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Thread: Power feed buy new or repair?
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5th Nov 2019, 04:01 PM #46Most Valued Member
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OK. I had another look at the feild winding coil. It's going to do my head in counting the no. turns. I suspect it's near 1000 or so. So I have decided to use Barons' idea and weigh the winding and go from there.
I have ordered a set of "precision" scales that should arrive end of the week:
https://www.ebay.com.au/itm/0-01G-50...kAAOSw8a1ZsP6X
So Baron, or anyone for that matter. Whats the best way to do this?
Weigh the entire field winding, record the figure (call it m); then separate say 10 turns and weigh (call it m10). Divide m10 by 10 (for an average weight of 1 turn call it m1) and then divide the original winding weight m by that last figure m1 to get a rough estimate of the number of turns?
Sound like a plan?
To get a better estimate I could weigh 100 turns and divide by 100. But how accurate do I need to be?
SimonGirl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.
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5th Nov 2019, 07:19 PM #47Most Valued Member
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5th Nov 2019, 07:27 PM #48Most Valued Member
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Im constantly impressed by the way you think Stu. I get it now.
Wrt weight, are you suggesting that I can simply weight the windings and then wind some new ones based on weight without even worrying about turn count?
The reason why I suggested the above method is because it allows for deviations in weight from varnish residue/impurities and deviations in enamel copper weight from different manufacturers.
Simon
Sent from my SM-G970F using TapatalkGirl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.
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5th Nov 2019, 08:03 PM #49Most Valued Member
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Well thank you
As long as you picked windings of average length as there seems to be a fair difference between the inner and outer length.
But at least if you come up with a number making two the same will be easy.
How close they need to be to factory I have no idea and will leave to BaronJ, I'd count turns because I don't know enough to do anything else
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5th Nov 2019, 09:20 PM #50
Hi Guys,
The actual number of turns is not critical, 5% variation wouldn't make a lot of difference at all.
I must admit I like Stuarts idea, However yes simply weighing the whole winding and doing the sums will do as well. The only important thing is that both windings should be as identical as possible.
Now the original windings used two different wire sizes ! This was done in order to make secure connections between the very fine wire and the outside world. At the time this motor was made it was probably the most easy way to do this. I would probably go with a modern high temperature plastic covered wire to do the joint. Kynar covered wire springs to mind, since this type is a solid core and a high temperature rated material and is cheaply available in several gauges.
But, there is always a but... Its very hard to strip the insulation without nicking the wire ! It would be my choice rather than PVC, enamelled or similar. Also get enamelled wire that will self strip when you solder it ! Often called "Solder through" or "Self fluxing" Saves a lot of frustration.Best Regards:
Baron J.
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6th Nov 2019, 07:05 AM #51Philomath in training
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If the important thing is two identical coils, would it be more straight forward to make up two formers and wind both coils at once?
Michael
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6th Nov 2019, 07:26 AM #52Most Valued Member
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Hmmm. Well with a bit of pre-planning and some extra thought it maybe a worthwhile to do that.
I'm still not 100% convinced I can pull this off either way. I'm not part singularly good with delicate or fiddly work. I'll wait for my $12 "precision" scales to arrive and make some further measurements.
For $300 I can purchase a new power feed. It's becoming increasingly obvious to me that it's no longer about the money but more the challenge...... as long as I don't spend $299 in a failed attempt!
Simon
Sent from my SM-G970F using TapatalkGirl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.
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6th Nov 2019, 07:34 AM #53Senior Member
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Was poking around and found this company that sells reconditioned units and repairs them too. Maybe it is possible to get windings or a motor from them. A long shot but you have nothing to loose at this point.
https://calmetrics.stores.yahoo.net/powfeedrepse.html
Pete
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6th Nov 2019, 07:52 AM #54Most Valued Member
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Hi Pete,
In vast vast search for existing parts etc. I have visited their site and bought some parts from them such as new brushes, brush holders, bottom plastic cover, speed adjust knob and pot. All up about $60 worth of stuff. This was when I was expecting to repair the existing board and components. I replaced the SCR's and rectifying diodes. In the end I either missed something, did something wrong or didn't pick up another person's mistake in their attempt to fix.
I bought this mill from a machinist who wanted to rebuild it but either gave up or who's priorities in life had changed and no longer had the time or the will.
In that time he had it stored at his dad's house and it seems his dad had a "look" into fixing some things....
I saw it as an opportunity to own what seemed like a decent mill for cheap with repairs that were doable.
It came with a 200mm riser block and a universal dividing head so figured I'd get most of my money back i sold them if the mill was scrap.
For $1200 I'm still not sure if it was a bargain but it's probably worth a bit more now and it's nicer to use than my geared head mill!
Edit: they do reconditioning on servo power feeds. And can recondition my power feed even though they say parts are scarce. The cost is US$ 230 and I would have to ship to and from them. Unfortunately it's not an economical proposition.
Simon
Sent from my SM-G970F using TapatalkGirl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.
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6th Nov 2019, 09:57 AM #55Golden Member
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If it was me I'd be inclined to count the turns, if you feel the number of turns is around a 1000 and you are ok to count out 100 for weighing them then it's not that much more effort to do that 10 times.
I'm not sure if the following also applies to motor windings - I have wound many transformers and one of the steps is to calculate the total area taken by the windings and insulation - this means accurate measurements for the wire and insulation thicknesses are needed, if the total area taken by the windings and insulation is 75% or less of the available space then its good to go, at 80% it might be a bit tight to get everything to fit at 82% or more then the windings and insulation will almost certainly not fit.
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6th Nov 2019, 07:35 PM #56
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7th Nov 2019, 08:38 AM #57Most Valued Member
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Thanks for the input guys.
Baron, you have more faith in me than I do! I'm not very good with fiddly stuff. It's likely to end up thrown across the shed! BUT, I've got to at least have a crack before throwing it!
As familyguy says, anything more than 75 - 80% and it's going to be tight. Looking at the former (is that what you call it?) it was not easy removing the factory windings. There's not alot of room in there.
I think I'll do some more hand scraping on the shaper while I wait for my scales!
SimonGirl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.
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7th Nov 2019, 09:13 PM #58
Hi Simon,
No the former is the bit that you use to wind the coil on ! After winding you remove the former as its no longer needed.
The trick is that you put a layer of tape around the former that you then wind the coil onto, having first put strips of tape under that, bicycle spoke style, so that you can wrap the winding and prevent it coming apart when removing it.
I don't have any pictures that I can show you. I'll do a sketch !Best Regards:
Baron J.
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8th Nov 2019, 12:43 AM #59Golden Member
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I agree with BaronJ - it is not that hard - at the end of the day it is just a length of wire wound around a former - not really very technical at all probably there is more skill involved in your hand scraping - here's a couple of youtube links that will give you an idea of the process - each one uses a slightly different methods but end result is the same. Might help you to decide one way or the other.
https://www.youtube.com/watch?v=gJd5Ul3Kc4w
https://www.youtube.com/watch?v=maSxvrkfHNo
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8th Nov 2019, 04:43 AM #60
Hi Guys,
That first video is a great introduction to rewinding Simon's motor stator, particularly since it is so similar !
However he winds two layers at once ! This is fine for a high voltage heavy current motor, Simon's motor isn't.
So only use one layer not two ! I found it interesting that he made no attempt to keep the wires in a bunch when removing it from the former. Also he showed how to size the former to suit the stator, which was nice.
The way that he used transformer paper and super glue was very informative, I've learnt something there !
Former.jpg
This is the sort of former that I had in mind. The space underneath the windings would give you space to wrap them and keep them together. However after seeing that first video a wrap of transformer paper would do the same job.Best Regards:
Baron J.
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