Sunday, December 13, 2015

Bench build

Removing cup with the scrub plane
As with any woodworker the workbench is the center of activity and a good flat work bench is not essential but highly desirable. Much can be done with saw horses, 2x4s and other make do techniques but there is nothing more satisfying than having a nice slab top flat piece of wood on which to work.

The bench I used initially in my shed consisted of a steel frame with three 50x200x2000 slabs on top bolted to the frame with coach bolts. I mounted a 8" dawn vice on the front and drilled dog holes to clamp larger pieces. When I moved in to my current house all of the benches were inches high with rubbish, junk, tools and miscellaneous paraphernalia. After cleaning it off I discovered cupped, twisted and warped boards. This served as my bench for about three years before I became annoyed enough to want to do something better.

Small flattening jig
A few months ago I purchased a cache of hand tools including a Veritas quick release end vice for an excellent price. The problem is that it requires a flat bench with an apron, which I did not have. Time for some reconstructive surgery. The veritas quick release vice is more or less a mechanism that screws under the bench to which you can secure a slab of wood the same cross sectional area as your apron. You then drill dog holes in the top and side which gives you three methods of holding wood. First between the jaw and the apron. Thus you can hold long pieces such as stretchers for cutting tenons. Then using dogs along the top of the bench for planing for instance. Finally along the face using dogs to plane edges to to chop mortices.

Apron glue up
I began surfacing the slabs of the bench top by using a scrub plane to remove the bulk of the twist cup and warp. I made a small flattening jig to flatten each board. In the mean time I used some (what I think is) meranti timbers recovered from the house renovations jointed, glued and re-jointed for the apron and end vice jaw. I used the thicknesser to face the timbers for the apron which produced some nice clean glue surfaces. The timbers had some bow but gluing and clamping gave me a nice solid piece that I could then resurface for the apron. I used a scraper to remove the glue and then a random orbit sander to remove any residue left.

Apron jointed

I bought a jointer at this stage so I used that to true up the top face and edges of both the apron and bench timbers for a glue up. In the picture of the re-surfaced apron you can see the vice jaw glueup in the background. After the glue up I used a jig with a router fitted with a surfacing bit and a pair of jointed boards to surface the top of the bench so that it was dead flat. I will not go into the full technique since that is a topic all on its own and has been covered elsewhere by others including Mark Spagnolo, The Wood Whisperer. I then mounted the end vice to the under side of the bench and secured the sliding jaw to the vice.

End vice mounted under bench

Vice jaw

I glued the apron to the front face of the bench. I planed the apron flush with the bench top. I then drilled a series of dog holes along the top and side of the apron. Once the bench was complete I used a home made wax blend using 50/50 bees wax and boiled linseed oil with enough gum turpentine to produce a nice wipe on paste. This produced a nice finish on the bench.

Glueing the apron to the bench top

Plane the apron

Completed and finished bench

 At this stage my bench was flat and I had the end vice and apron fitted and it was sitting on the steel frame. The weight of the bench is sufficient to hold it in place. Being jarrah it is very heavy. The bench was serviceable but missing a front vice. To get around this hurdle I made a mini bench from jarrah to which I fitted my Dawn 8" wood vice to provide some clamping but this was not particularly convenient. 
Large quick release front vice
I bought a large quick release front vice online for $95 plus shipping. This is available from a number of suppliers in the quick release and standard versions. I preferred the quick release which was not available from my local supplier so I bought it online. There is no leaver for the quick release. It uses a split nut which closes when you screw the vice clockwise and releases when you twist the handle a quarter turn anticlockwise.

Front vice jaw
I began by marking out the position on the top of the bench where I was going to mount the vice. The position of the leg underneath determined how far from the end I was able to mount it.  This then set the jaw width. I wanted the jaw as high as the apron but I did not want to join the jaw and wanted to make it from a single piece.  However the piece of wood I was going to use was not quite wide enough but it was certainly wide enough for a substantial vice jaw. I cut a section from the rough board and jointed a face and one edge. I then faced the other side on the thicknesser and the final edge on the table saw. I cleaned up the saw marks with a hand plane. I finally cut each end on the sliding compound saw to final length. I wanted the jaw tapered either end so I marked out a taper on the ends of the jaw and cut to the line on the band saw. I then used a hand plane to clean up the bandsaw marks and to true the taper which was slightly off doe to the blade not being perfect. I need to get a new blade on the band saw since it does not cut perfectly straight.

Vice face
I found a nice piece of tight grained wood but quite soft to use as a vice face. I cut a piece slightly oversize jointed the faces and glued it to the vice jaw. I then planed it flush. This provides a nice clamping surface so as to not damage softer woods. Jarrah is very hard and can damage softer woods.

I wanted the vice screw to sit about half way up the jaw so I bade a spacer to fit underneath the bench to lower the vice mounting to achieve this. I flipped the bench and marked the position of the vice mount on the underside. I then checked that the bottom surface of the bench was square to the apron at this point since if it was out of square then the jaw would not sit flush against the apron which served as the inner jaw of the vice. The bench to apron was exactly 90 deg so I just took a few swipes of the hand plane to clean up the mating area. I marked the mounting hole position on the spacer I prepared and then marked four Xes on the spacer away from the vice mounting holes to drill for screws to mount the spacer to the bench. I drilled and countersunk pilot holes in the spacer and the bench. I glued the spacer in place and secured it with four 14G x 55 mm countersunk wood screws. The vice body has three 8 mm countersunk holes and 4 x 8mm plain holes. I drilled pilot holes for the three countersunk screws very slightly displaced towards the front. This meant that as the screws were tightened they would place a slight pressure into the back of the apron helping to keep it tight. I then secured the frame and used the holes in the vice to drill the holes through from the back of the apron for the screw and the two rails.

Underside of mounted vice
 I stopped as soon as the drill poked through then came in from the front to produce a nice clean hole. I then clamped the jaw to the front of the apron making sure that the top and end was flush with the apron then drilled through form the apron to the jaw. I then took the jaw to the table saw to dill nice square holes through the jaw. Again I came in from both sides to produce a nice clean hole.

I drilled and screwed the four 8mm coach screws, together with teh 8G x 75mm wood screws to secure the vice frame to the bench underside. I assembled the vice then tightened the vice with the jaw in position before drilling and screwing the jaw with three 12G x 75mm wood screws.

Vice handle blank
The vice does not come with a handle. It is designed to take either 3/4" standard galv water pipe which would be perfectly serviceable.  However it would be much nicer to use some dowling. 1" or 25mm would fit perfectly but I thought it would be nice to turn up a handle from some really hard wood I had. I cut a blank from some very nice clear piece of straight grained wood I had. The grain must be very straight and clear from any defects that may weaken the wood. I used a caliper to set the diameter and turned it on the lather. After sanding to 320 I used the same home made wax I used for the top to burnish the wood.

Finishing the handle

I need to make a trip to the hardware store to gt some 1" end caps for it.

I finally used the same beeswax, boiled linseed oil mixture to finish the vice jaw.

The vice operates smoothly and slides well back and forth. The jaw is nicely parallel to the apron and applies a lot of clamping pressure. I will finally drill three dog holes along the top of the vice then a series of dog holes in line with those three with spacing just slightly less than the vice opening.

Finished front vice
I am really pleased with the bench overall. It provides many clamping options which I will extend with some more judiciously placed dog holes in line with those I will drill for the front vice to provide even more versatility. It is flat solid and serviceable and will allow me to hone my woodworking skills as I produce some fine furniture. As a woodworker who loves the visceral feel of working with hand tools but enjoys the shortcuts of power tools I think that this bench is ideal. I can hold work for use with both hand tools and power tools.

Completed bench
Finally I would like to produce a set of sturdy wood legs for this bench rather than the steel frame on which is sits. The frame is certainly solid, no question, but I think a nice set of wood legs would be more elegant.

Thursday, December 3, 2015

Hand Held Metal Detector or Saw Saver.

If you always buy your timber from the local hardware or wood supplier then read no further, this article is not for you. However, if like me you are a little OCD and your internal self dies a little every time you see a nice piece of wood go to waste then read on. You will thank me later.

In every recycling woodworkers life there comes a time when they will encounter a piece of ironmongery in the most unfortunate of places. The latest episode for me (and the one which convinced me to buy a metal detector) was when I was milling the edges of my woodworking bench top. I had set up my brand new TS 55 to square the edge of one of the slabs, 50x400x2000 approx. and noticed some sparks about half way along the edge. When I checked I noticed a lovely shiny wood screw head flush with the edge and I just ruined a brand new festool blade. Ouch!

After some research I settled on the one pictured here.I picked it up for about $24 with free shipping from ebay. My criteria were that it had to be portable, have a audible and visual indication, have good sensitivity to both ferrous and non-ferrous metals and easy to use. There are a number of different models varying in price and specifications but this seemed to be the best value for money and satisfied al of my criteria. When you buy on ebay you often never know whether what you are getting will do the job but after getting it an testing it out I am not disappointed.

It has two positions, one for visual and vibration indicator and the other for audible, visual and vibration. It will pick up any ferrous or non-ferrous metals and will pick up a pin at 30mm which is more than sufficient to detect nails or screws inside of your wood.

A couple of examples. I wanted a piece of ply and there are some scraps of old 18mm marine ply knocking around. One piece looked rather ratty but it looked like I could cut out a piece that would be suitable. I grabbed the metal detector and swept the ply only to find several broken screws embeded in the ply. I grabbed a pencil and circled each of the screws as the detector picked them up and found that I was still able to cut around them easily to get the size I was looking for. I then scrapped the rest. The second example was when I was looking for a slab of jarrah for a small table top bench I was building. I found a piece that would have been perfect so I swept it with my metal detector only to find that there were several old rusty wood screws embedded into the side of the slab. I was unable to remove them since they had rusted in place and I had no idea how deep they went. I abandoned that piece and used two other pieces which I jointed and glued into s single slab.  I will probably use a hole saw to extract the screws and plug the holes with dowels and use it for something else.

I have a lot of reclaimed wood and this metal detector will hopefully save many saw blades, jointer heads, thicknesser blades et al.

Moisture Meter

The moisture meter seems to becoming a common component in the woodworker's toolkit. These can be a somewhat mysterious black box with magic inside. Their operation is somewhat complex and their principles are even more complex.

In this article I hope to uncover some of the mysteries of this device and describe my experience with my moisture meter giving hints as to its best use.

There are two basic types of meter, the pin type meter and the inductive meter. The pin type has several advantages, they are typically cheaper and you can drill holes into the wood to get a better moisture profile. The operating principle is pretty simple. The moisture in the wood conducts electricity so the meter figures out how much water is in the wood based on how much current it passes. The up side is they are cheap and simple to operate. The down side is that you have to get inside the wood to find out how much moisture it has. Not much good at the lumber yard where the owner would take a very dim view of cutting a few mm off the end of every piece of wood in a stack. Also a pain at home where you want to check the state of a flitch by having to cut the end off and re-seal.

However the inductive type are easier to use and you do not have to cut or drill the wood to get a good reading of the moisture content but you must have a flat surface to place the meter against. It works by using an RF (radio frequency) signal and testing how much it is affected by the wood. The better the meter the more sophisticated the technique used in the meter. I bought this one for about $58 off ebay. You can get meters that cost $350 or more  but the truth is that you can do all of what you need with one of these. The dearer meter may have a deeper penetration and better build quality but that is about it. This meter has a penetration of about 30-40mm. (For those electronic engineers I know the operation is more complex but this is a layman's overview.)

You need a flat surface on the wood being tested and typically the long grain will provide a more accurate reading then end grain since the cell cross section may distort the reading but not by much. The surface can be rough sawn but a jagged surface will produce inaccurate readings. Also make sure you keep your hand away from the reading area. This will give a high reading. Since the reading is affected by the density of the wood you need to adjust the meter for the wood's density or SG (specific gravity) using the Density selection. Most meters come with a table providing the setting (typically 0-9) versus Density (SG usually) and wood species for the more common woods.

Let me do some school revision for you regarding SG. The SG is a number which relates the density of the material to pure water which has an SG of 1. In short if the material has an SG of less than 1 it floats and is lighter than the equivalent quantity of water. If the material has an SG of higher than 1 then it will sink and is therefore more dense than water. Almost all woods will have an SG of less than 1 and will therefore float but some rare woods such as ebony will actually sink and Ebony has an SG of about 1.1. There are many tables online that provide SG values for various woods but it is easy enough to calculate with a ruler, scales and piece of wood. Again this is covered elsewhere using various techniques but the one I prefer is to square a sample of wood on all six faces, calculate the volume, divide it into the volume of one litre (10cm cubed) and divide by the weight in kg. This should give you a number between about 0.3 and 1.2 and this will be the SG.

I had to do this for a piece of mallee for which I could not find a value online. I think it came out to about .4, I should have made a note.

If you are planning to use local timber or even local hardware store timber then an inductive moisture meter is a welcome investment and can save a lot of grief.

Wednesday, December 2, 2015

My Sharpening Regime

Much has been written over the years about sharpening hand tools and it seems that everybody has their preferred method but much of it seems to me to be trying to design a better mouse trap. A lot of fuss and effort to produce an exact same result as the old traditional method. Some of them are really expensive but do no more than the traditional sharpening method. For instance someone on Gumtree was selling his old sharpening station for $1,800 second hand which still required you to use a sharpening stone and/or strop after you had finished there. 

In this entry I will describe what I do to sharpen and why I use that method. Although I could spend many pages going through all of the various methods devised over the years most people would not bother to read it and this has been done so many times elsewhere.

The principle I adopt is simplicity coupled with tradition. The method I use has been used since time immemorial in both the western and eastern tradition in one form or another. It was the method my dad used and the method I was taught at school will little variation.

It is basically a two step method. A rotating stone for rough grinding to establish a bevel then stones to refine the edge. If you want a super sharp edge then stropping can provide a third step which is useful for knives or razors but I don't bother for hand tools. There may be a pre-first step of linishing for restoring old tools such as in the picture to the left but that is not part of an edge maintenance regime.

Step one is grinding the primary bevel. I do this on a grinding stone on a medium speed grinder. This is often mistakenly called a high speed grinder, it is not. An 8" high speed grinder uses resin wheels and spins at over 6,000 RPM. Your medium speed grinder is the most common type and runs at about 1800 RPM. The best grinder for this step is a slow speed wet grinder that runs at 600 - 800 RPM and runs in a bath of water. This keeps the steel cool and produces a much finer edge but is very expensive and can cost up to $1,000.

The grinder I use is an 8" medium speed grinder and uses a white aluminium oxide wheel. They can be had for $100 for a cheapish unit up to several hundred for a name brand. The white wheel runs cooler and creates a finer finish but does wear more quickly. I use a $20 diamond dresser to maintain a clean wheel and a slightly convex face on the wheel. The convex face will help prevent burning of the edge. I also keep a pot of water next to the grinder and dip the tool into the water after every pass. I set the tool rest angle by eye against the existing bevel, but if I need to reset the primary angle I can use a protractor. I then grind the bevel by hand resting the chisel on the toolrest and continually dipping it in water.

Step two is the actual sharpening. I was taught with oils stones sharpening freehand. Although with careful attention I can still sharpen freehand I find that I get more consistent and faster results using a jig. Since it is not my day job (if it was I would refine my free hand skills) I cheat and resort to a jig. I now use a double sided water stone, 1000/6000 grit. The oil is somewhat messy and requires more careful cleaning so as not to transfer the oil to the wood. If I was super keen I could get an 8000 or 10000 grit stone but I get acceptable results from 6000. This combo stone is about $86 from Carbatech which is pretty good value. Ceramic stones do not require soaking, you just need to spray them with water but they are much more expensive. I use a 400  grit diamond plate to keep the water stone flat. A few strokes after each sharpening is sufficient. I use a $40 stone holder which is quite convenient. I keep a spray bottle of water next to me to make sure the stone is kept moist, especially if I am sharpening a number of tools at the same time.

The jig I use is the Veritas Sharpening Jig Mk II which is $109. It comes with a gauge to set the angle accurately. I also added a camber roller for $38 which allows me to round the edges of smoothing plane blades.

I use a few strokes to establish the secondary bevel at 1000 then flip the stone and apply a few strokes to polish the bevel. If you apply a gentle pressure to the tool then you will not round over the edge. This is one of the biggest mistakes at this stage. Too much pressure may cause the bevel to distort and round over the edge and create a large burr which will produce a less than perfect edge. The burr must be extremely fine, almost impossible to detect. Once the edge is polished remove the tool from the jig and polish the back on the 6000 stone. Job done.

Using this method your ongoing costs are nil. After your initial outlay your grinding wheel, stones and diamond plate should last indefinitely. You do not need the more expensive Veritas jig, your side griping jigs which can be had for under $20 are just as effective if you are careful. You can set up a wood jig with depth stops for your common angles to make setting your bevel angles faster using the side griping jig. Although a wet grinder is better it is a lot more expensive compared to your regular medium speed grinder. The only thing I need now is a dedicated sharpening station. I really only need a small wet area with a laminex bench top set to a convenient height to allow me to lay out my water bath stone lapping plate and jig. If it is relatively close to your working area, but not close enough to get covered in shavings you will be into the semis without dropping a set.

My sharpening resources are;
  • 1000/6000 combination water stone
  • 400 diamond lapping plate
  • Sharpening jig
  • Stone holder
  • Water bath
  • 8" bench grinder with fine white stone
 Also when I get around to it a sharpening station.