Full Chisel Blog

January 26, 2012

Cutting Wooden Threads

Spiral threads have been cut in wood for centuries.  I discussed making thread by hand earlier.  During the nineteenth century the tools had been perfected but still retained their original design.  There are two components to threading; there is the screw and the nut.  The screw has external threads and is referred to as the male element and the nut has internal threads and is referred to as the female.  While these can be meticulously cut by hand, it is much easier to accomplish this by using some simple tools.   There are two tools used to make the threads by hand and they are the tap and the die or die box or screw box.  Wooden threads can also be cut on specialized lathes from a design first proposed by Leonardo da Vinci.  This discussion will be about using the two hand tools to make the threaded screw and nut.

There is nothing quite like creating wooden threads.  The process is a unique experience and the results can be rewarding.  You are capable of making your own wooden screw clamps, veneer presses, vices and adjustable items such as music stools, embroidery frames and candle stands.  Threading wood is something unique, a wooden nut and bolt is unusual, something that few others have.  The projects, tools, furniture and fun things you can make with a set of these tools are endless.  Wooden threads have always intrigued me; there is just something fascinating about them.

Wooden Thread Cutting Tools

There are two ways to go, the first is to buy a set of wooden thread cutting tools or you can make your own.  The new wood threading tools are of good quality and generally follow traditional designs.  If you choose to make your own you will need to have made a tap of the proper size that you are interested in making.  This should have sharp edges to make clean cuts; a machinist or good blacksmith can fabricate a tap to your particular dimensions.  These taps are similar to modern metal cutting taps except they are larger and have fewer teeth per inch.

Eight teeth per inch is about the minimum for a ½” tap and larger should have 6 teeth per inch and on very large screws for presses 4 TPI to withstand the pressure.  To make a tap the threads can be cut in the metal for the tap and then the four sides flattened to produce 4 cutting edges at each thread.  Regular taps have a tapered end to make it easy to start the tool into the wood.  Bottoming taps are not tapered but will cut to the end or the bottom of a blind hole.  Do not use a bottoming tap for initial threading as it can easily cut off centered internal threads.

There is another old design that has the threads machined on the outside and a hole drilled in the center of the end of the tap.  On the end of the tap, the threads are machined down to form the taper and at the first thread a small hole is drilled at an angle into the large center hole.  This forms a very sharp tooth that cuts and the chips go through the small hole and out the larger hole in the end of the tap.  This type of tap does produce a very smooth cut, but the traditional 4-sided tap, if it is sharp and used properly will also produce clean cuts.  The wooden handle should be strong and long enough to give leverage for the sometimes difficult process of cutting internal threads.  The handle should be rounded and shaped to fit the hand as the hand is touching the handle a lot during tapping.

Once the tap is made it is possible to make the die box and all that is required is a V-shaped cutter that is secured in the box and cuts the external threads.  Unlike the tap, which will cut with four cutters on each thread, the die has only one cutter that cuts all of the threads.  A proper sized hole is drilled for the tap into a piece of hardwood such as beech or maple, see list below.  This hole must be square to the body of the die box.  The holes are then chamfered or countersunk to prevent the tap from splitting out the wood as it enters and exits the hole.

The tap should be lubricated with linseed oil to make the threading easier.  The tap is then inserted carefully into the hole and started squarely to insure a straight threaded hole.  It is very important that the tap is started perpendicular to the surface and square to the hole.  If the tap binds up gently back a ½ turn then start again, if it becomes too difficult, remove the tap, lubricate and try again.  Make sure the exit hole is countersunk to insure that the tap doesn’t break out any wood when it exits.

Now that you have the die box drilled and threaded, the next step is to cut a mortise for the V-shaped cutter that is on the front leading edge of the die box.  The cutter is positioned right over the first complete thread peak at an angle of 30ºand the leading edge of the cutter should engage the wood at the widest part of the cutter first to score the wood being removed.  The end of the cutter is ground at an angle of 15º with the top of the V leaning forward, with the bottom of the V trailing.

The cutter needs to be sharp and set to cut just slightly deeper than the threads that were cut by the tap.  This insures that the newly cut external threads will not bind up in internal threads of the die box.  The die box can also be equipped with a removable plate that will center round pieces as they are fed into the screw box.  The plate needs to be thick enough to line up the piece to be threaded and removable so the external threads can be cut all the way up to the shoulder of a turned piece if necessary.  The internal threads of the screw box should be well lubricated to make the cutting of the screw shaft easier.

Nut – The Nut is the part with the internal threads that are cut with the Tap.  The nut is prepared by drilling the hole using the following starting holes sizes.

Starting holes:

½” threads use a 3/8” drill

¾” threads us a 5/8” drill

1” threads use a 7/8” drill

1 ¼” threads use a 1 1/8” drill

1 ½” threads use a 1 3/8” drill

1 ¾” threads use a 1 5/8” drill

2” threads use a 1 7/8” drill

2 ¼” threads use a 2 1/8” drill

2 ½” threads use a 2 3/8” drill

 

It is important that the hole is drilled square and perpendicular the flat surface of the nut.  The wood for the nut should be a wood that is capable of taking the threads.  While most hardwoods will hold the threads some are better than others.  Beech, maple, hickory and oak can be used for nuts and will take threads, as can alder, elm and poplar.  Some brittle woods such as cherry are difficult to thread, but it can be done.  The thicker the piece of wood that is threaded, the stronger the threads will be.

On thin pieces for the nut, the threads can easily be cut at an angle, so make sure the hole is straight and the threading is done properly.  When threading in an angled hole, the grain orientation is important as is beginning the cutting with the tap.  The tap needs to go straight down the hole; if you get off at an improper angle the threads will be too deep on one side and too shallow on the other.  While the internal threads on the nut are not as critical in terms of strength, the screw needs to be constructed of specific woods.

After the proper sized hole is drilled, the edges need to be chamfered or countersunk to prevent split out during the entry and exit of the tap.  This must be done on both sides, as the tap will chip out the wood.  The tap is lubricated with linseed oil or beeswax and it is inserted in the starting hole.

It is very important to make sure that the tap is perfectly square and lined up with the hole.  The tap is twisted and forced into the wood, taking care to make sure that it is perpendicular to the surface of the nut. Enough downward pressure is exerted to engage the tap into the hole, after the cutting begins, the tap is self-feeding.  If the tap binds in the hole, gently and carefully back it off a half a turn and start again.  If it still binds, back the tap out of the hole, lubricate it again and carefully start the tap back into the cut threads.

Be careful when doing this so you don’t cross thread the screw and ruin your work.  Every once in a while, back the tap out a half a turn and continue until cutting becomes more difficult, then repeat and go at it again.  It is better to take your time and make sure that the work is done properly.  Continue until the tap comes out the exit hole, clean out the shavings and back the tap out of the hole.

If you are threading a blind hole, your starting tap will hit bottom, then back out the tap, remove the dross and carefully place the bottoming tap into the threads and run it down until it cuts the internal threads on a blind hole.  If the wood is fuzzy on the inside of the threads, I wet the piece with water and raise the grain.  I allow it to dry completely and run the tap down the hole again to remove the raised grain and fuzz.  Sometimes running the tap in from the opposite direction will remove the fuzz and clean up the internal threads.

Screw – The Screw is the part with external threads and is cut by the Screw Box or Die.  The selection of the material for the screw is important as certain woods make excellent threads while others are more difficult.  Softwoods are difficult without an extremely sharp cutter in the screw box.  Hardwoods are preferable and woods such as beech, maple and hickory are the best for wooden bolts or screws, those with external threads.  Strong, tough woods such as elm are better than brittle woods like cherry.  Walnut also accepts threads as well.  With care any wood can be threaded.

It is also important that the grain be as straight as possible.  This is for strength and for a more uniform cut.  The piece to be threaded should be turned to the size of the thread box.  Therefore if the threads are for a 1 ½” screw then the dowel or piece should be turned to just under 1 ½”.  All it takes is just a 32nd under to make the piece just the right size.  It may take a slightly smaller say 16th under to get a proper fit, it may take some experimenting.  But I guarantee if it is too large the threads will crumble as it is forced through the screw box.  If it is too large it will not fit into the screw box and if it is too small it will not properly thread through the screw box.  A slightly smaller screw works much better than one that is too tight.  I like nice crisp threads, so I always turn the pieces just under the required size.

For some applications where you don’t necessarily need sharp peaks, such as heavy duty tools, the screw blank or dowel can be slightly undersized producing flat topped threads instead of sharp peaks.  Small fine threads such as 8 threads per inch can be difficult and these fine external threads can easily break off.  Denser woods work better for these fine threads.  If the dowel is undersized, it is important to make sure that the screw box travels over the dowel in a uniform manner to insure proper threading.  If flat-topped threads are required, I usually turn the dowel to the proper size, thread the piece, then re-chuck it in the lathe and turn off the peaks.

When you turn the screw or dowel on the lathe, just use your gouges and chisels, do not use sandpaper.  The sandpaper can leave residue in the wood fibers that can dull the cutter in the screw box.  Also you will want to chamfer the edge of the dowel or screw blank to make it easier to start the screw box.

I always dip the end of the screw blank or dowel in linseed oil to provide lubrication for the cutting process.  I usually clamp the screw blank in a vice to hold it during the threading process.  It is important to make sure that the screw box engages the screw blank or dowel perfectly square to insure accurate threading.  I always look down the waste hole in the screw box where the chips come out to see how the cutter engages the threads.  I try and exert enough pressure to engage the wood on flat grain first rather than the side grain.  It just seems to start better if the cutter enters the wood on the flat grain.

Once the cutter has began to make threads they engage and pull the screw blank into the screw box, so the pressure can be reduced.  After cutting begins, simply turning the screw box is sufficient.   When the cutter has made the first part of the threads, they will engage the internal threads of the screw box and advance the screw into the tool creating a perfectly cut spiral thread.  The first ½” or so is usually not perfect and I always allow for an extra half inch or so to cut off after the threads have been cut.

Once the cutting has started, the tool should ‘sing’ through the work.  If the stuff is tight in the tool, the cutter may be set too shallow or the dowel is too large.  Most screw boxes have a removable plate that guides the screw blank into the screw box.  This is removed if the threads are to be cut up to a shoulder.  The plate should be used to cut well into the screw blank and can be removed to thread just the last inch or so.  A properly positioned and very sharp cutter will make the cutting much easier.

It is important that you keep your tools sharp and well maintained.  The teeth on the tap need to be clean and sharp at their cutting edges.  The new made tap and die sets require sharpening.  The screw box has a V cutter that needs to be honed mirror shiny on the outside and perfectly flat on the inside. The V-shaped cutter in the screw box should be ground at the proper angle of 15º and should be very sharp and properly positioned.  The bevel is ground on the outside of the cutter.  Both edges must be honed for a good clean cut.

New set of ¾” taps and V-cutter, factory ground, NOT sharp.  Note improper ground V-cutter, burr protruding from the bottom of the V.

New set Sharpened.  Threads and slots have been dressed and V-cutter sharpened and honed.

The tap needs attention as well.  The V-teeth need to be dressed to remove the grinding burr left during manufacture.  Make sure to get both sides of the slot and both places where the slot and the V groove meet, especially on the leading (cutting) edge.  Use a triangular file to dress the teeth.  Use a thin flat mill file to dress the gullets so the cutting edge is sharp.  Then go back and re-dress the V-grooves with the triangular file to remove the last of the burrs.

The sharper your tools the easier the work.  I use a bit of sandpaper over the files to hone the edges to a mirror gloss.  Your holes need to be clean, straight and countersunk and your turnings need to be of the proper size and chamfered to produce the desired results.  Use linseed oil or beeswax to lubricate the parts being cut, it just makes the job easier.  Make sure the tool engages the work squarely to produce quality work.

Clean out any shavings that can interfere with the cutting operation.  Work slowly and carefully.  This is not like cutting metal threads; it is a continuous operation, only backing out when the cutters jams or the cutting is complete.  After you are finished using the tool make sure to clean off all excess linseed oil before it dries!

There is no end to the possibilities for using wooden threaded devices and the results are delightful.  Wooden screws are capable of exerting incredible pressure when used for clamping applications and can provide for ease of assembly and disassembly for transportable furniture.  There are endless applications and uses of wooden threads and they are fun to make.

Stephen

December 28, 2011

‘Little Shaver’ – product review

Filed under: Historical Material,Of Interest,Proper Tools,Reviews,Sharpening,Uncategorized — Stephen Shepherd @ 10:26 am

Annually, my family selects names for gift exchange as well as a list of items as suggestion for gift ideas.  And this year this tool was on the top of my list.  Originally produced in the early 1900’s, it looked like a cool tool and is available from Lee Valley.

I don’t use any of my chisels or sharp knives to sharpen graphite pencils as they leave residue on the blades and is tough on a fine edge.  I have a designated small clip point knife that I use for pencil sharpening, now I can clean it up, sharpen it and keep it for other purposes.

As luck would have it I got the sharpener, thanks Travis [great nephew].  It worked right out of the box, although when I get back home to my shop I will hone the blade just a bit.  I also noticed a small casting defect [to the right of the cone], but it doesn’t effect the operation.

I first tried #2 pencils which were made to a surgical fine point and later on a 3H pencil.  To my surprise it got that very hard graphite to the same degree of sharpness.  I then tried to sharpen a tiny pencil I keep with my pocket ivory notepad and it worked.  I am impressed.

Stephen

October 31, 2011

My Queer Creek Stone has a new home

Filed under: Historical Material,Of Interest,Sharpening,Uncategorized — Stephen Shepherd @ 8:21 am

I bought this a while back at the local swap meet and gave the guy his asking price, something I normally don’t do.  It has remnants of the original Norton Abrasive Co label and I thought it said ‘Queen Creek’, but on doing some research I discovered it was in fact ‘Queer Creek’ and was the name of the stone/quarry from which it comes.

I decided I needed to make a box to hold and protect the stone.  I selected a scrap of pine and chopped out the mortises with a chisel and smoothed out the bottom with a wooden router plane.

There are points at the corners on the bottom to hold it in place on my workbench while I am sharpening or honing.  I used a square cut headless brad, pounded it in then snipped it off leaving a tiny point projecting.  One long nail took care of all 4 corners.

Now I need to make an appropriate box for the fine  Guangxi waterstone that I just acquired.  I want to cut one end off the stone to make an ink stone, then I will make the box.

I will mention my unusual method of sharpening on an oil/water stone in the near future.

Stephen

September 27, 2011

Sharpening traditional drill bits and augers

Because of the many questions asked on this subject I have decided to write an article devoted specifically to that subject. Many old drill bits and augers may be brought back into serviceable and usable condition with a little attention to the overall bit and the cutting edge. The difference between a bit and an auger is the spelling and well maybe auger is used to describe larger bits. Whatever you call them, they make holes
and to work properly they must be clean and sharp. Many people sharpen up old
bits without any attention to the rest of the bit. While this will work it is not necessarily all you may do to these old bits.

First I make sure the bit is straight.
Many old bits such as gimlets are manufactured with a twist but some bits;
especially the small ones may be untwisted when forced in hardwoods. Putting
the correct twist back into the bit may rectify this problem. Take care, as the
metal in some old bits may be brittle. Now some collectors would say not to do
anything to the old tools, but if you are going to use them they need to work
properly. Also any bend in the shaft should be straightened out; the tapered
square shank  goes into the brace should be   filed to remove any burrs.

When originally manufactured many old bits were finished in the ‘bright’. In other words the surfaces were draw filed and polished for a shiny finish. This does two things, a bright surface resists rust (for a while) and makes chip extraction smooth. This is important on twist augers that cut more aggressively and require removal of chips from deep holes. Time and exposure have rendered many old bits pitted and rusty. It is important to clean off all rust, using electrolysis or surface abrasion.
Polish up the surfaces and keep them protected to prevent further rusting.
Always clean chips out of the augers after you use them to keep them in proper
condition and ready to use again.

Now that the bit is straight and shiny it is time to get to the cutting edge. There are three types of common old bits; gimlets, center bits and twist augers. Pod augers,
spoon bits, gouge bits and nose augers are not as common and are fairly easy to
sharpen. These bits have shafts are basically shaped like a gouge or marrow
spoon. The cutting edge is just at the bottom; the rest of the shaft should not
be sharpened as this may widen a hole if there is any wobble. The idea is to
cut a straight hole doesn’t tend to follow the grain and the cutting edge is just
at the beginning of the cut and the shaft guides the bit straight. Nose augers
have a turned in bit or nose that is sharpened first on the outside, then filed
on the inside edge to make a sharp cutting edge.

Gimlets or gimblets are a unique largely overlooked drill bit is readily available at flea
markets and antique stores. It is one of the few bits  produce a clean exit hole without a backup scrap of wood. It doesn’t make the neatest entry hole, there are trade-offs.
The first thing to do with all sharpening is to get the flat parts flat. See drawing #1. On a bit it may not look like there are any flats but there are.  With a gimlet, I use a fine flat mill file to make sure the cutting edge is flat on the outside edge. Keep the file flat on the outside of the bit, do not over-file this part of the bit, it needs to be flush with the rest of the outside of the bit or it will bind in the hole. Filing too much will result in the cutting edge being inside the circumference of the diameter of the bit and
it will not cut but bind. I file it until all nicks and pits are removed. I will also use a fine triangular file to dress the lead point on the outside edges. Make sure to get all edges that will be involved in the drilling process, all leading edge surfaces. See drawing #3

I then use a fine cut round file to work the inside curved surfaces. See drawing #2. This must be done at an angle as the twist of the gimlet progresses up the shaft. I have a couple of small chain saw files that are slightly altered for this operation. I broke the
un-toothed ends off the file and ground them square. This allows getting into
some areas where the non-cutting tip gets in the way. I will then go back over
the outside to remove any small burrs, and then go over the inside again and it
is ready to use. The gimlet bits cutting edge begins at the point and goes out
to where the bit is at its widest diameter, so make sure it is sharp out to
that place.

 

Left – Center Bit Right –
Gimlet bit

Showing sharpening sequence.

Center bits are perhaps the nicest traditional bits in my opinion. I like the way they look and I love the way they drill holes. They are not intended for deep holes, an
auger would be used for that purpose. But for shallow holes they work great
when properly sharpened. They may also drill a shallow hole with a slight curve
as you may change drilling angles as you drill. These should not be used for
dowels as they may produce crooked holes, bits like gouge bits and nose augers
are better suited for that purpose.

 

Again when sharpening a bit it is important the cutting edge be on the outside circumference of the diameter of the bit. With a center bit you have two cutting methods, the outside scoring spur and the angled excavation blade pivoting around a center spur. Make sure the spur is in the center of the bit and is sharp to a point. See drawing #5.  The scoring spur should be flat on the outside edge (to prevent binding)
and filed to a sharp point and leading edge towards the direction of rotation.
See drawing #1 & 2.This needs to be long enough to score the wood ahead of
the excavation blade to prevent tear-out. The excavation blade is sharpened
like a plane iron or chisel edge, first flatten the bottom (outside) and then
file the bevel on the inside, repeat to remove any burr. See drawing #3 &
4. A properly sharpened center bit is a pleasure to use.

Twist Augers are perhaps the most common type of traditional bit and are still manufactured today. Irwin pattern with a single twist are newer, but the Jennings pattern with its double twist has remained largely unchanged since L’Hommideau came up with the design in the first decade of the nineteenth century. There are some
variations at the cutting edge, spurs pointing up, down or both may be straight
or curved but all do the same process, cut and extract wood.

Sharpening Twist Auger
showing sharpening schedule

Like with all bits the outside edge must be on a plane with the circumference of the diameter of the bit. I place a file on the auger and go all the way around keeping the file mill flat against the cylinder formed by the twisted metal. This removes any burrs and insures the outside of the bit is flat, paying particular attention the spurs on the
leading edge. A special auger bit file is necessary for smaller auger bits and handy for larger auger bits as well. It has safe edges (no teeth) to allow filing up into corners on spurs. It is possible to do the same work with small flat and triangular files, but an auger bit file is a handy tool to have.  I then file the inside of the scoring spurs on their leading edge, which includes the top (leading) edge of the spur. If there is a spur in the inside (shank side), file it sharp just on the leading edge. See drawing #1 & 2.

Auger file, flat mill file,
triangular file & round file (9″)

The next part is the excavating blades, which are also sharpened like plane irons or chisel blades. I sharpen from the topside (center lead screw or spur) first getting it flat from the center screw/spur to the outside scoring spur. I then go to the other side
(shank side) and file that part of the excavating blade flat to a sharp edge.
Dress the top again, then the inside to remove burr. See drawing #3 & 4.

The final process is to sharpen the center point or freshen the threads on the lead screw. Some augers do not have lead screws but solid square or round pointed center points and these need to be sharpened to a point. Those with lead screws may need to have their threads freshened. This is done with a triangular file is run around the threads to remove any burrs and sharpen so they grip and pull the auger into the wood. The coarseness of the threads determines the kind of wood the auger was intended to use on. Those with fine threads are for hardwoods and those with coarse threads are for softwoods. Coarse threads for softwood are sometimes referred to as ‘Double Speed’. See drawing #5.

Initial straightening, cleaning and sharpening of old bits will require some time; work and attention to bring them back to serviceable condition. After the primary work bits are easy to maintain in a sharp condition by periodic touch up with a fine file.

If you live in an area of high humidity or are drilling a lot of green wood it is a good idea to oil the bits to prevent rust. Also make sure you clean out any chips before putting the bit away. Protect the new sharp cutting edge of the bit by storing properly.

Stephen

March 5, 2011

The Grind

Filed under: Historical Material,Of Interest,Proper Tools,Sharpening,The Trade,Uncategorized — Stephen Shepherd @ 8:06 am

 I found this file on my computer and thought it interesting:

 The Mechanics’ Magazine, Museum, Register, Journal, and Gazzette April 4 1835.

 We extract from the last Part of the Transactions of the Society of Arts the following valuable descriptive catalogue of a collection of hone-stones and grindstones, presented to the Society by Richard Knight, Esq., of Foster-lane :

 1. Grit or Sandstone.—Of this variety the celebrated Newcastle grind-stones are formed. It abounds in the coal-districts of Northumberland, Durham, Yorkshire, and Derbyshire; and is selected of different degrees of density and coarseness, best suited to the various manufactures of Sheffield and Birmingham, for grinding and giving a smooth and polished surface to their different wares.

 2. Is a similar description of stone, of great excellence. It is of a lighter colour, much finer, and of a very sharp nature, and at the same time not too hard. It is confined to a very small spot, of limited extent and thickness, in the immediate vicinity of Bilston, in Staffordshire, where it lies above the coal, and is now quarried entirely for the purpose of grind-stones.

 3. Is a hard, close variety, known by the name of carpenters’ rub-stone; being used as a portable stone for sharpening tools by rubbing them on the flat stone instead of grinding. It is also much employed for the purpose of giving a smooth and uniform surface to copper-plates for the engraver.

 4. Is a much softer variety of sandstone, usually cut into a square form, from 8 to 12 inches long, in which state they are used dry by shoe-makers, cork-cutters, and others, for giving a sort of coarse edge to their bladed knives, and instruments of a similar description.

 5. A stone of similar properties, but of a more compact and harder description, and therefore better adapted for sharpening agricultural instruments, and may be used with or without water.

 6. A porous, fine-grained sandstone, in considerable repute, from the quarries of Slack Down Cliffs, near Collumpton. and well known by the name of Devonshire Batts.

 7. Is a variety called Yorkshire Grit. It is not at all applied as a whet-stone, but is in considerable use as a polisher of marble, and of copper-plates for engravers.

 8. Is a very similar stone, of a softer nature, and made use of by the same description of workmen, and is called Congleton Grit Hone-Slates.

  9. Norway rag-stone. — This is the coarsest variety of the hone-slates. It is imported in very considerable quantity from Norway in the form of square prisms, from 9 to 12 inches long, and 1 to 2 inches diameter, gives a finer edge than the sandstones, and is in very general use.

 10. Charley Forest stone is one of the best substitutes for the Turkey oil-stone, and much in request by joiners and others, for giving a fine edge. It has hitherto been found only on Charnwood Forest, near Mount Sorrel, in Leicestershire.

 11. Ayr-stone, Scotch-stone, or snakestone, is most in request as a polishing stone for marble and copper-plates; but the harder varieties have of late been employed as whetstones.

 12. Idwall, or Welsh oil-stone, is generally harder, but in other respects differs but little as a whet-stone from the Charley Forest; but in consequence of its being more expensive, is in less general use. It is obtained from the vicinity of Llyn Idwall, in the Snowdon district of North Wales.

 13. Devonshire oilstone is an excellent variety for sharpening all kind of thin edged broad instruments, as plane-irons, chisels. &.c, and deserves to be better known. This stone was first brought into notice by Mr. John Taylor, who met with it in the neighbourhood of Tavistock, and sent a small parcel to London for distribution; but, for want of a constant and regular supply, it is entirely out of use here.

 14. Cutler’s green hone is of so hard and close a nature, that it is only applicable to the purposes of cutlers and instrument-makers, for giving the last edge to the lancet, and other delicate surgical instruments. It has hitherto been only found in the Snowdon mountains of North Wales.

 15. German razor-hone. This is universally known throughout Europe, and generally esteemed as the best whet-stone for all kinds of the finer description of cutlery. It is obtained from the slate-mountains in the neighbourhood of Ratisbon, where it occurs in the form of a yellow vein running virtually into the blue slate, sometimes not more than an inch in thickness, and varying to 12 and sometimes 18 inches, from whence it is quarried, and then sawed into thin slabs, which are usually cemented into a similar slab of the slate, to serve as a support, and in that state sold for use. That which is obtained from the lowest part of the vein is esteemed the best, and termed old rock.

 16. The same, with the hone in natural contact with the slate.

 17. Is a dark slate of very uniform character; in appearance not at all laminated; is in considerable use among jewellers, clockmakers, and other workers in silver and metal, for polishing off their work, and for whose greater convenience it is cut into lengths of about 6 inches, and from a quarter of an inch to an inch or more wide, and packed up in small bundles of from 6 to 16 in each, and secured by means of withes of osier, and in that state imported for use, and called blue polishing-stones.

 18. Is a stone of very similar properties, but of a somewhat coarser texture and paler colours, and thence termed grey polishingstone. Its uses are the same, and they are manufactured near Ratisbon.

 19. Is a soft variety of hone-slate, the use of which is confined to curriers, and by them employed to give a fine smooth edge to their broad and straight-edged knives for dressing leather. They are always cut of a circular form, and are called Welsh clearingstone.

 20. Turkey oil-stone.—This stone can hardly be considered a hone-slate, having nothing of a lamellar or schistose appearance. As a whet-stone, it surpasses every other known substance, and possesses, in an eminent degree, the property of abrading the hardest steel, and is at the same time of so compact and close a nature, as to resist the pressure necessary for sharpening a graver, or other small instruments of that description. Little more is known of its natural history than that it is found in the interior of Asia Minor, and brought down to Smyrna for sale.

 21. The French Burr mill-stone, so justly esteemed as the best material for forming mill-stones for grinding bread-corn, having the property of separating a larger proportion of flour from the bran than can be effected by stones formed from any other material.

 22. Conway mill-stone very much resembles the French in appearance. A quarry of this was opened near Conway, about twenty years since, which at first appeared very promising; but it was soon discovered that it was the upper stratum only that possessed the porous property so essentia], the lower stratum being found too close and compact to answer the purpose.

 23. Cologne mill-stone.—This substance is an exceedingly tenacious porous lava. Mill-stones are made of this material in great quantity near Cologne, and transported by the Rhine to most parts of Europe. Smaller stones, from 18 inches to 30, are much used for hand-mills in the West Indies for grinding Indian corn, for which purpose they are well adapted.

 24. Emery-stone.—No substance is better known, or has been subservient to the arts for a longer period, than this. The gigantic columns, statues, and obelisks of Egypt owe their carved and polished forms and surfaces to the agency of emery. It is obtained almost entirely from the island of Naxos, where it occurs in considerable abundance in detached irregular masses. It is reduced to the state of powder by means of rolling or stamping-mills, and afterwards by sieves and levigation.

 25. Pumice-stone is a volcanic product, and is obtained principally from the Campo Bianco, one of the Lipari islands, which is entirely composed of this substance. It is extensively employed in various branches of the arts, and particularly in the state of powder, for polishing the various articles of cutglass ; it is also extensively used in dressing leather, and in grinding and polishing the surface of metallic plates, &c.

 26. Rotten-stone is a variety of Tripoli almost peculiar to England, and proves a most valuable material for giving polish and lustre to a great variety of articles, as silver, the metals, glass, and even, in the hands of the lapidary, to the hardest stones. It is found in considerable quantities both in Derbyshire and South Wales.

 27. Yellow Tripoli, or French Tripoli, although of a less soft and smooth nature, is better adapted to particular purposes, as that of polishing the lighter description of hard wood, such as holly, box, &c.

 28. Touch-stone is a compact black basalt or Lydian-stone, of a smooth and uniform nature, and is used principally by goldsmiths and jewellers as a ready means of determining the value of gold and silver by the touch, as it is termed—that is, by first rubbing the article under examination upon the stone, its appearance forms some criterion ; and, as a further test, a drop of acid, of known strength, is let fall upon it, and its effect upon the metal denotes its value.

 29. Blood-stone is a very hard, compact variety of hematite iron ore, which, when reduced to a suitable form, fixed into a handle, and well polished, forms the best description of burnisher for producing a high lustre on gilt coat-buttons, which is performed in the turning-lathe by the Birmingham manufacturers. The gold on china ware is burnished by its means. Burnishers are likewise formed of agate and flint; the former substance is preferred by bookbinders, and the latter for gilding on wood, as picture-frames, &c.”

Stephen

November 8, 2010

Early style spokeshave

The handles on late 18th early 19th century wooden spokeshaves are a little more utilitarian than those on later models.  Later versions have thinner handles that flair out on the ends and I must admit look quite attractive.  But most of the early styles the handles are straighter with not much attempt to embellish.

The upper spokeshave I have had and used for several years.  A friend made it for me as a joke after I showed him my little bronze spokeshaves.  I made a dogwood handle and as you can see by the wear, it has been well used.  I showed some traditional spokeshave blades to Mark Schramm, Master Blacksmith, in order for him to reproduce them.

The first one he made and delivered this weekend and I couldn’t resist making a handle for it and put it to use.  I selected curly maple and made it thicker to raise the handles up a bit, helps in close work.  A coat of linseed oil/turpentine last evening and here it is.

The 1831 penny is there for scale [it is 1 1/8″ in diameter], and yes I am a Copperhead Democrat.  The traditional tangs are friction fit into small square holes that I worried through the wood.

 

I sharpened the blade with a fine file then honed it on a soft Arkansas stone then a leather strop.  It cuts beautifully with its extremely low angle blade.

Stephen

September 3, 2010

Why I think laminated [laid] steel tools are better, restated.

I apparently didn’t make one thing perfectly clear when I posted this before, and before, etc.  At the onset, I do not want to say, nor do I say, nor do I imply, nor even hint at that the steel in the nineteenth century is better than we have today, I just don’t know, but that is not the point.  Now what is the point by my bold heading, the key work here is laminated or restated laid steel tools are better, not the steel but the configuration of soft wrought iron and hard steel.

Now in order to prove this theory, I had a blacksmith friend make a laminated [laid] steel tool and when finished and ground to rough sharp, the blade will be properly heated and quenched in brine.  There will be no tempering process.  And yes you may say ‘the steel will be brittle’ and that is true, but it will also be very hard, so it will hold an edge better, but again you will say ‘the steel will be too brittle’ and because it is supported with the matrix of soft wrought iron [which can not be hardened], so brittle is not a problem.  The very hard steel is more difficult to sharpen, but it is thin, so most of the sharpening is softer material, again not a problem.

The photograph above is the billet of wrought iron [from an old wagon wheel] with a piece of steel forge welded on the working end.  The blade on the right is the original blade [early nineteenth century] that I lent the blacksmith to copy.  Mark Schramm, the blacksmith at This is the Place Heritage Park made this for me.  I had him bring it in before grinding so I could shoot these photographs, as I have never seen this part of the process before and wanted to document this historic event.

A side view of the blade clearly shows the thin piece of steel laminated [laid] onto the iron.  Mark did an excellent job and when asked about the economy of doing this instead of solid steel, the answer was that this took much longer.  So if it wasn’t to save money it had other purposes, those I have alluded to.

I and others feel that these blades have less chatter than solid steel tools because of the unique construction techniques of the softer wrought iron dampening any vibrations that may cause chatter.  The blade also has a lower center of gravity putting more mass closer to the thicker working end of the tapered blade.

This is completely subjective, so you can’t disagree with me [but some will].  The real subjective part; these tools just fell better when you use them.  There is something about them that makes them feel different.  I don’t know that I can describe the difference but when I plane a board, the sound is not as intense with a laid steel tool verses a solid steel tool.  The tool seems to work easier, I have two chisels that are about the same size and weight, but the laid steel tool feels better in my hand [identical handles] and seems to cut better as well as definitely hold a sharp edge longer.

I didn’t really want to get Zen with this, but I have used a variety of tools over the last nearly 40 years, and these old tools are better for reasons beyond the materials involved.  There was a reason our ancestors went to the trouble to make laminated steel tools or they would not have continued to do so.   They were not knuckle dragging hay seeds that just fell off the cabbage wagon.

When it is completed I hope to make a worthy wooden plane body to properly show off its unusual properties.  Will this prove my theory?  Well I am already convinced and so are others, but at least I will have one fine unique tool.

Stephen

August 20, 2010

New Toothing Plane – finished

Well I got to spend several hours in the shop on my days off and finished up a hand saw and this toothing plane.  I fitted up the blade, then to my horror it stuck out 1/16″ more on one side than the other.  I immediately checked the body of the plane and everything was square, so I checked the iron which was out 1/16″.  A quick trip to the grindstone and everything was square.

I used the pistol grip hand saw that I made to rip out the maple wedge, then worked over the cut areas with a rasp and float to smooth the surface, then gave it a work over with a card scraper.  I then did some more shaping and shot the edges to fit the mortise.  A little more work on the throat and bedding of the iron and the piece was ready for a coat of linseed oil/turpentine [50/50].

I made the entire tool by hand, drilling the holes was the most precise work, together with the mortise for the blade and wedge.  I drilled from both sides to insure proper alignment.  I really need a good throat float, guess I should talk to the Blacksmith.

Also called a Gluing Plane, Veneer Plane, Keying Plane and Truthing Plane.  Not only does it work well for preparing the surface for gluing [with hide glue of course] but also for handling troubling grain like burl, curl and knots without tear out.

This is my second toothing plane, I am numbering my planes because I don’t make that many, but this one was fun and I may have to make one for myself, although I own two original toothing planes.  This one is for a trade and I have made arrangements to meet with my friend tomorrow to complete the trade.  I will post what I get from the trade.

Stephen

August 18, 2010

Pistol Grip Hand Saw 2

Well I finally got it finished, had problems with punching the holes in the blade.  The steel proved too difficult so after sharpening a twist drill bit, I used a gear drill to make the holes for the rivets.  I upset some barbs on the edge of the tapered tang with a cold chisel.  These will grip into the handle, I also used liquid hide glue to glue the tang into the square mortise. 

The saw is a bit 18th century, a bit Dutch with a little American thrown in.

I first fit up the yellow brass ferrule to the handle by using a slitting gauge to score the shoulder, then going cross grain removed the extra wood, then a float to make it round.  Once the brass ferrule was fit, I scraped down the cherry handle to make it fit smoothly.  I then used a gimblet bit in a brace to drill the hole for the tang.  I used a 1/8″ chisel to square up the square tapered hole.

I used the saw to rip a maple wedge for a toothing plane I am working on.  I tried two different grips, the first with the index [trigger] finger pointing forward.

This seemed awkward to me so because I had made the handle large enough for four fingers, this grip, which was much more comfortable and I felt I had more control over the saw.

I should have cleaned my nails before this photograph.

Stephen

August 16, 2010

Why laminated [laid] blades are better.

Let me make one thing perfectly clear, I am not commenting on the quality of the steel used then and now. I am not saying that the old steel was better than the new steel, I have no idea and for this discussion, I really don’t care. That is not the point. For the quality of steel is only one small, I repeat small portion of the overall equation.

By laminated blades, be it chisels or plane irons; I mean tools made largely of wrought iron with a thin veneer of steel forge welded to the cutting edge. Now I would like to take to task those who say that this was done because of economy; steel is more expensive than wrought iron. In the nineteenth century steel costs 5 times that of iron and the steel on these old tools is usually less than 10% of the blade. Then there is the two or three heats it takes to forge weld the steel to the wrought iron. There is no economy, it would have been cheaper to make them of solid steel, but they didn’t and here is why.

First steel will hold an edge longer than the softer wrought iron and the iron could not be hardened like steel. The steel had to be reduced by forging to the thin veneer before it is forge welded to the wrought iron. This forging, both in making the thin slips of steel but the forge welding to the iron as well, compacts the grain of the steel. It even happens today following the same process, and the tight grain in the steel produces a higher quality steel.

However the most important result of this process is that the completed forge welded laminated [laid] steel blade can be hardened by quenching in brine, producing a very hard and brittle steel. If it were made of solid steel then it would need to be tempered in order to remove some of the hardness or the tool would break as the solid steel with be too brittle. Made largely of wrought iron, which can’t be hardened, the steel can be hardened much harder than a solid tool. And because it is supported and protected by the soft iron, the steel can be left very hard from the brine quench.

Some say the older tools have better steel, I am not sure the steel was any better but the process did leave the thin veneer of steel very hard, holding an edge longer. And when grinding and sharpening only a small amount of the hard steel is ground/sharpened while the bulk of the tool made of wrought iron is easy to remove.

So let me say it once again, it is the combination of iron and steel that makes for a better blade, probably reduces chatter [as opposed to a solid steel blade], puts the center of gravity toward the cutting edge of tapered plane irons and can be made much harder because of its unique structure.

Stephen

« Newer PostsOlder Posts »

Powered by WordPress