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bonding magnets to drain plugs

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  • bonding magnets to drain plugs

    I have some nickel plated rare earth magnets from Lee Valley which I want to glue on to steel drain plugs (for gearboxes).

    Don't suppose they'd move anyway but I believe it's standard practice to have them attached.

    What's the best product to use for this job?

  • #2
    Herb --

    I'd be inclined to bore a recess into the drain plug and glue the magnet into the recess. Just about any oilproof adhesive should work, but I'd lean toward an epoxy such as J B Weld.



    • #3
      JB weld, supermend, or a flexible epoxy, maybe loctite has a product. I wouldn't use any of the standard epoxies, they're just not that good and won't hang on with the temperature changes. The recess is a really good idea, but don't make it a press fit, let the epoxy fill the gap. Coat the magnet also.
      I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-


      • #4
        Use this stuff that I found when looking for something for Thrud. Oil makes it stronger.

        The description:

        LOCTITEآ® Hysolآ® Product E-214HP is a light paste, industrial grade epoxy adhesive. This one-component, no-mix, heat activated formulation develops tough, strong, structural bonds which provide excellent peel resistance and impact strength. When fully cured, the product offers superior thermal shock resistance, excellent mechanical and electrical resistant
        properties, and withstands exposure to a wide variety of solvents and chemicals.

        Bonds to a wide variety of materials, including metals, glass,
        ceramics and plastics.

        Try this link:

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        • #5
          Herb, I bought some of those magnets and they work great. I thought about doing the same thing, but the plating is pealing off the magnets and I don't want that in my oil. Don't know if they all do that or not. You could cover the magnet with jb weld to prevent the plating from coming loose.


          • #6
            They don't do that unless broken or defective. Contact Lee Valley and they will replace them.

            If you machine a recess for the magnet as JG suggests you will not need the adhesive. You will also never get the magnet out again and its attractive force will be multiplied quite a bit. The steel cups LVT sells for these have a slot milled in them to use a small prybar...I mean screwdriver to "pop" them out. Yeah, you can pop them out, if you can get a pryb...screwdriver under the magnet!

            If you add a small amount or RTV or Permatex #2 on the back of the magnet and then set it in the recess it will never come out. Set it even or slightly below the surface of the plug to prevent damage to the magnet if it grabs on to some steel accidentaly.

            We used to glue Magnetron magnets in rear end covers and tranny pans - it is a bitch to clean off the filings off of them.

            [This message has been edited by Thrud (edited 09-24-2003).]


            • #7
              Like Thrud, I have used magnetron magnet CHIPS (which don't hold as well as the unbroken stuff), in oil pans, transmissions, lawn mowers etc. They really don't shift. I doubt I would epoxy them in place- epoxy surely would not hurt, but I don't think those Lee valley magnets will shift.

              BTW: Hard drives have some good magnets in them. Small capacity hard drives are worth pennies in flea markets around here- they may not be working, seller may think he has fooled his customer, but if the case is good there should be good magnets in there.

              I needed a timing mark (old mark needed mirror and eyeball on a stalk like a crabs to see. I put one of the Lee Valley magnets on the engine- not a real flat surface either- and forgot to take it off. The corner I used for marking still agrees with the manufacturer's mark after years and thousands of miles. I would not even epoxy, and I just try to slide the magnet through the drain hole and let it lay on a magnetic surface. The number of "whiskers" on the magnet are scary,

              Edit comments: 1>I failed to consider the nickel plating peeling- Maybe the old alnico chips would be better than those Lee Valley magnets.
              2. THose lee valley magnets are so strong that that if the crank shaft is on the down stroke and near the magnet, your starter won't break the shaft loose. and you will lose 10 HP, the induced currents in the crank shaft journal will weld the bearings.

              GO on gents- First liar ain't got a chance!!!

              [This message has been edited by docsteve66 (edited 09-24-2003).]


              • #8
                Quite so doc...the largest size of these magnets (1"dia) must be used with great care.
                Been known to suck C clips from axle shafts.

                Also been reported that owners of precision lathes like say a Monarch 10ee or a Hardinge have to be very careful... one of these stuck anywhere on the machine can cause enough distortion to affect the accuracy of the work by .0000002 maybe even .0000003". That kind of gross error drives those poor guys right wild...


                • #9
                  These magnets may be found on the laser head in a CD-Rom drive. They are tiny, some as small as .01 square. Handling these require great care as they are incredibly powerfull. I took apart such a drive once and dropped one of the magnets on the floor. Luckily, there are always two. To find the dropped one I waved the other about 3 feet above the floor. I suddenly felt excruciating pain in the finger holding the one I was waving. Imbedded in my finger was the lost magnet. I tried to pull the other magnet off my finger but that only succeeded in pulling the one that punctured my finger deeper. I finally hit upon the answer. Using a soldering iron and ignoring the terrible pain I heated one of the magnets above the Curie Point so it lost it's magnetism. I was then able, through a red haze, to pull the imbedded magnet out of my flesh. BE CAREFUL!!

                  [This message has been edited by Evan (edited 09-24-2003).]
                  Free software for calculating bolt circles and similar: Click Here


                  • #10
                    Holy cow! I can see these hip boots aren't high enough. 'scuse me while I go find my chest waders.
                    Lynn (Huntsville, AL)


                    • #11

                      [This message has been edited by pgmrdan (edited 03-08-2004).]


                      • #12
                        You really do have to be careful with those new magnets. If you are carrying more than a few at a time, you have to walk east to go north, and west to go south. Be very careful when getting in and out of a vehicle, and never go into a metal building alone.
                        I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-


                        • #13
                          Uh. What about attaching it to the outside of the drain plug?


                          • #14

                            Unfortunately, that won't work. Steel has fairly high magnetic permeability, meaning that it basically short circuits the magnetic field. The field mostly can't penetrate the steel. It would be possible to magnetize the drain plug but steel doesn't make a very strong magnet.
                            Free software for calculating bolt circles and similar: Click Here


                            • #15
                              I was worried about the magnet coming away and going into the works of the engine, but in hindsight, they stick so well that unless another piece of metal comes in contact over a significant area of the magnet, it isn't going to go flying off anywhere. I'd still want to coat it over with whatever you use to hold it in place, as a wear resistant coating (you'll be wiping metal bits off of it when cleaning it), and to keep it's own coating intact.
                              I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-