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Member postings for Glyn Davies

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

Thread: Does anybody know what this is ?
03/08/2019 09:45:00

A Victorian electric shock therapy machine with bits missing to make it safe?

Thread: Electric Cars
11/07/2019 17:25:07

I read that the grand master plan is to equip all houses with some kind of ground or air sourced heat pumps for heating/cooling. Then use smart meters to draw power from all the electric car batteries that will be plugged in for when the wind doesn't blow or the sun shine.

I think gas heating is banned for new build houses within the next couple of years.

11/07/2019 11:54:42

I just wondered if anybody else was mildly depressed about the prospect of having to switch to a Battery Electric Vehicle, or electric car, at some point in the not too distant future?

The energy content of petrol is about 10kW-h per litre, so a full tank, weighing 35kg, gives about 500kW-h – compare that with the 30 odd kW-h and 300+kg in a Nissan Leaf battery. I know a petrol engine is down to about 20% efficiency against 90%+ for electric motors, but our ecoboost Fords get twice the mpg of the old Cortinas of old, so maybe the 20% figure is now pessimistic. But with only a couple of litres left in the tank, I can still squirt from 50 to 70 mph as quickly as ever.

Leeds City Council has just declared a “Climate Emergency”, whatever that is, so the swing to electric is obviously here. But the idea of having to keep a constant eye on the charge level, of probably not being able to keep up with traffic as the charge depletes or the battery ages, of having to plug the blasted thing in to a socket every night, of having 320 volts ready to connect to the body shell in the event of the slightest accident – I’m really not keen.

I just think there has to be a better way. Power lines in the road with contactless connection to the car? With a small battery to cope with ‘off piste’ excursions? I’m sure that if IKB was still around, he’d come up with something better than the BEV. What do you think?

Thread: Stuart No. 1 Build Progress
11/07/2019 11:19:23

I find the way to happiness with a four jaw chuck is to use two chuck keys. Tighten one whilst slackening the other. I made a second key for my 6 inch four jaw chuck that was small enough to use at the motor side of the chuck.

Thread: Free cutting mild steel
17/06/2019 17:20:06

Thanks for the replies - I'll grind a right hand knife tool with 55 degrees top rake and give it a go with whatever EN1a steel I find.

I think a 100 thou depth of cut is going to make it chug a bit though!

17/06/2019 10:40:09

I want to make some grinding wheel adapters for my universal cutter grinder, which involves a lot of turning 50mm bar down to 20mm. Much of the BMS I've bought in the past does not really turn well using HSS tools on my little Myford so I'd like to get some mild steel that is truly free cutting.

Should I be asking for EN1a Leaded as being the free-est cutting BMS that money can buy?

Thread: 1959 Nsu quickly
03/05/2019 11:49:35

Me and my sister on dad's NSU (photo dated 12th June 1960)

12 jun 1960.jpg

Edited By Glyn Davies on 03/05/2019 11:51:49

Thread: Using a propane cylinder for partable compressed air.
04/04/2019 21:33:38

Many thanks to all those that troubled to reply!

I’ve just been examining the cylinder for any information marked on it. It is dated 1978 and a plumber gave it to me; there is no gas company mark on it, so I’m going to class it as mine!

It is marked TP 33.2 bar (481psi), SP 30.9 bar (448psi) and WC 9.2l. I assume SP is the Safe Pressure? The fact that propane molecules seem to embed themselves in the internal surface of the cylinder and then eke out over time did worry me a bit (the air coming out does smell a bit of propane, or whatever they add to propane to make it smell) and I see that the lower flammability limit for propane is just over 2% by volume at 150psi. That means that there needs to be 184cc of propane in the 9.2 litre cylinder when I fill it for there to be a combustible mixture and I just can’t see that much propane detaching itself from the steel interior. On the matter of condensation, I wonder if all the free water in the air will have condensed when it was first compressed by my shop compressor; I inverted the propane tank and opened its valve and no water came out.

I fully understand the views of those replies that urge caution (or cessation!), but having seen the test pressure value and lower flammability level of propane at high pressure, I’m fairly reassured that it won’t go bang. I think I’d be very wary of pressurising the 50 litre receiver of my Clarke compressor to 480psi, particularly after having regularly drained very rusty water from its drain tap over the years.

04/04/2019 14:59:01

I visited the US back in the 90s and saw some portable compressed air tanks for sale in Walmart. Never seen them here and often thought how useful one would be around the car and home. Anyway, I recently acquired an empty 3.9kg propane cylinder and thought I’d try it. It works a treat. When filled with compressed air at 150psi I can top up eight car tyres with ease before it empties. My question – can anyone see any safety issues with this that I’ve missed? I thoroughly purged any remaining propane from the tank before I filled it with compressed air and I see that the vapour pressure of propane is 150psi at 32 deg C, so the tank must be designed for this level of pressure. I tried unscrewing the valve on the tank so I could fill it with water and proof pressure test it to say 300psi, but the valve is too tight to unscrew.

Thread: broken calipers
04/04/2019 11:08:10

I would turn and file it from solid silver steel bar, hardened and tempered to blue.

I did a search on cheap calipers to see how much it would cost to buy one for the spring and came across this one from RS:


I'm not sure why it's listed as being metric!

Thread: DraftSight no longer free
25/03/2019 15:52:58

Just opened mine and cannot see a message - is it hidden somewhere?

Thread: AutoCAD substitute
05/03/2019 14:08:34

Just in conclusion - the more I play with Draftsight the more capability I find. Things like spline, rotate reference, scale reference, fillet are all there, just not on the main ribbon. So thanks again for the suggestion - life is good once more!

05/03/2019 09:32:03

Hmm.. The ebay listing gets seven glowing five star reviews and one one star review in Spanish that warns that you all get is a link to the free educational version of AutoCAD.

Ah well, as the atomic scientist said..

05/03/2019 08:58:05

Well, as usual with this forum, an absolutely brilliant response to my question. Many thanks for the replies. I've just downloaded Draftsight free and have been having a play. It imports my AutoCAD drawings, so that's a relief, and as has been said, the interface is kind of familiar.

But I sort of feel that having lost autoCAD, my life has taken a slight turn for the worse, so, in desperation, I did an ebay search and, behold! - Autocad 2019 full 3 years subscription for £8.95! I'll give it a go and report back.

04/03/2019 16:59:33


For about the last eight years I have enjoyed access to AutoCAD 2011 and have used it extensively for creating 2D drawings of parts to make, for importing images at scale and creating 2D drawings of from them and the odd bit of 3D modelling to create photo realistic images and to calculate surface areas to calculate anodising currents.

My access to AutoCAD has now been removed and I need something affordable that ideally is similar to use and at least gets me my 2D capability back. Are all CAD packages now subscription based (autoCAD 2019 is £1700 per annum!) or can I buy one for a one off price? Any help would be much appreciated! Thanks

Thread: Setting lathe top slide angle accurately.
25/12/2018 11:37:43

If I need to set the top slide to match an existing taper, such as a Morse taper, I hold some silver steel bar in the chuck and use a DTI to check that the top slide is set to zero by running it along the silver steel. I then slacken the nut clamping the Dickson tool post body to the top slide and bring the plain face of the body into contact with the silver steel. Then lock the tool post. I next fit the taper I’m trying to match into the chuck, release the top slide lock screws and bring the plain face of the tool post into contact with the taper. Then lock the top slide and turn my taper.

Thread: Cheap 3D printers
08/11/2018 19:40:42

Thanks for the replies - time to dip a toe I think!

08/11/2018 13:03:48

Hi Sorry if this is a question I could answer with a quick search, but - I just had a look on Amazon for 3D printers and couldn't believe how cheap they are, Some less than £200.

My question - if I buy a printer with a heated base plate, can I create prints in ABS or PLA from CAD models that I export as STL files? Is it really that cheap and simple? Will the printer come with software to slice the STL file and then print it?


Thread: Small Carronade model - 68 pdr.
15/09/2018 13:18:50

As regards bluing the metal - I think you'll find that the sodium nitrate is now classed as an explosive precursor so that, for our safety, the freedom we once had to buy it has been removed.

An option is to rust blue it. You can still buy ammonium chloride (sal ammoniac) on ebay and if you dissolve 2 grammes into 100 grammes of water, you have an effective rust bluing solution. I'd try on scrap steel first and see if you like the result. Method is to swab the solution sparingly onto the degreased steel and leave supported above a dish of water for a couple of hours until a light grey/brown rust forms on the surface. Then immerse the item in boiling water for a few minutes, let it cool and rub off the loose fine rust with 0000 wire wool. Repeat the swabbing, rusting, boiling and wire wooling five or six times until the metal looks a sort of grey colour after the final wire wooling. The last step is to rub in some linseed oil, which will give some corrosion protection and turn the colour from grey to blue/black.

You can actually use sodium chloride at a pinch(!) in place of ammonium chloride but the process might take longer to get to a good blue.

Thread: Painting anodised aluminium
05/09/2018 08:58:42

I thought the last step in anodising after the oxide surface had absorbed the dye was to seal it by boiling in straight water. Anodising is easily removed by immersing in caustic soda solution for only a few seconds. You can tell if the anodising is gone (apart from the colour disappearing) by touching the surface with an ohm meter. The anodised surface will be non conducting, if you have conductivity, the anodising is gone.

I don't see why anodising would prevent paint adhering though.

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