ractica 



A PROFILING FIXTURE 



By E. P. Fickes 



In the construction of small machines, 

 such as cash registers, sewing machines, 

 etc., there are parts that must be ma- 

 chined with the least amount of varia- 

 tion possible, and the manner in which 

 these parts are held is worthy of much 

 consideration. Difficulties arise when the 

 part has no projection or lugs, making it 

 impossible to use clamps. The fixture 

 described is designed to hold two castings 

 while profiling the top and the bosses on 

 the inside. One of these castings is 

 shown clamped in position on the fixture 

 at A. 



The base, B, Fig. I, consists of a cast- 

 ing finished on the top and bottom. Holes 

 should be drilled and reamed for the sta- 

 tionary jaws, C, C, and for the movable 

 jaws, D, D, D, D, as well as for locating 

 pins, E, E, E, and adjustable supports, 

 F, F and H, H. 



Two holes should be drilled, counter- 



bored and tapped in the sides for the ad- 

 justing screws, /, /, and J, J. The jaws, 

 C, should be turned from a piece of tool 

 steel to the desired shape, then hardened 

 and ground where necessary and driven 



fig 2 



into the base, B. The movable jaws, D, 

 shown in Fig. 2, should be made in two 

 parts. The body, K, consists of a tool 

 steel forging finished to fit the hole at L, 

 then milled flat on each side at M to fit 

 into slot, N, in the base, B. A hole is 

 drilled and reamed in the end for pin, 

 O t after which it is cleared away, as 

 shown at P, to allow the body, K, to move 

 back and forth. The jaw, D, is made of 

 tool steel, hardened, ground, and lapped 

 to fit shoulder on body, K, and is held in 

 place by screw, S t which also serves to 

 hold in position dust washer, T, thus pre- 

 venting chips or dirt from interfering 

 with its movement. 



In Fig. 3 is shown the adjustable sup- 

 port, which is operated by means of the 

 cone-shaped screw, /, against the inclined 

 surface of pin, F. This support is also 

 used at H, taking care of the thrust of 

 cutter while profiling the bosses or lugs 

 on the casting, A. This method of clamp- 

 ing affords little chance of springing or 



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