Barrel drilling tools. A is plan and detail see of oil tubing supplied on barrel drills. B is plan and also end view of barrel drill when C is underside watch of same.

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into the tool post slot in the rest. This tongue is just thick sufficient to expand a quick distance under in the tool post slot and also the block is hosted down by two cap-screws pass down with it and into a bar of stole in the wide groove at the bottom the the slot. This block is drilled and also reamed, out past the tool short article slot, on the exact facility line of the lathe, clear with from next to side. This hole is a nearby fit around the drill drive tube which has no vee-groove in it in ~ this suggest This block is slotted with a saw-cut indigenous the outer end earlier through this hole because that the drive tube to a brief distance ago of the hole, the full width of the block. Out beyond the drive pipe hole two cap-screws, from optimal to bottom v the block, clamp the sawed outer end of the block together, squeezing the tube tightly in that hole.

The rate the barrel turns throughout the drilling procedure is high and the feed of the drill right into the blank is slow, together you have yet one modern on the drill. Oil is pumped under pressure through the tube from the rear finish where a connection for a flexible oil pipe from the pump is sweated onto the tube. This oil passes v the oil hole in the drill, comes out listed below the point, and returns, delivering the chips v it in the vee-groove on optimal of the drill and also drive tube. The drill is ground to drill a hole .010" come .012" smaller sized than the diameter the finished bore is to be made. The empty is carefully centered in the barrel chucks and also the hole is began with a center drill and also then drilled for a distance through a twist drill to give the barrel drill a true start.

After the barrel is drilled it must be reamed come size and for this procedure three reamers room used, a roughing reamer and also two finishing reamers, the last yes, really being a burnishing reamer. Reamers room made of highspeed steel and are do with six grooves, other than the roughing reamer which may be made with 4 or 6 grooves. This barrel reamers have a rather lengthy front pilot, the front end of which is turned down for a quick distance so that the tube which color etc the reamer through the barrel can be brazed come the reamer pilot. . The end of the reamer flutes just behind the pilot are provided a slight taper to bring the reamer diameter at this allude to just under the diameter of the drilled feet in the barrel empty so the the reamer will start to cut easily. The cutting portion or flutes that the barrel reamers vary from 6" to 7" in length. A feet of small size is drilled lengthwise of the pilot native the front finish to a necked part just front of the flutes so the oil might be pumped to the reamer with the traction tube. From the finish of this feet in the necked part of the reamers, three little holes spaced equidistant about the neck are drilled at right-angles come the axis that the reamer so the the oil comes the end at the front finish of the flutes. These front pilots space made to just fit the drilled feet of the empty on the roughing reamer, to fit the rough-reamed feet on the finishing reamer and also to right the finish-reamed feet on the burnishing reamer. The roughing reamer clears .005" to .006" native the drilled feet in the blank, the finishing reamer gets rid of .003" come .004" and also the burnishing reamer finishes the boring to size.


Barrel reamers. A is roughing type reamer, four groove, all carried through rear pilot. B is finishing form reamer, six groove, 3 grooves lugged through behind pilot. C is burnishing reamer, 6 groove, three grooves brought through rear pilot.

The flutes the the roughing and also finishing reamers are reduced .010" front of facility as are those the the roughing and finishing chambering reamers, when those top top the burnishing reamer are reduced on center and finished to form as room those that the burnish-type chambering reamer. Barrel reamers carry out not have actually clearance floor upon lock as do the chambering reamers, their clearance is stoned upon castle by hand. Barrel reamers v spiral flutes are more efficient than those with right flutes together they have a shearing cut yet these spiral flutes are much more daunting to stone than room straight flutes. Barrel reamers are occasionally made through rear pilots and front pilots and in this case the flutes are milled out through the rear pilots so that the chips deserve to pass off the reamer and on under the barrel.

In making use of the barrel reamers, the reamers are hosted stationary and also the barrel empty revolves in ~ a low rate as the reamer is drawn through the barrel by the oil tube which is attached come a movable carriage such together the lathe carriage in case a lathe is used. A floating link at the end of the oil tube need to be used, so that the reamers are entirely guided through the bore of the blank. The finish of the oil tube might be plugged for 2" and also a straightforward universal share used, attached come this plugged portion, or a floating journey of the form described on chambering reamers might be used. The versatile oil heat from the pump is led into the next of the hollow part of the oil pipe ahead that the plugged finish through a screw connection like a nipple. This connection must be gotten rid of to pass the oil tube through the barrel blank, as the oil pipe is brazed to the reamer, and then placed in place and the oil line associated to the before beginning the lathe.

Shotgun barrels space made from stole tubes and although castle may therefore be reamed to size with a collection of barrel reamers, such together those supplied on rifle barrels, they space usually bored v a long, four-sided, square little bit of high-speed steel, soil to size on a surface ar grinder. These bits are 10" to 12" long and also have a tapered lead at the front end, about long top top the roughing reamer and also an inch lengthy on the finishing reamer or bit. The driving rod because that these bits is brazed come the rear finish of the bit, the opposite end from that which has the tapered lead, and the bits are moved through the bore as the barrel tube revolves.

A timber packing strip, rotate on one side to the contour of the barrel bore, is placed versus one next of this bit, its complete length, and also on the roughing bit the two edges of the next diametrically opposite the next upon i beg your pardon the packing piece is inserted do the cutting. Strips of file are placed in between the lumber strip and also the boring little bit to reason it to reduced larger ~ each pilgrimage through the barrel.

A wood strip that the same form is used on one next of the finish or fine boring bit yet the leading edge of the opposite side has a tiny radius stoned upon it so the it does no cutting, which is every done through the rolling edge of this next opposite to the on i beg your pardon the lumber strip is placed.

Shotgun boring bit, additionally sometimes supplied on rifle barrels. Finish view shows just how wood packing strip and also shims space used.

A third square bit, the choke boring bit, is supplied in shotgun barrels. After the complete or well boring little is supplied this throttle boring bit which has actually a tapered command an inch long which tapers around .050" in this distance is supplied to bore out the choke part of the barrel i m sorry is no bored out by the finish boring bit, but only through the roughing bit. A wood packing strip is used, with record shims on the tapered portion of this throttle boring bit and also this little cuts upon two edges as does the roughing bit. This shotgun boring bits are run in ~ a low speed and plenty of cutting oil is used. In do the bits they space hand honed after gift ground to form by a surface ar grinder. They have to be carefully checked for straightness. In act the grind ing, if lot stock is to be removed, perform not grind a lot turn off of one side and then off the opposite side but take a little amount turn off of the an initial side, climate a favor amount native the opposite side, then take the very same from an nearby side and also the very same from the critical side and also repeat this till the bit is ground to size, as this technique of grinding will avoid warping the bit.

Drills for boring out old barrels for relining (the insertion of rifled tubes) might be do from standard, high-speed steel, three or four-groove drills v the continual twist flutes together made by all drill make firms. This manufacturers will certainly grind a pilot on this drills, to order, come fit the old bore of the barrels to it is in re-lined, or by utilizing an electric tool article grinder you have the right to grind your very own pilot upon them. The cutting edges at the rear end of the pilot must be ground through relief, as were the cutting edges at the end of the drill originally. These drills will not drill holes in solid metal yet are offered to enlarge cored or previously-drilled holes. A carbon-steel shank of any type of length might be welded to the shank of these drills.

If you wish to do your very own drills because that drilling the end barrels because that relining they might be make of a brief section, l/2" come 2" long, of high-speed stole by transforming a pilot ~ above the front finish to to the right the old boring in the barrel and turning down a short section of the rear finish to a smaller size so the an oil tube might be brazed top top it. The human body usually has three straight grooves milled lengthwise the it through a fluting cutter. The front end of the lands in between these grooves space relieved or ground as room the lips of a twisted drill. A small hole is drilled lengthwise the the human body from the shank end about halfway with the body and also holes space drilled into this in ~ the finish toward the allude of the drill from each of the grooves so that oil pumped with the oil tube can be forced out into the flutes, washing the chips the end of the barrel front of the drill and also keeping the cutting edge cool. The pilot is grooved v the milling cutter which cuts the flutes so that the chips have a cost-free passage.

After the old barrel is drilled the end with among these drills the is generally reamed with a barrel reamer the the continual fluted t}"pe come straighten the hole perfectly and also bring the to size to take the lining tube used.

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Six-groove barrel reamer, the the type commonly provided in set of three, in graduated sizes.