Bigger Hammer
Dear Dave: A proper coupling fit is not a slip fit. If the coupling you removed is the same one you are trying to place back on I'm surprised that it is so difficult. Usually when a coupling is forced on years ago and then removed , the opening of the bore will have become larger. It’s not uncommon to have to replace the coupling halve to get the tolerances back to normal. When a coupling is bored it usually is bored with a -.001 fit or "blind clearance". This will require you to use some device to persuade the coupling back on. Hence the term bigger hammer. This may include tapping it on with a rubber mallet. You may try a slight chamfer to the end of the shaft being placed in the coupling. Try using some 300 to 600 wet and dry sandpaper to both the end of the shaft and to the bore of the coupling to remove any calcium or other rusts and foreign material. If the coupling is a new coupling you may have to have the coupling and shaft taken through a procedure called fit and face. This is were the coupling is fitted to the shaft and the contact face of the coupling is then machined so that it is perpendicular to the bore and shaft. Hope this helps, Sincerely, Kevin L. Woody
