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Adjustment Knob2

On the previous page we constructed the adjustment knob by turning pine on the lathe. We will now build the adjustment knobs from 3/4" plywood using a bandsaw, sanding disc and drill press.

 

Adjustment knods marked out on plywood board.

 

The photograph on the left shows the layout for one of the adjustment knobs.

 

The top layout has the main shank diameter 7/8" marked on and the inside diameter is the diameter for the 9/16" counterbore.

 

The bottom layout is for the handle. As you can see the four spokes have been marked out, with the width of the spokes being 9/16". The center diameter is 9/16" and this represents the counterbore for the socket head cap screw. The overall diameter of the handle is 1 1/2".

 

Now that the basic layout is done and before cutting out on the bandsaw we need to drill the holes for the socket head cap screw.

 

For this adjustment knob we will use a 2"x 3/8"-16

socket head cap screw.

 

Set the drill press up with a 3/8" Dia. drill bit and drill a hole through the center of the top layout, the shank of the adjustment knob.

 

Remove the drill bit from the drill press and replace with a 9/16" spade bit. Drill through the center of the bottom layout, the handle of the adjustment knob. Replace the spade bit with a 5/16"drill bit and drill out the four connecting radii's to the spokes.

 

With all the drilling complete we can now cut the shapes out on the bandsaw and then sand the shape on a sanding disc.

 

Components for the adjustment knob.

The internal shape of the spokes will have to be hand finished with a dowel sanding block. The 2"x 3/8"-16 socket head cap screw can be screwed into the shank of the adjustment knob with a 5/16" hex key.

 

You will find that the 3/8" drilled hole in the shank is not a clearance hole for the socket head cap screw so the 5/16" hex key makes it easier to screw it into place. At this stage you should have the same as the above photograph.

 

Second set of components for the adjustment knob.

 

For the second adjustment knob we will use a

1 1/2"x 3/8"-16 socket head cap screw.

 

The difference in the procedure for this adjustment knob is that we will set the stops on the drill press to counterbore the shank to a depth of 1/2". This is to ensure that the shorter cap screw will have enough thread to engage the T-Slot Nut.

 

Once the counterbore for the shank is complete replace the spade bit with a 3/8" drill bit and drill through the final 1/4" of the shank.

The main handle for the adjustment knob requires no counterbore as the socket head cap screw already falls below the surface of the handle.

 

Drill out the four connecting radii's then proceed to cut out the shapes on the bandsaw. Finalize the shape on the sanding disc and hand finish the spokes. Once this is done, screw in the cap screw with a 5/16" hex key. You will then be at the same stage as the photograph above.

 

With both adjustment knobs at a stage where they can be glued together, drill a couple of 7/16" holes into a piece of 2"x 4" lumber, 4" apart. This is to support the shanks while the 5 minute epoxy resin cures.

 

On adjustment knob No.1 coat the resin around the head of the cap head screw then push the handle over the top. Pushing on firmly to squeeze out any excess resin. The head of the screw acts as a dowel to ensure correct position.

 

On adjustment knob No.2. Unscrew the cap head screw from the shank enough so as to be able to coat with resin. Re-screw into place and add additional resin to ensure a good bond. Coat the top of the shank and position the top handle using the connected spokes as a guide to position centrally. Allow both adjustment knobs to cure.

 

All parts ready for assembly.

Adjustment knob for angle bracket glued together with epoxy resin.

 

Two different methods of constructing the adjustment knobs.

As you can see from both of the photographs above the resin has secured the cap head screws into position. All that needs to be done is to clean off any excess resin and the adjustment knobs are good to go.

 

The two adjustment knobs side by side showing no visual difference even though completely different construction.

 

The two different length socket head cap screws used in the adjustment knobs are the same length after completion. It is a matter of preference as to the method used in the construction and of course the length of the socket head cap screw available.

 

To construct the adjustment knobs for the angle bracket and angle head, download the technical illustration.

 

Adjustment Knob PDF    

 

 

Copyright © 2004 - 16 Steven Austin

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