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Member postings for Chris Gunn

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

Thread: Recycling Fire extinguisher pressure gauges
27/09/2020 20:09:05

Ian, I do hold the club boiler testing gear, including a calibrated gauge,.

John, I did not realise the gauge on the extinguisher was was a much higher range, I should have realised the contents will be at a higher pressure then say 100PSI to be effective. I guess that is why they use coloured sectors rather than indicate the true pressure. Also the construction of the body would point to a higher pressure than is useful to us.

Martin the boiler test includes checking the pressure gauge against the calibrated test gauge.

Chris Gunn

27/09/2020 12:50:55

Has anyone tried recycling the nice 20mm diameter fire extinguisher pressure gauges for use on Models? I have some that are about 20mm diameter with a face marked in red green then red sectors.

It seems that a new face could be added once the gauge had been calibrated.

Chris Gunn

Thread: Steam Raising Blower
25/09/2020 22:28:54

Duncan, in my case the fan does not run for many hours in a normal rallying year, and the exhaust fans are light. I am using an ex lorry wiper motor which is pretty chunky with decent bearings.

Peter, my exhaust fan is quieter and seems to run cleaner than my home made one, and there is much more clearance around the impeller of the exhaust fan, which may help in this regard.

Chris Gunn

24/09/2020 16:28:18

Bill, thanks for the info on blades, I went to a lot of trouble to make a 6 bladed impeller with forward facing blades, and after 2 or 3 outings it collected enough soot to make it vibrate, bits would break off and jam it. At rallies it whined so much that folks would shout "all clear" when i switched it off.

I adapted a central heating exhaust fan in a tenth of the time, and it is much better. British gas service engineers are replacing these daily, so if you know someone on a maintenance contract, get a request in early.

Chris Gunn

22/09/2020 21:47:02

Plus one for a central heating boiler exhaust fan. The 240v motors fail, and it is easy to remove it and fit a 12v motor instead.

I ditched my home made one which sounded like an air raid siren for one of these.

Chris Gunn

19/09/2020 21:47:13

Noel, an expanding reamer will not take much out, much quicker to make the boring bar I mentioned, and bore 1/2" back. you can do it in one cut if your tubes are 1/8" thick, leaving a 10 to 15 thou wall for example. I did some research before trying the method I describe in my article, it seemed half pulled the tubes out from the front, and half knocked them through into the firebox. Some folks I know worked on a 4" Foster, and knocked the tubes from the front into the firebox, and cut a piece off, and repeated until the tube is fully out. it is a 2 man job, 1 to hold the drift, and one to wield the sledge hammer. This seemed rather brutal to me, very hard work, and was quite time consuming, 2 or 3 tubes an evening if all went well. unless one makes a series of drift/mandrels it is not possible to support the tube internally as it is driven through. The chance of damaging the front tube plate seemed higher to me that way too.

I could get my tubes out on my own. If you plan take the tubes on your engine out this way, i am having difficulty in seeing how you could use the hydraulic rams in the firebox, or would you push from the front?

Chris Gunn

19/09/2020 12:42:42

I had a couple of tubes crumple as they came out, if one uses a mandrel that is as good a fit as possible in the bore this stops the tube crumpling. Then one must make a drift and knock the bent tube back in the boiler, and hook it out of the mud hole, and cut bits off it untll you can get it all out.

Noel do not be put off, it can be done with patience. However if you are not happy to have a go there are folks out there who will do it for you, at a price of course.

Chris Gunn

18/09/2020 21:01:38

Noel, I hope you can get a copy of the 2 articles I wrote longer ago than we all think, but to answer your question, I ground the ends of the tubes back to the firebox back plate, so any swelled tube ends were removed. I could get in with a 4" disc grinder to get most of the corner ones. Today i would use a power file as well to get in the corners. At the front I made a bar to fit the tubes, and fitted a boring tool to it, and adjusted it to remove most of the material in the bore just about 1/2" in. I was surprised how easily it cut using a power drill. then I used 16mm studding to pull the tubes out, and they came out OK. However it is easy to strip the studding if you get a tight one. If I were to do it again, like one of my fellow club members this year, I would use a hydraulic puller. It has been a bad year for tubes in our club, a 3" McClaren, a 3" little Samson and a 3" Allchin have all been done more or less this way.

Chris Gunn

Thread: Amazon Prime scam?
07/07/2020 19:55:23

We had the same type of call today, relating to an alleged fraudulent payment on our Mastercard credit card.

I am told that if you press 1 you get connected to a premium rate line, can anyone confirm this?

Chris Gunn

Thread: Making Parallels
20/06/2020 20:48:24

Andrew, I would use bar stock for your parallels, they will be good enough for most purposes, and if you accidentally drill or mill into them, you will not damage your cutting tools. You can buy enough material for a couple of sets of any size, and offcuts never go amiss. Mark them up when you get them so you always use a pair from the same original stock. You can get a lot of bar stock parallels for the price of the hardened and ground sets.

Chris Gunn

Thread: Boiler
20/06/2020 20:32:57

Robin, it depends who put the number on. Your number could be one from a club, or if made by a professional boiler maker could have his or her mark on it.

Most Model engineering clubs who carry out boiler tests call for a number to be added for identification, if the boiler is not already numbered. The club or owner would stamp the boiler, and this could indicate the club that tests the boiler. A club would be happy to use a boiler makers number for I/D if there were one. A boiler makers number could have a makers code as well. Why not share the number with the community who may well be able to answer your question?

Chris Gunn

Thread: UNF reducing bush
20/06/2020 18:07:59

Could you open up the 7/8" thread to say 1", and then you will have more wall thickness to make a 1" to 3/4 adaptor? or find what adaptors you can get, and open up the 7/8" to suit. Without knowing what you are trying to fit together it is hard to advise a good solution.

Chris Gunn

Thread: Mystery leadscrew nut
20/06/2020 17:41:20

nut p6204093.jpgI have just had a good tidy up, and found this bronze leadscrew nut, which is brand new but scruffy. It is .875" O/D and 1 1/4" long, with a good chamfer on 1 end. It is LH and about 1/2" acme or square thread. I have reason to think it could be a nut for a Harrison L5 tailstock barrel, I had an L5 a long while back. Can anyone identify it please?

Thread: Stuart 10V Build Log - Complete Beginner...
15/06/2020 20:49:30

Hi, if you are worried about the end faces, you could always make a slightly tapered mandrel, and carefully polish the taper on, and taper it so the cylinder goes about 3/4 of the way on, put a bit of thin oil on it, then gently tap the cylinder block on tight while the mandrel is still in the chuck, and then take a skim off the end of the block, I guess only one end will be off, the end machined at the same time as the bore should be square. Whenever I make a Stuart engine, or any other for that matter, that is the way I always machine the second end. One the end is faced, remove the lot from the lathe and tap the mandrel out.

Chris Gunn

Thread: Jumping in
11/06/2020 21:56:24

Ian, another happy Bantam owner here, if the electrics are original there is a selector switch on the front under the drip tray to select high speed or low speed ranges. If you have not installed it yet, you will be able to see the original motor plate which also indicates it is a 2 speed motor. I elected to stick with the original motor on mine, and I run it via a Transpower converter. After about 15 years I did have a burn out, and got the motor rewound, and it has done another 15 years. I also acquired a back up 2 speed motor from someone who put an inverter drive on theirs. I never tried the back up motor.

Chris Gunn

Thread: The Workshop Progress Thread 2020
11/06/2020 20:45:22

Here is my Undertype now painted and with a tiled and bricked plinth. I used printed glossy tile paper and embossed brick effect paper, but I should have done it Jason's way, as the oil from the engine is working its way under the paper. Chris Gunnp6114015.jpg

Thread: Brush motor repair
02/06/2020 13:42:32

KB, go to the local tip, ours has a container full of duff dysons, you may be able to get a spare there.


Thread: Frustration in taking photos using my Galaxy A20e mobile phone
30/05/2020 10:03:31

GS, just had a play with my phone and can confirm that when in camera mode, all external buttons will trigger the shutter, I did not try the home button though.

Chris Gunn

30/05/2020 08:56:31

GS, Ega is right, I can use the volume control button to trip the camera shutter, and sometimes I too have the problem you describe, but it seems at random.sometimes the shutter will click as I am giving up and move the camera away so I get a nice picture of my feet or somesuch.

Chris Gunn

Thread: J.T.Slocombe micrometer very old
27/05/2020 20:09:08

Here is my vintage Mike, it is an Elliott, and is dual reading, the thimble can slide and be set to "English" or "French" divisions.

dsc03646.jpgIt also has a ratchet for the right feel, way ahead of its time. I believe it could be pre 1850.

Chris Gunn

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