Member postings for Bill Pudney

Thank you SOD!! You are quite right ....officious nonsense!!

cheers

Bill

As Neil and others have said "Vellum" is a trade name for what is basically high quality tracing paper. Probably, mainly used by artists rather than draftsmen these days. I would imagine that the only people who use tracing paper/vellum or mylar these days would be those who produce "original" drawings on a drawing board in pencil or ink. In this context an "original" drawing is a valuable commodity. In any worthwhile organisation original drawings are kept under the control of a person whose job it is to ensure that "originals" are kept safely and not allowed out of the control of the drawing office. Drawings produced on CAD only have an electronic "original". Control of issue status is a major, some would say the major factor, especially with electronic drawings.

The printing process described by Nicholas Farr is the "dyeline" process. It can be used for making prints on either specially treated paper which is opaque, or secondary masters which are transparent. These are the drawings which would issued to a workshop make something. Then there is the secondary master type of print. This uses a specially treated mylar sheet (trade name "Ozalid" ) which can be used to produce duplicate originals, which can then be modified and given a new drawing number and a new issue status. Secondary masters can be used to produce dyeline prints. No doubt that this Dyeline process has become something of a niche process with the advent of CAD, but at one time any drawing office would have a dyeline printing machine, sometimes two or three. Now of course it is possible to take an electronic original to your local office supplies shop and they can print it on a large format photocopier.

cheers

Bill

Edited By Bill Pudney on 11/01/2022 21:42:50

ps I cannot get rid of the stupid yellow winking emoji thing

Edited By Bill Pudney on 11/01/2022 21:43:59

Fixed the emoji by putting a space between " and )

The forum editor generates emojis from certain character sequences. Supposed to help, I think it's an officious nuisance!

Edited By SillyOldDuffer on 11/01/2022 22:11:39

"Most probably a misnomer in this context, Bill

MichaelG."

I thought it must be, I started drafting in the mid 60s and gave it up in the late 80s and my only memory of the use of Vellum was for things like the Magna Carta and Acts of Parliament. Some of my drawings were pretty good but I don't think any of them could be categorised in the Magna Carta!!

Maybe it's a proprietary name.......

cheers

Bill

When I was involved in such things, checking of a pack of drawings amounted to 30% of the estimated hours required to produce the drawings. This included all data lists, parts lists, wiring lists etc etc

cheers

Bill

p.s. "Vellum" was mentioned with some relish a few times. As a medium for producing drawings on, I used linen, tracing paper, paper and mylar (a.k.a.polyester) what is "Vellum"??

I was a draftsman for about the first half of my working life. When CAD was arriving I "moved on". I believe, as has been hinted at previously, that drawings produced by draughtsmen on a drawing board with pencil or pen have "soul". It's frequently possible to recognise who drew it without looking at any signature. It is my theory that with each introduction of new technology there has been a diminution of skill. So when drawing media changed from linen to tracing paper skill was reduced. Anyone who has had to work on linen will know what I mean!! The same applies to the introduction of mylar; the introduction of CAD etc etc

The drawings produced in the twenties by draughtsmen at Norton Motorcycles were a thing to behold!! drawn on linen, in ink, with even the tyre tread, and makers name shown they were simply beautiful!! I would love to have an original GA of a motorcycle, drawn at half size, framed on my wall....The Boss might not approve however!!

cheers

Bill

Size of the laser beam..........Some twenty years ago I had some balsa wing ribs for a model aeroplane cut, approx 70 off from 1/16" thick wood and approx 140 off from 1/32" wood per aircraft set. At the extreme leading edge there to was to be a 0.8mm diameter carbon rod, which required, naturally, a 0.4mm radius cut out for about 270 degrees.

Imagine my surprise when after a very short time a parcel arrived with two sets of ribs. My major concern was the tiny cutout at the leading edge, into which the carbon rod fitted beautifully with a very satisfying "click".

I appreciate that my task involved cutting balsa wood and not tool steel or whatever, so the power of the laser could be lower and therefore presumably the beam smaller. Hopefully it gives some idea of the versatility of the process.

cheers

Bill

A long time ago in the mid 70s I had the good fortune to have a Norton 650SS, which was a VERY fast motorcycle. I had just finished running it in from a major engine rebuild and was having a nice ride around. It was a beautiful day, little or no traffic it seemed like a good idea to ask the classic question....."Whatwillitdo mister". So on the Andover by-pass, which was still a relatively new road at that time, no traffic around so flat in third, change to fourth, well over 120mph on the chronometric speedo. All of a sudden out of nowhere appeared a white MGB GT V8, with flashing blue lights. "Oh dear, now I'm in shtuk". I had visions of my licence being ripped up and me being frogmarched into clink, as exceeding the speed limit (50mph on a non motorway) by 70mph would probably be looked on as a bit irresponsible. Anyway I pulled over and the police car pulled up behind me. The officer came up to me and we went though the usual routine....any reason, do you realise etc etc. Anyway he told me that I was doing 126mph. We then had a really good chat about motorcycles in general and Nortons in particular. He explained that he wouldn't give me a ticket I cannot remember the reason, I was too relieved, and that I should consider myself a very lucky chap. After a bit more of a chat, and a cigarette or two I went on my way suitably chastened.

cheers

Bill

ps For those about to comment that a 650SS was roadtested at 116mph in the January 17th 1968 edition of "Motor Cycle" by Fred Bloggs on the A1 dah de dah....my 650SS had high compression pistons (9.5:1 if I remember correctly) and a Dunstall racing cam

I had never considered 3D printing. So now I'm convinced that it's worthwhile in some areas. It still seems like a lot of (computer) power being used to draw pretty pictures though. That's what passes for progress I suppose.

cheers

Bill

Thanks for that JasonB, I can see the advantage that you describe. I am clearly a luddite because I still think it's a (slightly) nice to have rather than something of much value. It's probably an age thing!!

cheers

Bill

Are accurate thread profiles really required?? In my lifetime of being involved in producing and analysing professionally produced drawings, the only time that accurate thread profiles had to be drawn were at night school during my apprenticeship, and even then it wasn't about the thread profile, but the accuracy of the drawing.

Surely this is a classic case of "want" over "need"?? Convince me I'm wrong.

cheers

Bill

My Sieg C3 7" x 16" mini lathe is probably 15 years old. It has a metric leadscrew and two half nuts. The threading dial was removed in the first week or close to it. The machine has cut a lot of threads, the half nuts do require adjusting fairly often....maybe annually. Cleaning the leadscrew is a simple matter, usually done at the end of the day as part of the clean down procedure. Most of the things I make are fairly small, so the leadscrew generally only gets used for screwcutting

I believe that the new machines have a sheet metal leadscrew cover not the telescoping spring one as suggested earlier, along with the single halfnut. If the machine was mine I would get a 2 halfnut conversion kit from Arc Euro, ditch the silly shield, and set up the halfnuts carefully and remember to clean the leadscrew occasionally.

cheers

Bill

p.s. I've just had a look at the Arc Euro site and the kits are available for metric or imperial machines their part number SC3-63B-MET or IMP, for under GBP30.  Sounds like a bargain to me.

Edited By Bill Pudney on 22/12/2021 05:01:54

I'm in Australia and am still awaiting the arrival of 308.

cheers

Bill

Living in Australia the system here is based on the UK one. Although obviously adjustments have been made to suit our unusually law abiding population. Twenty five years ago I was called up and was selected for an interesting dangerous driving case. I found the whole process fascinating, and would do it again in a heartbeat if asked.

cheers

Bill

A long time ago, I had to make a test rig to demonstrate the importance of lubricating threads when tightening to a specific torque. It had to convince a very dubious Electronics Engineer,,,,,,,,,,,

cheers

Bill

In the 20s and 30s RR did a lot of basic research into many engineering issues. One that has always stayed with me was, they investigated the optimum number and size of fasteners in any joint, whether structural or fluid retention. The conclusion was that "more small fasteners is better than less big fasteners". It sort of makes sense, but it's nice to know that RR worried about these things!!

cheers

Bill

Both of these statements are intriguing, do you have any evidence for either or both??

cheers

Bill

About 15 years ago I was looking for a lathe. My first thought was "...Aha...a Myford". So I asked for a quote for a well specified, but not unreasonably so, machine from my local Myford agent. This is Australia, so in this case "local" is 2,200 km apart. They came back with in excess of AU$15,000 and a six month delivery time. This seemed somewhat excessive, so from the same shop I bought a Sieg Mini Lathe, similar but slightly smaller work envelope to a Myford, similar list of options for less than AU$1,500. Delivery Ex stock. It was in my shed within a couple of weeks.

I've made countless things on this lathe and it has performed well. Whenever it has needed new parts, they have been available at a sensible price. Of course there have been breakdowns, some my fault some genuine machine faults, but they are few and far between and always solvable.

cheers

Bill

I'll stick to my TurboCad 20. It's a bit clunky, but it's cheap, it works and does what I want it too. I don't have the time, either short term or long term, or the interest in drawing pretty pictures, to indulge myself with anything more exotic.

cheers

Bill

The concensus of the people that I used to work with, was that the accuracy achieved by a manual machine depended on the skill of the user, not so much on the machine. The accuracy achieved by an CNC machine was determined by the design of the machine, not so much on the user, or "button pusher" in the cruel parlance sometimes used by those who should know better.

Obviously as with all sweeping generalisations this is open to debate!!!!!

cheers

Bill

During my apprenticeship we had to make loft plates, typically 1/8" al.alloy, with an accurate photographic "picture" of what was required, printed on the sheet. They were usually developments of folded/pressed structural members, some were small 6" x 6", some were long and with a complex shape, the biggest I saw was about 72" x 12". The outline had lines from memory 0.006" or 0.010" wide, holes were indicated by crossed lines, with a circle appropriately sized for the drill bush destined for that hole, usually either 3/32" or 1/8" bore, with an outside diameter of something like 5/16" or 3/8". The bushes were very accurate, I think that they were sintered. The outline had to be filed to (ideally) half the line thickness, and the drill bush ideally would show half the line thickness all the way round. This is a long winded way of saying that, in my yoof I regularly achieved +/-0.003" or +/-0.005".

cheers

Bill