Centering the cutting tool more over saddle can be a help.I have seen set-ups with the tool set way to the left and then having problems. Yes this might be with having/setting your compound at perhaps 30. or even parallel to the work and extended it way out to the left. Turner, Head, Department Of Pattern Making, Mechanic Arts High School, Boston. Consulting Mechanical Engineer Expert Patent Attorney American Society Of Mechanical Engineers Author Of 'Modern Machine-Shop Construction, Equipment, And Management', 'Lathe Design, Construction, Operation.', Etc.
A lathe center, often shortened to center, is a tool that has been ground to a point to accurately position a workpiece on an axis.They usually have an included angle of 60°, but in heavy machining situations an angle of 75° is used. Lathe Machine Repair Service, Lathe Repair Services Providers in India. Get contact details and address of Lathe Machine Repair Service, Lathe Repair Services firms and companies. Mechanic / Machinist Four Tests will be administered: 1. Basic Machining/Mechanics Test Different types of metal Lathe/machining Welding Types Pressure settings Equipment specifications Safety Oxygen/acetylene Types Pressure settings Equipment specifications Safety 2. Tools and Precision Measurement Test Basic Tools Types Applications.
Description
This section is from the book 'Machine Shop Work', by Frederick W. Turner, Oscar E. Perrigo, Howard P. Fairfield. Also available from Amazon: Machine shop work.
A piece to be turned is supported on the two centers of the lathe. In order that this may be done, it is prepared by drilling and countersinking a hole in each end. This is called centering the work. The countersunk hole should have the same angle as the lathe center upon which it is to run. The hole should be drilled deep enough so that the point of the lathe center may not strike. The shape of the hole is shown in Fig. 133. The generally accepted standard angle is 60 degrees. The effect of using a 60-degree hole on a 90-degree center is shown in Fig. 134. The result of such an application is that the bearing will be concentrated on a line AB, causing rapid wear of the outer end of the hole, and a cutting of the dead center.
Fig. 133. Hole and Center of Correct • Angle for Centering Work.
Fig. 134. Effect of Using Different Angled Hole and Center.
The size of center holes varies with the weight of the work and the character of the operation. Heavy work and rough turning require large center holes, while small work and fine turning can be done without countersinking deeply. As bearing surfaces in cast iron must be large to be satisfactory, center holes in cast iron are likely to give trouble by unequal and rapid wear. When heavy turned work in cast iron must be very accurate, it is well to drill a hole in each end, drive in a plug of Wrought iron or mild steel, and form the center holes in the plugs thus driven.
Lathe: Work Centering The Mechanic Position
When the piece to be turned has been put in place, the dead center should be oiled and screwed up into position. It should be tightened so that there is no lost motion, and yet allow the work to rotate freely.
Chuck Method
The turning of shafts and bars is not, however, the only kind of work to be done on a lathe. Pieces can be turned that are thin, that have holes through the center, or which are so shaped that they cannot be held upon the centers. In such cases it becomes necessary to hold the work firmly without distortion. This may be done by use of the lathe chuck.
Fig. 135. Work Clamped to Faceplate.
Faceplate Method
Still another method of holding a piece to be worked is that shown in Fig. 135. The piece is clamped to the faceplate. When this is done, there should be a bearing on the faceplate immediately beneath the clamping strap. For example, consider Fig. 136. Suppose a disc having four feet on one side is to be faced off on the front. The clamps should be placed directly over the feet, as in B. If they are placed between the feet at EE, the work will be sprung out of shape, as shown by the dotted lines in A. Then, when the tool has done its work, the shape of the piece, while bolted to the faceplate, will be as shown in C. As soon as the pressure of the straps is removed, the elasticity of the metal will cause the piece to assume the convex form shown in D; whereas, if the straps had been placed as shown in B, no distortion would have been produced.
Fig. 136. Proper and Improper Method of Clamping Work.
An angle iron may be clamped on a faceplate, as shown in Fig. 137, presenting a surface parallel to the lathe axis, to which work may be attached. The angle irons may, of course, be at any angle to the faceplate, but 90 degrees is the one most commonly used. When work is held in this manner, it is desirable to counterbalance it, as is also shown in Fig. 137,
Fig. 137. Angle Iron Clamped to Faceplate and Counterbalanced.
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Lathe: Work Centering The Mechanic Training
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