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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: 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.


Thread: What sort of light source to use a strobe disc?
24/09/2020 18:54:37

LEDs will work, depending on how bright or how large an area needs illuminating. But I've use printed strobe disks to check the speed of my mill against multiples of the 50Hz mains.


Thread: Steel stock for newbie ???
10/09/2020 21:48:44

Strictly, Ian, the EN series is obsolete (introduced during WW2), but EN1A is the weakest of the mild steels. It is offered with and without lead, and the leaded version must not be welded or brazed, as it formed a weak joint. Both machine well, especially the leaded variety.


Thread: Surface gauge reconditioning
11/08/2020 09:19:48

Or even a bit of firm polishing with green 'scotchbrite' scouring pads. If case hardened, the case may not be very thick.

Thread: Arduino low power alternatives
06/08/2020 20:02:48

Unless things have changed, you would need to burn a bootloader onto blank atmega328 chips and the like. I've used a few with very few external components (crystal, ...) on veroboard, but not recently.

Thread: Basic Electrics
13/07/2020 16:02:17

Alan's comment reminds me of the 'gut-buster' power drills used where I worked for drilling holes by hand on top of 20 ton castings. Big motor, a pipe handle sticking out on each side, usually a two-man job. I can't recall what make they were, but I imagine there was a genuine risk of rotating the operator !


Thread: Myford chuck not gripping
10/07/2020 19:33:44

Perhaps the scroll needs some lubrication.

Thread: Gear software
19/06/2020 14:10:53

To show it's not too tedious to draw the curve, here's part of a scan of an A3 drawing I made a few weeks ago to give me some idea of the error between a circular arc and an involute, so I haven't actually drawn the involute, just tested various radii to detemine the fit. It's not very clear because the pencil drawing was quite light; I've attempted to increase the contrast. The scan is in my album.



19/06/2020 13:52:45

Perhaps cut a base circle from plywood, plus a length of string and a pencil, which would provide a suitably accurate involute for this project. Or even get the long-unused compass set and protractor out, and draw it.


Thread: Mono or Multi tube water heater
19/06/2020 13:46:59

Interesting problem, raise a body of water to temperature, and simultaneously stabilise it against heat losses. A a general rule, gas is one third the cost of electricity generated from gas, due to conversion losses.

Dave's comment is interesting,regarding solar. Assuming direct solar heating, we've all felt the heat of water from a hose pipe on a hot day. But how doable? Today, in Cardiff, it's cool and overcast, so it depends on where Fizzy is located.

What's the power of the electrical heater?

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