Propeller Shaft Bushings

This is the first ship I have built since Diana gave me the lathe (don't I have a wonderful wife!?). Instead of using small bits of telescoping tubing I decided to make proper bushings for my propeller shaft assemblies. To make things a little more interesting I decided to make them tight enough for an interference fit so I would not need to glue or solder them.

I made two sizes of bushing for each shaft assembly housing. Both have a #30 through hole (which is just a bit bigger than 1/8"). Both are 0.1900" diameter for the length that gets pressed into the 7/32" shaft assembly housing. However, one has an overall diameter of 1/4" and the other 7/32".

The 7/32" bushing will go at the end of the shaft assembly that will be outside the boat. It will slide through the stuffing tube. The 1/4" bushing will go at the end of the assembly that remains inside the boat. It will not slide through the stuffing tube so the shaft can not fall out of the boat. It will also insure there is always a nice brass surface protecting the stuffing tube from wear.

The process is pretty simple. However, it requires a very accurate tail stock. You might want to read my post on Improving the Accuracy of Mini-Lathe Tails-tock. Do not attempt to do this if you do not have an accurate tail-stock. All of these operations were done at 120 rpm.

1. Face the end of the 1/4" solid brass rode
2. Use a center drill in the tail stock to start a hole dead center on the rod
3. With a 1/8" drill bit in the tail stock drill 3/8" into the rod
4. With a #30 drill bit widen the hole down to 3/8" deep
5. If this is one of the bushings that needs to slide through the stuffing tube turn 1/4" of the rod down to 7/32"(-)
6. Turn 3/16" of the rod down to 0.1900"(+). Do not make it smaller than 0.1900 and not larger than 0.1920 or you will need to solder or glue the bushing into the brass rod.
7. Part off 1/4" from the end of the rod, debur and press into the housing for your propeller shaft assembly.
8. For a bushing that need to fit through the stuffing tube I turn a few more thousandths off of it and the end of the brass rod it was pressed into. It makes it a little cleaner looking and easier to insert through the stuffing tube.

This does not lend itself to pictures as the parts are small.. Here is a a picture taken after step six for a 1/4" bushing.

Lots of people will tell you that you need to solder the bushings into the assemblies. That has not been our experience. Most of us have been gluing them in for years without any problems.

Don't Have A Lathe?

I didn't until recently and most of us still don't. You can get great results but cutting small pieces of consecutive sizes of telescoping brass tubing and gluing them into the assembly. They only cost a couple of dollars to make and you will get five or six years out of them before needing to replace them.