By continuing to use this site, you agree to our use of cookies. Find out more

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: Increasing Friction??
15/01/2021 18:15:36

It may be helpful to put a washer of what is known as 'red fibre' - used for fibre washers on petrol fittings and in electrical parts as an insulator - between the brass surfaces. Search hard and you might even find the same stuff but black, if you prefer.

I am guessing that the crutch is set by rotating it to what seems a good position, listening to the ratios between tick and tock, and making final adjustment again by sliding. And once set, until small brother or big dog nudges the whole thing again, it will carry on ticking and tocking steadily with both parts of the device moving in unison.

Cheers, Tim

Edited By Tim Stevens on 15/01/2021 18:16:30

Thread: What nut and bolt material?
15/01/2021 17:52:34

Tony - just don't look too closely at silver steel.

What we call things is not always clearly related to what they look like or what they do. Consider, for example, a carbon brush from an electric motor, and the points we used to adjust to set the timing. Nothing like brushes and never pointed.

Cheers, Tim

Thread: Free inserts.
12/01/2021 22:51:17

Hello Stephen

If you still have inserts spare, I could use them - thanks

Tim Stevens 5 Offas Road Knighton LD7 1ES

12/01/2021 18:27:19

A load of old cadgers, as well as codgers, aren't we?


Thread: Identifying Internal threads
12/01/2021 18:20:08

I have had success using a simple wooden toothpick. Break off the sharp end, and slide the pick around the thread while keeping it in line with the axis, using pressure from a finger (etc). This should result in a series of grooves or dirty lines (or both) along the pick, so you can measure how many fit to an inch or to 25mm. Then a moment's calculation should reveal the threads-per-inch, or the pitch in mm.

Cheers, Tim

Thread: Ford Quadricycle Engine
12/01/2021 18:01:41

Another way to have adjustable timing would be to make the bore of the tapered thread fitting eccentric, so the lever could be moved up and down a bit in relation to the piston - but that would only work with a better fixing than a tapered thread.


12/01/2021 17:58:01

Ignore this if you are already up to speed on the Ford drawing:

This shows a very primitive (early) version of the final option I suggested it might be. The circle top left is the view down the bore if you take the head off. Top right of this is the insulated 'plug' which produces the spark. It is not clear how this is fixed in the bore, but it needs to be insulated against lots of volts, heatproof against petrol flames, and not able to be blown out by the repeated explosions.

The screwed fitting at the right - fitted through the bore with a tapered thread (a tradition which was later used for sparking plugs and lasted to the end of the model T in about 1928) - carries a central spindle, on the inside end of which is a lever as shown to the right of the page - and the bar carried by the spindle rests against the projecting electrode of the plug. This connects the plug to earth (chassis) and completes the circuit (we'll come to that). When the piston approaches the head on the compression stroke, a peg on the piston thumps the other end of the bar, and disconnects this earthing connection, causing a spark. The lever is sprung loaded to hold it against the plug (square-head fitting, and timer spring details are shown), so as soon as the piston descends, the connection is once more connected to earth.

At the bottom of the page a sketch shows a 'distributor' but actually only some bits of it. Somewhere on the engine there is an insulated distributor post carrying a pivoted blade, which is moved to and from by a cam (eg). the end of the blade makes contact alternately with a blade on the sparking plug of each cylinder, switching on the current to that cylinder so that there is current flowing as the piston starts to rise on the compression stroke for that cylinder. When the current has stopped and the spark has jumped, the pivoted blade is flicked across to the other cylinder ready for its piston to start up the bore.

The timing of the piston opening the circuit is fixed by the geometry of the piston peg and the timer blade inside the cylinder. This is not clever, as it cannot easily be be adjusted from outside, and to start with you won't know what timing to use. Too late and you will make lots of heat but not much power; too early and you risk breaking your arm of bending engine parts if the explosion pushes the piston back down before tdc. I suggest that you think hard about some sort of adjustable plug so you can try different settings - perhaps by using an L shaped rod end and rotating it (once the engine has cooled off a bit) to meet the piston rod higher or lower as you find best. It would be better to have adjustment 'on the move' but Henry Ford was very early with this design, so this would surely have been tried on his next version.

On the other hand, timing of the switching on of the current requires easy adjustment of the 'cam actuated lever' and its related parts. Switch it on too early and you waste battery power and heat the coil too much, too late and the coil does not have time to build up a decent wallop of spark.

Along the bottom of the page is the circuit. The dry cells would have been 1.5 volt torch battery type cells, all connected in series to give 8 x 1.5 volts = 12V. The low tension coil (there is only this coil, no high tension coil at all) is a simple winding of 200 turns or so of insulated wire round a laminated steel core. As is suggested above, a suitable coil may be found inside an old fluorescent lamp fitting. As this coil is a magnet switched on and off as the engine runs, it will attract any iron or steel bits around - not a good idea. Make a special box for it so this cannot happen - but leave space around it for ventilation as it will get hot in use. For modern purposes, a small car or motorcycle 12v battery would suit well instead of man-sized torch batteries. You will need to restrict the flow of current to about 2 amps, by adding a resistance in the circuit, if the resistance of your chosen coil is rather low.

A period detail in relation to any visible wiring: In 1896, there was no stranded (flexible) wiring with insulated covering. What would have been used is likely to have been DCC - Double Cotton Covered - plain stiff copper wire, given some flexibility by winding it around a rod of say 8 or 10mm, so it would dangle and bounce around rather than breaking off straight away over the first pot-hole. A reasonable modern version would be to use a small size of pvc covered braided wire, and where it shows, use an extra amount and wind it on a bit of bar before fitting to look (vaguely) like the original. This will last much longer and short out much less than the original. The wire will only be carrying about 2 amps so the smallest vehicle-type wire will do nicely.

I hope these details will help as you get towards the magic day when your mates stand idly by and say 'Go on then, start it up ... '

Cheers, Tim

12/01/2021 12:38:26

Hi - yet again

I have a copy of the ICS reference library volume 24 - ... Ignition & Carburettors. very useful for stuff pre 1907.

It refers to a Lodge Igniter, of which the principle was 'the discharge of condensers through the sparking plug'. So far as I can find, this system is the first reference to what we now call CDI. Lodge is the same Lodge whose name was attached to sparking Plugs in the days when we made them in the UK. The text then explains how the spark is useful for 'sweeping away all obstructions, such as oil or soot, that may be in its path. It is therefore extremely useful for ignition purposes, especially for engines running on kerosene, alcohol, or other less volatile fuels.' It seems that the term Ignitor used earlier in this strand refers to the same sort of device.

My reference to a system using only a primary coil (and no condenser) is not the same as an Ignitor (Lodge or otherwise), but a more primitive device relying on breaking an inductive circuit by a contact within the cylinder of the engine. Not very clever, but used in many cars before ww1.

Hoping this helps to clarify ... And please note - we had a reference in this forum to the ICE Reference Library about a month ago, recording that the whole series of books was now available to view on line.

Regards, Tim

Thread: Nitrogen as an Energy Store ...
11/01/2021 21:36:12

I suggest that the most efficient engines use fuel that will run out, or minerals ditto, and while they remain in use they are damaging our ecosystem, might be a good reason not to shy away from alternatives which are less efficient but more sustainable.

And particularly if they are excellent for driving fridges which it happens are needed, right now, to get us through a disaster.

Cheers, Tim

Thread: Ford Quadricycle Engine
11/01/2021 21:16:34

The model T was much later, and used an alternator (yes!) mounted between the flywheel and the clutch. The trembler coils it had were fed with AC, so this has little in common with pre-1900 motors.

Please don't take my descriptions as any more than a guide to what might have been fitted, perhaps to help you interpret any pictures diagrams etc from the original period. There is also a possibility that the engine had a magneto, but a very primitive one, with one coil connected directly to a sparking plug of the switched type I described earlier. You need to remember, too, that whatever is fitted now is very likely not to be anything like the original. Early electrics were noted for short lives and failure often involved their complete destruction, sometimes involving the whole vehicle.

Unless you are sure that a trembler coil was fitted, AND you wish to replicate the buzzing or clattering noise, I'm sure a more modern coil and battery system (see John Olsen above) will take up less space than any original battery and coil. And work at least as well, and for longer.

And regarding fuel, the nearest equivalent to the motor spirit of 1900 would be 'petroleum ether, SG 0.65'. The main characteristic thought useful was that it evaporated readily.

Finally, it can help to remember that the pre1905 vehicles which trundle down to Brighton so gloriously each November are not a representative sample. They are mainly vehicles that were so bad that after the first two or three trips their (rich) owners threw them in the back of a barn, where they remained until discovery - prompted by the film Genevieve in many cases. Anything that worked well was driven, and mended, until it failed utterly, by which time there was nothing worth saving, and anyway, there was a war on.

Regards, Tim

11/01/2021 18:17:26

A trembler coil is a conventional ignition type coil - a steel core on which are wound one thicker winding (the primary), 200 turns or so, and one of much thinner wire and lots more turns (the secondary), but with an extra device. This is the addition of a steel blade at one end which is attracted by the magnetism when the primary coil is energised (connected). The blade is part of the primary circuit, and as it moves towards the core of the coil it opens a switch (just two contacts called 'points'] and the current and magnetism stop, releasing the blade. This closes the contacts again, and on and off it all goes, usually making a buzzing noise, and a high voltage (for sparks) is generated within the secondary winding. This coil needs to be connected to the sparking plug, so the fuel is ignited. There must also be another switch in the system, to set the sparking in progress at the right time (as the piston finishes the compression stroke), and to disconnect the whole thing soon after (to avoid overheating the coil, and flattening the battery). This was often a wipe contact rotating with the exhaust cam - just a brass blade and a brass section in an insulated strip. This is the contact which is set to time the engine.

But ... you might find that the car did not have such a system, but instead used an earlier version. This has a similar type of battery and coil, but with only a primary winding, and no vibrating blade. Instead, there is a contact in the cylinder worked by a different version of sparking plug, operated by a rod worked by a separate cam on the exhaust camshaft. If you need more details of this system, come back to me.

Funny things, very old cars. Sometimes they are so different that they are generally not understood, even by their owners. And sometimes, especially by their owners.

Regards, Tim

Edited By Tim Stevens on 11/01/2021 18:20:44

Edited By Tim Stevens on 11/01/2021 18:21:10

Thread: ME BEAM ENGINE - Something to Run.
10/01/2021 18:21:08

You could dig down to the nearest coal seam, and use your engine to pump out the water. If you really are looking for originality of purpose, that is.

Regards, Tim

Edited By Tim Stevens on 10/01/2021 18:21:23

Thread: Super 7 Lathe Clutch, Countershaft or Pulley Wobble
04/01/2021 15:29:55

Yes, Noel, I was understanding the term countershaft to mean the one that sits in the headstock under the output spindle. And the same applies to the clutch plate - as I now remind myself that the S7 had a cone clutch as distinct from a plate clutch, and therefore I guessed wrongly (silly me) that the S7 had a plate clutch (while the ML7 I know can have a cone). The term 'clutch plate' was used in comments by others, remember.

Just remind me, someone, what the proper term is for the shaft which is used for low ratios. It is part of a gearbox, and the normal name for a shaft which runs alongside the mainshaft and can be engaged or not is - guess what - a countershaft. Silly me, again.

Cheers, Tim

Edited By Tim Stevens on 04/01/2021 15:32:07

04/01/2021 12:25:10

The countershaft should have no effect on the lathe's working - in fact, the countershaft need not be there at all - until you engage the back-gear for low speed drive. When the countershaft is turning - whether driven by the back-gear or turned manually - the shaft and the gears on it should run true, with no wobble, no up and down, and ideally no slack end to end. Or at least, very little. A shaft which does wobble is likely to be difficult to restore to perfection, but not too complicated to make new from scratch (except that you can't do it on your lathe - you ned a friendly and competent mate with his / her own kit). If only the back gear itself wobbles, on a true-running shaft, then the gear itself is at fault - but this is not likely in my limited experience - a damaged centre might be mendable by re-bushing it.

I cannot comment on the clutch plate issues, as I am not familiar with Myford practice. But, most clutch plates have a steel disc with either holes for inserts (often cork) or a rivetted (or bonded) sheet each side of the stuff that brake linings are made of. If the corks are worn level with the steel, or the facing is very thin or oil soaked, or distorted from heat, it will be obvious, but you usually need to dismantle to get a proper look at it.

Hope this helps - Tim

Thread: Er25 collets
03/01/2021 15:25:22

It is normal for ER collets to fit a (small) range of sizes - normally they are marked eg: 12-13mm. So that size would do for a 13mm shank and a half-inch shank (=12.7mm). For 5/16" you will find 8mm to be within a couple of thousandths, and for 1/4", use 6-7mm. Theory tells us that the accuracy and grip reduces as the collet is compressed. You can get inch-sized ER 25 collets, but you may have to search (and quite likely, pay extra). When I clicked on your link, a quarter-inch version was shown below the advert, at over 60 dollars ... !

Regards, Tim

Thread: Wallis & Steevens Water Cart in 1' scale
03/01/2021 14:56:50

Sorry - twice again!


Edited By Tim Stevens on 03/01/2021 14:57:28

03/01/2021 14:56:49

The only comment I make on your lettering is this: To anyone versed in the history of lettering design, the style you have chosen does not match the date of the original. Unless of course, your water cart was made after about 1927. In typeface terms, it might be Futura, or Spartan, or one or two others - I would need to see other letters to be more certain.

I wonder if there is enough interest in this 'arcane corner' of design history (from an ME point of view) for an article about matching the letters to the job?

Regards - Tim (who once, long ago, designed typefaces for Amstrad)

Thread: Removing soft solder from brass before silver soldering
03/01/2021 14:36:20

Do be sure that the soft solder is ALL removed, if the part is to be subject to significant loads - especially alternating loads. Or anything where a failure will release eg hot steam. For that reason, I concur with the 'start again' suggestion.

Cheers, Tim

Thread: need a bullgear for myford ml4 lathe
03/01/2021 14:31:22

Andrew - you ask about companies making spares for obsolete 75 year old machines. Well, last year I was able to buy from Lea Francis Ltd a wide range of spares - engine, gearbox, half-shafts, etc - for my Lea Francis car dating from 1928. And in almost every case, the bits fitted and worked. The odd case needed oil-feed holes added, so nothing is ever perfect. But that is years longer than 75 years. Time for a retraction, perhaps?

Cheers, Tim

Thread: Gear Cutting
28/12/2020 21:06:27

Part two of my response:

Once the grooves have seen sorted, you need to round the edges of each groove. You can do this with a rounding cutter - or radius mill* - or do what I did and use a smooth file with the coupling held facing upwards. It is helpful to have a new rubber insert as a gauge for this operation. I have never seen dimensions quoted so a guess is better than nothing.

* I'm sure there is a 'proper' term for an end mill with a cut-out in each corner.

Hope this helps - Tim

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Latest Forum Posts
Support Our Partners
Eccentric July 5 2018
Eccentric Engineering
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest