Also Boring

This is a continuing discussion of the art of making holes.  Besides the typical brace and bit there are other methods of drilling holes, these include some of the earliest tools used by mankind.  Some of these ancient inventions are still of use today.  The whole idea is to make a hole.  Some of these methods make crude, rough holes others can make very fine, delicate piercing.  During the stone age when man first used tools, sharpened rocks were used to scrape holes in wood.  About 6000 years ago man developed the technology to make bronze tools, which were hard enough to make augers to drill holes.  Some archaic methods of hardening bronze and copper gave them a very hard edge that would take wear, a technique that is lost in history.  Then about 3000 years ago our ancestors smelted and produced iron, which was a superior improvement over bronze and would hold an edge.  Then sometime before the 12th century, blacksmiths were able to include nearly 2% carbon into their iron to produce steel, which could be hardened much harder than iron.  Steel held an edge, did not wear like iron but was more brittle and expensive.  Used in conjunction with iron and placed on the working edges of tools and later these tools were made entirely of steel.


Burn Auger – The burn auger produces a hole in wood by burning the wood and reaming out the char with the auger itself.  This style of auger is thousands of years old and even the crudest bog iron can burn a smooth hole.  Usually square iron tapered to a point with the handle bent at 90º to provide leverage and a grip for this hot tool.  It is heated in a fire and the point is thrust into the wood and twisted, burning and reaming the wood to the desired size.  The taper allows for different size holes to be made with one tool.  Useful for work in the woods and for certain applications provide just the desired results.  The holes tend to have smooth edges because of the charring and this can be helpful for lacing such as canoe making.  The fire also hardens the hole so it will wear better than a mechanically bored hole.  Almost any piece of metal that can be heated to even a dull red will burn a hole in most woods.  A popular method of drilling used by the Native Americans.


Bow Drill – Perhaps the oldest mechanical drill, a quill or spindle is reciprocated back and forth by a string held in shape with a bow.  This mechanical advantage would quickly spin the drill back and forth, so the bit is sharpened to cut in both directions.  The idea undoubtedly dates to the Stone Age with refinements until fine ebony, brass and steel are combined into exquisitely made examples of nineteenth century pre-industrial revolution, craftsmanship.  I recently made yet another bow drill, a copy of an 1840’s piece in the Smithsonian, although mine was all wood.  I made the handle and bow from one piece turned and carved section of proper straight grain hickory.  The pulley and ratchet is beech and the pawl, maple.  I turned beech bobbins for the flat double cut bits made from large wire nails and are usually made as one unit with a fixed bit.  Some have round tapered chucks to hold interchangeable bits.  A separate wedge is used to remove the bits from the tight fitting tapered chuck.  The hand plate of mine is fashioned from chestnut with an iron bearing plate let in to the flat side.  Some of these plates were made to be worn as a bib on the chest for pushing on the bobbin/bit, others are just handles.  There is a trick to using this drill and it takes good eye hand coordination to keep the string on the bobbin.  If you are having trouble, try pointing the tip of the bow down as you work the bow back and forth.  An excessive amount of work for an archaic tool, but it is fun to use occasionally, especially for shallow holes and looks great on the shop wall.


Pump Drill – This is one of my favorite drills, perhaps it is from its unique reciprocal action, the rhythm necessary to successfully use this tool, you can use it with one hand or just because it is nifty.  A pump drill consists of  three parts and the bit, again this tool cuts in both directions so it requires special bits and some have chucks for changing bits, others have fixed bits that can not be changed.  The shaft has the bit (or chuck) at one end and the other has a hole through which the cord or string passes.  The shaft has to be long enough to allow the string to wind around the top as the drill operates.  On the shaft towards the bit, is placed a flywheel, which gives the bit momentum as it is being used.  Commonly made of hard dense wood, soapstone or other stone that can be easily worked can be used as can machined metal such as brass, iron or bronze occur on historical examples.  The handle has a hole in the center that passes over the shaft and a hole is drilled in each end, through which the string passes and it attached.  The string is tied to one end of the handle, the handle is slipped over the shaft, and the string is threaded through the hole at the top of the shaft and passes through the hole on the other end of the handle.  The handle is positioned just above the flywheel and the other end of the string secured to the handle.  To start drilling the shaft is turned while the handle is held with your hand.  The handle is pulled up as the string winds up around the top of the shaft and when it is pulled up, the bit is placed where it is going to drill and gentle downward pressure is applied to the handle causing the shaft to turn.  As you reach the bottom of the stroke, the drill reverses direction and the flywheel winds the string back up as you continue to drill.  A simple up down stroke is converted into the circular action needed for drilling.  Once you develop the rhythm this tool is a pleasure to use.  Why this tool is not used more is beyond me, it is easy to build and can be used anywhere.


Archimedes Drill – Whether Archimedes developed this drill is not known, however his principle of the Archimedes Screw lends its function and name to this drill.  These can have fixed bits or chucks for interchangeable bits.  There is a metal shaft made of square stock that is twisted from top to bottom.  A free spinning knob on the top is used to hold the shaft and bit in position and to provide pressure for drilling.  A hollow knob with a metal follower on one end of the hole has a square opening just slightly larger than the metal shaft.  As the knob is moved up and down on the shaft, it causes the square metal shaft to rotate back and forth producing the drilling action.  Linear motion is converted into circular motion in a rather novel and unique drill.  Another tool that is very handy for small holes.  Versions of this tool are still being made and work quite well.


Hand Crank Gear Drill – The most modern of drills considered here, this tool was developed in the nineteenth century and became common after the American Civil War.  These require machining to make the necessary parts and gears.  Commonly called an eggbeater drill a circular motion is converted and accelerated to another circular motion to do the drilling.  This type of drill used bits that cut only in one direction, however you can use double cutting bits in this tool.  A handle and framework provides the place for the gears, shaft and crank handle can be attached.  By turning the crank handle the action of the large gear spins the smaller gear attached to the drilling shaft and chuck.  The gear ratio gives a mechanical advantage as well as an increase in speed.  Another version of this tool is incorporated into a special stand and with two crank  handles for drilling large holes in timber frame construction and was introduced in the early 1850’s.  Early models used a leather belt on a pulley to extract the bit after it has drilled to depth.  Later models used a rack and pinion gear to pull the bit out of the hole and some were adjustable to drill at angles.  Having a wooden base framework, the worker could sit or kneel on the end to hold it in place.

Chucks & Collets – These are the devices that secure the drill bit to the drill.  A method of attaching bits to drills made of wood is a simple slot cut in the end of the shaft and a flat piece of metal, shaped to the size of the drill on one end is held within the slot or kerf and held with a screw, bolt and nut or a compression ring.  A metal ring is placed on the shaft that is turned with a taper from the bit end getting smaller as it goes up the shaft.  The ring is snug fitting and when it is forced onto the taper it pinches the bit in the slot securing it in the correct position for drilling.  This split collet is a simple and elegant solution to fixing bits to the drill.  Another traditional chuck is a tapered chuck.  These are used in metal versions of bow drills, pump drills or other types and require accurate machine work.  The bits need an appropriate taper turned on their shanks and the chuck has a tapered hole that the machined bits fit into.  The friction fit holds them in place and the downward pressure also holds them in place.  Because they can be difficult to remove, slots are provided on the shank that allows a small wedge to be driven in on the backside of the bit to force it out of the chuck when it needs to be changed or sharpened.  Square tapered chucks can also be used to hold traditional drill bits.  These can be friction fit, equipped with a spring chuck to catch and secure the bit or a thumbscrew to hold the bit in place.  The split collet holds straight round cylinder bits and have very little adjustment for size variation.  The split collets come in different sizes for different bit shank sizes.   Split chucks or double chucks were developed in the late nineteenth century (1880) and were capable of holding square tapered bits as well as larger round drill bits.  The Jacobs Chuck with 3 jaws was invented by Mr. A. I. Jacobs in 1902 and has become the modern standard to hold round drill bits.  However, they can not hold the old square tapered bits and many fine old examples of drill bits with square tapered shanks have been destroyed by cutting off the square part so it could be used in a modern drill.  The ratchet mechanism was incorporated on bit stocks in the 1890’s.

Box Engine – This is a rather unique drill that is capable of drilling large holes as well as tapered holes and was used by wheelwrights to make the tapered holes in wheel hubs (boxes) to fit the tapered thimble skeins.  This tool has a threaded shaft with a turning handle on one end, an adjustable L shaped cutter held by a bolt and a three tined, tapped flange.  There needs to be a hole previously drilled through the work, through which the threaded shaft is inserted and the flange (nut) holds the shaft centered in the work and the tines engage the wood.  The cutter is adjusted to the desired size of the hole being re-drilled.  The L shaped cutter is sharpened along the long and short leg on the inside to cut both down and out.  The handle is then turned advancing the cutter into the wood, when it reaches the other end  the cutter is reversed until the flange disengages from the wood and is turned off.  One advantage to this cutter is that it can cut a tapered hole, by stopping the cutting backing out, adjusting the cutter and continuing until the taper is cut.  Tapered reamers are then used to smooth the tapered cut with the box engine removing the bulk of the wood.

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