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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: 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?

Thread: Questions about lathe power feeds.
06/06/2020 16:23:56

Clive, looking at, the Ikegai A-20 (for example) has some very nice features and seemed to incorporate these quite early on, including the recirculating ball leadscrew. But then it is described as a toolroom lathe.

It almost breaks my heart to imagine what it might have cost new, and after a google-search to see the second-hand prices at the end of its life.


06/06/2020 13:23:54

The reason that the rack is used for sliding feeds is to preserve the accuracy of the leadscrew for threadcutting. Many of us are familiar with a lathe or mill's screws being locally worn. Apart from small 'amateur' lathes, even lathes produced for training or light engineering purposes had a separate feed bar usually driven from the gear train that drives the leadscrew, or a keyway cut along the leadscrew to serve the same purpose. Clive's point above about doing it right, I take it to mean using current technologies of recirculating ball leadscrews or other methods causing less wear of the leadscrew.


Thread: Soldering Iron
05/06/2020 00:46:44

Why North Americans call it 'soddering'? - possibly a French influence. Solder is souder, both soft and hard, and I think the word is used for weld as well. A quick search finds old French spelt it 'solder', but ultimately it's from Latin 'solidare,' meaning to make solid.

On the other hand, perhaps a desire to differentiate themselves from 'native' English (can of worms) or more likely, the Americans speaking the King's English and we've (meaning the Brits) moved on.


04/06/2020 01:11:07

I recognise speedy builder's problem with cold pvc leads. Antex also provide their irons with silcon leads, which remain flexible when cold, and are not damaged by accidental contact with the hot tip. Over time I have replaced my irons with these versions. The leads are also available separately. No connection, just a happy customer.


Thread: Help identifying collets
29/05/2020 23:00:59

I think they are 3C collets. The CC indicates that they were made by Crawford, and the 327 I think signifies 3C.

Crawford Collets is now part of the 600 Group, a long established group of British machine tool manufacturers.


Thread: Stabilising a Milling Machine
19/05/2020 14:05:00

Lee, I have the similar Wargo GH (geared head) Universal mill. Mine sits on a wooden stand, which in turn sits on a wheeled base I bought at the time to help me manipulate the mill around a small garage.

When I bought mine, Warco was out of bases. I was later delivered the next size up, and I wish I had your one. I have kept the wooden stand as it is a better height for me I don't like stooping.

From my experiences with the wooden stand, I don't think it's possible to destabilize 300kg of machine, even though there may be some wobble and vibration. Heavy stone structures withstand a lot, often even earthquakes. I look at buildings and marvel that they stand, yet I understand cognitively in which direction the forces are going.

If you can raise it up again, some rubber might kill the vibration, the wobble is due I think to the thickness (or otherwise) of the stand, but I don't think you need be concerned.


Thread: Unknown tool
17/05/2020 19:32:50

Or for a star wheel dresser for a surface grinder? Is the base of the block ground flat (and magnetic!)?

However, I've only ever seen surface and cylindrical grinders dressed using mounted diamonds, which I occasionally use on my 6 inch bench grinder.


Thread: Box-Shifters and Quality Assurance
12/05/2020 11:18:45

Michael's comment reminded me that the Sinclair scientific calculator was the first one I bought. Shame the trig functions were inaccurate, so it was of little use to me as a young engineer. I expect it's still lurking in a drawer somewhere, unused. I see that someone has reverse engineered it:

Sinclair Scientific

I also bought several other Sinclair projects, before I learned my lesson, including a stereo amplifier. It never worked. I was never as impressed by Sinclair as the Press seemed to be.


Thread: Show-stopper for a NewB
01/05/2020 10:34:56

Gary, does it expect G03 vs G3? The error indicates the G code in that line, although, as Nigel indicates, there may be within that line of code.


Thread: inland seagulls
30/04/2020 11:47:06

Clive, I only noticed this a few years ago, I have a video I can't can't upload. The birds wheel about silently, briefly squawking at any noisy ones joining them. I realised last year that it was flying ants that they were taking, bobbing their heads to catch them in flight. Quite a sight. But the seagulls do seem noisier this year, or perhaps the enforced quiet makes it seem so.


Thread: Did Stuarts marking blue really do that?
17/04/2020 21:03:03

Adrian, very annoying for you. Perhaps taking a small cut with the carbide insert was the problem. Inserts can lack the sharpness of HSS. Some are highly polished, I have no experience of them but some speak highly of those made for aluminium, when used on steel.

Prussian blue has been used for checking fit for a long time, and I have never found it abrasive, having used artists' oil paint before I bought the 'real thing.' So I doubt it is the cause of your problem.


Thread: Gear Cutting - Pressure angle.
15/04/2020 17:53:04

Steve, regarding the ratios 1.00 x module for addendum (in mm) and 1.25 x mod for dedendum are the correct ratios for metric gears.

The 3.142 pitch indicates it is a 1 mod gear/rack (conventional rounding: 5 and above round up, less than 5 round down). The pitch line (PCD in DP terminology) should have 1/2 the pitch in each tooth and space segment. This will determine the width of the tip of the rack. I haven't calculated the overall height to sharp corners (2.72), so you may be correct.

Hobs are not produced to a sharp angle, but obviously allow some clearance above the outside diameter of the gear.


Thread: Center drills
09/04/2020 11:08:16

I find I use a No.3 for most jobs, which matches the table provided by Thor. Looking at very large items turned on YouTube, I note that the centre sizes are quite small relative to the work. I wonder what the failure mode is.

I have never seen a centre point shear off, which is unsurprising given that centres are made from higher strength steel than the average workpiece. The ones I made as an apprentice were case hardened but I would expect commerical ones are through-hardened. Equally, it is difficult for a centre to 'tear out' of the work, although I have seen that happen, e.g., when a jam occurs.


Thread: Australian Crayfish?
08/04/2020 20:12:55

Eating yabbies brings back fond memories of staying with relatives near Moorine Rock, Western Australia, They were grown in large numbers in the 'dams' (pools) which are used for collecting water for growing wheat. But it was too expensive to send them to the 'other end' of Australia, where they commanded a high price.


Thread: New Mill
03/04/2020 11:42:18

And an earlier source than George's, indicating where it lies in a range of oils:

US Geological Survey 1909


Thread: New design of mains plug?
02/04/2020 10:57:46

And further to Michael's point, the socket 'safety' covers that people buy to protect children from accessing the sockets can defeat the included safety features. I had some that opened the live and neutral 'gates', but the plastic cover left small gaps around the socket holes that wire or other thin objects could be inserted into.


Thread: Coronavirus
01/04/2020 14:14:12

Martin, thank you and all your colleagues.

Such important work. Incredible that biology was considered so unimportant in my youth, that my generation of boys were not taught the subject. Just to be fair, the girls weren't taught physics.


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