servouser wrote:I bought everything directly from the manufacturer. They are the right ones. Even with the screw, I can turn the horn back and forth by about +-3 to 4 degrees easily without force. Is this common? How many degrees of such turning is considered to be acceptable? Of course, I prefer one that is perfectly, tightly fit.
No this is not common and there should be no significant play in the spline joint. If you are sure the horn is meant to fit the servo in question but it is loose, it is a manufacturing problem. Either the shaft is undersized or the horn is oversize. As you say the horn fits correctly on the other servo it is meant to fit, it sounds like the shaft is undersized on the servo in question. You have purchased directly from the manufacturer so the best course of action is to contact the manufacturer with your problem and have them rectify the issue by either replacing the faulty servo or sending the correct horn if indeed it turns out that there was an error in the documentation and that the servo in question DOES require a different horn. That is the correct way to solve the problem.
In a pinch, the problem could be fixed, but only as a last recourse and it's not easy. You would have to make up the space by using a metal filled epoxy and use a release agent on one surface of the splines. Doing this would in theory allow it to release so you could take it apart but it is by no means a sure thing as the joint is small and hard to make sure it is fully coated with a release agent. Any spot not coated properly would be permanently bonded which is not a good thing.
So I would contact the manufacturer and if needed, return servo and/or horn for replacement. If the manufacturer does not stand behind it's product, you should take your business elsewhere.
Regards
Christian