MEASURING RAM TRAVEL ACCURACY

Measuring ram travel accuracy The factors affecting ram travel are, and machined crank accuracy and twist (see illustrations "D" & "E").

Machined Frame Accuracy...

Machined Ram Accuracy...

Gib Machining and Adjustment and
Machined Crank Accuracy...

Once the machine is assembled, the press can be checked to determine the effect these factors are going to have on press operation. For the most part, these factors are the result of manufacturing tolerances (except gib adjustment). An initial check to determine the influence of crank machining can be made as follows:

A. Press bed must be level to .ooo5 per foot before making any type of parallelism checks.
B. Adjust counter balance pressure to assure crankshaft is lifted against top of main bearings.
C. At bottom stroke,adjust independent barrel screw/connection assemblies to provide best parallelism possible at points indicated as LC and RC (see illustration "F").
D. Indicate and record ram parallelism at points on the ram face indicated as LC and RC with stroke up, stroke midway down, stroke down, and stroke midway up.

Parallel differences at LC and RC in stroke up and stroke down positions will tend to indicate machined difference between the length of throws of the crankshaft or the eccentric gears. Deferences in parallelism at stroke midway up and midway down will tend to indicate (a) crank twist or eccentric gear misalignment, or (b) machined diference in angular throw alignment (see illustration "D" & "E" above)

This check can also be made by indicating the parallel travel against a "right angle square" attached to the ram face. This set up is difficult and the results may be difficult to interpret. On two point and one point presses, parallelism differences between LF to LR & RF to RR would most likely be due to gib clearances and adjustment. Gib clearance cannot be tighter than what is necessary to allow for the ram "squirming" that results from machined eccentric misalignments. Gib galling may result if an attempt is made to hold the slide against the forces generated by eccentric misalignments It is advisable to check gib clearances with stroke up, stroke midway down, stroke down, and stroke midway up. Once ram parallelism is determined with these manufactured tolerances factored in, changes affecting part quality can be monitored with parallel checks under load. When parallelism changes are noted, further checks can be made to determine cause.