Broher HS-50A eating a lower brush part
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    Default Broher HS-50A eating a lower brush part

    Hi

    I hope someone could help me with our Brother HS-50A wire EDM machine, which have been serving us well last 20 years. But now I have an issues, which I cannot solve. Machine does not cut well, it's very slow and cutting a groove on lower brush part very quickly, in half an hour. We have dismantled the lower section few times and made a new cable connections, but problems still persists. For me it looks that there is some issues in connecting the electricity to the wire.

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    The traveling wire by itself will not wear the carbide contact in any manner, so the wear you're seeing is the wire arcing against the brush.
    So, first thing is to make sure that you have plenty of brush coolant.
    You can test it by turning down the flush volume ( the flowmeters ), turn on water, cheat the float with your finger and you shoudl have a good amount of water gushing out at the contact.
    Brother for some reason thought it to have any value in putting on a valve in the coolant loop, even though it's best to have it always full-on.
    That brass valve is the lower left of the three in the font panel, make sure it's wide open.

    If you don't have any ( or just minimal ) amount of water coming out, remove everything from the lower head and do the same test.
    If that is still not showing any water, then you gotta remove the lower head ( just the brass head, not the insulator yet ).
    Check the passages of the water.
    I believe there are 2 water connections, one for the flush, the other is the coolant.
    The head removal can be a bitch as the two setscrews are small, facing up and the stupid little rubber plugs corrode away in a hurry.

    Before going any further, check these and report back.
    Power connections MIGHT be your problem, but I suspect the cooling of the power contact is what's lacking.

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    Thanks for the advice. Our guys tried to check the water flow, but they don't find any problem. It cuts about 15 minutes and then gives alarm "8033 SHORT CIRCUIT 2", which relates to worn brush.

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    It seems that our guy found the guilty part. It's probably the wire roller after the contact part. There was deep groove on it and by making a new roller make the machine run again.

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    Yupp, that would do it also, though it had to be a really deep groove ( don't ask how I know ... )
    What was probably happening is that the wire was riding in and out of the groove and it's walls, causing an intermittent loss of contact with the brush.
    Surprised you didn't get any wire breaks!

    While at it though, you should be able to source new bearings as well and replace them.
    I do it every 1000-1500 hours or so. Cheap insurance against seizing and keeps the wire travel smooth.

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    I have lots of Brother power pins but I have an easy way to assure lower power pin cooling without disassembly of the lower head.
    Simply remove the lower wire guide from the head assembly and drill a .031 dia. hole in the hollow cylinder of the guide. This will allow a small amount of the high pressure flushing, when rough cutting, to inter the inside of the guide and exit out onto the power pin. Oh yes deep grove in the lower roller shorting! Been there done that. I have about as many rollers and bearing as power pins. See attached.

    Regards,
    John

    img_0833-1-.jpg

    Why don't we all partition Brother to start making the HS70AM wire EDM machine again?!!
    I'd order five today.


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