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Member postings for Tim Stevens

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

Thread: yet another angle plate
16/03/2022 21:59:54

I found it easy to make one - using a length of round bar (20mm dia +/-) to which I bolted a flat steel plate with a few holes. In use, the bar is held in one of the table slots, or in a V-groove support or a pair of V-blocks. The 'far' end of the plate is supported by a small screw-jack and adjusted to the required angle. This is checked using a dial gauge fixed on an arm under the milling machine head, and this check allows me to adjust the rotation and the jack height to be sure that the plate surface is parallel with one axis and the correct angle to the other axis (either way round to suit the job). A simple calculation relating distance moved horizontally with increase or decrease in height of the gauge saves a lot of faff trying to measure angles in degrees. the last part I made was a steering support for a pre-war Bentley and I was told it was 'better than the original.'

Much of my work involves one-off machining, and as a pensioner I need not look too often at the time spent, so something like this meets my needs at minimal cost. Whether it will work for you, only you can say.

Cheers, Tim

Thread: FOR THE EXPERTS !
15/03/2022 10:53:35

Hello Hopper

Yes, when they are in a straight line makes sense, in theory. But how do you tell, from the engine in front of you, when they are indeed in line? You can certainly measure the piston position, but where is the crankpin when the piston is furthest up? Or, when the most significant bits of timing (ignition or valves) are around TDC rather than BDC, is that the most relevant place to measure from?

Of course, if you knew what the factory did, easy-peasy, but when the engine was made in a factory bombed in WW2, what chance?

cheers, Tim

Edited By Tim Stevens on 15/03/2022 10:54:19

15/03/2022 10:02:36

If it did hydraulic it would be a good idea to check the lengths of the relevant head studs/bolts, and the condition of the threads in the various bits affected. And even if the relevant rod 'looks ok' check its length.

The idea of offsetting gudgeon-pins (wrist-pins) is quite common, as is the idea of offsetting the cylinder bore to the centre line of the crank. This latter is called a desaxé design, and the word has three syllables, not two.

Those of a mathematical bent might care to think how such a design affects the calculation of capacity. And how the valve timing can be set when the two dead-centres are not 180 degrees apart ...

Cheers, Tim

Thread: Dykem Layout Blue Remover
13/03/2022 16:59:32

Anyone living in, or visiting France, might find it useful to know that their burning alcohol is made from rubbish brandy, and has a much nicer smell than british Meths. It is sold at builders merchants and DIY shops in litre bottles.

Cheers, Tim

Thread: Propane torch
13/03/2022 15:04:45

The best size for mending a 22ct wedding ring is the smallest, and if you want to melt the tarmac across your drive, the biggest. obviously.

Or, more realistically, it is the flame size and intensity which counts. So, work out what you will need to do with your outfit, and get a range of sizes. Not every one in the catalogue, but three, perhaps. And when you need something especially delicate, or beefy, consider adding another.

You are also limited by the size of the adaptors, the cylinder connection, the pipework, and - yes - the temperature. On a cold day, the gas (liquid in the cylinder) evaporates more slowly, limiting the max output.

And don't knock your cylinder over - it is not clear to me how a pressure regulator will stop liquid (at the same pressure) from flame-throwing.

cheers, Tim

Thread: forward/reverse switch from a forward only switch
13/03/2022 12:22:20

Alpine Major, eh? That will be a Sunbeam Alpine with a Fordson Major engine, I guess?

Tim

Thread: Railway station toilet signs
13/03/2022 12:16:47

In case anyone thinks (as hinted above) that vulgar colonials are responsible for rude words, they need to read some Chaucer. This was written before there were colonies for colonials to come from.

I do not understand why - in an age where superstition is widely regarded as silly nonsense, (and prohibited by some religions) there is still superstition regarding words for every-day activities and the body parts involved. The result is, of course, that any child who is deprived of the opportunity to know the words is unable to explain that he (she) needs to empty bladder or bowels, and the sky falls in on the poor sod.

Cheers, Tim

Thread: Screw cutting problem
13/03/2022 12:05:53

It would help (perhaps) to check that the lead screw is turning, and that the half-nut is engaging properly. As soon as you engage the half nuts, the carriage assembly should move slowly towards the headstock. If you have set up the correct gears for the desired pitch, and they are engaged properly with each other, the only other factor is the toggle arrangement at the far left end of the headstock. This is operated by a lever (like the similar one at the other end of the headstock with brings in the back-gear for very slow speeds), This is arranged so that there is a central position which is 'neutral' - giving no drive to the leadscrew, and the two - up and down - give forwards and backwards rotation.

And - If gears are turning but no drive results, there may be a key missing in one of the gears.

Check that all these bits are working as they should, and if the leadscrew is still not rotating, come back with further details and more advice should be available.

Cheers, Tim

Thread: "Angel eye" wiring colour code
11/03/2022 16:04:02

A suggestion: It is likely that you don't have a problem, but I suggest that you check. A good way to do this is to draw a black line on a clearly visible rotating part of the mill (etc) and turn the new light on so it shines of the mark. Turn on the mill at a low-ish speed, and increase the speed gradually. Keep looking at the rotating mark to see if any strobe-effect is there. If not, well done, no problem. But if the mark does appear to become stationary, and go backwards, there is still an effect - how much will depend on what other lighting you have.

An alternative solution is to use a battery to run the angel-eyes. Just remember to charge it as needed.

Cheers, Tim

11/03/2022 15:20:46

One thing to watch -

A switching regulator gives a low voltage by chopping slices of the higher current which goes in. This 'alternating DC' will switch the LEDs on and off at the same frequency - usually too quickly for the eye to notice. But it will cause a 'strobe effect' with anything that rotates - just as the switched frames of a movie can make the wheel on the wagon go backwards or stay 'still'. Not a good idea, as it can confuse you - just as tea-time is approaching and your concentration is slipping - to thinking that a rotating part is safe to touch.

the effect can be reduced by using an inductive load or a capacitor (or even both) - or by ensuring that there is also illumination by something that does not produce this effect (such as an old fashioned filament bulb). You get the same effect with some other LED lamps, and it can cause an odd flickering on video recordings and TV signals when LED illumination is used. And it has the same effect when looking at videos of aeroplane propellors, but that is the film being switched on and off, not the lighting.

The use of two LED sources, each with its own different supply reduction, should reduce the effect as the frequencies are not going to match exactly. Use two identical systems and you might find the frequencies match too closely.

Hope this helps avoid problems - Cheers, Tim

Thread: Hammer Handle Supplier??
11/03/2022 14:42:15

There is an ironmongers in Montgomery which stocks all sorts of useful things, and will sell you a single 2BA brass washer as well as what they describe as 'loose paraffin'. So when you are next passing...

That is Montgomery UK, the ancient county town of Montgomeryshire, roughly bang in the middle of Wales. Which is the bit of England which isn't England at all and sticks out in the West towards Ireland.

Cheers, Tim

Thread: Model Engineers Handbook
11/03/2022 14:34:32

I think jubilation owes its roots to the ancient Jewish notion of a grand piss-up every 50 years (called a Jubilee). But tubilation would certainly appeal when applied to a maker of bicycles, bed-frames, Wellington bombers, and - yes indeed - steam boilers.

Cheers, Tim

Thread: Internet access alternatives
11/03/2022 14:28:55

So this is an alternative way into the Internet (which seems to rely on existing wi-fi ?) rather than an alternative to the internet per se. So my thoughts about the (alleged) American Native scheme using smoke signals wouldn't help, then.

Cheers, Tim

Thread: Is this distasteful
10/03/2022 16:03:28

It would be helpful if anyone claiming that this, or that, is illegal also includes a note saying which country he (she) is referring to, and if possible the detail of the legislation.

There are 1000 and 1 things that are illegal in one country but not in others, and lots of things that are 'known' to be illegal and turn out to be no such thing.

I have been stopped more than once by a policeman in uniform claiming that some detail of my vehicle, or my passengers headgear, for example, was illegal, when I knew that they were OK.

Cheers, Tim

Edited By Tim Stevens on 10/03/2022 16:04:18

Thread: Always confused over threads and tapping
20/02/2022 21:00:18

If the thread is to be made in cast iron or light alloy a coarse (20 tpi) thread will be stronger than M6 which is 25.4 tpi and a smaller diameter.

And if you can tell the visual difference between a bought-in component with UNC threads, and one with Whitworth, please tell me the details of your optician.

Cheers, Tim

Thread: Releasing a corroded stud (steel) passing through a casting (aluminium)
20/02/2022 20:42:14

There is a trick - if you can get the right material.

Do this work out in the garden and away from livestock etc, as there will be fumes. The trick relies on the fact that aluminium will not dissolve in oxidising acids, as the process renews the Al2O3 coating which protects the aluminium. Nitric acid is the solvent, and it eats steel, cast iron, etc. The job should be immersed in the acid (which can be watered down a bit but not too much). It may take a few hours to eat through steel, but it does work. I have used this dodge ( back in 1975) to remove the corroded-in front engine stud from a V-twin Motor Guzzi engine. All that was left of the steel at the finish was a piece about 30mm long, with a tapered point on each end, which finally fell out as it no longer fitted the hole. And the Guzzi was rebuilt, and may well still be going.

So, all you need is an old crockery dish or aluminium pan, half a litre of HNO3, and some understanding neighbours.

Cheers, Tim

Edited By Tim Stevens on 20/02/2022 20:45:51

Thread: What is this Chester Mill Model
20/02/2022 20:14:36

The bottom line of the message panel starts with 'Message Member' - just click on it - so now you know why bankers are always interested in the bottom line (!)

Cheers, Tim

Thread: Green growth on car roof rails
06/02/2022 16:26:36

Just remember the rules about using herbicides etc - use them for what they are for, and not otherwise. Something to do with not destroying the planet.

I have seen shed roofs crossed by old wireless aerials - plain uninsulated copper. The line where the drips from the aerial fell had no moss and no lichen. Just a thought.

Tim

Thread: Installing drill chuck arbor
05/02/2022 11:11:19

There is a tendency in many of us to seek out the 'Ideal Method', whatever we are doing. But the answer, in my experience, is always 'It all depends'. Not only that, what it depends on can only be decided in many cases, at a later date. In my current occupation*, rewiring old cars, how a job is done depends on whether the car is intended to be a reliable holiday transport for several years, or a twice-a-year concours entry (and if so, what the rules actually say, and how clued up is the judge), or perhaps for sale, and in that case, whether the price is going to depend on how completely original the car is (or looks, not the same thing at all) or what, exactly? As we are no good at seeing into the future, we cannot know what the test of 'ideal' is going to be.

In this case, for example - does concentricity matter more than repairability?

Philosophy is a wonderful tool, as long as you don't mind the delay in completing the job.

* did you see what I did, there?

Cheers, Tim

Thread: Altering a new backpt
01/02/2022 20:45:20

It seems sensible to do nothing until you have tried the fit several times, measuring the run-out each time. Only if the results vary significantly do you need to alter fits etc.

Cheers, Tim

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