Before drilling commences the gun drill must be suported by a guide bush or pre-drilled start hole. Coolant is delivered directly to the cutting edges through the hollow shank and the chips are evacuated back along the V configuration of the tip and shank.

The periphery of the cutting tip is contoured in such a way as to provide both support pads and lubrication galleries. The forces generated by the single sided cutting action act directly on the support pads creating a burnished surface finish and size control down to IT7 tolerances.

Gun drill tips can be manufactured with a step that has either a cutting, or non cutting pilot. Coated tips are also available upon request. These may have a TiN (Titanium Nitride) coating, or a TiAlN (Titanium Aluminium Nitride) coating.

A regrinding service is available at our Hemel Hempstead factory for gun drills, Ventec drills and Speedfeed drills.
Hardened steel guide bushes and whip guides are available for purchase. See accessories. accessories.

Driver Design	Ref	d	h	h1
HAMMOND STANDARD	CA	16	40
	CB	25	50
	CC	35	60
AMERICAN STANDARD	AA	1/2"	38	26
	DM	3/4"	70	46
	AC	1.00"	70	55
	AD	1.25"	70	55
	AE	1.50"	70	55
EUROPEAN STANDARD	AF	10	40	24
	AK	16	45	31
	AG	20	70	34
	AH	25	70	34
	AJ	32	70	34

 

Driver Design		Ref	d	h	h1
		AN	16	50	47
WELDON		BF	16	48	24
	h2	BG	20	50	25
	17	BH	25	56	32
	19	BJ	32	60	36
	19	BK	40	70	40
		DG	10	60	M6X0.5
		DH	16	80	M10X1.0
		DK	25	100	M16X1.5
		DL	36	120	M25X1.5

Cutting Head Contours

Tubular Shank Dimensions Hammond gundrill shanks are manufactured from high quality chrome molybdenum steel and are designed to achieve maximum coolant flow, chip clearance and torsional rigidity.
Ø Range	Ø Tube	Ø D Range	Ø Tube	Ø D Range	Ø Tube
3,00-3,14	2,8	6,50-6,99	6,2	13,90-14,89	13,4
3,15-3,39	2,95	7,00-7,29	6,7	14,90-15,89	14,4
3,40-3,64	3,2	7,30-7,59	7,0	15,90-16,89	15,3
3,65-3,87	3,45	7,60-7,94	7,3	16,90-17,89	16,2
3,88-3,99	3,65	7,95-8,34	7,6	17,90-18,89	17,2
4,00-4,19	3,8	8,35-8,54	8,0	18,90-19,89	18,2
4,20-4,44	4,0	8,55-8,94	8,2	19,90-20,89	19,2
4,45-4,74	4,25	8,95-9,34	8,6	20,90-21,89	20,2
4,75-4,97	4,55	9,35-9,94	9,0	21,90-22,89	21,2
4,98-5,24	4,75	9,95-10,64	9,6	22,90-23,89	22,2
5,25-5,49	5,0	10,65-10,94	10,3	23,90-24,89	23,2
5,50-5,74	5,25	10,95-11,94	10,6	24,90-26,89	24,2
5,75-5,94	5,5	11,95-12,54	11,6	26,90-28,89	26,2
5,95-6,29	5,7	12,55-12,94	12,2	28,90-30,89	28,2
6,30-6,49	6,0	12,95-13,89	12,6	30,90-33,00	30,2
Updated August 2013

Hammond Recommended Geometry for Various Materials

Drill Diameter.	Primary Land	Chamfer at 20°
Ø 3,0 to 12,0	0,4 – 0,6	0,4 – 0,6
Ø 12,0 to 25,0	0,6 – 0,8	0,6 – 0,8
Ø 25,0 to 32,0	0,8 – 1,2	0,8 – 1,2

Facet Description		NG4 Aluminium (Order code B)		NG13 Grey Cast Iron (Order code E)		NG80 Flat Bottom (Order code G)
		Horiz.	Vertical	Horiz.	Vertical	Horiz.	Vertical
A	Outer Primary	+15°	+15°	+40°	+12°	+1°	+12°
B	Outer Secondary	+14,5°	+20°	+39,5°	+25°	+1°	+20°
C	Inner Relief	-20°	+15°	-20°	+12°	–	–
D	Front Clearance	0°	+25°	0°	+35°	–	–
E	Oil Dub-Off	-25°	-15°	-25°	-12°	25°	-12°
Point Position		D/4		D/4		D/2

Facet Description		NG82 Super Alloys (Order code H)		NG86 Wood Grind (Order code K)		NG90 Malleable MATL (Order code L)
		Horiz.	Vertical	Horiz.	Vertical	Horiz.	Vertical
A	Outer Primary	+42°	+14°	+30°	+20°	+20°	+20°
B	Outer Secondary	+41,5°	+25°	–	–	–	–
C	Inner Relief	-17°	+14°	-20°	+20°	-20°	+20°
D	Front Clearance	0°	+30°	0°	+30°	0°	+25°
E	Oil Dub-Off	-22°	-15°	-25°	-15°	-25°	-15°
Point Position		D/5		D/3,5		D/4

Cutting Parameters

Gun drills operate at relatively high cutting speeds with low feeds per revolution. Approximate starting values are shown in the charts on this page.

Feed rates are critical to chip formation. The values shown here may need to be adjusted for optimum results.

Reliable chip evacuation and good surface finish can only be ensured if sufficient coolant volume and pressure are available.

Pressure and volume vary according to length/diameter ratio.

Chart shows maximum unsupported flute length.