Member postings for Bill Davies 2

And to add to the concerns about lead pipes, a government research paper (1997) estimated that 34% of houses still received water through lead pipes. I wonder how many of our houses still have lead pipes (mine does). We don't demolish many and we build a relatively small number each year.

Research Paper

But don't be too concerned, the water companies are required to ensure the water is never acidic:

pH of tap water

Makes me wonder what that 1mm of exposed tin-lead alloy in a soldered pipe connection might do to me? So why do we have to use unleaded solder in potable water supplies?

Bill

After looking at loads of mills, several years ago, I came down to the same choices. I went with the GH Universal.

Looking at current specs, the length of travel on the three axes is better on the GH than the VMC. I wanted a geared head so that I would benefit from greater torque at lower speeds. I have not had experience of variable speed drives, except for a 'minilathe.' Both have the same motor power.

One benefit of the VMC would be that the cutting tool is at a fixed height, with the work moved up on the raisable knee, so better visibilty. A second one is that you have accurate control in the Z axis as well as X and Y. The fine feed of the vertical axis on the GH is through a worm and wheel, and I would expect that the VMC would be a bit better.

I'm happy with my choice, but do think sometimes that I might have preferred the VMC. However, it was the travel of the of the slides that nailed it for me.

Bill

And in the early 'seventies I worked a circular division tester that that had little plastic units providing the basic logic functions, powered by compressed air.

How big would a CPU be if built from such logic? And syncronising the events would have lead to a slow device.

Bill

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.

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.

Bill

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.

Bill

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?

Bill

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.

Bill

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.

Bill

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

Bill

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!

Bill

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.

Bill

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.

Bill

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.

Bill

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.

Bill

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.

Bill

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

Sorry, I've gone.

Bill

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

Bill

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.

Bill

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.