[Milsurplus] Dynamotor Repairs

[jimandterri at bellsouth.net]

It is with  interest that I have followed the contributions on  dynamotor repairs. I have something further to add to the discussion.
 Some time ago, I picked up a DM 21 dynamotor for my BC 342   only to discover later that the zinc end castings were cracked and shattered. in this  model dynamotor there is an abundance of damaged end castings and that makes for lots of Junkers and not so many extra  castings. (of course, I myself picked out a Junker)
almost as an afterthought before throwing the broken parts away, I decided to try super glue, now don't dismiss the idea as entirely misguided, the application of Cyanoacrylate (Super Glue) is at its best in jagged porous closely mating surfaces and that's just what I had with the cracked castings.  I carefully cleaned and dried the castings to remove all the oil that had migrated and absorbed into the cracks and fissures I repeatedly used  commercial cleaning solvents in a spray can, cleaning is one of the most critical steps to success and must be done properly. Drying of the solvents will be expedited with low heat for several hours. If the damage is severe you will have to get the alignment of the parts correct, I carefully reassembled the parts using masking tape on the armature to maintain some semblance of alignment and clearance  also keeping a light pressure pushing the castings toward each other. I then did the initial gluing followed a day later by several more sessions with the unit back apart. Here's the surprising thing, I used "Super Glue" brand glue that I got from  "Big Lots" this is the kind in a tiny 0.10 oz bottle with a yellow label and red fluted top. this glue (when new and fresh) is extremely thin and has a penetrating and wetting action that is ideal for filling spider web cracks in grainy, porous zinc. I let things harden for a day and cleaned up the excess on the flanges with a file. When I was done, I could suspend the bare casting on a piece of wire and could hear it "ring" when tapped with a small screw driver. Houston: we have integrity!
The dynamotor was saved and runs fine.  Might work for you too, if not, there's nothing much lost for the effort.

Steady as she goes Captain.
Jim Solsbury.