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Member postings for JA

Here is a list of all the postings JA has made in our forums. Click on a thread name to jump to the thread.

Thread: Smart meter
21/01/2022 16:20:20

To be realistic: In the end are you going to have the option of not having one?

The industry has obviously sold the idea to the government as a good way of controlling power useage. In the end they will get fed-up with us anti-smart meterers and make them mandatory.

JA

Thread: The future of casting kits
19/01/2022 17:53:47

I have followed this thread with interest.

In the outside world ordinary casting of metal appears to be dead. I don't think we used much at work during my last days of employment. What was used has highly specialised and outside the ordinary casters' skills.

We used a vast amount of investment casting which gives good finishes etc. However investment casting was adopted because it could produce a very large number of the same part such as turbine guide vanes. The wax patterns could be quickly and accurately produced in their hundreds by low pressure die casting. These would be assembled as a tree, coated in ceramic and the metal poured. Patterns for large cylindrical castings could be build from segments. No one understood it as a small batch casting technology.

There was excitement when 3d printing first arrived but the two technologies never married. Printing did not compete with the speed of die casting wax patterns. The use of lost wax for one off work is best left to jewellers dentists although there will always a demand from model engineers wanting one off castings.

CNC is obviously the way to go but the required investment, knowledge, machinery and time to for the coding, would be very large for our suppliers. I would suspect the number of models on offer to drop considerably and many would never be seen again.

Now to buy that big block of COLPHOS 90 for the cylinders.

JA

Edited By JA on 19/01/2022 17:56:42

Thread: 5"gauge speedy
17/01/2022 19:54:25
Posted by br on 17/01/2022 18:53:59:

Speedy . Well discussed on MECH , Currently 748 pages to wade through.

Seems to be the most discussed locomotive on there.

That is the real problem with the Speedy. It needs someone to summarise the knowledge.

JA

17/01/2022 19:50:41
Posted by Speedy Builder5 on 17/01/2022 19:25:36:

JA Why put the brakes on all 6 wheels when the driving trolley has sufficient brakes ?

I have no better reason than LBSC did so. He does discuss this in his book.

JA

17/01/2022 18:33:24

I started on a Speedy back in the autumn, well actually ordered a boiler. I do not intend to start cutting metal for at least another two months.. The trouble with the Speedy is that there is just too much information on modifications published and on the internet. From what I have seen the useful information in most blogs is submerged by congratualatory junk. One useful guide stops half way, last updated ten years ago (from memory). I have yet to have a good look at the MECH forum because of the time required.

In order to understand the locomotive I am buiding a solid model which has proved very useful. My understanding that moving the front of the frame forward by about 1/4" would be benifial giving more room for the front brake hangers and Don Ashton's valve gear.

I do not intend to post a blog on this forum but I would like to communicate with anyone interested or can give good advice.

JA

Thread: Engineering as Art
14/01/2022 09:36:51

I used a slide rule until the early 1980's. The company I worked for was too tight for everyone to have the pocket calculators. They were for bosses who occasional lent them to ordinary engineers.

I have recently dug out my slide rule and now use it since it is very fast. Its case also props up my computer keyboard.

JA

Edited By JA on 14/01/2022 09:37:55

Thread: Royal Fail
12/01/2022 14:58:15

I think these postings are a year old.

JA

Thread: Engineering as Art
11/01/2022 17:46:04

I think true vellum is still being made and is used to record acts of Parliment.

I just remember linen. It was treated as a curiosity in the drawing training office. We were told the best thing to do with it was to wash it in hot water to get rid of the starch and then use it as a handkerchief. You can't do that with polyester film. I doubt if you can even get polyester film now.

JA

Thread: Packing
11/01/2022 11:43:07

It may be expensive but I have used aluminium plate in such cases for smaller items. It is clean and after such use is re-useable for smaller fixtures etc. It also allows for other methods of holding the job to the milling table.

JA

Thread: Running 'nukes' in the red
11/01/2022 11:31:50

England, Scotland and Wales have always lived behind the curve with poor infrastructure and disinterested investors. It amazes me that we remained nations let alone gave birth to the Enlightenment and the Industrial Revolution.

The French always seemed to do it better, good roads, bigger canals, advanced industry in the 1700s, early maunfacture of cars and aeroplanes and so on. They get so far and then just lose interest (or become interested in politics).

JA

Thread: Engineering as Art
10/01/2022 17:55:32

Paul Parton's article was to sell the 47xx project which I admire and may have given money to. The second sketch shows five parts three of which are complicated. I have little idea what the driving side cover looks like. There is just too much information crammed into a small space. As for the stay for the piston, I just don't understand. There are 4 off without stud holes and 2 off with stud holes. The piston is shown with what could be 4 stud holes. I would expect to see the drawing of one of the covers on at least two sheets of A0 "paper".

I did O Level geometric drawing at school and went through the drawing training office during my apprenticeship. Fortunately a spell of three months in design told me I was not a designer. For most of my working life I have used detail drawings of very complex parts. The curse of my life was one part, about 250mm in diameter, 160mm long and weight about 8kg. This was described, including tolerances and manufacturing specs., by a detail drawing on sixteen sheets of A0 polyester film. One never saw the original but worked from A3 prints. It took over a month to understand the drawing (we never unstood the actual part).

I agree with Jason that one cannot expect most to produce good drawings. However someone producing and publishing designs should at least make an effort. I have been looking at an LBSC set of "drawings". He kept everything to a minimum and used both first and third angle projection on the same sheet of paper. I can only think he expected that person making the model would redraw everthing.

I don't think tolerances would be bad practice. The main problems is that most would ignore them. When I sit at my bench filing little bits of metal so they fit each other I often wonder if it would have been easier to work out the tolerances first so saving a lot of time and frustration.

JA

09/01/2022 12:02:34

I have just received issue 4681 of the ME and read the two articles on the 47xx project.

I am trying to understand the article "Engineering as Art" that has come from the above project. I am very aware that some, or a lot of, engineering drawings are artistic but the two shown are not. They are sketches, one level up from "back of the evelope". They could be used to get something made but only with a lot of conversations with manufacturing.

I am not sure whether these are being "sold to us" as engineering drawings which should clearly tell you everything about the item and be traceable (not as in tracing paper). I would expect to see, at least;

  1. A statement of the projection used
  2. A drawing number
  3. An issue number
  4. Clear, proper, dimensioning, away from the part drawn
  5. An unclutterd sheet of paper without a lot of different parts drawn on it.
  6. A standard format with an information box ideally in the bottom right corner

The above should hold true however the drawing is produced.

When I started model engineering I was amazed how bad the standard of drawing was (and generally still is). Anthony Mount's drawings are some of the best.

I may pedantic but I have had a good rant.

JA

Thread: ANTIKYTHERA MECHANISM not the first??
07/01/2022 11:17:37
Posted by Mick B1 on 07/01/2022 10:08:18:

Thanks to Diogenes for saving me the trouble of looking up those links!

When I saw the thread title,it brought to mind things I've wondered about with the Antikythera Mechanism - where are its antecedents and copies? It's like finding the remains of a Mondeo where there's no trace of anything like an Austin 7 or a Model T.

Mick, that is a very good question.

I have my doubts (expressed before). Just because a large part of the archeology community believe in it does not prevent it from being a hoax. Many want such things to fit their theories. It was once said of an academic that he would construct a whole civilisation from a chamber pot found in the Balkans.

JA

Thread: Fusion360 tutorials
05/01/2022 13:21:01

Roy

My local model engineering society held a Fusion360 course last year by Zoom which was a great success. I write this during lunch break from modeling a 5" gauge locomotive using it.

The official guide is "Autodesk Fusion 360. A Power Guide for Beginners and Intermediate Users (4th Edition)" It is dated 2020. There may be 5th edition now but the 4th covers everything I want to do. The book is published by the developer and is not cheap. I think it is sold through Amazon. There are essentially two indexes which can be a bit confusing. There is a companion website, www.cadartifex.com, which I have not looked at (I prefer to use a book).

I wish you all success at using Fusion 360.

JA

Thread: Running 'nukes' in the red
01/01/2022 17:33:28

I don't like Mr Putin but he does get an unfair press as far as gas supply to the West. There are two "markets" for gas. One is long term fix contract and Russia has thatwith the West. They have maintained the supply to the contracts. The other is the spot market which a free for all. The supply is short term and neither the customer nor the supplier needs to enter the market. Russia is quite within its rights to say no to the spot market. What happens between Russia and the neighbouring countries that it wants to influence is something else.

Little rant over.

JA

Edited By JA on 01/01/2022 17:35:13

Thread: Tolerance
01/01/2022 17:21:08

Most are happy with the terms press fit, force fit etc and Loctite.

However fits and tolerances are clearly defined and charted:fits and limits.jpg

tolerances.jpgmachining processes.jpg

The above takes quite some working out but should be useful once it is understood.

Try to make the hole first. The reamer, if not home made should have the size marked on it. Just as important is the limit and fit, usually H7.

An example: You want a bush with a sliding fit on a 25,00mm shaft. You ream the bore using an H7 reamer. This should give you a bore between 25,00mm and 25,02mm. The required limit and fit on the shaft would be g6. This gives a shaft diameter between 24,98mm and 24,99mm. The number 6 suggest that you should be able to achieve this by turning or grinding. You need good measuring instruments for this and experience.

Back to the Loctite!

JA

Thread: Is there too much choice?
01/01/2022 14:00:20

I stay away from comparison websites. They are all biased and want to sell you a, or their, product. For house, bike and car insurance I use a local insurance broker (remember them?). No time wasting, always a simple phone call that is answered quickly (no multiple options) and I think I get a good deal. As for gas and electricity, I don't switch. This may be stupid but being suspicious I ask myself why are you encouraged to switch. Money?

JA

Thread: Springbok completed
01/01/2022 09:40:14

Simon

Looks great, very fine. I trust it will run well and reliably.

Please excuse me asking, how long did it take you?

JA

Thread: How do you find someones 'profile'?
31/12/2021 13:07:22

Not posted

JA

Edited By JA on 31/12/2021 13:11:04

Thread: Myford Lathe Service
27/12/2021 19:49:55

Roger

Do you still have the old single phase motor? If so, you could fit it to the lathe and get used to using the machine. Inverters and infinitely variable speeds are just nice to have. After all almost no lathe had such a drive until recently and many good new lathes are sold with just a single phase motor, belts and pulleys.

JA

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