk by >0.1%. That's not going to worry me too much as I use it for drawing master plans for my model aircraft.

* Danny M *

[MuzzerParticipant @muzzer]

Who was it that used to make all the self-adhesive transfers, tape, pads etc? Letraset was it? Different set of tools – scalpels, translucent (matt) film, marker pens (to fill in islands), light boxes etc. Ah, manual PCB layouts – before CAD, like Cadstar, Pads, Mentor, Altium etc.

[Roger HeadParticipant @rogerhead16992]

Posted by John Fielding on 21/05/2016 15:34:45

Does anybody remember Amberlith and Rubylith method of laying out pcb's with pad and tapes? I have a drawer full of pad and tapes which nobody uses these days.

Do I remember!!! I'm still trying to forget that. CAD layout of PCBs was the greatest thing that ever happened. I still have a roll of Rubylith in the cupboard along with with a bunch of Rotring pens, my slide rules, etc etc.

The one item that I still use from those days is a couple of the Bishop Graphics AccuScales – transparent scales on a highly stable acetate base, graduated to 0.1mm. Very useful to lay over something that you're examining under a good eye loupe.

Roger

[JasonBModerator @jasonb]

Yes Letraset for the dry transfer lettering , tone, pens etc. Also Mecanorma did similar products.

[John FieldingParticipant @johnfielding34086]

Muzzer asked:

Who was it that used to make all the self-adhesive transfers, tape, pads etc? Letraset was it? Different set of tools – scalpels, translucent (matt) film, marker pens (to fill in islands), light boxes etc. Ah, manual PCB layouts – before CAD, like Cadstar, Pads, Mentor, Altium etc.

The pad and tapes I have in my bottom drawer are made by Bishop Graphics Inc, Westlake Village, CA. But there were many manufacturers, 3M seems to come to mind. Showed them to the electronic engineering students at the uni and they had never heard of such a thing!

Amberlith and Rubylith we used for double sided boards where a solid copper ground plane was required. Circular holes were cut with a pair of compasses with a carbide tip to cut through the top coloured film and then a scalpel blade was used to lift the doughnut leaving the clear mylar film underneath. A nasty part of Amberlith and Rubylith was it was very flammable. The off-cuts were normally tossed into the waste basket under the bench. One day a draftsman dropped his fag end into the basket and it burst into flames, filling the drawing office with acrid smoke and requiring an extinguisher to put it out!

The company had a LittleJohn plate camera which took up to an A0 drawing film for reduction to final size. Most pcb artworks were done at 2:1 or 4:1 and then photographed down to 1:1. For thick film hybrid circuits we worked at 10:1 of the final size. Layouts were done on a light-box with a transparent grid sheet to get the correct pin spacing. As most standard components used a 0.1" spacing these grids were made in house to suit the original layout ratio, 0.2" spacing for 2:1 and 0.4" for 4:1. Some silly bugger decided to use a metric grid of 2.5mm and then wondered why his pad holes ran out on a long IC!

The layout of a complex board could take several days and most of the time was working out how to orientate the devices to get the easiest tracking. For double sided boards rf boards, which was most of our work, two sheets of tracing paper were used and a red and blue wax pencil to draw the tracks roughly as to how they would run. On top of these another sheet of tracing paper had the components drawn in pencil, this was known as the "Puppet Sheet" and the outlines of the components was drawn using a stencil. The sheets were all punched and registered so you could move a sheet from top to bottom as work proceeded.

Once that was sorted then the pad sheet was placed on top and the pads stuck down using the grid lines to get the correct spacing. Then another sheet of clear mylar was added and the bottom tracks where routed using different width tapes. Finally the top sheet had the top tracks or Amberlith was used. The three sheets of mylar film were registered with a 3M Pin-Bar to keep the sheets correctly lined up. For the bottom copper the bottom tracks and pads sheet were then photographed to form a negative. Then the pads and top tracks were photographed to form the top negative. Targets were added to each sheet so the registration was always maintained when the copper clad board was screened and etched.

The good thing about manual tape and pads layout is it taught you to think ahead and to get the layout correct first time. If you "painted yourself into a corner" you had to start again. With CAD you can pick up and move a whole section and move it around to gain some space. The best pcb layout draftsmen were the older school who had used pad and tape, as they rarely got into trouble when converting to CAD based layout systems!

The various track layers and pads were always viewed as if you were looking from the top or component side of the board. So the bottom copper sheet had the writing reversed when looking through the stack of mylar sheets from the top. This was to ensure the board manufacturer got the film negatives the right way up.

On 4-layer and higher boards it could be a real nightmare and most draftsmen preferred to be locked in a room with no distractions and no telephones!

[norman valentineParticipant @normanvalentine78682]

Duncan, Snopake is opaque so how did you make prints from the drawings on linen? We used to use a sharp blade to remove the errors, the ink did not soak right through the coating. You had to be very careful if you were going to draw over the erased area because if you took too much of the coating off and exposed the linen the ink would soak in and create a blob.

[Anonymous]

Hooray for computer aided PCB layout. It's way better than faffing around with tape. Computers also make it easy to generate all the ancillary layers such as silkscreen, assembly, resist and paste masks.

Traditionally PCB draughtsmen came up through the drawing office. Unfortunately they sometimes didn't have any electronics knowledge, so you ended up with components all in neat rows. Which looks good, but may be a disaster from the electronics point of view.

Professionally I now do all my own PCB layout, in close contact with our assembly house. That way I can control both the electrical aspects of the design and make life easier (and cheaper) for the assemblers. With switched mode PSUs, RF and precision analogue on the same PCB I find it easier to do the layout myself. I'm going to get the blame if there's a problem. So I might as well have everything under my control.

Andrew

[Gordon WParticipant @gordonw]

Corrections on linen- scrape with old razor blade, then apply a sealer over the scraping. We made our own "sealer", Some sort of wax in a solvent. Remember it as candle wax in meths, but a long time ago. When things got a bit more modern and only tracers used linen stopped making our own, what a good excuse to visit the tracers.

[John FieldingParticipant @johnfielding34086]

Andrew you are 100% correct!

In the early days a prototype schematic was given to a draftsman and when it was done it often was a disaster, for all the reasons you have given. After a few failed attempts the RF engineers, like myself, did the layouts and the chief draftsman checked for compliance of track width, spacing etc before the job was signed off for manufacture. Over time the engineers did all the work themselves as they learnt the drawing standards.

Today with CAD schematics things tended to go backwards. Look you can do a very good schematic, which the engineer checks and corrects, then the PCB layout program loads all the components from the library and rats-nests the connections. But the placement of certain items is critical, so the engineer has to sit with the draftsman to get the layout the way it needs to be. This is unproductive as whilst I am spending many hours telling the layout chap where to move components I am not doing my real job. So an engineer has to learn to do both tasks and it is quicker and less liable to have cock-ups!

Often when designing a board layout you need to leap over an adjacent track with a zero ohm resistor, this doesn't appear on the original schematic so the cross check software throws up an error. You then have to "back annotate" the layout to the schematic to correct the error. This going backwards and forwards takes time and other errors can creep in. Today I have just a simple schematic with the vital building blocks and leave the final schematic until the layout is finalised. You might want to add extra components, like additional decoupling caps etc, as you go along. The original pad and tape method worked in a similar manner. As you put the tracks down you ran a highlighter pen through that part of the rough schematic until all the connections were completed.

At Marconi, in the early days, they had a rigid layout standard which decreed that via holes were bad news, so two had to used in case one went AWOL. If the connection from the board top to bottom used a component lead then only one via was mandatory, but with improved etching and plating methods this has fallen away.

Some of the published pcb layout plots I see in amateur publications make me cringe. They are obviously made by someone who has no experience in the art of laying out boards. Our chief layout draftsmen would chuck the films back at you if you made such a cock-up!

The old guy who ran the photographic department was old school, he had been a silk screen expert back in the days when domestic radios had the stations and wavelength printed on a glass sheet. Often if you took a layout down to him he would glance at it and hand it back and tell you to do it again. Slowly one learns the right and wrong way to do a good layout and with his advice I learned a lot.

Going from pad and tape layout to CAD was a transition but a better result with less effort. But you can't sit any monkey in front a computer and expect a good layout to appear! That takes years of experience.

[duncan webster 1Participant @duncanwebster1]

Posted by norman valentine on 22/05/2016 10:06:36:

Duncan, Snopake is opaque so how did you make prints from the drawings on linen? We used to use a sharp blade to remove the errors, the ink did not soak right through the coating. You had to be very careful if you were going to draw over the erased area because if you took too much of the coating off and exposed the linen the ink would soak in and create a blob.

I can't remember, after all it was 40 years ago and we just used to hand them in at the print room, so it was someone else's problem (always the best kind)

[ANDY CAWLEYParticipant @andycawley24921]

60odd years ago when I was a small boy my dad was the deputy borough surveyor and was involved in clearing out an old drawing office. He brought home a load of old linen plans that my mum cut up and boiled starch ( that's my small boy's memory) out of it and made beautiful linen hankies.

I don't know what that has to do with the op but mention of linen drawings brought the memory back!

[Bill PudneyParticipant @billpudney37759]

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

[GeorgineerParticipant @georgineer]

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

[BazyleParticipant @bazyle]

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.

[Neil WyattModerator @neilwyatt]

Posted by Georgineer on 23/05/2016 14:49:34:

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.

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

[Anonymous]

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

[JasonBModerator @jasonb]

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

[norman valentineParticipant @normanvalentine78682]

Georgineer, that is a work of Art!

[Neil WyattModerator @neilwyatt]

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

[norman valentineParticipant @normanvalentine78682]

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.

[Author]

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