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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: Is Iron / Steel endlessly recyclable ?
16/07/2020 12:52:44
Posted by SillyOldDuffer on 16/07/2020 10:33:16:

Since Bessemer's time steel-making has shifted to scientific principles, with chemistry to the fore. Steel isn't normally made by melting a pile of mixed scrap in a pot and hoping for the best - it doesn't sell well because it's too unpredictable. Modern steels are made to a specification, and most of it is spot on. Huge quantities - 1869.9 million tons in 2019.


In the 1970s the price of ordinary steel scrap dropped below the cost of producing raw, blast furnace, iron. Quite a number of mini-steel works were set up world wide that used cheap scrap in an electric arc furnace. The resulting steel was rolled to produce concrete re-enforcing bar. One was next to the railway station at Sheerness on the Isle of Sheppey. I suspect it has gone long ago.


15/07/2020 17:52:40

There is scrap steel and then there is scrap steel.

Much scrap steel is rubbish, old cars and such like, and contained metals, such as copper and zinc, that are “poisons”. Then there is good scrap such as ships hulls. Then there is very good valuable steel scrap of known providence. Such scrap usually comes from within steel works or rolling mills etc.

When steel is made from blast furnace iron in a converter an awful lot of heat is produced. It is usual to stop the process half way and add scrap steel, good or rubbish, to cool everything down.

The really good scrap is kept for making high quality alloy steel in furnaces like an electric arc furnace. The higher the quality of steel, the higher quality of steel scrap required. This is known the rising scrap system.

The metal that is really desirable to recycle is copper. I believe the mining of 1950s and 60s rubbish tip for copper is seriously being considered.


Edited By JA on 15/07/2020 17:55:14

Thread: Con rods, stressman needed
14/07/2020 17:38:28

Considering railway locomotives, the connecting rods are long and thin compared with most IC engines (that is really stating the obvious). They are subjected to a number of loads, compression and tension along the rod and their own weight. At speed this weight (remember, equals mass x acceleration and acceleration increases with speed) may be very high. The rod would be a simply supported beam with a continuous load with the maximum deflection would half way along it. The deflection can be reduced by increasing its second moment of area (that is B x D^3 where D is the thickness of the rod in plane of motion and B is the thickness across the rod). Considering the mass of the rod is B x D (per unit length) thickening the rod where it is going to deflect the most has a major effect on the stiffness.

IC engine rods are rather different, because they are short, but I believe most fail in bending close to the little end.

I am sorry if the above is rambling.


Edited By JA on 14/07/2020 17:40:53

Thread: Neowise
12/07/2020 09:26:00

A comet. All we need!

Tonight is going to be fine so I will have a look. The two I have seen were interesting but not really impressive.


Thread: We need Pi
11/07/2020 12:53:01

Pi squared = 10

(Used to be used in electronics)


Thread: Amazon Prime scam?
07/07/2020 14:33:11

Many thanks for the replies.

Off to the workshop for a few hours.


07/07/2020 13:28:19

About a year ago I mistakenly opened an Amazon Prime account which I did not want or need. Amazon closed the account immediately and I was happy.

I have had two phone calls this morning supposedly from Amazon Prime saying, in a recorded voice, that they are going to take next years payment from my bank account and if I was no longer interested I should press button 1.

I have no idea whether this is serious or a scam. Amazon seems impossible to contact unless you have an account. However I have chatted to my bank and their advice is wait for a payment which it can be tracked.

I did 1471 on both calls: The first came from 04072 217909 and the second was unknown.

Has anyone else experienced this?


Thread: Centering Microscope
06/07/2020 12:27:04

The Hemingway centring microscope is a redesign of the one described in the September 1999 issue of the Model Engineer.


Thread: We need Pi
06/07/2020 12:19:29
Posted by John Haine on 06/07/2020 09:48:31:








A random number table. I jest not.


Edited By JA on 06/07/2020 12:20:25

Thread: Centering Microscope
06/07/2020 08:47:20


I made a centring microscope that followed D A G Brown and R O Stephens' design which appeared in the Model Engineer in September 1999. I made a couple of changes: Used different focal length lenses (that were available) and a prism instead of a mirror. In both cases the mirror or prism was fixed and adjustment was made by moving the graticule. The graticule carrier was laterally held in place by four grub screws.

The microscope is a useful tool but suffers from two failings: The object viewed needs to be well illuminated and one needs to be a bit of a contortionist to use it in a vertical milling machine. If I was making one now I would try to put a camera on it and view using a computer.



Thread: Coronavirus, advice from ME
04/07/2020 20:59:05


Thanks Neil.


04/07/2020 19:33:58


Using your link I opened the document which says as of 19 March COVID19 is not considered to be a high consequence infectious disease. This document was last updated on 17 June. I don’t think the government could claim COVID19 was not a high consequence infectious disease two weeks ago.. No government would have updated such a document.

I leave others to judge its providence.


04/07/2020 18:38:26
Posted by blowlamp on 04/07/2020 18:03:37:

Here's some advice from me: Read this government web page. thinking

Look at the last update date. Fake news.


Thread: ISO Container for Workshop
30/06/2020 08:15:32

The Army use, or used, containers for workshops. They may come up for sale in the military disposal market which now highly specialised.


Thread: Coronavirus, advice from ME
29/06/2020 21:33:11


Edited By JA on 29/06/2020 21:34:31

Thread: Stroboscopic effect
29/06/2020 08:21:27

What is the lowest speed that the stroboscopic effect will freeze the motion of a spinning four jaw chuck? In the UK I think it is 375 rpm but I could be wrong.

I have just run my lathe fitted with a four jaw chuck through this speed (slowly changing the speed) and did not see any stroboscopic effect, at all. This was done, first, with only the general workshop lights on (two old fashioned fluorescent tubes) and then with only the lathe light on (cheap domestic LED tube). There was a low level of day light present.


Edited By JA on 29/06/2020 08:22:58

Thread: Yipee the F1 is back on
28/06/2020 22:06:13

MotoGP for me. I don’t think Silverstone is on this year, though.


Thread: Weeds in a 'lawn'
21/06/2020 14:06:40

I am with Bill on this one.

If it is green it is grass. I like small flowers in a lawn even if they are weeds. The last you do is to put down plastic or flag stones.

I like the idea of a meadow type lawn with long wild grass and flowers but I guess it would not be maintenance free unlike my present grass. I pay someone to mow it.


Thread: Lollipop maybe?
20/06/2020 12:02:40

I bought a very nice used Mitutoyo height gauge about 10 years ago which has an attached magnifying glass. Even with good eye sight I have to use the glass.

I would bet on a magnifying glass.


Thread: Off cuts ?
16/06/2020 08:04:20

Out of curiosity: If you buy off-cuts, have you any idea of the material specification?


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