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Posted on April 30, 2016 One of the most interesting bushing arrangements can be found on U.S. Wind Energy sheaves in the CDP and in the wood rollers. Brilliant use of a steel outer wheel with a farmer replaceable oak center axle bushing. A good oak center bushing would last a long season of heavy use or a couple years of normal use. When spent the farmer simply pulled the cotter pin on the bolt (no nuts….no threads) and the sheave just comes out. For those of us that have seen the damage done over the years, well, I have huge respect for the U.S. Wind Energy designers!
Lets replace one with a beautiful oak bushing!
1. The steel wheel looks like this when empty.
Examine the square hole and you will see that one side has two opposing tabs inside the whole. Those are stoppers for the new oak block. IMPORTANT : If you are removing an old ruined oak bushing you drive it from the side WITH the tabs out through the side WITHOUT the tabs.
Now we find some really good looking hard oak and cut a 1 1/2″ by 1 1/2″ by 1 1/2″ cube. I used a table saw.
Now we need to find dead center. We do this by drawing a corner to corner “X”. IMPORTANT : We drill the whole on a long grain side, we do NOT drill the whole on the end grain side.
We are going to use a set of spade drills with center points to get things dead center.
And, since we need to hold things while drilling, we use a clamp. Folks, dead center…..I used a drill press.
More accurate than “in the day!”
Now we need to pay some attention.
Mark one side with the hole as the “entry face” I used the side with the “X”
On a belt sander take down the “X” side face evenly on all four outside faces. We will be constantly checking to see when the block begins to be sized enough to allow the “X” side hole to enter the steel sheave hole.
We DO NOT take the four side down the evenly, rather we create a wedge from our entry face enlarging as it goes to the other face with the hole.
Here is a highly technical CADCAM drawing of an EXAGGERATED view of what we are doing. In reality we are just doing a slight angle.
We keep doing this until the entry face can go into the hole 1/3 of the way. Now you will have to remove some of the back facing probably. Just keep a nice clean angle on the four sides.
1/3 of the block fits in? You are ready done!
ON THE SIDE WITHOUT THE TABS, Insert your leading face hole. With a RUBBER hammer and the steel sheave supported fully on a nice piece of hardwood….bang it in until the tabs cut into AND STOP the block on the other side.
Now, using a round wood file, open the hole up on either side so that the axle feels just right!
You did it!
Dan[/vc_column_text][vc_column_text]
– Responses:
Nice tutorial, One version of the US Wind line pulleys also have a wood bushing but it is round
Kenny[/vc_column_text][/vc_column][/vc_row]