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Member postings for duncan webster

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

Thread: Saving the Planet or is it ?
27/09/2021 13:15:59

Anyone who manages to ignite gas coming from a water tap has connected the water to the gas. Don't believe everything you see on youtube

Thread: PM Research#1 Cylinder Can it be saved ?
26/09/2021 13:34:03

By the time you've machined a recess, fitted a plug bored out the cylinder, made and fitted a liner, you'd have made a new cylinder from a lump of iron bar. If you are making a new one make the valve chest a loose piece, then you can see what you are doing when machining the ports

Thread: Material selection or additional process
25/09/2021 23:03:09


Edited By duncan webster on 25/09/2021 23:03:48

Thread: cutting spur gears on a mill
25/09/2021 19:01:31

ANSI isn't a government organisation, and it doesn't develop standards. To quote the interweb 'The American National Standards Institute (ANSI) is a private, non-profit organization that administers and coordinates the U.S. voluntary standards and conformity assessment system'. The actual standards are written by the Standard Development Organisations, one of which is probably AGMA. Perhaps the OP would like people who don't understand gearing to write the standards, politicians say. If it was all secret the standards wouldn't be on sale.

BSI is much the same, but I believe it co-ordinates industry experts in the actual writing of standards, or it did until ISO took over. Except for safety related equipment, no-one is forced to follow these standards, but they make life a lot easier for industry (both makers and users), who can buy specify say a 100*50*10 channel to BS4-2004. The First BS was for tram rails in 1901 or thereabouts, co-ordinated by John Woolfe Barry of Tower Bridge fame

25/09/2021 14:44:37

It sounds as tho' the OP thinks the AGMA is run by shape shifting lizards intent on confusing everyone, perhaps to achieve world domination. I've managed perfectly well with DP, PCD etc in my working life, as has the rest of industry for well over 100 years, but because the OP struggles to understand he reckons it's all rubbish.

Thread: Fly cutter face angles
25/09/2021 14:37:31

You often get a better surface finish if the spindle axis is ever so slightly not square to the table, as the cutter is then clear on the second sweep. However, this then produces a very slightly concave surface if the job is of any width. You pays your money.......

Thread: cutting spur gears on a mill
24/09/2021 18:54:04
Posted by brian jones 11 on 24/09/2021 16:13:28:

I think the article by Jannick referring to Base Pitch is meant to be what we call the CP

His Base Circle is what we call the Pitch circle or defined as PCD



Not according to the interweb. The base circle is the circle from which the involute is generated, and the base pitch is the circumference of this circle divided by the number of teeth


Edited By duncan webster on 24/09/2021 19:18:25

Thread: Fly cutter face angles
24/09/2021 13:20:21

Unless I'm losing it (always possible) I think you have a normal right hand tool profile in John's setup.

Added this to my list of to-do jobs

Thread: Back to Imperial
23/09/2021 16:49:24


I remember reading an article about AutoCAD in MEW or ME where the author reported lines not joining. I wondered if he was driving AutoCAD wrong, either by not selecting the right tool, or not setting the appropriate snaps. The latter are important and not always obvious.


I think that was old versions of TurboCad, later ones have fixed this. Of course you can make anything misbehave by driving it incorrectly. Snaps are essential in my book.

Thread: Recommend a grade of steel
22/09/2021 19:28:08

Have you tried working out the stress? Can't be too difficult, pump diameter, pressure and offset in rod needed. Then you can tell what grade steel you need.

as long as you get it red hot, bending shouldn't be in issue.

Thread: cutting spur gears on a mill
22/09/2021 18:52:34

I think this shows that involute is perfectly good for clocks, in fact better fuse. After all, a fuse is a clock that goes bang at the end of its set time

Thread: Pendulum spring steel hangers
20/09/2021 00:22:02

I've got the return spring from a retractable dog lead here. It is 0.2mm thick * 8mm wide. If It's any use pm me your dirt mail address and I'll send it to you

Thread: Galvanising small items
18/09/2021 10:55:47

When I had a gate done it was so much per tonne or part thereof, so potentially expensive. Explain no paperwork or receipt and cash payment and the price suddenly became much more reasonable.

Edited By duncan webster on 18/09/2021 10:56:04

Thread: Back to Imperial
17/09/2021 18:50:56

This is going to degenerate into a stand off between die hard imperialists and rational people who can see beyond the ends of their noses

17/09/2021 13:52:48

Ridiculous, they will bring back empire day next. No wonder politicians are held in contempt

Thread: Tap Extractor
14/09/2021 23:45:05

1: find someone local with a spark eroder

2: grind it off flush and drill/tap another hole adjacent

Thread: electronic cylinder indication
14/09/2021 00:24:57

I'm wrong, the top one on the link is piezo. Max pressure oscillation frequency is more like 10hz. Railway locos were designed for ~6 revs/sec, models a bit faster.

The sensor is rated for 120C, so you don't need much heat dissipation, length of copper pipe and a cooling fin, even better stainless pipe

13/09/2021 18:30:59

Farnell have sensors for as little as £13+vat, I think they are strain gauge type and made of plastic, but should be useable with care to add heat isolation


I think the linear sensor for a 5"g loco is a bigger challenge

Thread: Saving the Planet or is it ?
13/09/2021 18:20:44

I'm not rich enough to shop in Waitrose, so it doesn't apply to me.

Thread: Multimeter recommendations
12/09/2021 17:53:46

I've bought the proper fuses for my Fluke, found them at £5 each. At least my widow will be able to sue Mr Fluke if I get blown up.

It would be interesting to get Farnell and RS comments on this thread, but I'll not hold my breath

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