Unlocking Codes for Router Bits

[DavidCBaker]

I'm assuming that HSS means high speed steel--what does HW mean?

 

[peter halle]

You are correct - HSS = high speed steel.  I believe HW stands for Hard Wearing.

Peter

 

[AlexThePalex]

I am not 100% sure but I think HW stands for Hartmetall Widia or Hartmetall Wolframcarbid.

It's German. 'Hartmetall' means 'hard metal' and is the name of specially hardened metal for tool use. Widia is an abbreviation for 'Wie Diamant' which means 'like diamond'. Widia is originally a brand name from a company that made specially hardened steel for tips of saw blades, drill bits and router bits, but it is now often used as the common name for all specially hardened metals made from wolfram carbide or tungsten carbide.

HSS can mean both High Speed Steel or High Strength Steel, depending on the application.

 

[DavidCBaker]

Thanks, guys.

Is one more suited than the other for certain applications? I see that a lot of bits are available in both materials.

 

[AlexThePalex]

HSS and HW have very distinct properties. HSS is softer metal and HW is very hard metal. HW is a lot more expensive than HSS. As a result, HSS is often used as the shaft of a bit and HW is used for the cutter tips.

HSS is softer than HW, but HW's hardness makes it more brittle than HSS. This means if you use HSS for the cutting tip (which is done often in cheaper bits) it will dull quicker than HW. But on the other hand, if you use HW for the shaft of, lets say a drill or router bit, it can break quicker than HSS.

You'll find that in the cheaper DIY aimed drill and router bits, and saw blades, that they are made entirely out of HSS, while with pro grade bits, the shaft or blade are made from HSS and the cutting tips are welded on HW.

 

[peter halle]

Alex is so correct about the differences.  A confusing part is that in the North American Festool catalog, some of the bits that would to be carbide tipped by designed usage are not labeled HW.  That could just be some language or translational thing.  Or I am wondering if that designates some of the bits - like the dovetail bits - as being solid carbide versus carbide tipped.

Shane! 

 

[AlexThePalex]

Peter, you won't find solid carbide bits. They would cost a ton and would break too easily. This would make it uneconomical and dangerous. HW is really only used for the tips. Because of it's hardness it is very good in withstanding the wear and tear you get with cutting, but this hardness makes it brittle so that it is not good in withstanding the high forces a shaft has to endure.

In short, the cutter tip gets a lot of wear and tear to endure, but not such a big force because the contact area is small. The shaft on the other hand gets to endure a lot of force because it has to transport the torque of the motor to the wood.  

I think the difference you talk about in the catalog is purely cultural. In Europe we call it hard metal, HW or Widia, and Americans call it Carbide.

 

[Wood_Junkie]

Peter, you won't find solid carbide bits.

This is untrue.  Whiteside, in particular, makes a whole assorment of solid carbide bits.
(see left column)
http://www.whitesiderouterbits.com/catalog.html#catimgs

Almost all good quality manufacturers also make their spiral router bits from a solid bar of carbide.
This includes CMT, Amana, Freud, Onsrud, etc  and even MLCS, Woodcraft, etc.

 

[mastercabman]

Peter, you won't find solid carbide bits.

This is untrue.  Whiteside, in particular, makes a whole assorment of solid carbide bits.
(see left column)
http://www.whitesiderouterbits.com/catalog.html#catimgs

Almost all good quality manufacturers also make their spiral router bits from a solid bar of carbide.
This includes CMT, Amana, Freud, Onsrud, etc  and even MLCS, Woodcraft, etc.

That is correct!  Anytime you have a bit that is too small to have carbide tip,it is made out of solid carbide.

 

[AlexThePalex]

Alright, then I stand corrected.

But ...... now I'm gonna wonder if the carbide used in those bits you mention is of the same type of carbide as I'm talking about.

Because the HW metal used here for cutting tips is certainly not meant for shafts. If you put an all HW bit in a router that is gonna spin with 20.000 rpm it will simply break eventually. It is extremely hard, but just too brittle. Comes with the territory. If you want a shaft to survive the forces of a router it needs to have some flexibility and extremely hard metal doesn't have this flexibility. The HW I'm talking about, the HW I'm used to, doesn't have this.

And HW is very expensive. What makes a router bit or saw blade expensive is the HW metal in the cutting tips, and not the blade or shaft itself. If you were to make it completely out of the HW I'm talking about, and the HW Festool uses, I think you should be prepared to lay down 500 $ for one bit and 2000 $ for a saw blade.

Maybe in America 'carbide' entails a bigger group of metals than HW or Widia does over here and should not be used as synonyms. Because I'm starting to think the carbide in those bits on the site you linked to is not as hard and expensive as the wolfram or tungsten carbide used in Festool's router bits and saw blades.

 

[mastercabman]

Alex,you could be right.Maybe a different metal.Those small carbide bits that we have here are usually used on trimming laminate.I used to run a laminate shop and never had any breakage.
Most laminate trimmer spin at 25000-30000 rpm.

 

[Rob-GB]

Another factor that concerns the difference between the tungsten carbide tipped and solid HSS is the cutting angle they are ground to.
HSS can be ground to a more acute angle to give a sharper edge, this makes them good for routing solid timber were a cleaner finish is required. It was for this reason the inventor of the Woodrat would only sell HSS dovetail bits.
Due to the brittle nature of TC it needs more material to 'back up' the edge, thereby making the cut angle less acute. While they perform well in solid timber, particularly those like Iroko that may contain silica deposits, their hard wearing nature is suited to man made boards, melamine coated and laminated not forgetting solid surface materials.
Of course in most pro' workshops TC cutters are the norm, as there longer life span makes them cost effective.

I wish Festool would actually do complete translations and save some of the confusion, my biggest niggle is the "splitting wedge" it neither splits nor is it a wedge and is known in english as a riving knife and it's job is to prevent the kerf in the material closing up and pinching the blade  ;D but thats another topic [wink]

Rob.

 

[ajones]

hss cutters are a lot sharper and give a better finish but have a shortetr life. tct not as sharp but more durable especally  when used with man made boards which are very tough on cutters. some cnc machines use a tct cutter to rough out then a pass with a slightly larger hss for the superior finish.

 

[Nigel]

  I have a couple of solid cardbide bits.One is a half inch upcut spiral and heavy like lead.Never needed to sharpen it 4 years,cuts beautifully.I,ve some woodrat hss aswell.They cut cleanly when sharp.

 

[DavidCBaker]

Thanks for all the discussion, guys. Good information.

 

[fshanno]

I know of one interesting use for HSS in router bits.  Whiteside makes a family of HSS dovetail bits for the Woodrat people that have a very small diameter at the top or narrow end of the dovetail.  They they make a socket that will accept a needle pin, or almost needle pin.  It's one of the best looking machine cut dovetails I've seen.  I think you have to do a small bit of chisel work to finish the joint but no measuring or special skill is involved. 

You can make the tails for needle pins with a standard TCT bit in a Leigh jig but you have to cut the sockets by hand because those bits are too fat at the top.  I don't talk about it to anyone looking at my machine cut drawers but I would only do needle pins if I was cutting by hand, specifically because they don't look machine cut.  I often thought about getting a set of the Whiteside bits from Woodrat and seeing if I could adapt my Super18 to use them.

 

[Michael Kellough]

The softer the wood the sharper the cutting tool needed whether it's a router bit, knife, chisel, or saw. A dull cutter will crush and or burnish soft wood (not to mention burning). HSS will dull faster than carbide but you can successfully freshen up the cutting edges of HSS with a fine stone or diamond plate.

 

[greg mann]

There are various grades of carbide (HW) that are either tougher but less wear resistant or harder but more brittle. A good toolmaker will use different grades depending on the demands of the tool. A solid carbide bit, especially a small shanked tool, will need a slightly tougher grade selection to mitigate breakage. This will also make it less wear resistant but these are tradeoffs that exist in most all cutting tools.

Interestingly, The bit selection that Festool offers in its replaceable insert range solves some of these issues. Because the shanks are steel the body is tough and strong and because the inserts only need to do the cutting they can be especially wear resistant. In addition, since they are mechanically attached and not brazed on they are not subjected to other stress factors that would necessitate a softer grade of carbide, one that can withstand the brazing process without thermal cracking. Since the edge can be renewed by rotating the insert they soon become economical in use, and the shank should never wear out under normal use. These inserts are of the best wear resistant grades. The only drawback to these cutters is that they cannot be made in many configurations because of the necessity to have room for screws.