12.18. 'Cool Tool' for stud extraction

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contributed by Ken French....Kibokojoe

Another busted stud and another botched attempt to drill the center of the stud so it can removed with an extractor. Has this ever happened to you? Well fear not for about a dollar and about 30 minutes of your precious time you can nail the center of the stud every time and here is how you do it.

As an example I will show you how to make an 8mm drill centering tool which I have named the "Cool-Tool". After you make one you will agree too.

First of all you will need to purchase an 8 mm nut with a nylon lock ring. Then purchase a bolt or screw that is about 2 to 3 threads longer than the nut. It can be longer than this but that means more drilling and if you are working in tight quarters you may run into problems. In my case I purchased 8mm x 1.25 x 10mm length screw.

Image:Cooltool.pic1sm.jpg    Image:Cooltool.pic2sm.jpg    Image:Cooltool.pic3sm.jpg

If you don't have an extractor set you will need to purchase one. For this example we will be using a #2 extractor and its 7/64" drill.

Ok lets make a Cool-tool

Step one... Starting at the threaded end of the screw, drill all the way through with the 7/64" bit. Fortunately for me I have a metal lathe, finding and drilling the center is no problem. One trick you can use is to first drill a small indentation using a sharp 1/4" drill bit. This makes a nice start so your smaller 7/64" drill bit will not wobble around as much.

Step two... Drill the nylon end of the nylon lock ring nut with a 0.310" drill about 0.15" deep. The 0.310" is the diameter of the base of a broken 8mm stud.

Step three... Let put her into action...

If you assemble the Cool-Tool as in picture 2 you can insert the tool into a threaded hole where the stud has broken off below the surface.

If you assemble the Cool-Tool as in picture 3 you can slip it over a broken stud that has snapped off above the surface.

Once the Cool-Tool is in place simply drill through the tool with the 7/64" drill.

I used this tool to remove a stud that had broken off below the surface on my 88 Honda Accord's exhaust manifold. The stud was located in very tight quarters and the surface was angled where I could not see the hole. The first night I tried to drill the hole "blind" and managed to get off center and ended up cutting into some of the threads. No matter how I tried I could not recenter the bit and so I gave up in frustration. Over night I had time to think about it and came up with this idea. I had no idea it would work so well. When I installed the Cool-Tool I made sure that the end of the screw was flush with the broken stud and I did not rush the job. Not only did the tool keep the drill bit centered as it cut into the stud it bypassed my screw up from the night before.

Let me know what you think

Kibokojoe www.freewebs.com/kibokojoe

cfsboy<at>sbcglobal.net

PS Someone told me that you can buy drill-centering tools from Mac Tools, but if it is like any of the other Mac Tools you will need to take out a loan to purchase one.

edited by --Admin.chris 09:50, 30 Jan 2006 (CET)

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