basic toolwork

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Old 01-11-03, 05:14 PM
tele kishta
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basic toolwork

i need some information on creating a new thread in where one has snapped off.

i have drilled out old bolt but need to know how to use a tapping tool.
 
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Old 01-11-03, 06:35 PM
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tele kishta:

A lot would depend on the material and what the piece is.

Assuming you have enough material you would have to rethread the hole one size bigger.

You would obtain the correct size tap to match the bolt size and also get the correct size drill bit to drill the hole. The correct drill bit would be listed in a chart.

The hole would be made, the tap threaded into the hole by keeping the tap straight and going in a little at a time and backing out to clear the threads.
You also use a threading lubricant to keep the tap cool and to help clear the metal chips.

If the hole is straight through something then a standard tap will do. If you can't drill straight through then you would need a bottoming tap.

Describe your project in more detail for a more concise answer.
 
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Old 01-15-03, 09:13 AM
NutAndBoltKing
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Hello tele kishta!

Greg H has given you an excellent description on the use of a tapping tool. You can't go wrong with his how-to.

I see from your profile that you are a farmer. IF perchance your re-threading repair project involves some of your heavy duty farm equipment please remember that the nuts and bolts and other threaded parts of your equipment are usually made of high grade materials and can not be replaced with substandard grades. Be sure to use the same or a superior grade.

Often times a question arises as to what drill and which tap should be used. The tapping industry produces drill-tap charts that indicate what size drill must be used for each tap size. These charts usually work off 75 percent full thread, which is more than adequate for most applications.

Drill tap charts are available at hardware stores, are free and easily downloaded on line; and apply for all metric, fractional, machine, iso, and pipe threads. This chart will help you match your bolt to the tap and to the drill size required.

FYI:

A). The drill and tap industry has four classifications of threaded holes: 1). the first and most common type is a hole into which a threaded part is inserted for fastening purposes ONLY - and is left there either for the life of the part or until repairs are made. 2). Holes which are used to adjust parts of a machine where the screw or bolt may be tightened or loosened MANY TIMES. 3). Holes in which a screw is used to move a slide or nut, and hold it at some desried location. 4). Holes bored for studs.

While a standard tap will work at threading a hole for any of the above applications - the right sized drill is required, or the hole may be too tight or too loose for one of the 4 above applications being used and/or for the desired results.

B). There are two types of taps: 1). The most common and most popular easy to use type cuts treads and exhausts the chips of metal it's removing out along the flutes. 2). The second type forms threads without removing any metal.

Each of these two types pf tap is available in a standard (pointed) tap for use on through holes - or as a bottom (blunted) tap for use on holes that are not bored completely through the workpiece.

++ Selecting the right tap is just as important as selecting the right drill as is using the right size and grade of bolt. ++
 
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Old 01-15-03, 09:53 AM
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Thumbs up NutAndBoltKing:

Thanks for the extra info.

Much appreciated!
 
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Old 01-15-03, 11:09 AM
NutAndBoltKing
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Tap Drill Charts .....

.... can be found at and easily downloaded or printed out from:

http://www.wattonenterprises.com/watton_tap_drill.html

http://www.nutty.com/tapdrillchart.html

Both sites have metric, fractional, machine screw, pipe and etc.
 
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Old 01-15-03, 11:27 PM
josh1
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a little advice from the rusty british car world! Turn the tap handle slowly, one turn forward, half turn back. Keep going that way. Its slow, but tapping threads is really rewarding. If the tap is a bottoming one ie the hole doesnt go the entire way through, you can coat the tap with grease to extract all the metal shavings. Nothing like a smooth gliding bolt! -Josh
 
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