Aluminum Yoke

Bending the aluminum

Start by cutting the aluminum stock to the length called for in the parts list. Next, make a wood block out of ¾” hardwood stock to use as a form to bend the yoke around.  Make it 2-1/8” wide by 1-3/8” deep.  Round the top corners where the bend will take place to approximately a 1/8” radius.

Clamp the straight aluminum piece adjacent to the right edge of the wood block in a vise, so that the top of the block faces up and the aluminum piece is vertical.  Line up the bottom edge of the aluminum with the bottom edge of the wood block and carefully along the blocks side.

Most aluminum bends pretty easily, but some alloys do not. If you have trouble bending it, you might want to apply a little heat from a propane or micro torch at the point of the bend, to aid in the bending.

Tap with a wood or rubber mallet a little above the bend location and slowly bend the aluminum around and across the top of wood block. If you don't have a mallet, you can tap a hammer on a block of scrap wood pressed against the aluminum.

After the bend is complete, try and ensure that the top of the yoke is flat against the wood block.  You should now have an L-shaped piece of aluminum, with the right leg and top of the yoke formed.

Turn the aluminum/wood block 90º in your vise so the left side of the block is facing up and the remaining leg of the yoke is vertical.  Now repeat the previous procedure to bend the third side of the U-shape.

The yoke is basically formed, but may need some finishing before you drill the holes and assemble it. You may need to grind a little off the third leg to make it even with the first leg.  You might also need to do a little more adjusting of the legs to get them at 90º to the top and parallel to each other.  You also may need to work a bit to try and get the top of the yoke as flat as possible. None of these needs to be done to critical dimensions, but you should get them fairly close or your NF4 won't look good and may not work properly.

Drilling the yoke

Using a square, measure down the yoke from the top to mark the locations of the holes to be drilled in the yoke:
	A 5/16” hole will be drilled through each leg. A ¼” hole will be drilled through the top center of the yoke. Now, clamp the wood block, inside the yoke, into your drill press and drill these three holes.
The holes you will need are now drilled.
File or sand, etc. any sharp edges off the exposed ends of the yoke and it should be ready to assemble with hardware according to the component assemblies’ list. When completely assembled, the yoke, toggle clamp, and front bearings will look like this.