Friday, September 18, 2015

Making holes and reaming

We talked previously about the shell(s) and hollow taper bits, but what do you do with them and how do you restore them in order to used them?

Well, first lets start with some history behind how making holes has evolved to better understand how we got there.
Making holes has a very long history, the Egyptians woodworkers knew and had tools to make them, and some tribes of humans long before used bow drills and pump drills. These drill types were also used to make fires, by friction...
These were evolved from the earliest tools that merely used sharp objects that were twisted back and forth with your hands.

North American tribes using both bow and pump drills to make fire.

Modern reproduction of Native's pump drills.
The stone act like a flywheel to keep momentum going.

It was very laborious work, so the idea was to make a small piercing hole then enlarged it successively to required size.
It was somewhat difficult to apply sufficient pressure to help the cutting action, various methods were employed, using a board on top, putting pressure using your chest or your mouth, even using an apprentice to apply pressure while you drilled.

All kinds of holes are required to fit various parts together to build something, wood joinery method we have long taken for granted, simply did not exist.
Neither did they had Singers sewing machines, so they had to pierce materials and wove in a thread like material (sinew, fibers etc)
Although I have read recently that some tribes were using fish glue to keep the seams of their garment together, instead of stitching.
Yes I still have sewing machines on the brain :-)
The piercing tool Awls, needles, are probably the first kind of tool man used to make holes.

For the longest time, no one ever heard of sizing drilling implements as we currently uses. That is mostly a by product of the industrial age.
The sizes of natural needles, bones and how well you could shape a piece of stone flint dictated how big or small of a hole you could make.

Using diagonal shaped bits of stone were the drilling implement of choices, the further you drilled, the wider the hole. Want a bigger hole? Use a bigger stone's flint, OR, ream the hole bigger.

Drilling in the Middle Age

Once man discovered how to work metals, he could make stronger, smaller bits and make neater holes faster, well relatively faster, as long as he was using reciprocating motion (pump and bow drills) since we are only cutting half the time. Continuous motion (brace) cut at least twice as fast but took surprisingly long to show up in tool evolution (never heard nor seen much braces before the 12th century)

We had intermittent rotary motion before, like hand operated augers, and tapering tools (reamers). These were mostly used for big holes, since the physical effort required demands more strength.

Roman auger bits, shell bit and twisted end

A 19th century "modern" auger, 2-1/4 in.

The business end of the auger above. 
A threaded center pin is used to help start the auger and to 
pulled it through the material. Notice the upturned lips?
Cook or Gedge pattern bit, 

Wheelwright using a hand reamer to enlarge 
the center hole for the bearing/axle

Even then, the first bits used in braces duplicated known forms of existing bits, hence shell bits and the next logical reamer design, tapered hollow bit. They worked very well were easy to make so they survived very long until supplemented by nominally graduated, woodworking bits. Think a set of 13 Jennings, Irwins etc.

Why thirteen? Because it cover a wide range from 1/4 (smallest practical twist bit design) to 1 inch by 16th of an inch.
So they are numbered No 4 (4/16=1/4 in) to 16 (16/6=1 in)

A No 5 would be 5/16 etc. This was a typical numbering system 
for various drill bits.

My collection of Irwin, missing No 13,14,15.
Numbers are most often found stamped on the tapered end.

 For holes greater than one inch, a different type of bits would be more efficient.  As the need for various size holes were required in various materials, a large variety of patterns and designs evolved. Today you can buy set of typical twist drill bits in 1/64 increments.

So back to reamers. They are required for various jobs besides enlarging holes.

To create a matching angle for the head of the fastener to sink it flush .

Old fashioned brace's rose head taper bits.
The last one on the right, and small one on top are different, 
not a rose head cutter. Notice that the angle cut is pretty standard.

The angle is roughly 45, which means it cut a 90 degrees cone.
Screws heads came traditionally in 82 and 90 degrees head taper.

To ream the inside of pipes or holes to deburr, or to facilitate fitting pipes together

These large brace reamers are used on pipes, not woodworking.

To match the tapered body of a screw better, to increase holding power of fasteners.

Modern screw tapering bits for pilot holes.
Drill a tapered hole for the screw body and a recessed (adjustable depth)
taper for the screw head

These are the first uses that come to my mind, but they are surely others I'm not aware of.
Some modern forms of reamers I used

A set of hand operated reamers.
I also used the bits in a powered drill.

An adjustable depth reamer. The taper body slides 
in and out  in the outer sleeve.

These rose head cutters work well in soft metal like iron and brass also, but careful not to overheat them (by going too fast in a powered drill).
You are NOT going to overheat them using a brace...

Now that we seen how making holes and varying its size by reaming, there is one more thing to mention. When the object is to big for the hole, you have two choices:
1- make the hole bigger, or
2- reduce the object size to fit the hole

How you reduce the end by tapering or simply turning its tenon smaller, has an effect on the resulting strength of the whole, both methods are used depending on the intended uses. Chair making uses both applications and also uses a combination of both.
The wedged round tenon in a tapered hole on the exit side, merely locking strongly the tenon in place.

Next will take a closer look at the brace and how to uses some of the bits such as the shell and tapering bits to cut both the hole and the tenons

Bob, making some holes in man history


  1. Interesting - I like knowing the why behind these.

  2. Thanks, me too!
    I always felt the need to understand how things work, and have taken apart most of everything that I ever own :-)
    Dad always encouraged me to do so, but mom draw the line at our first color tv, but there was so many colorful buttons in the back, how was one to resist touching them to see what they do :-)

    Bob, the tinkerer

  3. Great stuff once again, Bob. I love your posts, especially the historical info, it goes so far back. I have a brace and bits set that I really like. Got off eBay or Etsy and the bits came with an original three-tiered box. They were all fairly sharp, too. I'd still like to find some other types of bits, countersinks, and reamers, though.

  4. Thank you Matt, appreciate your comments. I love old tools, and researching their history. One of my next drafts is on restoring and using shell bits an etc.

  5. Matt your three tier box is probably an older box for Jennings patterns bits.