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Member postings for Bill Davies 2

Here is a list of all the postings Bill Davies 2 has made in our forums. Click on a thread name to jump to the thread.

Thread: Shipping to the EU - beware!
06/05/2021 15:08:42

So, regarding fishing, the Norwegians choose to not give us rights to fish in their territorial waters, because we wouldn't come to an agreement with them sharing ours. Ane we are equally surprised that the French, having long enjoyed fishing in areas between us and them, and now finding themselves (or maybe some them) shut out.

I wait with interest to see what the value of fish against the cost of running gunboats against our neighbours will turn out to be.

Thread: Gear, Gauge, or Cutter ?
24/04/2021 21:03:50

Looking again, I assume the double rake that Michael refers to is the chamfer on the back of the teeth, which makes them a bit safer to handle, and limits the regrinds. The profile changes towards the back and at some point could produce an inaccurate profile on the gear produced.

There were two methods used to produce the cutter's tooth space. One was to grind each flank separately to its involute shape. The wheel and work would 'roll' to produce the involute. The second method, using a reciprocating grinding wheel formed to the appropriate form using a Diaform pantograph to dress the grinding wheel. This had the advantage of allowing 'corrections' in the form such as chamfering the gear tooth tips, or to give a well-formed fillets for maximum strength. Slight undercuts produced by 'protuberances' on the cutter tip to give undercuts for gears that would be finished by shaving. This was the case for motor vehicle transmission gears.

Too much info, I know. I find gears and their cutters things of beauty probably due to my exposure to them in my youth.

There is no date etched on the top. It might be quite old, as 14 1/2 degree pressure angles were becoming less common, if not already obsolete, in the late 60s/early 70s when I worked for the firm.

It should polish up nicely, Michael.


24/04/2021 18:14:54

I was in manufacturing and inpecting similar ones at W E Sykes, a gear cutting machine tool manufacturer, who also made gear shaper cutters, hobs, shaving tools, standard gears (for gear rolling tests; e.g. Parkson) and some gear measurement equipment. The front angle is probably 5 degrees, dish ground. If there is a second angle, it's only to reduce grinding wheel wear when re-sharpening. The clearance angle, relative to the axis, is probably 6 degrees. Note; all from memory.

The shaper cutters can take a lot of resharpening on the front face before they are beyond use.


Thread: Tea Spoons
23/03/2021 16:42:57

I've also observed that frequently using Cif (originally the pronouncable Jif) tends to create fine scratches, causing teaspoons to rapidly become tea stained again. It seems to contain a soft abrasive (chalk or crushed limestone?) as well as what seems to me to be a strong acid or alkali, from its irritating effects on my fingers. Acid, I suppose, as it claims to remove limestone. But then it can't contain a limestone abrasive, unless activated by additional water. Any chemists here?


23/03/2021 15:27:06

Like Dave W, I have some 'stainless' items that have slowly stained (the French have it right- inoxidable). Steel spoons pressed from sheet have a dark tinge, other stainless cutlery are not affected. Different grades of SS?

Also, aluminium pots that have been used for stocks/broths seem to darken. Obviously different chemistry is involved.

I shall try citric acid for removing tea stains. When I worked in a factory, not cleaning cups was a mark of honour, boiling water addressed any biological hazard. So perhaps Duncan has it right. But the female householder at my location is intolerant of this viewpoint.


Thread: A question for the Chemists ...
14/03/2021 13:36:02

As Bizibuilder's links indicates, it's sodium acetate. Perhaps Brian is remembering some long-ago 'chemical' photography, like me. Sodium thiosulphate was used as 'fixer' after developing the image, at least in black and white photographs.


Thread: Involute Gear ... Profile approximated
07/03/2021 12:49:59

Ken Walsome was my apprentice instructor, during my first year of work in 1968. He worked for several years for W E Sykes, a gear cutting machine manufacturer at Staines, Middx. He was a good instructor and made some very nice models, and a plate camera during my first year at the company. He may have worked previously at HEGTA (Hounslow Engineering Group Training Association), if anyone here is from that place and time. After his death some years ago, items he had made were sold at auction. He encouraged me to build an enlarger when he dicovered I was interested in photography.

As Andrew says, this grinding jig approximates the involute to two straight lines; it would be interesting to see how the form works on the Parkson gear rolling tester in Martin's photo, above. That brings back memories of my time in the Inspection Department at the above firm


Thread: Covid test
13/02/2021 18:41:51

My wide and I have had our jabs, yesterday (Friday) mid afternoon. We both have a slight headache today, not much, a small 'naggy' one, if that means anything to you. I also have a slight backache - but I'm prone to get those, so probably unrelated. No other issues so far. We've both been taking 200UI (50ug) of vitamin D, from March last year, 'just in case.' We don't get out in the sunlight enough, especially in recent weather!


Thread: Plans for updating the archaic forum?
10/02/2021 21:06:18

I have to agree with you, John.

Someone took the 'max seven ines of text per page' to heart. There must be money in white space.


Thread: Case hardening a part with tapped holes.
19/12/2020 22:01:24

Mike, it appears not:

Kasenit - US alternative is Cherry Red

There has been discussion here on the ME website before, such as

Making your own case hardening compound

And a UK supplier:

Knighton Tools - Beta No. 1

Is it out of beta test yet?

I haven't used any of the substitutes, I have used Kasenit long ago during my apprenticeship, and on occasions subsequently, and have a tin knocking around somewhere but who knows where?

I expect others will be able to discuss the virtues of additives to the base material charcoal, such as sugar and/or various cyanide salts, with a better understanding than I have. In earlier times, leather, horse hoof and other organic materials were used to provide carbon, nitrogen and other elements to diffuse into the material.

Clickspring on Youtube provides some interesting examples:

Clickspring - the first hardened steel

I have accidently flame carburised a pair of tongs made in a gas/air blowtorch, which when I attempted to 'tap' one of the jaws into alignment, it snapped off cleanly with the fine crystalline fracture one would recognise from a broken file. So a gas torch alone may provide enough carbon for some applications.


19/12/2020 12:15:53

As Rik says. We used fire clay to seal the cast iron pots with parts to be pack carburised. The carbon used looked like the school charcoal sticks for drawing, broken into short lengths. The parts were in the furnaces for hours, so I hope IRT appreciates that the depth of added carbon depends on the length of time it is red hot.

An alternative to pack carburising would be to use Kasenit or similar to give a thin hard surface.


Thread: Maybe a scam and a treat in these hard times
17/12/2020 14:19:02

I had two from DPD today, the URL looked bona fide, claiming two failed deliveries, and a small fee for a third one. However, I have no outstanding orders at the moment, and furthermore at least one person has been in the house for some weeks. They looked worryingly plausible.


Thread: Drawing Projections
11/12/2020 14:31:54

And further to Nigel's point about units, I haven't yet come across a trade that uses centimetres. As a school technician in recent years, I've used centimetres, but my engineering training from the late 60's informed me that SI units went in steps of 1000 (10 to the power of 3), so km, metres, mm, etc. Other units were depricated.

No doubt I will be corrected, perhaps workers in textiles use cm.


11/12/2020 14:23:45

Keith, perhaps naughty stuff went on (or came off).

Sorry, I've gone.


Thread: Anyone have any idea what these are
12/11/2020 22:41:14

Are these free-running so that they don't mark the work when they contact it?


Thread: Calibrating Micrometers
12/11/2020 22:35:32

Not far from Stuart's employment, I did an HNC unit on metrology at Brookland's College. My employer had multiple inspection departments and a temperature control standards room, which I worked in for a while.

For our purposes, it's worth remembering that the micrometer, length standards and workpieces are likely to be steel, so we can relatively ignore temperature control as all will expand or contract to the same extent. Allow a few hours to pass and ensure that you handle everything as little as possible, to avoid diferentially heating them from you hands. Use cloths as insulators.

Length standards thet leave the thimble in different positions from the zero will check for a periodic error. But I would generally say that simply checking at a known length will generally suffice for us. In the workshops I worked in, there was always a series of discs, in one inch steps, to check micrometers and calipers against. The most likely problem is a dropped measuring instrument, which brings the jaws closer together, and in identical error at all positions. Easiest solution is to buy a new instruments.

I would caution against using ball bearings, as they have a theoretical point contact, and unless using a light feel, the ratchet will tend to cause the size to read slighly under - especially smaller balls. Cylindrical shapes are similarly a potential problem, but less so due to a theortical line contact.


Thread: What are these? My first post.
11/11/2020 15:06:00

They seem too thick for templates. It's difficult to see why there would be so many, just to highlight, say, module size. If they were very well finished, I might say master gears for use on a gear rolling tester, but they don't seem to be ground finished.

Thread: Vacuum Pump Advice Please!
24/09/2020 19:37:54

Do you need a 'high' vacuum Dave. The vacuum pump I used as a school technician would remove enough air that a buzzerl was all but silent, but would be nothing like the vacuum required for making bulbs, electronic valves (tubes), sputter aluminium onto mirrors or the like. I can't recall the pressure that it went down to, but a surprising amount of air had to leak back into the bell jar when the valve to the atmosphere was opened.


Thread: Spindle Speed
24/09/2020 19:03:00

Ooops, added to the earlier thread; go up the page!

Bill, blushing.

24/09/2020 19:01:08

Found this on our website:

Strobe disks

Go down the page.


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