HLV-H With a Noisy Brake Solenoid - Page 2
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  1. #21
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    Your post got me looking at my brake. You know when it has been a while since you last checked stuff when there are cob-webs inside the cabinet.
    It was not adjusted so I fixed that.

    I ran the lathe with and without brake stopping. My observation is that the brake is going to save a little time when running in the high speed range, like over 1000 RPM. Otherwise it's just a second or two.

    When the brake is in use the cork will engage the motor flywheel when the spindle is stopped. This prevents the operator from rotating the hand wheel. But I will often rotate and measure when I am creeping up on a dimension.

    Tip: I had coated the threads on the round adjustment nut with some gray anti-sieze paste. I do not regret that.

  2. #22
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    Thanks for the tip about coating the threads on the round adjustment nut... I'll do that.

    Not having the brake is not that big of a deal to me honestly... I'm just the kind of person who wants everything to be working as intended I guess. I'm going to try the Locktite / clamping trick that has been suggested tonight. Should that fail, I will probably make a new bracket and install a different solenoid. I checked with Hardinge and they don't stock that part any longer. Parts Source Center can get me one, but it's an 18 week lead time and costs upwards of $500!

  3. #23
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    I'm happy to report that I got this issue sorted. It involved milling all the connecting faces in the solenoid down to be perfectly flat and exposing fresh laminations. My unit was badly damaged from being operated with no retaining bolts, so the solenoid basically hammered itself to death, deforming all the faces and swaging the laminations together diminishing its holding power. I will elaborate tomorrow on exactly what happened and how I fixed it with photos.

    Also, Bill was 100% correct in his cracked copper loop diagnosis. It was just that, along with deformed connecting faces.

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  5. #24
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    Default How I fixed my brake solenoid

    OK, I promised I'd go into detail about this. When I bought this lathe I knew there was a problem with the brake. it buzzed very loudly, but was otherwise working. I figured I'd clean up the solenoid and all would be right with the world, yeah? NO! Not at all...

    When I got it apart I realized that both bolts that attach the solenoid to its mounting brackets were badly worn and had sheared off. The solenoid was literally just flopping around inside that housing. The fact that the brake was working at all is a testament to something, although I'm not really sure what... At any rate, because nothing was held firmly every time the solenoid retracted, it did so as some random angle, denting, swaging and otherwise deforming the mating faces. It has also deformed and cracked the copper loop that Billtodd mentioned in earlier in this thread.

    So repairing the crack was the first order of business, but that didn't resolve the issue. The solenoid was silent under no spring load, but any downward pressure on the lever caused it to buzz loudly. I visited an electric motor repair shop yesterday and they were able to help me understand the second problem. Namely that the angular strikes had swaged the laminations together on the mating faces of the solenoid body and armature. This is evidenced by the lack of distinct laminations visible in those faces. Consequently those distinct laminations were essentially shorted out on the faces, resulting is extremely diminished retracting and holding power.

    img_2001.jpg

    The faces were also deformed and not remotely flat. The solution was to mill them flat and to remove the swaged material to expose fresh laminations. A surface grinder would have probably been better, but I don't have one, so onto the FP-1 it went. The solenoid body had a large, flat reference surface on the back, so I milled those faces parallel to that. I was very careful to use a dial indicator to ensure the armature was perfectly vertical before milling the faces on it.

    img_2012.jpg

    The trickiest part was making sure to remove exactly the correct amount of material such that all three mating faces would come into contact. Not tricky really, but just a matter of keeping track of how much got removed and repeating it on the other faces. it took a few passes because I really didn't want to remove any more material than absolutely necessary. In the end I took about 10 thou off each face to expose a completely fresh and undamaged surface. Below are the surfaces I machined:

    img_2010-2.jpg
    img_2001-2.jpg

    After milling these surfaces and ensuring that all three mated smoothly and completely I reassembled the actuator mechanism and housing. Not only does the solenoid have vastly increased holding power, but it is now completely silent. I want to thank everyone who has commented in this thread to help me. I learned a lot during this experience and I really hope that this helps someone else who is having a similar problem. It's amazing how much money they want to replace this simple device, so the more time we can get out of the ones we already have the better!

    Cliff
    Last edited by crpearson; 06-05-2019 at 05:05 PM. Reason: Added conclusion

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  7. #25
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    Here is a pdf from Detroit Coil. https://www.rossdecco.com/support-an...our-literature
    Pages 3 - 5 are informative.
    I bought from these guys for repair of a 14" Cincinnati O.D. grinder that had Namco coils that failed.
    Congrats on your repair
    John

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  9. #26
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    Quote Originally Posted by crpearson View Post

    The faces were also deformed and not remotely flat. The solution was to mill them flat and to remove the swaged material to expose fresh laminations. A surface grinder would have probably been better, but I don't have one, so onto the FP-1 it went. The solenoid body had a large, flat reference surface on the back, so I milled those faces parallel to that. I was very careful to use a dial indicator to ensure the armature was perfectly vertical before milling the faces on it.

    img_2012.jpg
    I use diamond lapping plates to finish off something like that. Slow process but always produces a mirror finish. Woodworker's Supply of New Mexico has them.

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  11. #27
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    Quote Originally Posted by rons View Post
    I use diamond lapping plates to finish off something like that. Slow process but always produces a mirror finish. Woodworker's Supply of New Mexico has them.
    To begin with I tried stoning them, but they were actually quite far out of flat. So much so that I was worried I'd stone in some oddball angle and screw things up more. I took off as little as absolutely possible to expose a flat surface with fresh metal before lapping them slightly on a Japanese water stone. Certainly didn't take it to a mirror finish though. Do you think that makes a big difference? I could easily dig back into it and lap them further.

  12. #28
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    Quote Originally Posted by crpearson View Post
    Certainly didn't take it to a mirror finish though. Do you think that makes a big difference? I could easily dig back into it and lap them further.
    Not a big difference but I would do it anyway. Better than using 320 or 400 grit on a flat plate. With paper the edges of what I try to get flat rounds over slightly. With a diamond impregnated plate the edges stay sharp.

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  14. #29
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    Thanks Rons! I'll do that. Good thought!

  15. #30
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    Just a little observation:
    I bought a couple of diamond lapping plates a few years ago. I like the ones I bought 30 years ago a little better. The grade of diamond and/or how they are bonded to the steel plate is all I can think of.

    I guess you can ask the question before a purchase:
    "Are these plates conflict diamond free?" LOL


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