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Member postings for Clive B

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

Thread: Tempering
01/01/2019 11:09:53

+1 for the deep fat fryer. I have a cheap one from Asda which, on full power, cycles over 180-190 degrees C (measured with a decent thermometer). This temperature is fine for silver steel and gauge plate, not sure about unknown types of steel though....


Thread: Horn Antenna for Radio Astronomy
03/12/2018 20:30:57

Hi Joe,

I think your picture shows a double ridged horn which is optimised for a much wider bandwidth. Here is where my knowledge of antennas becomes extremely flaky however. The pyramidal horn I described is fed from rectangular waveguide (WG650 size in this case) which limits the bandwidth to approx. 1.15-1.72GHz. It is a very conventional design. The transition plates as I call them just connect the rectangular waveguide feed to the flared plates where the angle changes and there is no gradual flare. They serve a very different purpose to the tapered "ridges" shown in your picture, there are no "ridges" in the horn that I described.


03/12/2018 15:38:11

Thanks for the kind words everyone.

Joe, The horn was supposed to be a simple solution, although it is a bit unwieldy at 15kg! In the longer term, particularly for gains higher than 20dB, agreed the dish would be a better way forward but I believe the feed needs some care. The transition pieces are shown in the third figure.



02/12/2018 10:57:43

Hi folks,

This project made an interesting diversion form my Stuart Beam engine. There seem to be people on this forum who are interested in astronomy so I thought I'd post this. It was made for my brother in law who is a keen astronomer and is just getting started in radio astronomy.

It's a pyramidal horn antenna designed to operate at a wavelength of 21cm (1.42GHz) which is the hydrogen HI line **LINK**. The dimensions are quite large for a horn at 940 x 735mm aperture and approx 1.4m length including feed. This gives a theoretical gain of 20dB.

antenna 1.jpg

Because I don't have the skills or equipment for welding, the whole thing is bolted together. Some might be wondering why there are so many bolts; they are spaced at 1/10 wavelength to ensure good electrical continuity at the frequencies of operation. There were no particularly difficult parts apart from cutting some reasonably accurate tapers on the mill - these are for the transition pieces between the waveguide feed and the flared horn section - first time I used a sine bar. The large flared plated were cut at reasonable cost by Model Engineers Laser. The design for the mount is still being worked up.

The following picture shows the waveguide feed section and transition section:-

antenna 2.jpg

This shows the method of construction internally and the fixing/feed point for the coax connector:-

antenna 3.jpg

Hope this was of interest,


Thread: Small Carronade model - 68 pdr.
15/09/2018 02:57:19

Nice model Mick. A carronade is on my list of things I'd like to make. Where are you getting the rope eyes from?


Thread: Hand files for aluminium
06/08/2018 00:20:30

Thanks for all the helpful replies. The Millenicut files sound as if they will do the job. I see that they are available with straight or curved teeth - what would be the advantages of one versus the other?

The files that initially sparked my interest were by Nicholson - see **LINK** which are double cut however these don't seem to be readily available in the UK.


05/08/2018 10:41:59

Hi folks,

I'm looking for a files that are specifically designed for aluminium alloys but haven't had much luck finding one - anybody know of a source in the UK? I'm getting a bit fed up with clogging my normal files up - I'm familiar with using copper pipe, or chalk to mitigate clogging of the file - but I gather that specific files are available. I see that ARC sell "lead float" files but these look a bit coarse to me. Anyone used those on aluminium?



Thread: Jones .605 Glow engine
10/06/2018 21:30:10

Keith, The engine looks terrific; well done! Maybe you can post a video of it running?


P.S. Really like your Chenery Vee twin also. Might finish mine one day!

Thread: Picador Type Drill Grinding Jig Modifications
10/05/2018 08:46:30

Hi Marcus, Recently I acquired a genuine Picador jig which came without instructions. I haven't used it yet so I'd be really grateful if you would PM me the instructions.


Thread: 10 inch Mortar Scale Model
22/04/2018 08:49:52

Excellent job Richard. Where was the picture of the original taken? Looking forward to some pics of your RML.


14/03/2018 08:12:16

Hi Rich,

Thanks for the additional photos. I'd like to see a photo or two when it's finished and painted. I intend to screw the parts of the bed together on mine. I am sure there must be a way to machine the fillets for the trunnions - I just haven't figured out how just yet!


13/03/2018 09:52:42


That's a very nice model. I'd be very interested in more photos showing how the bed goes together and how you made/fitted the fillets next to the trunnions, these look very neat in the photos.

I am part way through a build of a 1;16 scale model of a 13 inch Victorian era land service mortar which will utilise a slightly later design of bed than yours. It's in brass as it's just a mantelpiece project (non-firing):-

13 inch land service mortar.jpg

Mick - I like your Jerry Howell cannon. I found the drawings to be pretty good, although I can't comment on their accuracy/authenticity. Here's my version at 1:20 scale:-

24 pounder 1779.jpg


Thread: Problem With Corrosion Of Stainless Steel
12/03/2018 07:22:02


I am sure that passivation will help. If you want to try it yourself, there is an easy to follow guide on passivating stainless steels using a citric acid/caustic soda (sodium hydroxide) three step process. I used this to passivate 303 stainless (another free machining grade containing sulphur) for some components for my home brew boiler/mash tun, Not seen any corrosion - although I know that doesn't prove anything!

Exposed sulphides in FM grades can act as initiation sites for corrosion (apparently, according to the article) and the citric acid must be removing the sulphur as you can smell it (hence the need for a final rinse in caustic).



Thread: Atom Minor Mk III
10/03/2018 10:07:02

Jorgo, Thanks for your suggestion, what type of glowplug could you recommend?

I've posted a short video of the engine running on YouTube, if anyone's interested!


09/03/2018 09:38:02

Hi Chris,

Initially I noticed a slight leakage in the crankcase - some sealant cured that (I used hylomar blue - perhaps someone could suggest a better sealant?)

Fuel supply - as stated on my first post, the fuel feed needed some fettling to avoid flooding (thanks for comments Trevor).

Other than that, very patient adjustment of the carb needle and air shutter to find the "working envelope". I did make a small mod to the carb re the position of the needle seating in the venturi; not sure if this really helped but this mod will be specific to this design of carb. If you're interested I can send you a sketch. Incidently the needle in the original drawing is not tapered enough.

I tried Easy Start but this didn't make any difference.

I tried measuring the compression with a car type gauge but I think that the volume of air inside the gauge itself led to misleadingly low readings for an engine of this small size (6cc).

A cold garage probably didn't help matters.

The cylinder and piston are both cast iron.

Best of luck!


08/03/2018 06:59:33

Thanks Andrew and Jeff. Please forgive me a dumb question (I am new to building ic engines), but can I run the methanol mix using the existing spark ignition or will it be better off with a glowplug? Clive

23/02/2018 15:23:26

Thank you Fred and Richard for your kind comments. The castings were from Woking Precision just before they were taken over by Hemingway. These castings were fine, although I made the cylinder head from round bar stock and didn’t use the casting for the contact breaker assembly. I believe that there was an article in ME on the design of a higher compression head for this engine so that it could run on glow fuel (methanol), might give this a try! There seem to be pros and cons for castor oil, perhaps a mix of synthetic/castor would be pragmatic if not after the highest levels of performance? Oh, and I’ll try to avoid standing in front of the exhaust! Clive

04/02/2018 16:38:00

Hi everyone,

After initially resisting all attempts to make it start, my recently completed Atom Minor Mk III finally burst into life; most satisfying! This is my first ic engine. I think the main issue was (and still partially is) the fuel feed which works on a simple suction principle – I have the initial level of the fuel at the same height as the jet in the carb. Anyone know if there is a better way?

The ignition timing could probably be optimised, I am using a Hall sensor and CDi module.

Also, can anyone advise on the best mixture of fuel to oil for this two stroke? I am currently using Aspen two stroke which has a 50:1 ratio; Westbury recommended a ratio with a lot more oil in it – but I guess that was in the days before synthetic oils.

atom minor mk 3 in action.jpg



Thread: Napolionic cannon
30/12/2017 14:22:37

Rod, You might find the following thread useful; it provides a summary of original references to carriage/gun designs and scale drawings;id=122454. Some of these references are available as reprints from DP&G Publications, Regards, Clive

Thread: High Speed Steel?
08/05/2017 23:09:02

You can purchase 6.5mm x 200mm HSS from CTC Tools, but they only seem to sell this size in packs of 5. By coincidence I have also been trying to source long pieces of HSS for woodturning tools.


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