When less is more

A recent release from Woodpeckers, this new square is of significant size.

Woodpeckers Mini Square

Woodpeckers Mini Square

Significantly small that is!  When so many other items work to convince you that bigger is better, this goes the other way and proclaims “less is more”

As with other Woodpeckers squares, this is guaranteed square (and to stay square for the gauge’s lifetime) to 0.001″

You may notice inside the stylish container, that Woodpeckers products are made in the USA, and that not only being small, it has decent width.  One use of the gauge is for checking that a sharpened chisel is square to the sides, and that width makes it easier to align the gauge with the chisel edge.

Checking a chisel is square

Checking a chisel is square

This is not the only use for this gauge, as given its small size it can easily get into small spaces (such as a small box or drawer), and check for square.  That ability to fit into small spaces isn’t something to undervalue – resorting to folding a piece of paper to create a makeshift square will not achieve 0.001″ accuracy!

Available in Oz from Professional Woodworkers Supplies for under $40.

 

Under Pressure

When using a featherboard, you normally don’t get to choose how stiff the fingers are – they are what they are.  When you put the featherboard into operation, it is pushed up against the workpiece until the desired deflection is achieved.  However, if you find it isn’t right, you have to start again with its setup.

I’m a big fan, as regular readers would know, of the MagSwitch range.  But they only works on ferrous materials.  My router table base is cast iron just to get to use the MagSwitch featherboard, which is all very well horizontally, but given the fence is an Incra LS Positioner with Wonderfence (from PWS), and that is all anodised aluminium, there is a bit of a problem.  I need a featherboard that works in a slot (and the Incra has slots that are perfect for this).

So where to turn?  Well when it comes down to it, there are two companies with incredibly similar ethos where it comes to innovation, quality and accuracy for woodworkers.  If one is Incra, the other must be Woodpeckers.

And sure enough, there is a new Woodpeckers featherboard that is an ideal complement for the Incra Router fence.  The Incra is not the only place the featherboards can be used.  Any slot, T or Mitre can be used. Router table, table saw, bandsaw, disk sander, spindle sander etc etc.

So you choose the Woodpeckers featherboard, put some load into it-get some deflection of the fingers (or feathers), but they are a bit soft for the application.  So instead of trying to achieve greater deflection (which also makes it difficult to feed the wood under or past the feathers), with the Woodpeckers you can choose to stiffen the feathers right up without having to reposition the whole setup with their innovative design.

It also works in reverse – if the feathers are too stiff, applying too much force against a soft timber, you can use the variable adjustment to get a softer action from the featherboard.

Horizontal or vertical, these featherboards are a real complement for the tool.  They come in sets of two – infeed and outfeed, or vertical and horizontal (or just have 2 sets!)

The real secret is in the method for controlling the finger pressure.

There is an upper plate, secured separately to the featherboard itself.  Small fingers insert in between the main featherboard fingers. By loosening the central knob, this separate plate can be slid up and down, effectively lengthening or shortening the feathers as required and thus controlling (and varying) the pressure without having to relocate the whole featherboard.

The shorter the fingers are made, the stiffer they become, and vice versa.

I haven’t taken a photo as yet of this setup on my Incra Wonderfence, but they definitely look the part, and are a perfect complement for my setup.  Being Woodpeckers, they are available from Professional Woodworkers Supplies down under

Inaccurate Perfection

The Science of Inaccuracy

Ever drilled a hole with a bit that was meant to be ‘exactly’ the right size, only to find the hole either too large, or too small?

Ever taken every care measuring the length of board to be cut, and found the result disappointingly long, or worse, too short?

Just how accurate is a ruler?

In the scientific, and particularly the engineering community, every measurement is given a tolerance range (+/- 1mm for example), every tool has a tolerance range, a degree of confidence. There are reasons why this sort of constant monitoring of precision is not translated into woodworking.

For one, it is cumbersome- constantly focusing on accuracy can get in the way of the work. Wood is also rather forgiving- it compresses, there are fillers (and filling techniques), glue can span small gaps, nails can span large ones.

But this doesn’t mean that there is not a lot of benefit to be derived from understanding measuring accuracies, the sources of error and how to control it.

When you are building a house, having a measurement out by 5mm or more is not the end of the world, and the measuring tools used reflect this. If you are making a fine box however, 5mm is an unmitigated disaster. 1mm is a disaster, and is the difference between a fine box, and one made by a 10 year old in a woodshop class at school.

We’ve heard the general rule about not changing what we are using to make the measurements during a project, so as not to introduce an error, but there is an underlying issue there that is glossed over. The accuracy of the device we are using, and while we are at it, let’s ignore the additional errors introduced by thermal expansion.

Any rule, or other measuring device, cheap or expensive has an error.  The more you spend, generally the smaller that error is, but it never goes away.  Every drill bit, every spanner, bolt, protractor, tape measure, setting block, square.  They are all in error. How much they are out, is the difference between whether we can accept the amount of the error or not.

A quality rule, such as one from Woodpeckers are manufactured to be accurate to within +/- 0.025 mm, which for a woodworker’s requirements is pretty good.  So if I was to measure the width of a board, does that mean I can be assured that it is (for example) 100mm wide, +/- 0.025mm.

Sorry – not even close!  Just because a rule may be manufactured with a high degree of accuracy, it always relies on one other tool – the eyechrometer. (Your eyeball!) The rule for measuring inaccuracy, is you cannot assure an accuracy any better than 1/2 the distance between the two smallest measuring marks.  And the error compounds.  If I used a normal rule, where the markings do not extend right to the edge, and the rule has markings every mm, then the best I can say is the board is 100mm wide, +/-1.025mm  Yuck!

Might explain a few things in the workshop though, when things go wrong.

Take the same example, and let’s ignore the error in the rule itself, and let’s also assume the tablesaw fence is calibrated as accurately as possible (which by definition is +/- the finest measurement shown, so that would typically mean it is accurate +/-0.5mm)

Using a steel rule, which doesn’t have markings extending to the edge, such as this one:

The width of a board is measured as 100mm.  The fence on the tablesaw is set to 100mm, and a piece of timber ripped, then laid it on top of the current board, and both stood on edge on the top of the saw.  Why are they not the same width?  Didn’t I do everything right?

Error has crept in. My original measurement of 100mm is +/- 1mm, so the actual board is somewhere between 99mm and 101mm wide.  Let’s say it is actually 101mm.  The next board that I rip has been set on the tablesaw, which has its own error of +/-0.5mm, so this board can be anywhere between 99.5mm and 100.5mm.

But wait, not only is the fence out a fraction, the blade itself has some runout which I didn’t know about- happens to be 0.25mm

My cut board can now be anywhere between 99.25 and 100.75mm!

The difference between the board I measured, and the one I cut could be out as badly as 1.75mm.  I’m back in my 10 year old woodworking class, and I was being CAREFUL!

Am I doomed to failure?

No: by understanding error, error can be controlled, and minimised.

For one, a rule that has markings extending right to the edge immediately halves the error in measuring.  You can feel it is flush with the edge, rather than eyeballing to see the edge is lining up with a marking on the rule’s surface, so that measurement is regarded as accurate.

By switching rules, I can now be confident that the board is 100mm wide, +/-0.5mm

By getting a better rule, with marks laser cut every 0.5mm, I can measure the width to be 100mm +/- 0.25mm

So the board is now somewhere between 99.75 and 100.25mm  Already quite a bit better than 99-101mm.

I use the same rule to set the fence to blade distance on the tablesaw, and by knowing the amount of runout of the blade, that error is also taken into account and controlled.

My overall error is controlled, and the resulting board is now also 99.75 – 100.25mm . At worst, the difference in widths of the two boards – the one measured and the one cut is down to 0.5mm.  At worst.  Probably less, as error is worst-case scenario stuff.

How about another example.

I want to measure the length of a board, and I have 2 ways to measure it on hand.  A cheap tape measure, which has it’s own inaccuracy of +/-1mm (a cheap one!), and I also have a good steel rule (the same one as pictured above), accurate to +/- 0.1mm

The board is 2m long. Or is it?

The tape measure measures it as 2000mm +/- 1.5mm (the error of the tape measure, plus the error of the measurement itself)

The steel rule, which is 10x as accurate in its manufacture as the tape measure reads it as

2000mm +/- 15.4mm!!!!  How on EARTH did a cheap’n’nasty tape measure absolutely thrash a steel rule?

Simple – every time the rule had to be moved, the error compounded.  The steel rule is too short, being only 150mm long, so it had to move a total of 14 times to measure the entire length of the board.  Each time, it is +/-1.1mm (because it has 1mm graduations, and the rule itself is already +/-0.1mm)  The +/- 15.4mm is a confidence level – you can be sure the length is between 1984.6mm and 2015.4mm.  It may be exactly 2000mm, but you cannot say that with certainty.  And if you measured it again, it probably wouldn’t come out the same.

What is it they say – measure twice, cut once?  But why is that?  One big part is that if you repeat the measurement, you might pick up an error you made first time, a total misread.  It also increases your sampling, and you can start to average out the measurements.  If you measure it twice, and get it to be 0.1mm different, you can increase your confidence you are getting a good reading of the actual width of the board.  How many times is enough?  How accurate is your rule, and how much variation are you getting each time – at the point you are confident of the measurement, then you are done.  If I measure something twice, and I get the same measurement each time, that’s typically good enough.  If I was needing some very fine tolerances, such as in precision metal working, 2 is probably no where near enough, and I’d be better off 3 or 4 times, even more, and over an area rather than in the same place.  It all depends on how accurate you want to be.

Now you’ve probably been reading all the above and thought “B.something rude”, I can be more accurate than that, and I’m sure that is right. Personally, I’d say I could take a mm rule, and be pretty close to 0.25mm accurately. But the point is, confidence and repeatability.  Repeatability from one job to the next, repeatability from one day to the next, repeatability from one tool to the next. Repeatability from one person to the next. But you don’t work with anyone else? Never used someone else’s plans?  They were made by a real person, with their own error rate.  May not be a big deal, but still worth keeping in mind.

With all that in mind, what do you do? All this has focused on the right tool for the job, and is not saying one person can be more accurate than another.  It also looks at being as precise as you need to be.  I’d love to build a house to 0.1mm accuracy.  But it is not practical (or affordable!) Would be a stunning house though!

If measuring a long board, you need a long rule.  A tape measure can be pretty accurate, a Woodpeckers 900mm rule isn’t too bad either. 😉

For small scale stuff, I regularly use a digital calliper, and the Incra rules.  They are particularly special.  Accurate to 0.001mm, and specifically designed for precision, with the pencil being captive in the rule for the required mark, that precision jumps dramatically compared to a conventional rule. The accuracy when drawing two lines a given distance apart, or a set distance in from an edge will be somewhere in the order of +/-0.1mm or so (it is probably more accurate than that : 0.1 is my conservative estimate.)

Making a mark can be done with a carpenter’s pencil, but at 2-3mm wide, do you then cut to the left, right, or down the middle for accuracy? A fine pencil is better (and a 0.5mm clutch pencil with an Incra Rule is exceptional), and a marking knife produces a razor-sharp line, with no width to speak of.  Oh, and don’t forget about parallax error. A good rule is designed to minimise parallax, and again the Incra rule doesn’t have that problem (yes, I am a big fan of Incra rules- can’t you tell?)

There are other ways of dealing with sizing timber correctly.  One I do regularly is to cut the first board close to the right length, then mount two together and cut them to the final length simultaneously.  This works particularly well when it doesn’t specifically matter how long the two boards are, so long as they are equal.

The Kerfmaker is an exceptional jig for what it is designed for, taking account of board width, saw kerf, blade runout, all without a single rule or scale.

Another useful tool is the story stick, whether this be a simple stick with some marks drawn on it which you then store until the next time you need to make the part in question, or a commercial one which is excellent for the current project, but you don’t keep it dedicated to a single project.

If you want to get into the seriously accurate tools, then the Incra LS positioner, either on the router table or the table saw (or drill press) is one of exceptional accuracy.  With the ability to position a fence to within 0.025mm of the required measurement is exceptional.  To be able to do it repeatably because of the unique design is quite unbelievable. I have the LS positioner on my router table (love that fence), and am very keen to have one on my tablesaw one day.

If you have ever done any car or motorcycle maintenance, then the concept of a feeler gauge would be quite familiar. Woodpeckers have decided to produce a limited run of an equivalent tool for woodworkers. Called Set Up blocks, these are being produced as part of Woodpeckers One Time range- they will be made to order, and then (at this time), never again.  If you are in Australia, you’ll need to order by the 27th June to be part of the manufacturing run from Professional Woodworkers Supplies – cost is $96.50 for the 7 piece metric version (imperial set shown).

The sizes are 0.5, 1.0, 2.0, 4.0, 8.0 and 16mm and there is an additional block which is 25x50x100mm.  Like feeler gauges, these can be doubled up to get all the other measurements required.  Looks a very cool set- it will be very interesting to see how they work for real.  The accuracy of a digital calliper, and no batteries required!

So that is just a brief look into the world of precision, something I am particularly partial to, (and hence why I have a reasonable collection of Incra and Woodpecker.

Quality costs, as does accuracy, but it is a great feeling when you absolutely nail something precisely.

Upgraded Bandsaw Circle Cutter Jig

Way way back in the history of this blog (around Episode 6 if anyone cares) I did a video on a basic circle cutting jig for the bandsaw.  That jig was decommissioned and abandoned after a few years of service as part of the cleanup during the shed expansion, but it has taken from then until now for me to do something about replacing it.  I’ve had plans in my head for a new version for a long time, and finally I have realised those into a new jig (which is still a bit of a work-in-progress).

So let’s jump into what I have been working on.

I started by raiding the jig drawer, and found some useful components that looked like they would work with my mental image of the new jig.  My main thing I wanted to be able to do with the new one, was adjust the diameter of the circle without having to use the agricultural method of hammering in a nail and clipping off it’s head to form a point to mount the work on.  So a rail was needed.

The other ‘problem’ I wanted to solve was angled circle cuts, which have a different bandsaw blade path, and over time would end up with the jig rather chewed up.  Will still be working on this as the jig develops.

Jig Components

Jig Components

What we have here is some Incra Rule Track, the Incra Mitre Slot runner (not sure it’s real name), a mitre slot lock nut and some scale rule.

I wanted to use the mitre slot lock as the pivot point – setting its position along the track and it then locks down with a hex key. I needed to put a pivot point into it, and what I came up with was a threaded bolt through the track lock, which is then sharpened to a point to mount the workpiece.  As much as my shed is a woodworking shop, there is still a number of invaluable metal-working tools in there and one that is invaluable for jig building is a thread cutting set.

Metal Thread Cutting

Metal Thread Cutting

It doesn’t have a large range, but there is enough in there for the sorts of small-scale jigs etc that I need to make.  Jigs are, after all, one of the most useful things in a workshop, so making a jig is an artform in itself. (Not that I’m particularly good at it, but I do recognise their value!)

Measuring Thread Size

Measuring Thread Size

First step was choosing a suitable bolt that I wanted to use, and then determining what thread size it was to cut the matching threaded hole in the Mitre Lock. There is a tool in the kit to determine the thread on a bolt, and in this case I was able to work out that it was M5 0.8 pitch.

Drilling the hole to be tapped

Drilling the hole to be tapped

Next, using the pro drill press table’s advantages with the clamps etc, I was able to hold down (with the aid of some Vice-Grips) the small Mitre Lock to drill the hole to be tapped.  I used a 4mm bit for this, as it will be tapped out to 5mm by the thread cutter.

Cutting the thread

Cutting the thread

Using the correct thread cutters, I then tapped the hole, first with the least aggressive 5mm 0.8 cutter, and progressing through to the final cutter which produces the sharp crisp thread required.  Using one is pretty easy, and it is just a matter of taking it slow, backing the tool off every 1/4 turn to break off the swarf that is forming, then continuing deeper and deeper.  This is repeated for the next two thread taps until the thread is fully formed.

Formed Thread

Formed Thread

Here is the final hole produced, and all tapped ready for use.  You can also see in this photo the grub screw (hex drive) that is used to lock the Mitre Lock into the track

Inserting the Bolt

Inserting the Bolt

The bolt is then threaded through, and with the aid of the Vice-Grips again, the head of the bolt was sanded right down on the linisher. Then, with a combination of metal files, the Triton Rotary Tool and the linisher, the bolt was shortened, and sharpened to a point.

Ripping the Jig

Ripping the Jig

The body of the jig has been made out of this heavy ply I have held onto for years, waiting for a good use to put it to.  It happens to be the ply that is used around electrical cabinets etc, and is quite weather (and electrically) resistant.  It has a shiny, smooth side, perfect for jigs.  This is probably one of the first photos on here of me actually using my tablesaw, so have included it for that reason (I normally don’t remember to take a photo while ripping a board!)

Routing the Dado for the Track

Routing the Dado for the Track

I wanted a stopped dado for the track (in other words a slot that doesn’t extend the entire width of the board, so as much as I was hoping to use the dado blades on the tablesaw for a legitimate job, I still needed the router table for the task.  The Incra fence again came into its own, allowing me to accurately position the fence so the track was an exact fit. I did use the micro positioner to do a couple of final fitting runs, taking off about 3/1000″ each pass to get the fit perfect.

The end of the stopped dado has rounded corners as a legacy of being cut with a router bit, so I needed to either square those corners up, or round the track over to match.  I have a small tool I bought from Carb-i-tool years ago, perfect (and designed) for this task.

Corner Squaring Chisel

Corner Squaring Chisel

A few quick raps with my home-made redgum mallet, and the corner is cut square.  It is a cool design, and the tool has a rebate on two sides so it fits perfectly in the corner over the top of the round section that needs removing.

After testing with the track, I decided I wanted to set it a bit deeper, and rather than making more passes on the router table, I had the perfect tool for that job too…..

HNT Gordon Shoulder Plane

HNT Gordon Shoulder Plane

…..my HNT Gordon ebony shoulder plane.  Sometimes a hand tool is the perfect tool (and yes, I am sure there are many other there that would argue that a hand tool is ALWAYS the perfect tool, but I don’t mind murdering a few electrons on the way).  It can be set so fine to take of just a fine shaving, delicately thin.  You can’t beat the feeling of working with a fine tool.

Track in Position

Track in Position

The track and Mitre Stop is now in position, and the track is significantly longer than the jig so I can cut rather large circles if required.  The size of the base board was chosen to roughly correspond to the width of the bandsaw table (including the area between the blade and the riser (the throat)), so the workpiece has plenty of support.

Marking up slider position

Marking up slider position

Another tool getting actually used in a real job was the Woodpecker T Square, used here to find the track that the bandsaw blade will follow, and therefore where the slider needs to be located.  I’ve used the Incra slider here because it can be fine-tuned to fit in the mitre slot of the bandsaw table for a good, sliding fit which can be adjusted and finetuned while the jig is fitted to the table with a simple hex key.   It also means I can reposition the slider easily, if I want to use this same jig on another bandsaw.  In my case this is important, as I am designing this primarily for my Jet 14″, but will also want the jig for cutting circles on the Triton 12″ bandsaw when I run my toy-making courses at Holmesglen.

The first cut

The first cut

Finally, we are ready for the very first cut, the one that the blade will follow for horizontal circle cuts.  This is done with the slider in position, but no table stop is yet fitted, as I have not determined its position.

circle-cutter-15I’ve then fitted a stop to the underside, which catches the edge of the table so the jig can’t pass through too far.  In this case I’ve used a bit of Incra rail which is a bit of a waste, but it was the perfect size, so sacrificed to “the cause”

All ready

All ready

The track is in position, the stop is in place, the initial cut is made, the jig is ready to go.

Initial cut

Initial cut

A board is located onto the pin set to the desired radius, then (with the bandsaw running obviously), the jig is slid forward until the stop on the underside connects with the table.

Cutting the Circle

Cutting the Circle

The board is then rotated through the blade as it pivots on the pin until the circle is complete, and as seen here, breaks free of the outside stock.

Backing out of the cut

Backing out of the cut

You then back the blade through the initial slot cut until the entire jig is free of the blade, and remove the cut circle.

Circle Cutting on the Bandsaw

Circle Cutting on the Bandsaw

Circle cutting on the bandsaw – a simple task that takes a lot less time than it took to write this article!

%d bloggers like this: