The 45190

It sounds like another Whovian thing (or more precisely, Torchwood) (aka “The 456“), but instead, it is a lot simpler than that.

The 45190 is a router bit.  For my current activities on the CNC, it is THE router bit.

It is not overly complicated – a straight 1/16″ (1.59mm) 2 flute solid carbide cutter embedded in a 1/4″ shank.

Amana Tool 45190 Carbide Tipped Straight Plunge High Production 1/16 D x 3/16 CH x 1/4 Inch SHK Router Bit

from: Tools Today

But it is what I have been able to do with it that sets it apart.  Or rather, that it gets done what many other router bits have failed to do.

As many would know, I am cutting out a lot of patterns on the CNC, particularly from 3mm thick MDF. To get the level of detail I need, I am using a router bit that is around half that thickness so it can get right into the various corners.  But it also needs to do some miles, and that is also where this router bit has been scoring some exceptional goals.

I have tried other router bits, with some (but decreased) success – spiral upcut bits work, but have a tendency to pull the resulting piece that has been cut out, right out of the sheet.  It can then be thrown or bumped to a point where the router bit plunges through it while cutting another.  I’ve even found small pieces that have been cut out subsequently stuck on the router bit, trying their best to emulate a helicopter!

Downcut spirals work better, but they still have a problem that the dust they are carrying downwards gets deposited under the sheet, causing it to lift, and in the worse scenarios, to completely detach from the vacuum table.  Granted my vacuum table might not be as strong as a commercial one, or may not be able to carry away any sawdust produced so this doesn’t happen.

I’ve also tried larger bits (specifically 1/8″), but they do not give the same degree of detail, and the joints are not as tight.

So that leaves the 45190.  Yes, I have broken a fair few (and am again down to my very last one, that makes me nervous!) but that has always been the result of something other than cutting normally.

So far, the router bits I have broken have been:

Forgot to slow the feedrate back to 100% from a previous operation, and the router bit tried to cut 3-4 times faster than I have worked out to be a good speed for my machine for that bit and that material.

I’ve hit the clamp on at least one occasion, and a screw on a couple of others.

I’ve had a piece come loose and wedge itself against the spinning bit, and it has broken when the CNC moved in that direction.

Sadly, I have occasionally forgotten which is Y and which is Z (or have simply clicked the wrong button), and instead of lifting the bit, have tried to drive it through the material.

And more than once I’ve had the CNC get its + and – directions confused, and it has driven down hard, rather than up.

In spite of all this, when the router bit is treated correctly, it does the energiser bunny thing – it keeps going and going and going.


Check out the teeth on the dinosaur (Spinosaurus) and you will see what I mean about retention of detail.  Remember that MDF is 3mm thick to give you an idea of scale.

The straight cutter is also not the worse solution either.  The dust that is produced gets packed into the cut, which helps hold the piece being cut from moving.  The top and bottom surfaces stay pretty smooth, and only a very light sand is required.

The detail is retained, which is important, and the yield from each sheet is maximised.


So when I am doing these CNC MDF jobs, and I keep mentioning this one router bit, there is good reason. The 45190.  Its a Whovian thing!




The router bit set of envy

Come into my workshop, and along with my standard range of router bits I have and use, there is a new display.  A set of specialty router bits designed to provide any CNC mill owner some stunning bits to complement their CNC machine, from

Photo 16-11-2013 10 22 01

Every CNC-centric router bit you could hope for, all in one display.  And they are not just any router bits either.  This is not like the set of router bits you can head down to the local hardware shop and buy a set of 20 for $20.  If the bits in this set are not carbide tipped, then they are machined from solid carbide, which ensures they are strong (given carbide is naturally brittle), and much finer than any carbide tipped bit can be.


There are two versions of the set – either with a 1/4″ shaft, or 1/2″.  I have the 1/4″ set to complement the CNC Shark, as I can always fit them in a 1/2″ router, but of course I couldn’t do that the other way!

The set comprises of the following:

 Example image  Router bit description  Purpose
 51402  Solid Carbide Aluminum Spiral ‘O’ Flute 1/4″ Dia. x 2″ Long x 1/4″ Shank “Mirror-Finish” Up-Cut Router Bit  Aluminium
51402  Solid Carbide Aluminum Spiral ‘O’ Flute 1/8″ Dia. x 2″ Long x 1/4″ Shank “Mirror-Finish” Up-Cut Router Bit  Aluminium
51411  Solid Carbide Plastic Spiral ‘O’ Flute 1/4″ Dia. x 2″ Long x 1/4″ Shank “Mirror-Finish” Up-Cut Router Bit  Plastic
51411  Solid Carbide Plastic Spiral ‘O’ Flute 1/8″ Dia. x 2″ Long x 1/4″ Shank “Mirror-Finish” Up-Cut Router Bit  Plastic
6225_6a  Solid Carbide ZrN Coated Ball Nose 5.4° Tapered Angle 1/16″ Dia. x 3″ Long x 1/4″ Shank Router Bit  2D & 3D Carving
5183_3_  Solid Carbide Carving / Engraving 7.5º x 3/16″ Dia. x 1/4″ Shank Router Bit  Fine line engraving
5891_2_  Solid Carbide Carving Liner 9º x 1/4″ Dia. x 1/4″ Shank Router Bit  Extra fine engraving
5807_2_  Solid Carbide Up-Cut Ball Nose Spiral 1/4″ Dia. x 2-1/2″ Long x 1/4″ Shank Router Bit  Ballnose carving
5638_4_  Solid Carbide Mini Compression Spiral 1/4″ Dia. x 2-1/2″ Long x 1/4″ Shank Router Bit  Melamine, MDF & Laminates
6208_3_  Solid Carbide Beadboard 1/8″ Radius x 1/4″ Dia. x 1/4″ Shank Router Bit  Fluting & fine roundover
4926_2_  V-Groove 90º x 1-1/4″ Dia. x 1/4″ Shank Router Bit  V Grooves
4926_2_  V-Groove 120º x 1-1/4″ Dia. x 1/4″ Shank Router Bit  V Grooves
4926_2_  V-Groove 60º x 1/2″ Dia. x 1/4″ Shank Router Bit  V Grooves
5645_2_  Solid Carbide Up-Cut Plunge Spiral 1/4″ Dia. x 2-1/2″ Long x 1/4″ Shank Router Bit  Clean production routing
6015  InTech™ Insert V-Groove 90° x 1/4″ Shank Router Bit  V Groove replaceable tip
6016  InTech™ Insert Core Box 1/4″ Radius x 1/2″ Dia. x 1/4″ Shank Router Bit  Coving replaceable tip
 Mini Surfacing Insert Spoilboard Bit 1-1/2″ Dia. x 1/4″ Shank Router Bit
 In-Groove™ Insert Engraving System 1/4″ Shank Tool Body, with
 30° In-Groove™ V-Tip Engraving Insert Knife
 Extra fine engraving 29 different tips avail


It is a pretty impressive lineup, making it very likely to have just the right router bit for the job at hand, no matter what the material (within reason!)  Wood (fortunately!), MDF, ply, Melamine, aluminium, copper, brass, plastic.

Solid carbide upcut for the finest finish, replaceable carbide tip bits for bulk jobs, or to ensure a fresh sharp edge and tip for a new job.

Although the router bit set I am referring to is sold as a CNC set, this is by no means the limit of what you can use the bits for.  After all, they are just router bits, and if you want to use them for freehand routing, or signwriting, or pattern following with a template, they are perfectly suited for these applications as well.




These are an interesting concept as found by the Roving Reporter, from Easy Wood Tools.  It is a concept I have seen elsewhere, but these look a well refined solution.

easyEach has a carbide tip, so sharpening on the fly is not necessary, as the tool dulls with use, rotate the cutter, and finally replace it.  Of course, if you have the Tormek Sharpener with the Blackstone Silicon wheel, then you can resharpen the carbide cutters.

Haven’t seen these in person, so I don’t know how they shape up in reality, or how they would compare to my Hamlet chisels for example.  Although carbide cannot be sharpened to the same degree as tool steel, in practice most wood turners don’t sharpen their chisels to the nth degree in any case, and the long durability of a carbide edge has a lot of appeal.

Scraping with Scrapers

These are not cabinet scrapers (which are a skill all of their own), but instead for scraping when you need to remove a surface – such as paint, varnish, stripper etc.

I have had an opportunity to put the Linbide range through some initial trials, and as much as I normally wait until I’ve had a chance to build up a real opinion on a tool, these had me sold straight out of the box (or packaging to be precise).

Linbide Scrapers

Linbide Scrapers

From right to left, are a straight (or flat) scraper, a corner scraper, a profile scraper, and a cutter.  All are sporting Tungsten Carbide blades which makes a lot of difference to the performance of the blade (and the durability of the sharp edge)

They are very utilitarian in their look, but that does not detract from their performance, and the handles are surprisingly comfortable and provide a good grip.  The blades are replaceable (and with the straight and corner scrapers, the blades are reversable).

I took one to my front windows (external) which are increasingly desparate for a repaint.  I had a mind to a couple of years back, but after trying with some sandpaper, decided that job was too big.  I then tried a heat gun, with no success (it might have worked elsewhere, but not on a paint designed to survive the Australian sun).  So I tried a waterblaster, and that stripped the wood apart faster than it did the paint.

So it was with interest that I gave the scrapers a crack at the task, and we had a winner!  Paint came away with ease, and the wood was undamaged.  I don’t need to remove all the paint, just that which is too loose to paint over.  Damn, now I have even less excuses not to paint the house!

To get into corners, and over the different profiles around the windows, we have the profiled scrapers.

Radiused and Corner Scrapers

Radiused and Corner Scrapers

All Tungsten Carbide blades.

Now speaking of Tungsten Carbide, the final tool is called a laminate score and snap knife.  It sports two carbide tips, and is designed to score laminates, and can be used quite successfully as a glass and tile cutter, and will make short work of drywall.  Given its design, it will be easy for it to follow a straight edge.

Not having had a decent scraper before (the last one I had came from a $2 shop), it is quite enlightening to see what difference a quality blade can make!

These scrapers are imported in Australia by the Woodworking Warehouse: and cost around $20 each.  You can get them from their store in Braeside, or order over the phone 03 9587 3999, or via email

Table of Blade Measurements

I have added a page to the Battle of the Blades review which gives a table of all the blade measurements side-by-side. Table of Blade Measurements

There were a few unusual measurements that came out of it, but all in all, it is the performance of the blade that really counts. Other than perhaps carbide thickness, which gives an indication of how much resharpening the blade can take.

One item that offered some correlation between the measurement and the cut quality was blade runout.

There were a few blades with a significant degree of runout, and each also gave a poor finish. I only get to test one blade from each, so I can’t say whether it was just a rogue blade, or batch, or if that is typical. It really did highlight the fact that it is definitely worth testing a new blade’s runout before putting it to use, and if you are not satisfied, return the blade.

The typical runout found was 0.005″ / 0.13mm. The lowest was a remarkable 0.002″ / 0.05mm. The highest was 0.030″ / 0.76mm. That blade literally screamed when it was run unloaded, with the noise going from a typical unloaded (but running) level of 95dB to 105 – 110dB after a few seconds. Not sure if one resulted in the other, but it is interesting.

It is not just the blade runout that affects the quality – variation in tooth width (the kerf) plays a large role as well.

I didn’t get into the angle of the grind and how it plays a part in quality – perhaps a job for another day.

Anatomy of a Saw Blade


The saw blade – irrespective of how good the saw is, how flat the table, how rigid the fence, if your saw blade is substandard, everything else is cheapened. The blade tends to be somewhat overlooked (ok a bit of a generalisation), as it just seems to keep going and going and going. What it is however, is a series of tiny chisels. A hand chisel gets looked after, cleaned, sharpened and stored correctly, and the saw blade should receive the same attention.


These days, the blade is often laser cut from high carbon alloyed steel, with the cutting edge being a Tungsten Carbide Tip (often a Tungsten-Cobalt alloy) The tip is very hard, but brittle, and is brazed onto the body of the blade. It is used because it will retain its edge for about 10 times longer than steel. The width of cut (the kerf) is primarily the width of the Carbide Tip, although there are other factors that come into play. In general, the kerf is 3mm, but there are also thin-kerf blades which are good for minimising wastage, and to get better performance out of lower-powered saws.

Click here to read full article


Steel. Perhaps a strange topic for a woodworking site, but then, so many of our tools, and particularly the sharp edges that actually work the wood are made from it, so it is useful to know a bit about it. In the near future, I will be doing an exposé on all things sharpening, so getting to know steel is really the start of that process.

(I will be pretty general in the descriptions, so don’t be surprised if you can drive a bus through my definitions!)

There are many, many versions of steel. Steel is not an element, but a compound of Iron (Fe) and Carbon (C) (and is actually called an interstitial solid solution, as the carbon atoms fit into the gaps in the Iron atom structure). In addition, you can add other metals into the one material, which is called alloying, and there are a huge variety of steel alloys out there with all sorts of different properties. I’m going to pretty much ignore the alloys at this point, and just focus on carbon steel.

Now carbon steel is just not a bunch of Fe atoms in a grid, with the carbon atoms in some of the gaps throughout the material. If this were the case, the concept of heat treating, tempering, quenching etc wouldn’t have any effect. What there is in fact, are areas of pure Iron (called a-iron or ferrite) then others which are a combination of Fe and C, which is iron carbide (also known as cementite), and is not a discrete molecule, but a crystal lattice containing iron and carbon atoms in a ratio of 3:1, written Fe3C.

If you have a huge amount of carbon, then you have massive amounts of cementite and ferrite (pearlite – see below), and even areas of pure carbon, and this is where we get into cast iron, which is not used for making sharp tools (very hard, and way too brittle!)

Back to steel. Carbide, as we experience it as woodworkers is generally tungsten carbide, a very brittle, very hard material that is used for producing durable cutting surfaces. Iron carbide (cementite) is similar, hard, but brittle, and if in the right amount gives steel a real edge over pure iron (sorry about the pun).

So what happens when we take our molten steel, and cool it to form our chisel or plane blade? If we let it cool slowly, it will have time to form the normal structures, and will be our basic steel – machinable, hard, but nothing special. It will have (and this depends on the % of carbon) grains of pure ferrite, then others that are a mixture of ferrite and iron carbide. It is these grains that are a mixture that give steel its ability to be heat treated (ok, gross generalisation). As these grains form, they produce a lamellar (plate-like) mixture of ferrite, and carbide, known as pearlite. The steel at this point can be cut, ground etc, to form the desired shape for the plane blade, chisel etc. The steel is ok, but not tough enough or hard enough to be used for a cutting edge. That’s where heat treatment comes in.

White areas are ferrite (Fe) , ‘worms’ are platelets of cementite (iron carbide, Fe3C)

The steel is then reheated, but not to melting point, held at the required temperature, and then cooled quickly. If you cool it slowly, you form coarse pearlite, which isn’t very hard, and therefore not useful (for us). Cool it quicker, and you get finer pearlite (ie smaller, thinner, and more platelets of carbide). This is harder and stronger material. If you cool it even faster (quenching), you form a new structure, called martensite. Martensite is supersaturated with carbon, and the change to the iron lattice means the atoms can’t slip over one another easily so the material is very brittle and very hard. The faster you can cool the steel, the more martensite is formed (and the smaller the individual grains). Although this transition to martensite happens very quickly, not all the material can get there in time, and retains the original structure. To force more of this to martensite, we need to cool the steel even further, well below room temperature, and is called cryogenic treatment. So now we have an extremely hard, brittle tool steel. (Yeah, I’ve generalised heaps here, but you get the jist). The structure is good – we have a very fine grain structure, but we need to ensure that there is sufficient ductility in the steel, so it can survive being pounded by a hammer into hard wood! (In other words, we want it hard, but also tough).


This is done by tempering – reheating the steel until we get just the right combination of ductility and hardness, and the result is called tempered martensite, an ideal combination of toughness and hardness in our resulting tool. The brittle martensite is transformed into a fine dispersion of iron carbide particles in a tough ferrite matrix. The carbide stops dislocations and slips in the structure (so the material can’t shear and fail, ie making the material hard (and is not unlike how the atoms of an alloying material help make a material hard)), and the ductile ferrite can deform locally, arresting any cracks that try to form in the structure (so the material is less brittle).

Thus we have a blade, hard and tough, with a very fine grain, ready to be sharpened to a mirror finish (and if you have 2 surfaces that are so flat as to be mirror-like, meeting at an edge, that edge will be razor sharp).

***Update*** Here are a couple of articles about the practical side of heat treating blades, and are definitely worthwhile getting to see this done in practice, as well as the theory above***

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