[PSUBS-MAILIST] magnetic coupler

[hank pronk via Personal_Submersibles]

 Sean,I did several strong tack welds all around the ring first, then I did short welds  between the tacks, then I ground out the tacks and welded all the way around in steps, just like you said, a bolt pattern.  I did four passes because it is only 3\8 material and full penetration of coarse and a pre-heat. Hank
    On Friday, November 24, 2017, 12:08:31 PM MST, Sean T. Stevenson via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  
 
 Took me a moment to visualize what you were talking about. Lucky there was no damage.

In order to minimize distortion, another good thing to do is to make a lot of initial tacks around the perimeter, and then complete the weld in small steps, moving around in a similar fashion to a bolt torquing pattern, depositing limited amounts of heat in any single location until the weld is complete.

If you physically constrain your parts with a jig or other assembly to limit deflection, the joint will likely carry more residual stress when the weld cools. Depending on how critical the joint is, such a joint may be a good candidate for stress relieving via post-weld heat treatment.

Sean


-------- Original Message --------
On Nov 24, 2017, 10:54, hank pronk via Personal_Submersibles < personal_submersibles at psubs.org> wrote:


Hi All,I did a very bad thing by mistake ;-(  I almost wrecked my magnetic coupler.  I welded the mating ring in for the drive unit and to help stop the ring from distorting to much.  I bolted the propeller shaft tube assembly, witch is a 5\8 plate to the ring.  After welding it up I was admiring my welds ;-)  and suddenly noticed the propeller shaft was still in the tube, that means the magnet  drive and barrier was still under the plate getting very hot!  Magnets don't like HOT so I scrambled to remove the plate and get it outside in the cold to cool it down.  Luckily the air space between the barrier and magnets insulated the magnets and they are okay. Whew!!!   I am sure glad I mig welded it so it only took 15 minutes, preventing the plate from getting even hotter ;-)Hank_______________________________________________
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