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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: Bolt or screw?
26/09/2023 18:06:01

Long ago I was taught bolts had a plain section, which importantly gave support to a hole, whereas a screw holds parts together. But with multiple anglophone countries and their definitions, anything goes.

Bill

Thread: Will this heater idea work
22/09/2023 13:00:15

If you considet the use of car batteries, calculate the tihe to run out of charge (battery amp-hours divided by current drawn). I ran down my car battery with one of those small 'fridge' coolers, which didn't have much current draw. A bit depressing when I went to retrieve my car later that evening, in the dark!

Bill

Thread: Gib Adjusters and the English Language!
21/09/2023 14:23:39

I've been in and out of mechaniscal engineering over the years, but never met a British engineer use the hard 'g' for the gib strip of a machine. Ditto the part of a crane.

Given the number of influences on the English language, there aaren't manu useful rules on pronunciation.

Bill

Thread: Stagger toothed S&F milling cutter regrind
11/08/2023 21:59:12

Oily, a slightly more subtle point should be made - the part of the wheel that's cutting should be in line (say, vertically, for most setups) with the finger. These are generally rounded, so if not aligned properly, the cutter will rotate a bit too much as the flute comes off the finger. We generally used cup wheels, where this is slightly easier to acheive, and dressed (carborundum stick) the inside of the wheel to leave a narrow edge that contacted the work.

Grinding wheels were often dressed to become quite narrow, disc wheels were dressed almost to a feather edge for grinding the cutting faces of small hobs (gear cutters). Similar to side and face, slot cutters and the like. The front face (of the flute) is ground to preserve the (rack tooth) form of the hob, any formed milling cutters (radius, angle, vee, etc) would be ground the same way.

Bill

11/08/2023 19:44:04

When I learned cutter grinding during my apprenticeship, we used Jones & Shipman and Clarkson cutter grinders.

The work is held on a tapered mandrel, and the spring-loaded 'finger' (usually made from a piece of hacksaw blade) rests against the face of the tooth being cut. In this video, the operator uses the finger against a a different tooth of matching hand.

Sharpening a side and face cutter.

This was deprecated where I worked, as there can be slight variations in the position of the flutes or gashes, especially some reamers which are deliberately milled with flutes separated by slightly different angles to minimise the risk of chatter.

Bill

Thread: 1920s lathe spindle removal
25/07/2023 10:47:26

Looks a bit like a Britannia lathe, except that the backgears at the screwcutting gear end look unusual to me. I would expect nuts at that end of the spindle, which control the tightness of the bearings, and which, if removed, may allow the spindle to come out through the front spindle, as Ady1 suggests.

Bill

Thread: House Extensions …
24/07/2023 12:58:08

Mea culpa, Michael. I thought it unlikely that you were having a super-sized extension, so assumed it was about the much needed improvements in our civil engineering industry. So apologies for hijacking your thread.

I shall take a look at changes for smaller scale building, but only for an academic interest since I had an extension completed last year. It has 100mm of insulation, but I think that this is already superceded.

Bill

23/07/2023 23:59:55

There's always more to learn, but, after the cause of ignition, the cladding was the proximate cause of the disaster by being the mechanism that the fire was spread.

The Inquiry received information that the cladding was highly flammable (Building Reseach Establishment, 'an immediate and present risk to life', 2002). Government failed to update advice to the industry. But, as Emgee implies, commercial pressure to sell the product overrode knowledge of its shortcomings. One must hope that the new regulations do not suffer from shortcuts and future desire to deregulate that seems to blight good intentions.

Bill

23/07/2023 20:45:51

Michael, very interesting.

Let's hope it avoids future tragedies. Interesting that hotels are not included, perhaps existing legislation cover such places. Part of the problem with Grenfell was that safety tests on materials were inadequate, and inappropriatematerials were used for cladding.

The 18m (approx 6 stories) falls in line with the National Fire Chiefs' Council NFCC link, presumably to do with firefighting equipment and techniques..It won't apply to too many house extensions (having just gone through the trauma of that, I wouldn't have wanted too much more bureaucracy!), but these kinds of requirements have a tendency to creep.

The presenter did upset me a bit in his intro with "a excerpt...," but I guess I have to get used to 'evolution of the language!

Bill

Thread: A trip to the scrap yard
18/07/2023 18:17:25

Thanks, Sonic, my assumption, regarding the brand of hobbing machine, but in defence the letter 'u' certainly looks likes the Cyrillic backward N, pronounced as an 'I'. Repair, recycle, reuse ! But if the scrap helps end the war, it's a benefit.

Bill

18/07/2023 15:03:28

As Pete says, hobbing machines. It's a shame, but it looks like they were left to deteriorate and pirated for parts before they were dumped. A shocking lack of oil inside the main casting - as dry as a bone. I couldn't quite read the cyrillic on the nameplate, as it is in cursive form, s-i-d-?-ya perhaps.

Bill

Thread: Safety gloves
14/07/2023 13:11:52

As a former apprentice instructor - no gloves, rings, even watches. No ties (who wears such things these days? OK, a few of you). And avoid loose shop coats or aprons, if you have bare leadscrew and feedbar.

Bill

Thread: Herringbone Gear
11/07/2023 13:39:53

Thanks, Gary. Of course, being double helical, I hadn't thought of (dis)assembly. It's impressive that small clearances can be acheived.

It's interesting what 3D printing can achieve, hopefully metal processes will come along for the amateur/hobby market at some point.

Bill

10/07/2023 17:54:58

Thank you, Michael.

These gears are an interesting, if niche, product.

Bill

10/07/2023 17:12:51

Is that 3D printed, Gary? And what's the pressure angle, it looks quite large, although it may be the effect of the helix angle, also large (45 degrees?).

Bill

10/07/2023 16:57:02

And finally, on the last page of this article, the bottom photo shows a somewhat distorted double helical cutter showing the form of the cutting edge on the gear profile.

Double helical cutter (p45)

Sykes uses the term 'herringbone' (as do others) in his patent for the machine, to indicate continuous teeth, but in the factory we referred to all such gears as double helical, perhaps because the Sykes 5E machine could be used for both single and double helical gears, as well as straight (cut) gears, up to 63 inch diameter.

Bill

10/07/2023 16:38:42

Here is a patent showing the general movement of the cutting tools, plus the shape of the cutters. Single helical cutters had the front face ground at a right angle to the helix angle. The double helical cutters were ground so that the cutting edges met in a flat plane. By the time I saw them, there was a chamfer along the face of one edge, and a curved groove along the other.

Double helical gear cutter (1923 patent)

Bill

10/07/2023 16:27:11

W E Sykes, my employer back in time (1910 - before my time... to avoid the wags), invented a machine to cut double helical gears. Previous methods required a gap as the helical gear shaper cutters couldn't meet at the same position.

As Bazyle points out, they avoid the axial load produced by meshed single helical gears. The avoidance of a central gap was said to make stronger gears. The rotation had to be such that oil, being virtually incompressible, would not be trapped in the 'vee' of the teeth.

The gears were usually used for large reduction gears, such as turbines.for electrical generation, possible ships. We made the machines, not the gears. The company had examples of a one tooth helical gear meshing with another with multiple teeth, to show the continuous contact at all positions of rotation.

Bill

Thread: Colour of Machines and Workshop Efficiency
09/07/2023 13:22:24

All the machines where I worked were green or grey, to the extent that I've never wanted green in my life subsequently. The walls were green, too."Restful" was the supposed logic in the use of green. Although, as a chind, older peoples' kitchens were always painted green or brown (or two-tone both).

Bill

Thread: DTI travel.
05/07/2023 22:17:37

Dave, you have a PM.

Bill

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