Member postings for Andrew Tinsley

Hello Clive,

Not so! This "thermal switch" operates on current NOT on motor temperature, so it would be ineffective as a device to keep the start winding temperature down,. As a current trip, surely it would be far more effective in the main run winding?

In addition to this, the motor is of the capacitor start variety. The overheating of the start winding when doing lots of stop / starting is a bad characteristic of split phase motors . Capacitor start motors are much kinder to the start winding in this respect, I always wondered why Myford persisted in using split phase motors for their lathes. The cost difference between capacitor start and split phase motors is very little.

Andrew.

I always listen to Radio 3. You don't get the interruptions and the music is better than the usual pop classics on Classic FM

Nothing wrong with Butterworth's Banks of green willow. If he hadn't been killed on the Somme I suspect that he would have produced music on a par with Elgar or even better.

As for Mozart "can do no wrong", well all I can say is that you have been very selective in the choice of his music. With such a vast catalogue, I can assure you that there are a good number of which are substandard.

Oh and I cannot stand Opera in any shape or form.

Andrew.

Edited By Andrew Tinsley on 02/08/2020 11:33:06

One of my 0.5 bhp, single phase, Crompton Parkinson motors, developed classic centrifugal switch, dirty contact syndrome.

On stripping the motor down, I was surprised to see that the thermal safety switch was in the start winding circuit. This is the type of thermal switch which has two or three turns activating a bimetal switch. So it monitors current, rather than motor temperature.

In past servicing of electric motors, I seem to remember that these thermal switches were in the main winding. Was I wrong about this? Seems to me that the run winding needs overload protection more than the start winding?

Do I have a motor that has been got at by someone, or is my memory playing me false?

Andrew.

Edited By Andrew Tinsley on 02/08/2020 11:12:40

I have just completed a spot test for cadmium (There are quite a few available) and my silver solder has cadmium present.

There is now no doubt about it. This is AG3 (Argoflo). No other silver solder has all of the measured characteristics by a mile.

If a boiler inspector does want provenance I can repeat the experiments for him. He should be totally satisfied with the results, unless he is one of our resident nit pickers.

Andrew.

Hello again,

I have at last managed to iron out problems with the measuring technique and have solidus and liquidus temperature measurements nailed down to plus or minus 1.5 degrees. The Easyflo No 2 that Rik Shaw sent me and my own 55% cadmium free silver solder confirmed the accuracy of the measurements. The unknown silver solder was measured at 604C solidus and 648C liquidus. This is in line with it being AG3 (Argoflo). There is nothing else that gives such a wide transition.

So it looks fine for boiler work, with somewhat larger gaps. I shall take suitable precautions as it has around 20% of cadmium as a constituent.

Thanks everyone, especially Rik Shaw for his samples.

Andrew.

P.S. This was a JIT experiment as the furnace started to play up at the end, luckily I had the measurements tied up by that time.

I use an IKEA Butcher's block for my big surface plate. It is tall enough for me and has two wheels so it is both easy and safe to manoeuvre around.

Andrew.

If the steel is really hardened carbon steel, then you could soften it by simply heating with a propane torch until it is red hot. Soak it at temperature for a few minutes and let it cool naturally. Otherwise you are looking at carbide tooling.

If you don't know what grade of steel it is, then you are quite likely to have something that is a tough steel alloy, if so then carbide tooling is required.

Andrew.

Thanks Neil. Your comment on the use of foils rings a bell. I am sure that is the objection i have come across. I wonder where it was?

Thinking back to making boilers. I have always used what I consider to be a sliding fit for the components. I now am becoming more convinced that it is the flux itself that creates the gap on assembly

Bob you make an interesting point about tight fits. I am not too sure that some of the higher melting point solders are that runny, those with a high solid to liquidus range especially. However as long as you are well above the liquidus range, I suppose it doesn't matter.

The use of foils on assembly sounds a good idea and one that I have considered. However I have a nagging doubt about this method. Somewhere I remember reading that there is a snag . Maybe it was in Keith Hales book, wherever it was, I can no longer find this reference, perhaps someone on the forum can remember seeing it? Maybe it was the price of the foils, but i think it was a more fundamental problem.

Andrew.

Well I never, how did the Cowell's advert get in on the act???????

Andrew.

Sorry for neglecting answers to my post. I have another two boilers to make so I shall be extra careful of my "gaps". It is odd that in all the boilers I have made, I have had only two very small leaks. I was quietly thinking that I was becoming an expert boiler maker. However Mr Walshaw took me down a peg or three!

I must have been taking note of clearances without really taking it on board, Otherwise I would not have got away with so few leaks. All the books on silver soldering / boilermaking make great play of the correct gaps and even quote figures. None of them give any tips on how one is to achieve this! Ian's mention of someone using centre punch marks to define the gap is the first example I have heard of that is practical.

I put my success (luck!!!) down to using very large propane burners helped out with the odd oxy -acetylene torch. Like most people, my early mistake was not having the joint hot enough.

Thanks,

Andrew.

Hello David and Michael,

I take the point that I don't need six terminals. But I would like to make it easy to go back to star if needed and the modern system for new motors is 6 terminals and 3 links. Much easier to do the deed that way and at least the terminal system is then to a modern "standard".

Michael your link is perfect, a standard six terminal block for less than a fiver. That will do me just fine. Thank you!

Living out in the sticks means a minimum of a 40 mile round trip to the nearest motor rewinder, so mail order wins hands down.

A sincere thanks to everyone for your time and suggestions.

Andrew.

Having found a 6 terminal block for £25 inc P&P. I think I will make up some myself. I can't afford £100 to convert 4 motors from star to delta!!!!!!!!!!!!

Thanks all,

Andrew.

Hello Michael,

RS and Farnell were my first port of call. Nothing remotely like the required terminal posts as far as I could see. Thanks for the suggestion.

Andrew.

Hello,I am just converting some Crompton Parkinson 3 phase motors from star to delta.

They only have 3 terminals right now. But having unpicked the star points, I need another 3 connection terminals to convert to delta.

Can I find such beasties? No, probably because I am using the wrong search term! I know I could just use nuts and bolts and bodge the terminals, but I do like the cupped washers that you get with the genuine terminal posts.

I am going to use a larger piece of tufnol plate to get the 6 terminals in, so I may as well do a pukka job.

Thanks,

Andrew.

Edited By Andrew Tinsley on 16/07/2020 16:18:14

It came from a deceased model engineers estate. I disposed of the workshop and was given the silver solder as a "thank you" by the family.

It has been around 40 years since I built a series of copper loco boilers. At no time was I ever asked by the boiler inspector about the grade of silver solder used. I suspect that this applies even now, but stand to be corrected.. The material I have, seems to behave like the old silverflo. that I used back then.

I would like to find out what this material is for my own peace of mind, not too bothered about a boiler inspector at this stage.

Andrew.

Edited By Andrew Tinsley on 15/07/2020 15:30:50

Edited By Andrew Tinsley on 15/07/2020 15:33:16

Hello Phil,

I will keep you in the loop about melting trials.

Regards,

Andrew.

Thanks gents,

I don't think that determining the SG would help a lot as silver solders contain quite a few elements and I don't have the apparatus to do it accurately. No sg bottle but I do have an accurate chemical balance.

Rik that would be a great help. I have plenty of the cadmium free stuff, but not the old material. I will PM you.

Thanks both,

Andrew.

I have been gifted with a large quantity of silver solder. I don't have any provenance, except it is probably 35 years old. It has the slightly golden colour of my cadmium free 55% silver material.

I do have a small furnace, so I can probably nail the melting point of the material. with a fair degree of accuracy

My query is, will this be enough to identify the type of silver alloy. I will probably use it in boiler making (if the melting point is reasonable). So I am concerned that I can identify the material correctly.

Regards,

Andrew.

From your name, you appear to be a clock enthusiast! The go to adhesive for sticking items to say a face plate, has always been shellac, in clock making circles. It works very well indeed and you don't need the higher temperatures that super glue calls for, when removing the item.

Andrew.