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drilling systems from sterling gun drills



Drilling Systems - Half Round Drills


Half round drills are ordered by specifying drill diameter and flute length. See the Half Round Drill Sizing chart for available diameters, lengths, and driver sizes


half round drill


Diameter
Ranges		 10X Series
Lf
inchmm		 Lo
mm		 20X Series
Lf
inchmm		 Lo
mm		 30X Series
Lf
inchmm		 Lo
mm		 Driver
.1250 -.1562 2.36* 60 (110) 3.54* 90 (140) ---
.1563 - .1875 2.75* 70 (120) 4.72* 120 (170) ---
.1876 - .2344 3.14 80 (130) 6.29 150 (190) --- HA-1
.2345 - .3120 3.93 100 (150) 7.08 180 (230) --- Dd=16mm
.3121 - .3906 4.72 120 (170) 7.08 180 (230) 9.44 240 (290) Ld=40mm
.3907 - .4688 5.51 140 (190) 8.66 220 (270) 11.81 300 (350)
.4689 -.5781 6.29 160 (255) 10.23 260 (325) 14.71 360 (425) HA-2
.5782 - .7031 7.08 180 (245) 12.4 315 (380) 17.71 450 (515) Dd=25mm
.7032 - .8125 7.87 200 (265) 14.56 370 (435) 21.25 540 (605) Ld=50mm
.8126 - .9688 8.85 225 (295) 16.73 425 (505) 24.80 630 (710)
.9689 - 1.1406 9.84 250 (330) 19.09 485 (565) 28.34 720 (800) HA-3
1.1407 - 1.5000 10.82 275 (355) 21.85 555 (635) 33.07 840 (920) Dd=35mm
Ld=60mm
* Drills have V (gun drill) style flute mm
25.4 = inches


For Expert Support Call us - Gun Drills and Half Round Drills




The Deep Hole Drilling System Setup Procedure

The gun drill and half round drill standard drill point position is offset to 1/4 of the drills diameter. This does not allow the drill to start unless guided by either a gun drill bushing or a pilot hole. On conventional machinery, a pilot hole is usually the most practical.

Should you have any questions regarding materials, speed and feed, machine application or operation, contact Sterling Gun Drills for assistance.

Should you have any questions regarding materials, speed and feed, machine application or operation, contact Sterling Gun Drills for assistance.

 
Step 1) Mix lubricant at 10:1 ratio in a separate container then fill up the reservoir.
Step 2) Prepare a pilot hole for the gun drill or half round drill to a diameter of +.001", -0, by 1/2 to 1 diameter deep. If tolerances require, keep the pilot hole diameter closer but NEVER undersize. NOTE: Standard gun drills are not measurable, prepare the pilot hole as above to the label diameter.
Step 3) Secure the drill in a toolholder mounted in the spindle, turret, or toolpost true to the part or spindle centerline. Connect the nozzle from The Spraymist Kit to the male fitting of the toolholder, or transfer block on a CNC.
Step 4) Connect the Spraymist Kit to shop air at 100-120 psi. Select the proper drilling parameters from the Sterling Gun Drills Speed and Feed chart.
Step 5) Insert the drill tip into the prepared pilot hole just short of the bottom. Start the spraymist by opening the slide valve. Adjust the mist jet needle to create a fine mist. (a white ring will be visible at the bore opening during drilling). Caution: NEVER rotate the drill outside of the hole.
Step 6) Turn on the spindle, then start the feed. Chips should clear the bore continuously to depth. If packing occurs, reduce the feed. At depth, back off the bottom slightly if a blind hole then stop everything and remove the drill. Inspect the cutting edge often for wear.

Drilling Systems:
Gun Drills | Half Round Drill | Spraymist Kits | Stationary or Rotary Toolholders | Resharpening

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