Shift knob inserts

jhjacobs

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I have been making up a larger number of shift knobs (will post results soon) and in the process is became very clear that a source of cost effective yet classy threaded inserts was needed. I did an engineering drawing and went out for quotes but the "cost effective" requirement was not possible to meet. I have now come up with a solution that is fairly elegant and inexpensive to make; the highest cost item is the tap at $17. Once you have all the tools you can crank these out for <$2 worth of materials (plus some elbow grease). I've provided a photo below showing the general steps and dimensions.

The general process:

- Cut a small length of standard 1/2" water pipe (I use about 4.5").
- Use a reamer or Dremel to remove crimp from rotary cutter.
- Clamp pipe in a large vise (I put a hex head bolt in the pipe to prevent complete crush - tapping stress will shear pipe otherwise)
- Tap threads using cutting oil or similar to about 2" deep (end of tap teeth); this ensure a clean section of threads at end. Make sure tap starts very straight or it will cut through the pipe wall as you go deeper).
- Cut off 1.1" to 1.2" of the clean threads from end.
- Use a dremel grinder to remove threads and rotary crimp from new the cut (bottom side) so it will pass over shifter threads easily.
- Pass the tap through finished item a few times to ensure clean & smooth threads.
- Add a standard end cap to end with threads. Bottom out end cap on the threaded end.
- Add a standard coupler to end with ground down threads (bottom)
- Adjust the oupler deep for a desired finish length (about 2"-2.25")
- Lightly solder parts together

This insert will fit into an 18mm hole; I picked up an 18mm bit for about $13 from Woodcraft. You can also bore an 11/64th hole and used a rotary rasp to open it up a bit. Alternately, a 3/4" hole might work if the insert is wrapped with a shim material.

I use 5 minute epoxy to hold the insert in the hole. After it sets I go back and sand down the bottom of the knob and the copper and then I hit it with a final coat of finish to keep the exposed copper shiny. This gives a great finished look and I works as well or better than the original plastic inserts. :)

[Broken External Image]:http://i198.photobucket.com/albums/aa208/jhjacobs/Knobs/Insert1.jpg

As you might tell, I am getting fairly serious about making shift knobs. I've been getting quite few requests and I want to make sure I can deliver a top quality product if I take an order. Stay tuned!
 
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