Member postings for Andrew Tinsley

Having done the full size version on several locos, I can assure you that the tubes do not "just fall out" after drilling. There is a small matter of scale on the tubes and they can be a swine to get out!

Andrew.

The chances of finding anyone to supply a one off industrial diamond is pretty well zero. If you did find one, how are you going to bond it to a steel substrate?

Do yourself a favour and just buy one from Clarke, for a tenner, you won't regret it.

Andrew.

A "dollar" was definite 5 bob! Most people of my age used the term, definitely not a local or regional thing. I still use the term for 25p!

Andrew

Hello SOD,

Not all single phase motors have start and run windings. A capacitor run motor has two windings which are permanently energised, for example.

The OP's problem is almost certainly a sticky, or more likely dirty contacts on the internal centrifugal switch as detailed by others.

Andrew.

Hello Jason,

I have always used technoweld / lumiweld for soldering aluminium. I have just followed up your lead on Cupalloy. They certainly do a flux for aluminium. However the only solder that they sell for aluminium, says that it is only for pure aluminium and aluminium / copper alloys. Is there any solder that works for the type of alloys that we commonly use?

Regards,

Andrew.

Even if the motor is star only connection, you can modify the winding connections to give a Delta set up. There are motors where it isn't possible, but they are very rare. I recently converted a load of motors from star to delta even though the terminal connection block only had the 3 phases, neutral and earth The oldest motor was a dinky little 1/4 horse, BTH motor from the early fifties.

Andrew.

Thanks for the heads up. The art of electronics has always been my bible.

Andrew.

Hello Paul,

It would help if you put the rough location of the magazines. If anyone would like them then it would be a "pick up" job, so location is important.

Regards,

Andrew.

I have exactly the same PB chuck on my ML10. It is in the same state as yours (which isn't a copy but the real McCoy)

It was knackered when I purchased the lathe, but everything else was fine. I suspect it is far too lightweight for any serious work apart from very small objects.

I took the Bull by the horns and enlarged the slots and loctited in some spacers to bring it back to nominal. The jaws were OK. It isn't perfect but infinitely better than it was.

Andrew.

Hello Ron,

I don't have much problem silver soldering these days, as I have done a good number of boilers. Like most people replying, you state a gap measurement. Most manufacturers supply the gap range for the various grades of silver solder, so that isn't a problem.

The query I have, is how do you set the gap to 0.01mm ? Apart from the centre punch method, there have been no answers, I know the basics of the science behind the soldering. What I don't know is how do you jig the gaps?

Cheers,

Andrew.

It depends how neat you are. I have seen boilers that have so much silver solder where it should not be, such that there is very little copper showing.

I use a chalk solution (suspension) in meths and paint this around the joint. so the solder is confined to the area that I want it to be in.

Andrew.

Hello all and thanks for the feedback.

Larry, MEC 90 motors are designed for compressors and they come in single and 3 phase versions, so I have no doubt that this motor could be used on a compressor.

Emgee, I have not stripped it down, but I would strongly suspect there is a centrifugal switch. I . I don't know of any single phase motor, of the power type, that doesn't have one. It definitely isn't the very ancient type that was mentioned a few weeks ago. I had one powering my backup compressor and know them inside out!!

Clive you have hit the nail on the head. I had a niggling doubt about it being a capacitor start. That would explain the peculiar external wiring which I cut through when the machine was dismantled for transporting back to my place. There were no caps apparent, but then the previous owner never got the Centec working. I hasten to add that I have no intention of using it on an air compressor!. In fact I cannot see much of a use for a 3 HP, 2800 rpm single phase motor. Even so I will get somewhere near the correct caps and a box and make it a runner.

Thank you all,

Andrew.

Edited By Andrew Tinsley on 12/08/2020 20:24:51

Hello,

I have just been looking at a single phase motor which came out of my Centec, when I opted for a 3 phase motor,on first first commissioning it.

There is no makers or information plate on it and the "Box" which houses the terminals isn't there, simply a blanking plate.

Cast into the aluminium housing is MEC 90. Googling this, leads me to believe that it is intended for a 3 HP air compressor, so quite hefty for a single phase motor.

Removing the blanking plate reveals 4 wires flopping around. Checking these shows that they are two separate windings.. One is about 3.5 ohms which must be the main winding and the other around 25 ohms which must be the start winding.

I would wire this up as a capacitor start motor, using an 80 microfarad capacitor (simply because it is about the sort of value I would expect, but more honestly because it is to hand).

I have a niggling doubt about doing this, because I assume the start current surge is likely to be high on an air compressor, unless there is a system to bleed the pressure in the tank supply line.

Does anyone know if these air compressor motors are usually capacitor start? Or is there some other starting method for these "specials" I might as well put it into good order, although I can't think of any use for such a beast.

Andrew.

Edited By Andrew Tinsley on 12/08/2020 17:56:41

Hello Bob,

It seems you are convinced that thick copper plate is better than flanging thinner plate. Well go ahead and do it, I would like to see and hear how you get on. There are quite a few people on the forum that stick to the tried and tested ways of boiler making, me included.

I am all for someone else experimenting and showing how wrong we have been.

Andrew.

Depending on size of tap either a centre hole or a point is left by the manufacturer. They are there so that the tap can be accurately aligned on a tool and cutter grinder for resharpening.

Andrew.

,Hello Keith,

I do indeed have the book! There has been lots of replies, but only a couple answered the question. To remind people, it was "How do you set up the correct gap for the alloy that you are using" I may well be wrong, but I don't think that even your book addresses the question.

There are lots of references saying what the gap should be, but virtually nothing on how to achieve said gaps. Apart from some information in Alec Farmers book re brazing tubes in the inner firebox plate.

For example I have seen people, including myself, riveting a structure to hold things together during brazing. The gap around the rivet must be close to zero, yet it still seems to solder well.

I must have been very lucky , because I never gave gaps a thought in the past, unless it was subconsciously.and I have never had a major problem.

Regards,

Andrew.

Brian, the thermal trip is in the start winding. Once the motor starts, then there is no current flowing in the start winding. The motor can fry and the thermal trip may open, but the current is flowing in the run winning. Hence the trip offers NO motor protection in this scenario.. It will NOT shut the motor down, It will run to burnout.

This is why I feel that the trip should be in the run winding. I have done a little research and apparently in some Crompton Parkinson motors the trip is in the run winding, but in others it is the start winding.

Andrew.

Brian, the thermal trip is in the start winding. Once the motor starts, then there is no current flowing in the start winding. The motor can fry and the thermal trip may open, but the current is flowing in the run winning. Hence the trip offers NO motor protection in this scenario.. It will NOT shut the motor down, It will run to burnout.

This is why I feel that the trip should be in the run winding. I have done a little research and apparently in some Crompton Parkinson motors the trip is in the run winding, but in others it is the start winding.

Andrew.

Hello Emgee,

The switch is in series with the start winding, not buried in the winding, If for some reason the start switch doesn't drop out on getting up to speed, the start winding will not be protected by the "thermal" switch as the current will, if anything, drop as the start winding overheats.

This is why i think the switch should be in the run winding, where it will act as a DOL thermal over current trip.

Andrew..

Hello Nick, the switching action is thermal. However the heat is produced by a winding which takes either the start winding current or Run winding current. It does exactly the same as a "thermal" trip in a DOL starter So it has nothing to do with the motor temperature or winding temperature. It purely trips on over current for exactly the same reason as the over current trip in a DOL starter..This switch is stood off the case by 1/2" or so. If it were supposed to detect motor temperature it would not be mounted on standoffs.

It is not an effective use of time to debate if it is a current trip or temperature trip and is pretty irrelevant to the main question, which is, should it be in the start winding or run winding? I am pretty convinced that it should be in the run winding. So I suspect someone has altered the internal wiring of the motor.

Come on, is there not a practical sparkie in the house? Steviegtr where are you!!

Andrew.

Edited By Andrew Tinsley on 02/08/2020 13:58:24