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9.14 Pocketing

Micky R. Jennings

An end mill rests inside a finished pocket on a manual milling machine.

Figure 9.180. An end mill rests inside a finished pocket on a manual milling machine. / Image Credit: Micky R. Jennings, courtesy of Wenatchee Valley College, CC BY 4.0Pocketingis the process of creating a recessed cut inside of the outer contour of a part. A simple pocket is generally round or rectangular shaped and at a singular depth. However, pockets can be any shape the designer desires and can contain multiple steps and depths.

Step by step process for pocketing:

  1. Apply layout dye to the area that will receive a pocket.
  2. Layout the pocket’s boundary.
  3. A hole may be drilled of similar size to the endmill required to mill out the pocket, generally the same size as the internal radii. Drill the hole to about 1/64″ from finished pocket depth.
  4. Load an end mill into the milling machine equal to the interior radii of the pocket’s corners.
  5. Calculate the spindle speed of the endmill chosen.
  6. Turn on the spindle.
  7. Engage the end mill into the workpiece to depth.
  1. Use a previously drilled hole.
  1. Lock the quill
  2. Touch the tool off the top of the work with the knee.
  3. Zero knee collar.
  4. Raise the knee inside the drilled hole.
  1. Use the endmill to plunge to depth.
  1. Toughing off the top of the work with the quill.
  2. Set the quill stop.
  3. Zero knee collar.
  4. Raising the knee to set the depth.
  5. Gently plunge the endmill to depth using the quill, breaking chips when needed.
  6. Lock the quill at final depth.
  1. Ramp into the work with an endmill.
  1. Lock the quill
  2. Touch the tool off the top of the work with the knee.
  3. Zero knee collar.
  4. Gradually move the knee and table/saddle handwheel simultaneously to create a shallow ramp.
  5. Continue back and forth until the desired depth is reached.
  1. Apply some initial cutting oil and continue throughout the cutting process.
  2. Rough the material from the inside of the pocket visually, leaving 1/32″ of an inch on the walls and 1/64″ on the floor for a finishing operation. An air blast can aid in chip removal and help prevent re-cutting chips and damaging the tool.
  3. Load a finishing end mill if needed, touch off the top of the work, and bring the tool to the full depth inside the pocket.
  4. Finish the bottom of the pocket.
  5. Gently make skim cuts along all four sides, recording the handwheel positions on each side.
  6. Measure the part and calculate the material remaining on the four surfaces.
  7. Calculate the positions of the tool to remove the rest of the material, minus .010″ for a final finish.
  8. Conventional mill to the calculated positions.
  9. Measure the part and calculate the material remaining on the four surfaces.
  10. Calculate the positions of the tool to remove the rest of the material, making a final finish pass.
  11. Climb mill to the calculated positions.
  12. Measure the finished pocket size.

Step 2: Layout the pocket’s boundary.

Lines have been laid out on a rectangular piece of material for the outer boundary of the pocket.
Figure 9.181. Lines have been laid out on a rectangular piece of material for the outer boundary of the pocket. / Image Credit: Micky R. Jennings, courtesy of Wenatchee Valley College, CC BY 4.0

Step 7-b-i: Toughing off the top of the work with the quill.

Touching off the bottom of the end mill to the top of the part.
Figure 9.182. Touching off the bottom of the end mill to the top of the part. / Image Credit: Micky R. Jennings, courtesy of Wenatchee Valley College, CC BY 4.0

Step 7-b-ii: Set the quill stop.

A hand adjusts the quill stop up to meet the position of the quill.
Figure 9.183. A hand adjusts the quill stop to meet the position of the quill. / Image Credit: Micky R. Jennings, courtesy of Wenatchee Valley College, CC BY 4.0

Step 7-b-iii: Zero knee collar.

The graduated collar of the knee has been adjusted to zero.
Figure 9.184. The graduated collar of the knee has been adjusted to zero. / Image Credit: Micky R. Jennings, courtesy of Wenatchee Valley College, CC BY 4.0

Step 7-b-v: Gently plunge the endmill to depth using the quill, breaking chips when needed.

Step 7-c-ii: Touch the tool off the top of the work with the knee.

Step 7-c-iv-v: Gradually move the knee and table/saddle handwheel simultaneously to create a shallow ramp. Continue back and forth until the desired depth is reached.

“Step 9: Rough the material from the inside of the pocket visually, leaving 1/32″ of an inch on the walls and 1/64″ on the floor for a finishing operation. An air blast can aid in chip removal and help prevent re-cutting chips and damaging the tool.”

Step 13: Measure the part and calculate the material remaining on the four surfaces.

A pair of calipers are used to measure the right side wall thickness to establish the remaining amount to cut.
Figure 9.185. A pair of calipers are used to measure the right side wall thickness to establish the remaining amount to cut. / Image Credit: Micky R. Jennings, courtesy of Wenatchee Valley College, CC BY 4.0

Step 13: Measure the part and calculate the material remaining on the four surfaces.

A pair of calipers are used to measure the front wall thickness to establish the remaining amount to cut.
Figure 9.186. A pair of calipers are used to measure the front wall thickness to establish the remaining amount to cut. / Image Credit: Micky R. Jennings, courtesy of Wenatchee Valley College, CC BY 4.0

Step 16: Measure the part and calculate the material remaining on the four surfaces.

A pair of calipers are used to measure the left side wall thickness to establish the remaining amount to cut.
Figure 9.187. A pair of calipers are used to measure the left side wall thickness to establish the remaining amount to cut. / Image Credit: Micky R. Jennings, courtesy of Wenatchee Valley College, CC BY 4.0

Step 18: Climb mill to the calculated positions.

Step 18: Climb mill to the calculated positions.

An end mill rests at its final position inside a finished pocket on a manual milling machine. An air blast nozzle, used for chip evacuation, is to the left of the pocket.
Figure 9.188. An end mill rests at its final position inside a finished pocket on a manual milling machine. An air blast nozzle, used for chip evacuation, is to the left of the pocket. / Image Credit: Micky R. Jennings, courtesy of Wenatchee Valley College, CC BY 4.0

Step 19: Measure the finished pocket size.

A pair of calipers are used to measure the left side wall thickness of the finished pocket.
Figure 9.189. A pair of calipers are used to measure the left side wall thickness of the finished pocket. / Image Credit: Micky R. Jennings, courtesy of Wenatchee Valley College, CC BY 4.0

Attributions

  1. Figure 9.180: Finished pocket by Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  2. Figure 9.181: Pocket layout lines by Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  3. Figure 9.182: Touch off endmill by Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  4. Figure 9.183: Set quill stop by Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  5. Figure 9.184: Zeroing the knee by Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  6. Video 9.52: Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  7. Video 9.53: Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  8. Video 9.54: Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  9. Video 9.55: Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  10. Figure 9.185: Measuring the right side of the pocket by Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  11. Figure 9.186: Measuring the front of the pocket by Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  12. Figure 9.187: Measuring the left side of the pocket by Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  13. Video 9.56: Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  14. Figure 9.188: Finished pocket by Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  15. Figure 9.189: Measuring the finished pocket by Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
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