Fitting Tenons and Receivers

This is the process we use in the shop on students flutes and saxophones in fitting the tenon/receiver area.

The first step is to determine whether the tenon and receiver are both round. There's nothing like trying to fit an oval peg into a round hole! For this we use what we call "plug gages". These are steel rods two inches in length and of varying diameters to fit the receivers in the different brands of flutes and saxophones. The correct fitting plug gage is inserted into the tenon and the tenon is "coerced" into round by tapping with a rawhide mallet. This step is especially needed for flutes that have their brand stamped instead of engraved on the receiver.

The tenon is then put on an expander. The expander has several fingers that are spread by a tapered shaft being tightened as the handle is turned. A small turn of the handle is all that is necessary. The head joint or neck is pulled off the expander while being rotated. From here on out the process is: expand a tiny bit and test the fit, expand a tiny bit and test the fit, etc. If a tenon is over-expanded <gasp!>, shrinking dies can be used to reduce the tenon size and then expanded to fit again. Once a good fit is obtained, this is the end of the journey for tenon fitting on play condition repairs.

Overhauls and repads are taken one step further. The tenon and receiver are then "lapped" to a "silky smooth" fit using a water-soluble lapping compound. Bits of the minute abrasive suspended in an oil-based liquid are brushed on the tenon and in the receiver. The two pieces are assembled and turned and turned and turned until the proper fit is obtained. This creates a nice mess that is taken care of when the instrument is disassembled and cleaned in preparation for the repad or overhaul. However, the results are a smooth fit and airtight seal.

Posted 8/29/2005 @ 1:30 PM | Band Instrument Repair

Thank you Michelle for such a great web site.
Please Help! I used an expander I bought from Ferree tools to expand my old Conn Alto neck, and it worked great. It was a little out of round and after being very careful I got a perfect fit. So I decided I was ready to tackle my Selmer Mk VI. Ha ha. It had the exact same problem as my Conn. I thought I was really being careful, but I've got a very tight fit. Too tight! You mentioned using the shrinking dies. It looks like you have the dies from Ferree tools. Is this what I need to purchase to save me from me? Ha ha. Also, you mentioned the "Plug Gages". I haven't seen them in any of the catalogs. Where do you get them?
Thanks

Posted by James Bentley on 10/5/2005 @ 12:06 AM

Hi James,

Is the fit just tight or will the tenon not go into the receiver at all. If the fit is just tight, buy some lapping compound - lapping compound and lap the receiver in (you'll probably need to take the octave keys off to do this)

If it's a case where the tenon will not go into the receiver at all, then yes, you'll need to buy a tenon shrinker.

Plug gages: Example here. I get singles from Vermont Gage and sets from Ebay.

Glad you like the site!

Michelle

Posted by Michelle (email) on 10/5/2005 @ 2:39 PM

The neck does still fit in the receiver. It's just really tight. I have some lapping compound so I'll try that. Thank you very much Michelle for the info and the links.
James Bentley

Posted by James Bentley on 10/7/2005 @ 12:14 AM