How to test a blanchard magnet
Close
Login to Your Account
Results 1 to 8 of 8
  1. #1
    Join Date
    Oct 2014
    Country
    UNITED STATES
    State/Province
    Texas
    Posts
    29
    Post Thanks / Like
    Likes (Given)
    1
    Likes (Received)
    1

    Default How to test a blanchard magnet

    My operator on our Blanchard feels that the magnet is not as strong as it once was.
    She has had some small parts move on her.
    How do you go about checking a magnet?

  2. #2
    Join Date
    Jul 2009
    Location
    Peoria, IL
    Posts
    11,736
    Post Thanks / Like
    Likes (Given)
    51
    Likes (Received)
    8984

    Default

    The service manual should show a test spec. Typically it requires a chunk of steel of a specific size attached with a string to a fish scale. I can't remember if you try to slide the blank or lift it straight up. The manual will tell you.

    It's possible I'm remembering the procedure for a Mattison. But, there will be a test in the manual for your machine.

    The wires that run under the saddle to the magnet take a beating. I'd start there. You could also have issues with the brushes. If the windings are bad, obviously that's a much bigger issue. They can be re-wound. It's not cheap.

  3. Likes repairguy, cash liked this post
  4. #3
    Join Date
    Jan 2007
    Location
    Flushing/Flint, Michigan
    Posts
    7,984
    Post Thanks / Like
    Likes (Given)
    403
    Likes (Received)
    6602

    Default

    Small parts care a lot about where they sit on the poles.
    The paperclip test is the first to find out if you have lost a winding.
    If you have new(old?) voltage and current numbers these will tell brushes and wires but you likely do not have that info stored.
    Older machines with a mechanical neutrol have problems with dirty contacts on the pins and spider.
    Also in these older machine you can loose half the rectifier and it still seems to work but it is weak.
    I've never seen wires go bad without a shorting problem.
    I have had to replace worn out brushes a few times which is fairly easy. (well easy if you call pulling a Blanchard chuck an easy task...it just lifts straight off)
    If the top has been ground too thin it will be weak and this can only be fixed by a new chuck which is why we emphasize not grinding the chuck and when doing so only cleaning up what is needed and leaving the divots.

    Perhaps just blocking the small parts is an answer to the problem.
    We have to block everything, carbide and ceramics don't stick to the magnet.
    Just for giggles sake what size is the machine?
    Have you run parts in this size and thickness before without problems?
    Bob

  5. Likes cash, cattledog, Richard King liked this post
  6. #4
    Join Date
    Aug 2007
    Country
    UNITED STATES
    State/Province
    Wisconsin
    Posts
    2,078
    Post Thanks / Like
    Likes (Given)
    1111
    Likes (Received)
    944

    Default

    There is a formula for a "pull test". But you would really have to get with the mfg or reliable magnet re builder to get the exact info. You can as well do some OHM and Megger readings to see if you are getting a breakdown in the insulation.

    It as well really depends on the size and thickness of the parts you are running.

    About 2 years ago my operators were telling me we had a bad 42" Magnet. Since we have 2 42" grinders it was easy enough to put the same parts on the other machine and we did see there was a pretty big difference.

    Besides the insulation breaking down you can possibly have some issues going on with the collector ring or the brushes. On a Blanchard you need to pull the magnet off the carriage to see these parts, it is a pretty simple process. If you want to do any electrical checks you need to pull the magnet anyways. As CarbideBob said above- it is pretty simple.

    A very initial check you may want to do is make sure your chuck control is putting out the proper voltage. I assume your chuck should be a 230V chuck, make sure on C1 and C2 you are seeing 230v or about this when on FULL magnet. Make sure you remember this is DC current so make sure you use caution when doing these checks.

    Jim- if you have any further question feel free to contact me direct, you know where I am and should still have my info.

  7. Likes jim may, Richard King liked this post
  8. #5
    Join Date
    Feb 2004
    Location
    Carrollton IL
    Posts
    216
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    20

    Default Bourn & koch Blanchard parts

    Contact Bourn & Koch they bought out Blanchard and offer services parts. Their is a pull test per square inch I did one some years ago. It was listed in a Blanchard service manual on a 96" machine that I worked on. I will do some looking in my notes to see if I can find anything. Good Luck
    Brian




    Quote Originally Posted by jim may View Post
    My operator on our Blanchard feels that the magnet is not as strong as it once was.
    She has had some small parts move on her.
    How do you go about checking a magnet?

  9. Likes Richard King liked this post
  10. #6
    Join Date
    Oct 2014
    Country
    UNITED STATES
    State/Province
    Texas
    Posts
    29
    Post Thanks / Like
    Likes (Given)
    1
    Likes (Received)
    1

    Default

    Thanks everyone for the input. The Blanchard is a 42" chuck. We have had the magnet off
    our gear on that was missing some teeth.
    We are doing some small parts but in a nesting situation. Alot of our parts are in the shape of a U\
    and have been heat treated and we get some twist in them. So we shim them but a lot less surface area
    that you can magnetize to.
    I will check some of the electrical from the control that sounds like it is the easiest. Will look for the
    pull testing for that machine

  11. #7
    Join Date
    Jul 2009
    Location
    Peoria, IL
    Posts
    11,736
    Post Thanks / Like
    Likes (Given)
    51
    Likes (Received)
    8984

    Default

    I've seen that happen before. You need to clean out the labyrinth seal around the chuck OD and drill out the drain holes that go down through the saddle to drain the labyrinth seal groove. My theory is that the seal area builds up with crud and seizes up the chuck. That leads to the broken teeth.

    FYI, the gear is also the main bearing for the chuck. Replacing that gear will require the bearing to be scraped flat using a qualified surface and then the saddle has to be scraped to match the new bearing surface.

    I did this same repair a few years ago. It chronicled here along with some other nasty surprises.

    Repairing severe wear on Blanchard grinder

  12. #8
    Join Date
    Jul 2005
    Location
    Cottage Grove, MN 55016
    Posts
    7,659
    Post Thanks / Like
    Likes (Given)
    4120
    Likes (Received)
    4566

    Default

    If you pull the chuck off be sure to clean before hand to avoid dropping crud into the bearing area. Also plan on draining and replacing the sump oil while it is off. Missing teeth on the bull gear sound like an accident waiting to happen. I have had several Blanchard's apart too and I will be teaching a scraping / machine rebuilding class at Bourn & Koch August 19 - 23 and if you come we can talk directly with the people who build and rebuild those machines. Also you may want to have a plate cut with a water jet to lay on the magnet to trap those U shaped parts in say 1/2 the thickness. This helps a lot. Plus what the others said about the pull test and electric test. Bourn & Koch bought out Blanchard. If I can help please email me at [email protected] and I can get you to the right person at B&K.
    Note center picture shows the brushes in the base. Also picture shows how B&K replaces the wear pads with Rulon/Turcite and it's scraped.
    20180316_101044.jpgimg_20150527_062906230.jpg20160315_145114.jpg


Tags for this Thread

Bookmarks

Posting Permissions

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