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Development and Design of
Deep-Hole Drilling and Rifling Machine.
Chris Whitehead, North Yorkshire England

Pictures of the gun-boring and rifling machine for sale here

Introduction:
With more than 52 years use of firearms - and a professional background of more than 40 years in mechanical and electrical manufacturing disciplines - I have built the machine to incorporate many refinements. Of modular build, most parts except the main channel can be lifted by one person - the whole thing able to be carried in a family-sized estate car (station wagon). All major components are bolted on (no welding), are infinitely adjustable but it is, in the main, self-aligning if assembled correctly.

Basic build dimensions and capacities:
The machine will currently drill and rifle 28.0 inch solid bars of any material composition up to RC50 in the range of 1 in 7 through 1 in 16 but may be extended further by gearing. Small gears EN8; larger gears by compressed fibre or nylon at 16DP 20PA.

Machine total length:                 94.0 inch.
Main channel length:                  78.0 inch.
Main channel width:                     9.0 inch.
Main channel depth:                     3.5 inch.

Channel feet made from the same section as the main channel, are fully boxed with level adjusters and tie-down bolts held in recesses.

Channel foot (head stock)          18.5 inch long x 4.875 deep.
Channel foot (tail stock)               5.375 inch long x 4.875 deep.
Ground full hard bar length:     60.0 inch.
Ground full hard bar diameter:   1.5 inch.
Pitch of full hard bars:                  7.0 inch.
Bar mounting blocks line bored as a pair.

Sled, rounds cut from EN8:   65.0mm.
Sled, bronze Oilite bush's: 1.750 OD x 1.5 ID x 1.25 wall x 2.0 length.
Sled, front 5.0 inch x 9.0 inch x .625 CRS.
Sled, whip guide 2.0 inch x 9.0 inch CRS.
Sled, rear tool post 7.0 inch x 9.0 inch CRS.

Whip guide upright 9 inch x 4 inch x .625 CRS (step bored) 50mm mandrel side to fit rotating high-speed bearings 50mm OD x 30mm ID. Rear side, bored at 44.5mm to fit over drill holder snout for ease of alignment.

Chip box: 5 inch deep x 5 inch tall x 6 inch wide.
Chip box front drill bushing, professional carbide to suit required drill.
Chip box Gun drill insert, professional alloy steel (hardened) to suit bush.
Chip box rear rotating high-speed bearings 50mm OD x 30mm ID.
Chip box rear drill guide bush and chip deflector seals professional.
Chip chute Top section: 7.25 inch long x 4.75 inch wide.
Chip chute Bottom section: 3.750 inch long x 2.5 inch wide.

Mandrel pillow block housing and bearings NTN212-39 60mm ID, (version 1).
Mandrel EN8 12.5 inches long 60mm OD 41.5 ID, (short barrels)(version 1).
Mandrel pillow block housing and bearings NTN212-39 2-7/16" ID, (version 2).

Mandrel Hollow bar E355/ST52 27.25 inches long 2-7/16 OD, 1-1/2 through ID. EN24T internal bushes at both ends to take 40mm turret to MT4 adapter or ER32 collet chuck, (version 2).
Mandrel over-shoe (indexing head) 12, 8, 7, 6, 5, 4, 3, 2, twist, (as version 1).


Mandrel cat head chucks, Allen cap heads 3/8 x 24 UNF.
Mandrel drive motor 2HP 3 phase inverter 200-3000+ RPM reversible.
Mandrel drive by twin pulley A section belt.
Mandrel mounting plate, 18.0 inch x 10.0 inch x 0.625 inch CRS.
Mandrel mounting plate, with fine adjustment elevation screws.
Mandrel alignment to mounted bars by 1mtr ground full hard bar or byER32.
Mandrel used to centre and line-bore sled uprights.
Lead screw drive motor 0.75 HP DC reversible and RPM adjustable.
lead-screw motor reduction ratio 15.38:1 (more would be better).
Lead-screw 0.750 x 10 TPI  in 304 stainless x 51.0 inch long.
Heavy duty bronze split nut drive engage / disengage.

Chain drive gears 1:1 ratio, 0.5 inch pitch.
Chain adjusters at rear tool sled, twin sliding pillar type.
Chain drive mandrels 0.625 W1 (silver steel) with locking collars.
Chain drive bushing (4) steel with inner Oilite bronze bushes.

Tool holders, mild steel, 2 x matched pair 4 bolt cap head's with 2 steel dowels.
Tool holder block, drilling / reaming, 3.625 tall x 3.0 inch x 3.0 inch.
Tool holder block for drilling / reaming, bored and reamed through 1.25 inch.
Tool holder spindle for drilling / reaming 817M40T 6.5 inches long x 1.750 inch bored 2.75 inch deep at front with nitrile o-ring seal, through bored at 1/4 with tool holder lock-down and 1/4 BSP threaded pipe nipples.

Tool holder block for rifling, 3.625 tall x 3.0 inch x 3.0 inch
Tool holder block for rifling bored 1.5 inches through; flanged I.250 inch ID bronze Oilite bushes fitted front and back.
Tool holder spindle for rifling 817M40T 7.625 inches long x 1.750 inch diameter bored 2.75 inch deep at front with reduced section to pass through block bushes; further reduced at rear end and keyed  to accept Boston spiral mitre gear.

Rifling rack 52.0 inches long x 0.625 x 0.625 mounted on 52.0 inch x 4.0 inch slotted alloy plate.

Rifling rack drive 16DP 20PA spur gears on 0.625 W1 (silver steel) shafting with lock collars. Rifling rack gears are reversible spiral mitre gears able to cut left and right hand twist all mounted on bronze bushed removable pillow blocks.

Machine has double filter pans by filter bag and magnets on the drill cycle with additional filtering for the ream cycle also by filter bag and magnets to the Main tank with Pre-pump filtering at 10 microns.
Main hydraulic tank, 25 litre capacity.
Italian 6 piston constant displacement type 150 bar pressure washer pump.


Hydraulic pump pressure regulated with bypass unloader valve at 1000 psi for safety considerations. Pump normal setting for 6mm drill size about 70 bar pressure on Excelcut 433 hydraulic gun-drill oil.

Pump drive motor is 1.5 HP single phase through belt gearing and motor starter control.

Auxiliary mounting rack at rear to accommodate pressure gauges and controls 61.0 inches long x 6.750 inches deep.