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Member postings for michael potts

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

Thread: This looks an interesting small milling machine
16/02/2020 19:24:46

It is either a Westbury or a Dore Westbury.

Thread: Threaded Norman Toolpost
10/08/2019 09:55:09

Hello BW.

I have two of these toolposts. I bought one for the Myford Speed 10, and made another to for my Cowells lathe. They are very much better than the standard toolpost, and well worth having in my opinion. They are also a lot cheaper to either buy or make than QCTP s. There was a Myford sized one on ebay a few weeks ago.

The body block will be split so that it grips on the threaded upright when the bolt is tightened. I assume that the upright has a 40 tpi thread about 3/4" diameter. It appears to be a useful design variation.

Regards. Mike.

Thread: Another "what is it lathe"
23/07/2019 14:51:53

One model of the Randa lathe, also sold by Grayson seems to have an infill in the bed slot. The first photograph seems to show parallel lines along the bed which could mark the slot infill piece.

Regards. Mike Potts.

Thread: Yesterdays Car Boot Haul! Odd items
03/09/2018 09:20:20

`Hello Martin.

The Boxford item is a dial indicator as Clive says. It is for checking variations from a zero position ( In the centre of the dial ) such as centring in a lathe chuck, or on a rotary table.

Mike Potts.

Thread: Stuart D10 very early model.... nuts and bolts
09/08/2018 16:12:03

Hello John.

Stuart Turner used a 3/16" X 36 TPI thread, usually for small pipe connections pre WW 2. They had a number of standard threads of various sizes, and sold the taps and dies for these threads. They were in their catalogues. My son has these catalogues at the moment, but when he comes in I will get one and put the list in a post.

Tracy Tools stock these taps and dies, Whitworth form.

Regards. Mike Potts.

Thread: Todays Mystery Object?
19/07/2018 10:42:58

The equation E = mc^2 is the first term in an infinite series giving the energy of an object. The second term is

1/2 mv^2 which is the kinetic energy of the object. The other terms are miniscule as all are divided by c^2 and higher powers of c^2. The series derives from the calculation of the kinetic energy of an object. The mass of the object changes as it moves and is calculated by the equation M = M0 / ( 1 - v^2/c^2 )^0.5. M0 is the rest mass of the object, M is the mass of the object moving at a velocity of v, so if the object is moving, its' mass is M0 divided by something that is less than 1 making it more massive, and the moving mass gets larger as the velocity increases. If the velocity of the object reaches the speed of light then the mass is then infinite. In practice if the velocity of the object is less than 10% of the speed of light then normal Newtonian mechanics can be applied with little error.

The mathematics of relativity become very complex very quickly, making an already difficult subject even more impenetrable. Infinite series of terms do not help either.

Radioactive fusion or fission is another issue. Both processes work because the mass of the resultant particle is less than the mass of the starting particle (s). This loss of mass appears as energy, heat,light or kinetic energy of the particles. The amount of energy can be calculated knowing the loss of mass. All the work of measuring the mass of atomic nuclei was carried out after work began to develop atomic weapons during WW 2.

Mike Potts.

Thread: Change Wheels for Myford ML10
27/04/2018 17:29:58


Start with the gears for fine feed. You will need 65, 70, 75, 20 and 20 tooth gears for this.With these you will be able to traverse the saddle slowly under power. That suffices for me most of the time. If you need to screwcut then buy as needed. As Mike Poole said, you may find a set on ebay. What ever you buy, the next one that you need will not be in your collection - its called Sods Law.

Regards. Mike Potts.

Thread: JWST: Hubble successor faces new delay
31/03/2018 16:17:31

Every time a new type of telescope or detector comes into use we learn something more about one aspect or another of the universe. These instruments are a far cry from optical telescopes. When the gravitational wave detecting instruments were first got going, they found something within a day, and have since seen another type of event that would appear to explain how the heavy elements were formed in nature. Before this observation the physics did not really work, but the idea was published in 1957 in a paper that described how all the chemical elements had been made in various places and times. The neutrino detectors around the world have seen one event, the 1987a supernova, when around forty neutrinos were detected. One instrument saw a group about five hours before the other instruments saw another burst. That was over thirty years ago, and I am not sure that anyone has ever worked out what happened.

Last week a paper described a type of galaxy known as an ultra diffuse galaxy. A number are known, but how they formed and evolved has got a lot of head scratching going on. I first saw this on Phlil Plait's blog, Bad Astronomy, the next day it had reached the Outside Source on the BBC news channel where an astrophysicist was trying to explain it . That blog is worth reading if you are interested in astronomy, cloud formations or anything else in the sky.

Mike Potts.

Thread: Unidentified Rule
25/02/2018 21:06:51

Hello James.

There are currently seven sector rules on ebay at a variety of prices, all fairly high, all similar to yours.

Wikipedia has a long explanation detailing the various scales on the rule. Further editing seems to be needed on most of the scales. The origin of the rule appears to have been Italy in the early seventeenth century. It allowed the user to perform a number of calculations, some stated, and others described as 'complex'.

Put 'sector scale' into google or whatever, and be prepared spend some time looking at the various items that come up, because it does not take long to become complicated and complex.

Regards. Mike.

Thread: Malware bytes anti virus
29/01/2018 10:36:17

I have the free Malwarebytes on both of our computers. From somewhere Immunet installed itself on one computer and some other anti virus program on the other. That started doing all sorts of unpredictable things, and the other computer started to run slowly. I asked our daughter to uninstall both programs, Hey Presto. Everything started to run correctly and quite a bit faster. Malwarebytes had an upgrade and it became a lot easier and quicker to use. Now it tells you when there is an update, and runs a scan very quickly.


Thread: Unknown Engine
25/12/2017 20:01:21

Hello Sam. The following has been written by my son, Edward, who recognised this engine inside a few seconds.

"You have the engine unit from a German toy steam engine, made between the late twenties and late thirties by Doll. Originally it would have sat on a tin base with a horizontal boiler. The reference number underneath is correct: model 365, size 1. They ranged from size 1 to size 4, which had a 6" flywheel and sat on a base 23" by 18".

There were two versions of the engine, one had a single piston valve and both cranks going round together like a Triumph parallel twin; the other (like yours) has two piston valves and quartered cranks. The Walschaerts valve gear isn't original, its unusually complicated for a modification to a toy."

Mike Potts.

Thread: Why Column gear shift
28/11/2017 09:34:41

Or ! Once on my Austin Metropolitan I managed to select two gears at once. Luckily I noticed and managed to deselect the original gear and start again.

Mike Potts

Thread: Unusal Stuart Turner No. ? engine
27/11/2017 16:25:52

The # 5 engine did not exist in 1961. By then the # 5a was supplied as it had been for over 35 years.

How are you intending to restore it, because Stuart standards changed a lot after WW2, notably in pipe thread standards. Before they had a list of thread standards, 13 in all, in the catalogues. Six were brass gas sizes, three were iron pipe sizes, the smallest three sizes were standard Whitworth threads. The fourth size, designated # 3 was a real Stuart special, 3/16" X 36 TPI. It was used for small fittings, and has caused us no little trouble over the years.

Station Road Steam used to have a list of Stuart engines, but that seems to have vanished recently. It was useful, because over the years there have been a lot of different engines, many now completely forgotten. They are usually seen as auction lots, that is if the photographs are good enough to be useful.

Mike Potts.

27/11/2017 12:41:27

And, to the catalogues.

The # 5 engine was listed in our 1906 reprint, was listed in 1928, but not listed in 1930.

BA threads appeared for the first time in the 1948 catalogue.

Mike Potts.

26/11/2017 17:44:28

If everyone can wait until I get hold of my Stuart catalogues we will find out, because I have them back to the year dot. Stuarts used Whitworth threads until at least WW2, I thought that they changed to BA after 1946 because that was when they started to sell off their stocks of Whitworth studs, nuts and bolts. The catalogues may be back tomorrow evening, otherwise Tuesday morning.

Mike Potts

Thread: Murray's Hypocycloidal Engine - Antony Mount
26/11/2017 16:40:06


This engine was one of the first small rotative engines, apart from the Bell crank engine of Boulton and Watt. Even Richard Trevithick had barely started in earnest. No one knew how to guide the piston rod without bending it rather too much for its own good. The cross head had not been invented by 1802, but when it was used it swept all else away.

Matthew Murray must have designed this engine about 1800, just as the Boulton and Watt patents were lapsing. Two examples exist, one in the Thinktank museum at Millenium Point in Birmingham, the other is in America, probably in the Ford Museum. Both came from the same site in the West Midlands.

Mike Potts

Thread: Unusal Stuart Turner No. ? engine
26/11/2017 16:20:50


I do not have my early Stuart catalogues ; my son seems to have them for some reason. However what you have is probably an early No 1 engine, and by early I mean pre WW2. I seem to remember that these machines had two cast standards rather than one standard and a support column. When I lay hands on my catalogues I will have a look.

Mike Potts.

Thread: Unidentified lathe
17/10/2017 08:13:19

Not an EW lathe. Velox appears to be right with the leadscrew supported in a bearing at one end only like the Adept. For a few minutes I thought that it was a Portass round bed lathe, but that has bearings at both ends of the leadscrew.

Mike Potts.

16/10/2017 16:27:39

You are right. My mistake.

Mike Potts.

16/10/2017 14:23:52

I saw this lathe a year or so ago. It is a CAV Wade lathe.

Mike Potts

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