I think that the rotors can demagnetise if they're out of the pole pieces for any length of time.
I think that the rotors can demagnetise if they're out of the pole pieces for any length of time.
varnish is a heat setting polyester
Which resin do you use? I've a 50 year old motor and I'm thinking about trying to get some resin into the windings to help beef them up a bit. It would just be poured on since I don't have access to a vacuum
you could warm it up and pour air drying anti flash over resin thru it ,the red stuff messy job ,
motor guys wouldnt be keen puttin a old motor in there bath and contaminating[ it
the varnish i use is heat setting polyester it was made by a company STERLING no longer on the go
but a new company WES do all the sterling range and all sorts of coatings
Hi,
Many thanks for the plug eddie49; yes I'm always interested in coil winding of all kinds.
During my ten years restoring vintage radios I started from scratch adopting this as a winter hobby and as the years passed I became increasingly competent to the point of even winding my own tuning coils; chokes and assorted transformers. I always considered transformer winding to be hugely complicated but for a home workshop and a bit of research once the basics are grasped transformer winding is reasonably easy and interesting.
Slightly off subject zeppelin builder because it's not magneto winding but still coil winding I can highly recommend this following book;
Wireless Colis, Chokes And Transformers by F.J.Camm.
It's a small book of about 180 pages but written in a style any novice can understand it; just a few pages on transformer winding which I read over and over again until I grasped the basics and I was soon winding transformers. Rewinding is quite easy because the wire sizes are known and the laminations too are matched to the windings; some accurate means of measuring wire gauge is needed; I used my imperial micrometer and if the same gauge wire is used then it's one big problem already solved.
I started rewinding small output transformers these using small amounts of very fine wire but if things went wrong little was lost. As I progressed I could rewind mains transformers; these used to strike terror into restoration guys if their mains transformer went open circuit because they knew it was often cheaper to scrap the radio. For members unfamiliar with vintage radio mains transformers these transformers often had lots of "taps" including a center tap; these taps gave different voltages for different components within the radio; valve heaters; panel lamps and rectifier etc; very daunting indeed and also very dangerous for a novice to play around with; just picking up one of these vintage radio chassis whilst switched on could and would kill it being live to the supply even when switched off and unplugged often fully charged electrolytic capacitors were just waiting to give a nasty shock. Every unknown chassis on my bench was connected to a 100W lamp in series plus an isolation transformer and I also used a Variac to bring the voltage up; if the lamp glowed it was time to switch off and investigate before something exploded.
For quite a while I used to count the turns of wire as I unwound them which was tedious especially when the wire had breaks then one day I realized I didn't need to count every turn of every winding; could I simply unwind one of the secondary windings say a 6V panel lamp; if this gave say 24 turns then it saved no end of time and frustration; transformers are actually very basic machines; put a voltage in and get voltage or voltages out; wire gauge and laminations took care of amps. So knowing the panel lamp to be 6V and with 24 turns the transformer turns ratio 1 to 4. Now I could work out every other voltage needed including the primary winding on this transformer with a 240V supply gives 240 x 4 which equals 960 turns for the primary; it was common to need 350V secondary to feed the full wave rectifier valve but the 350V was equally split by a center tap giving two at 175V. 350 x 4 gives 1,400 so this was the number of turns for the rectifier winding but with a center tap; these taps were simply short leads soldered in at the wanted number of turns and by adding taps any voltage could be obtained; both step up and step down transformers are used. I found transformer winding to be fascinating.
The winding wire I used was enamelled copper and I had a big stock of industrial sized bobbins of many gauges; very thin transformer insulation tape and also special 3 thou thick brown lamination paper was was used; If my memory is correct a small Bush 90 output transformer needed around 3,000 turns of very fine wire which was easy to break. It was great fun but years ago I stopped restoring vintage radios after restoring my only vintage TV and having done this I felt all the challenges were now behind me so quickly lost interest and sold all my winders; test gear and most of my 70 plus collection of radios. The last transformer I wound was huge by home workshop standards it weighing around 75kg; I wound this using conduit wiring to give 3 phase on full power in my workshop to my big industrial machines; over the years I've down scaled and sold most of my big machines and sold the highly dangerous transformer to an electrical engineer otherwise I'd have scrapped it because it would prove lethal if tinkered around with; I installed 3 phase using the home wound transformer for just under £120.
Sorry everyone; I know installing 3 phase is the wish of many home workshop owners but I've been quizzed and doubted too many times about just how good my 3 phase installation worked; I didn't invent the method and I always made it clear the method was indeed unique but on other forums I became fed up of a number of "experts" who had never tried the method knowing better than me who had used the transformer for years and the guy in America who invented the transformer method which I can honestly say works as many visitors to my workshop could agree having seen me switch on my 3 phase industrial bandsaw and 3 phase extractor just as if 3 phase 415V was installed from the electricity company.
I can however add details of the method and inventor so anyone interested please visit Doug the inventor at his website;
http://unique3phase.com/
I believe I could have been the first in the UK to successfully follow Doug's instructions because of supply voltage differences; here in the UK we run 240V and when I got my transformer and machines up and running Doug put two other guys here in the UK in touch with me so Doug's method works on any voltages; step up; step down but once installed and the machine phase balanced then the machine works at full power on 3 phase. Enough said.
Sorry to hijack this interesting thread but transformer winding isn't too difficult but as you rightly say zeppelin builder the high cost of any rewind isn't in the actual winding it's the actual amount of work in hours that push the bill up. These skills aren't valued whereas our solicitor charging £300 to write our wills years ago managed to marry me to a Mrs brown; his regular cost per hour at the time was £200 so taking his skills (?) into account I'm sure 8 hours winding a transformer would be well worth £1,600 but who would pay this; sit on your backside and make a silly mistake and charge £200 per hour or get your hands dirty using expensive winding machinery and materials for a few quid per hour; who has the more skill ?
I've rambled on enough but a word of caution to any novice; PLEASE DON'T PLAY AROUND WITH MAINS ELECTRICITY IT COULD PROVE THE LAST THING YOU'LL EVER DO.
Kind regards, Col.
View attachment 221401
The two German Aumann winders I owned.
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A close up.
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The AVO hand winder I used a great deal.
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The AVO wave winder I fully restored and was honoured with best restoration in 2009 by The British Vintage Wireless Society (BVWS).
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This was the reading from my home wound 3 phase transformer; it doesn't get better than this and I used the transformer for years without the slightest problem.
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The completed 3 phase transformer ready to be installed into my workshop; boy it was heavy.
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The scrap transformer with its original windings removed now ready for new windings.
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Here's the transformer on test hooked up to our mains supply; lethal for a novice to even attempt.
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A method I used to insert tight laminations; it worked a treat but great care was needed to drive the laminations home without damaging the former or windings. What fun I've enjoyed over the years and am still learning lots of new things now aged 72; during the last few months I've learnt metal spinning; tig welding (aluminium) and some panel work. I'll have a go at anything which catches my interest; I'm never bored.
Well done zeppelin builder with your magneto repairs which I find interesting.
clean the points first !I just kicked my bike over and not a sausage from the mag.
I am going to show it the above pic and hope it encourages it to show a bit of life.
heres some usefull info from an old brough book for fellow View attachment 230060 View attachment 230061 View attachment 230062 View attachment 230063 View attachment 230064 View attachment 230065 v twin nutters
I converted the Mag/dyno for my 1929 Matchless model X from a single to a twin, a covered wagon type, has been starting first kick for 16 years until last year when I suspect the condenser failed, but it got me home, just, a few years after I had done it I was speaking to a magneto guy and he said that as the singles only had one magnet and the twins two it would never work, well it did! fyi I have found a few single covered wagon mag/dyno bodies with two magnets, maybe a sport version?