Page 2 of 3 FirstFirst 123 LastLast
Results 16 to 30 of 34
  1. #16
    Join Date
    Sep 2005
    Location
    Bendigo
    Age
    60
    Posts
    419

    Default

    Have you googled for information on the particular model of pump / motor you have ?

    I dont know what model yours is so just looked for general Grundfos info:

    http://net.grundfos.com/Appl/ccmsser...ature-6692.pdf

    In section 10.8 it has instructions for stator removal

    4. Block up the stator housing so that it stands on the flange at a height where the stator can come outunderneath.
    5. Heat the stator housing until the stator drops out. Heat the stator housing uniformly so that it is not deformed.When using a gas burner, to approx. 200 °C. When using a pre-heated oven, to approx. 300 °C.


    Other video's I found online show Grundfos stator being pressed into the housings in a robotic production line.

  2. #17
    Join Date
    Jun 2010
    Location
    Canberra
    Posts
    1,322

    Default

    I hadn't thought of Googling for that (I did hunt around to see if I could get the stator and housing as a spare part).

    Useful info, suggests I might be on the right path?

  3. #18
    Join Date
    Jul 2006
    Location
    Athelstone, SA 5076
    Posts
    4,255

    Default

    Quote Originally Posted by droog View Post
    Have you googled for information on the particular model of pump / motor you have ?

    I dont know what model yours is so just looked for general Grundfos info:

    http://net.grundfos.com/Appl/ccmsser...ature-6692.pdf

    In section 10.8 it has instructions for stator removal

    4. Block up the stator housing so that it stands on the flange at a height where the stator can come outunderneath.
    5. Heat the stator housing until the stator drops out. Heat the stator housing uniformly so that it is not deformed.When using a gas burner, to approx. 200 °C. When using a pre-heated oven, to approx. 300 °C.


    Other video's I found online show Grundfos stator being pressed into the housings in a robotic production line.
    thats is how we used to remove stators on large semi hermetic refrigeration compressors...120 hp etc...lots nn lots n lots of heat...3 flame throwers all going at once...did I mention lots n lots n lots of heat

  4. #19
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,439

    Default

    Hi Rusty,

    Quote Originally Posted by RustyArc View Post
    But there's nothing solid for those lips to engage - there's a slight ridge where the laminations end and the coil former starts, but I can't image being able to hook onto that.

    Actually there doesn't appear to be any epoxy or varnish anywhere, but I could be wrong.
    What is all that stuff ringed in red ? It looks like Epoxy or varnish to me !

    IMG_3081.jpg

    There looks to be a small lip of laminations, but whether you can get underneath it to lock puller lips onto it is debatable.

    Edit: When I posted this, I had not seen the previous posts.
    Best Regards:
    Baron J.

  5. #20
    Join Date
    Jun 2010
    Location
    Canberra
    Posts
    1,322

    Default

    Quote Originally Posted by BaronJ View Post
    What is all that stuff ringed in red ? It looks like Epoxy or varnish to me !
    I think it's kapton tape or something similar.

    There looks to be a small lip of laminations, but whether you can get underneath it to lock puller lips onto it is debatable.
    Looking again, the lip is bigger than I remembered, however I think if I went in that direction, to get more surface area engaged, I'd probably machine a 1/4" thick disk of steel to a tight fit, slice the middle out of it so two bits can be lowered down to the bottom, then have some kind of expanding mechanism to hold it in place (in place of your bit of wood) and then some threaded rods coming up for pulling purposes.

    However, for the moment I'm going to continue with the freeze-heat-smack down on the bench approach. I had one attempt today: -20C out of the freezer, one pass around the outside to bring it up to 100C then a second to bring it to 200C, then smacked it face down numerous times onto a sheet of cement board protecting the bench. No movement in the stator, so I think I'll just repeat the process up to 300C. Bit iffy about bringing one side up to full temp in one go, but may have to go that way if I want maximum difference in temperature between the stator and the housing.

  6. #21
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,439

    Default

    Hi Rusty,

    Quote Originally Posted by RustyArc View Post
    I think it's kapton tape or something similar.
    No not the spaghetti, that transparent yellow stuff.

    The spaghetti is that white woven glass fibre tube slid over the wires to insulate them.
    Best Regards:
    Baron J.

  7. #22
    Join Date
    Jun 2010
    Location
    Canberra
    Posts
    1,322

    Default

    Quote Originally Posted by BaronJ View Post
    No not the spaghetti, that transparent yellow stuff.
    Yep, kapton tape.

    https://www.jaycar.com.au/heat-resis...-50mm/p/NM2817

  8. #23
    Join Date
    Jun 2010
    Location
    Canberra
    Posts
    1,322

    Default Success!

    Well that was all rather satisfactory.

    IMG_3096.jpg

    Brought it out of the freezer and up to 250 degrees, tapped it on the bench and the stator slid out part of the way, stopping as it met the bench, so set it face up and re-applied heat, trying to make sure I didn't get any heat on the exposed portion of the stator, and after a few seconds, the stator dropped down again into place, so I quickly flipped the housing over and the stator just dropped onto the bench, no thumping required.

    Stator was only about 100C or so, so hopefully haven't triggered any other thermal fuses in the windings (assuming that's what the culprit is).

    So now to let it cool, and work out how best to unwind the suspect coil.

  9. #24
    Join Date
    Jun 2010
    Location
    Canberra
    Posts
    1,322

    Default

    The next bit, unwinding the faulty coil, ended up being a less than pleasant nor quick process.

    While I couldn't see any varnish on the outer windings, it certainly had it throughout the rest of the coil, making removal a fairly destructive process. But I got it all off in the end.

    IMG_3097.jpg

    So it turns out there was no fuse, but a small, burnt out break in the second or third last winding before reaching the former. There was slight discolouration in the enamel of the winding below, but no evidence of widespread heating, making me think it was a damaged (pinched or nicked) part of the wire that had higher resistance and initiated the failure, so perhaps it was just a manufacturing fault, and nothing to do with getting wet. However, the coil in question was the lowest in the motor, so would have been immersed for the longest period, making hard to dismiss immersion as a factor.

    Next challenge is rewinding the coil. The wire measures 1.02mm dia, so I'm going to assume it's nominally 1mm dia wire, although I'd have thought the enamel would be thicker than 0.01mm. I weighed the chopped up bits of wire at 88 grams, I can get a 100g roll locally for $16. So I could have a go at rewinding it, but there's a few challenges: I don't know how many windings to apply. I could either try and measure the total length of the removed bits, and cut my new wire to that length and wind on all of it, or I could use weight to do the same. Given the chopped up bits are not straight, the error between the length versus weight approach might be pretty similar.

    IMG_3099.jpg


    Then there's the varnish. I think it has to be there, otherwise the coil will buzz and maybe heat up, but I think I'd need to apply it layer-by-layer somehow.

    I'm tempted to take it to the local rewinder to see what they think...

  10. #25
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,439

    Default

    Hi Rusty,

    Just weigh out the wire and wind it on the former, keep it neat. 10 grm isn't going to make a lot of difference. When finished just dribble shellac or yacht varnish over it and let it dry. Wire it all back up and reassemble and test.
    Best Regards:
    Baron J.

  11. #26
    Join Date
    Sep 2005
    Location
    Bendigo
    Age
    60
    Posts
    419

    Default

    Then there's the varnish. I think it has to be there, otherwise the coil will buzz and maybe heat up, but I think I'd need to apply it layer-by-layer somehow.
    The normal way was wind the coil, dip it in varnish, then bake it in an oven.


    As for failure, yes the water would have played a major part, for whatever reason there has been a failure of the insulation water getting in corrodes the wire causing a higher resistance. The heating from the higher resistance multiplies the effect until it fails, the heating can be very localised and only appear as a spot on the winding.
    Dipping the coil in varnish should protect it from any localised minor damage to the enamel caused during the winding process.

  12. #27
    Join Date
    Jun 2010
    Location
    Canberra
    Posts
    1,322

    Default

    Between school and uni I worked in a power tool shop for a year that also did rewinds, in hindsight I probably should have paid more attention to what the rewinding guy did. At the time I just used him for a supply of really nice silicone wire for an amplifier I was building.

    I can't really dip the coil in varnish, but I'm thinking I could try using aerosol circuit board laquer which might serve the same purpose. Also toying with the idea of using the odd dot of superglue to hold the windings in place as I go.

  13. #28
    Join Date
    Oct 2015
    Location
    melbourne
    Posts
    473

    Default

    Could you elaborate on why you can't dip in varnish?
    I am Iikely missing something, but tin - varnish - dip- drain?

  14. #29
    Join Date
    Jun 2010
    Location
    Canberra
    Posts
    1,322

    Default

    Quote Originally Posted by russ57 View Post
    Could you elaborate on why you can't dip in varnish?
    I am Iikely missing something, but tin - varnish - dip- drain?
    Well, first I'd need some varnish I guess, and I'd need to remove it from the outside of the stator before putting it back in the housing, but apart from that, I probably could.

    I'll see how I feel after winding it all on. Which I've started. I think I've done maybe 8 turns so far. Not a fun process.

  15. #30
    Join Date
    Jul 2006
    Location
    Canberra
    Posts
    288

    Default

    Interesting repair you're working on. There is a freely available old textbook on motor rewinding available at the internet archive, might be useful:

    https://archive.org/details/Armature...agen5/mode/2up

    Also look at the 'similar items' that come up at the bottom of the screen - there are a few books on aspects of motor repair there on ia.

Page 2 of 3 FirstFirst 123 LastLast

Similar Threads

  1. Cleaning stator windings on a grinder
    By Bryan in forum METALWORK GENERAL
    Replies: 14
    Last Post: 24th May 2012, 03:52 PM
  2. Dead Bench grinder?
    By jimmyratsbreath in forum METALWORK GENERAL
    Replies: 13
    Last Post: 29th Oct 2011, 12:59 AM
  3. 1/2 notch dead centre
    By tanii51 in forum METALWORK GENERAL
    Replies: 2
    Last Post: 15th Feb 2010, 08:46 PM
  4. CIG Eaywelder EC - dead
    By nexusone in forum WELDING
    Replies: 11
    Last Post: 24th Nov 2008, 10:26 PM
  5. #2mt Dead Centre
    By DJ’s Timber in forum METALWORK GENERAL
    Replies: 11
    Last Post: 24th May 2007, 08:50 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •