SNIPS
Straight Pattern | Combination | Duckbill | Pipe and Duct | Compound, Aviation, Offset | Proper Use | Do's and Dont's

INTRODUCTION
Snips, sometimes called tinner's snips, are used to cut sheet metal. They are used by the sheet metal worker, the automotive mechanic, in industrial plants, and by the home owner. While their primary purpose is to cut sheet metal, snips are also used to cut screening, chicken wire fencing, steel strapping, gaskets, linoleum, canvas, and other hard to cut materials. However, some snips are designed to cut mild sheet metal up to 18 gauge thickness.

There are five basic types in common use today – straight pattern, combination, circular (or duckbill) pattern, compound leverage aviation, and compound leverage offset.

Straight pattern snips are generally used for making straight line cuts, although curved cuts can be made if the curve is not too sharp. When cutting with a straight pattern snip, a straight line can be easily maintained by guiding the material sliding it, butted firmly against the wall of the inside ground surface at the bolt hole. (See Figure 66) Their cutting edges are sharpened at an angle of 78 degrees to 85 degrees to the inside of the blade. The sizes range from 7 to 16 inches in overall length, with the most popular sizes being 7, 10, and 12-1/2 inches.

FIG. 66. The straight pattern snips are generally used for making straight cuts. They can also be used for making shallow curves.

Combination and duckbill snips are used for cutting curves in either direction. They can be used for straight cutting, but will require slightly more effort to cut with than the straight pattern snip. The most popular sizes are 7, 10, and 12-1/2 inches, although 14- and 16-inch sizes are available. The thickness of the metal that can be cut is approximately the same as for the straight pattern snip.

FIG. 67. The duckbill snip can be used for straight cutting as well as cutting curves. Make certain that the bolt holding the blades together is tight; looseness between the blades will cause ragged cuts.

FIG. 68. The duckbill snip will cut smooth curves in sheet metal in either direction. They can also be used for straight cuts, but not as satisfactorily as the regular straight pattern snips.

There are other types of snips available, such as the curved blade, hawkbill, bulldog, light metal, jeweler's, and pipe and duct. These are used mainly by the professional metal worker or in a specialized profession. There are also straight and combination snips available which have a high carbon or alloy steel blade welded to the basic snip frame. They do not cut any easier than a regular solid steel snip, but may stay sharp longer. There are also straight pattern snips with aluminum handles and replaceable blades. Snips are made for right-handed use although they can be used in either hand.

FIG. 69. Hazardous Harry is using snips to cut heavy wire. It may work, but he could ruin the cutting edge of the snips leaving a nick in the blades. And the next time he tries to cut sheet metal with these snips, he will get a ragged edge. Too bad, Harry!

WRONG

FIG. 70. Pipe and Duct Snip. This type of snip has a compound action. In use, it cuts out a narrow section of metal equal to the width of the center blade. The work on either side of the blade tends to stay flat as only the narrow waste takes a curl as it is cut out. It is used for cutting panel openings in gutter and downspout work where metal distortion on either side of the cut is not wanted.

Compound leverage snips have become popular in all fields of metal working. Their double fulcrum compound lever action requires less effort to cut. The blades of these snips are usually made from an alloy steel so that they are harder and tougher than regular snips. Standard size for the professional-type compound leverage snips is 10 inches overall.

Aviation snips are available in three types of cut; straight for cutting straight lines; left cut for cutting curves to the left; and right cut for cutting curves to the right. These snips are generally used for heating, air conditioning, gutter work, and for general industrial use.

Offset snips are available in two types of cut: left cut for cutting curves to the left; and right cut for cutting curves to the right. The left and right offset snip will also cut straight. Offset snips permit the user to cut without interfering with the flash or the finished piece.

When cutting sheet metal, the hand stays clear. Metal flows under and over the blades permitting a cut directly through the center of a sheet without distortion.

FIG. 71. Careful Cal knows enough that only wire cutters should be used to cut wire. Metal cutting snips are for cutting sheet metal, not wire.

RIGHT

FIG. 72. Right cut snips will make straight cuts as well as cuts to the right as shown in drawing.


FIG. 73. Left cut snips are for making cuts to the left as well as straight cuts.


FIG. 74. Straight cut snips are used for making straight cuts as well as shallow cuts to right or left.


FIG. 75. The offset snip permits your hands to remain above the cut, cuts directly through the center of a large sheet.

PROPER USE OF SNIPS

It is advisable not to cut exactly on the layout line (to avoid extra finishing work). It is good practice to leave about 1/32-inch of metal beyond the layout line for final dressing and finishing. As the cut is being made, try not to make the cut the full length of the blades. If the point of the blades are allowed to meet at the end of the cut, the sheet metal will have a tendency to tear as the cut is completed. Stop the cut about 1/4-inch before the tip of the blades and then take a fresh bite.

When cutting a large sheet of metal, it is best to cut at the left side of the sheet. This way the waste will be curling up and out of the way while the rest of the sheet will remain flat.

FIG. 75A. If you are right-handed, cut so that the waste is on the right, as shown above.

When making a straight cut, place the work over the work bench so that the layout line is slightly beyond the edge of the bench. Hold the snips so that the blades are at an exact right angle to the sheet metal. The edges of the metal will be bent and even burred if the blades are not at right angles to the work.

In order to make a large hole in sheet metal, start by making a hole in the center of the sheet and proceed to make a spiral cut leading out to the desired circumference. Keep cutting away until all the non-wanted material is removed.

To cut a disk in sheet metal, start from the outside and make a cut tangent to the layout line but slightly beyond it to allow for dressing and finishing. This way you will always be able to see the layout line and still have material left over for final dressing and finishing.

FIG. 76. How to start and cut a disk out of sheet metal. Use a curve-cutting snip for this job.

DO’S AND DON’TS WHEN USING SNIPS

1. Wear safety goggles when using snips.
2. Be careful of the sharp edges on the cutting edges of these tools.
3. Wear gloves when working with snips.
4. Never cut sheet metal that is thicker than 0.062-inches.
5. Use snips for cutting soft metal only. Hard, or hardened metal may damage the cutting edges of the snips.
6. Use the right size and type of snips for the job on hand. Don’t try to cut sharp curves with straight cut snips.
7. Avoid springing the blades. This is the result of trying to cut metal that is too thick for the snips you are using, or by trying to cut heavy wire or nails.
8. Use only hand pressure for cutting. Never hammer, or use your foot to get extra pressure on the cutting edges. If you are resorting to such a technique, you are using too small a snip – the metal is too thick for the capacity of the snip.
9. Oil the pivot bolt on the snips occasionally.
10. Keep the nut and the bolt properly adjusted at all times.
11. The average user does not have the proper equipment to resharpen snips. Do not attempt to resharpen a snip blade in a sharpening device designed for scissors, garden tools or cutlery.
12. Do not use "cheater bars" on handles of snips. You are trying to cut material which is too thick if you have to resort to this.
13. Don’t use snips as a hammer, a screwdriver or a pry bar. There are tools for such purposes – use them. If the snips you own have locking clips, use them when the tools are not in use.
14. Snips should be carefully put away after use. Wipe the cutting edges with a lightly oiled rag. Don’t dump them in a drawer with other tools. Tools with cutting edges should always be treated with extra respect.

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