In a lathe machine work, different operations require different types of lathe cutting tools, according to the process of using the lathe cutting tools. The main function of a rough turning tool is to remove the maximum amount of metal in minimum time that the tool, work, and the machine will permit. The cutting angle is so ground that it can withstand maximum cutting pressure. Turning tool is used to remove the very small amount of metal.
A tool angle is so ground that it can produce a very smooth and accurate surface. Straight turning tools are also used as a chamfering tool when the cutting edges are set at an angle of the chamfer. Where a large number of chamfer works are to be performed a special chamfering tool with its side cutting edge angle ground to the angle of the chamfer is used.
A square shoulder is turned by a knife-edge turning tool or facing tool. A bevelled shoulder may be turned by a straight turning tool having a side cutting edge angle and zero nose radius. A filleted shoulder is turned by a straight turning tool with a nose radius corresponding to the fillet radius of the work.
Metric, B. Its cutting edges sharpened to the shape and size of the thread to be cut. The shape of the tool is determined by the included angle at the nose of the tool which should correspond to the angle of the thread. W threads. The size or cross-section of the cutting edges of the tool depends upon the pitch of the thread. Below figure illustrates an H. So for machining different screw threads having different pitches separates tools are used to produce accurate threads.
The nose of the tool is pointed, flat or rounded according to the shape of the root of the thread. The side clearance of the tool for cutting square thread is of prime importance in order to prevent the tool from interfering or rubbing against the vertical flank of the thread.
The cutting edge of the tool is exactly similar to an external thread cutting tool but the front clearance angle is sufficiently increased as in a boring tool.
The tool is a forged type orbit type and held on a boring bar. The point of the tool must be set square with the work. A facing tool removes metal by its side cutting edges.
So no top rake in necessary in a facing tool. The figure shows H. The length of the tool is , ,, and mm and the nose radius varies from 0. Grooving tool is similar to a parting-off tool illustrated in the figure. An ordinary lathe turning tool may sever the purpose where a copying attachment is used to reproduce the form of a template.
Flat forming tools are made of two types:. These tools have their cutting edges ground to the shape of the groove, undercut, or thread to be cut.
Flat dovetail forming tools have a wider cutting edge corresponding to the shape desired. Dovetail end of the tool is fitted in a special tool holder. These tools are preferred in production work as a very long cutting surface can be used resulting in longer tool life.
The centre of the tool is set slightly above the centre line of the work to provide an effective front clearance angle on the tool. The tool will rub against the work if the centres are of the same height. Regrinding is done by grinding the flat only.
A boring tool is similar to a left-hand external turning tool so far its cutting edge is concerned. The tool may be a bit type inserted in a boring bar or holder, or forged type having a tool shank. The figure shows an H. A boring bar is made of mild steel with slots or holes cut into it to accommodate the tool bit which is locked by an Allen screw. The amount of projection of the cutting edge of the tool from the centre of the bar determines the finished hole diameter of the work.
The bit is generally inserted at right angles to the centre line of the bar for boring a continuous hole passing from one end to the other end. The bit is set at a single to the axis projecting beyond the end of the bar for boring a blind hole. The counterboring operation can be performed by an ordinary boring tool. The tool cutting edge is so ground that it can leave a shoulder after turning. A counterbore having multiple cutting edges is commonly used. Undercutting or grooving tool has a point and form of the cutting edge exactly similar to the form of the required groove.
Clearance angle is given at all the sides of the tool. For the recessing groove cutting edge, the longitudinal feed is employed. The front clearance angle depends upon the bore of the work. A parting off tool is normally forged and used as bits for cemented carbide tipped tools. Parting off tool is made as narrow as possible to remove the minimum of metal.
The width of the cutting edge range from 3 to 12 mm only. The length of the cutting tool which inserts into the work should be slightly longer than the radius of the bar stock being machined.
As the tool penetrates deep into the work, clearance is provided all around the tool cutting edge to prevent it from rubbing against the work surface.
As the tool is purely ended cutting it has no side rake slight back rake is provided on the tool to promote an easy flow of the ships. A right-hand tool is shown in the figure. Is that which is fed from lathe bed, i. A right-hand tool is formed on its left-hand end when viewed from the top with its nose pointing away from the operator.
Clear your work area of other nearby objects to keep the canvas from getting snagged while you're working. Wrap a strand of yarn around the shaft of the latch hook. Adjust the yarn until it rests in the shallow crook just above the handle of the tool.
Pull the ends of the strand taut around the latch hook with your opposite hand. A little tension will make it easier to maneuver the tool through the holes in the canvas without losing the yarn. Part 2. Thread the latch hook through one of the squares in the canvas.
Guide the tip of the tool under the string at the edge of the square, then up and out through the other side. Keep sliding it until the crook of the latch hook is nearly level with the square, but don't let the yarn go through. Be careful to only insert the latch hook through one square at a time. Draw the ends of the yarn to one side.
This will place the strand in the correct position for knotting. It will also get them out of the way so you can concentrate on threading the latch hook.
If they come apart, they may end up being two different lengths once the strand has been knotted. Pull the latch hook back out through the hole. To complete the knot, all you have to do is go back out the way you came. As you withdraw the tool, the swinging latch will gather up the loose ends of the yarn, pulling them under the section that's anchored to the canvas. It's that easy! Tighten the knot by hand.
Each time you complete a strand, pause and give the loose ends a quick tug. This will both secure the knot and make the looped section less visible. Be careful not to pull on the knot too forcefully, or you could stretch out the canvas and leave it looking misshapen. Part 3. Start with basic designs. When you're first learning how to latch hook, it's best to keep things simple. Try following a template for your first few project to get an idea of how the yarn looks on the canvas.
From there, you can move on to freehand shapes like lines and circles a shot. Get creative with your projects. As you improve, you'll learn to produce more complex patterns and contours and begin producing your own unique designs. These could be anything from formless swaths of color to distinct patterns like stripes, spirals, waves, and rainbows.
Advanced latch hookers have even been known to weave detailed portraits and scenes. Don't be afraid to be abstract—experiment with yarn placement and weave whatever patterns your eye suggests. It can be helpful to think of the canvas squares as a guide for forming precise edges and curves, similar to drafting paper.
Trim the yarn to the desired length. Rather than spending hours cutting the yarn to size before you make a single knot, wait until your design comes together, then snip the strands wherever you want them to be shorter.
Touching up your work after the fact will offer you more control, as it allows you to make just as much of an adjustment as you need instead of being forced to guess at the right length. Use two strands of yarn at once. Wrapping, threading, and knotting one strand after another can take all day. By doubling up your yarn, you also stand to double your speed.
Line up two separate pieces of the same length, then knot them as you ordinarily would, being careful not to let the two strands overlap in the process.
This method can be especially useful when you're covering a large area with a single color. I tend to hold it in my lap, but you can also tape the edges to a surface with masking tape. If you do this, make sure it's something that won't get scratched up by the hook. Not Helpful 0 Helpful 6. Include your email address to get a message when this question is answered.
To make especially challenging designs easier to follow, trace over the canvas with a felt-tipped marker. Helpful 0 Not Helpful 0. Stitch your completed latch hook patterns onto sweaters or household items like pillows, afghans, or placemats to provide a little DIY flair. Sort your leftover yarn by color and place it in plastic bags to keep it from getting lost or mismatched. Submit a Tip All tip submissions are carefully reviewed before being published.
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