Draughting Pens

That will be the gold end!

In the  Isograph range the main body was grey rather than maroon and I think the earlier Variant had a grey end to the cap on the film version

Edited By JasonB on 21/05/2016 13:16:29

We get these pens and heads fairly often in engineers cabinets or tool lots, also some by UNO along with various stencil sets etc

Usually filthy dirty and mistreated but if we find a good set or some nice single ones we put them in our small ultrasonic cleaner with warm water and a drop of Fairy for about an hour and when rinsed off and carefully dried they are perfect.

When we have a few we put them on EBay and are often amazed bty the prices achieved. We do however make a big point of the fact that they are cleaned.

Regards,

Martin

I still have a full set of Rotring hand drawing pens and the new ink. Plus I have a good collection of Staedlter Sprint plotter pens which I use for the Roland A3 plotter when I want a draft plot when designing pcb laypouts. The plotter pens have a very hard tip so they don't get abraded away. The ink is a plastic (PVA?) solution which is waterproof and sets very quickly so it doesn't smear.

At the saltmine back in the days we had a whole collection of HP plotters from A4 up to A0 for the largest CAD drawings.

Nowadays the pcb file gets sent to the manufacturer by email and they make a Gerber plot straight off the data file. How times have changed with modern inventions! 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.

Unfortunately Rotring no longer make the 'gold' series for film- which from memory have a carbide tip for wear resistance rather than the conventional steel. I still have 2 gold pens, but the rest are conventional.

I am 30, work as an architect, and probably do 15% of my work by pencil & pen. There's a time and a place for everything (most things..?) and a romantic quality can be instilled in CAD work just as well as in a pen drawing- but it's quicker and easier by hand... Sketch and scribble for a first draft, work up detail in CAD, then final iteration for presentation with hand detail for the visual impact.

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.

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....

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

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

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.

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 *

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.

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

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

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!

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.

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

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.

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.

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)

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!