# How long do bits last?



## Blooch58 (Jan 1, 2014)

As the title lists, how long do , in this discussion, carbide bits last? Is effective to have the smaller bits resharpened or just replace them?

I guess this would be figured in feet of board routed and dependent on type of board by hardness.


----------



## jw2170 (Jan 24, 2008)

Blooch58 said:


> As the title lists, how long do , in this discussion, carbide bits last? Is effective to have the smaller bits resharpened or just replace them?
> 
> _I guess this would be figured in feet of board routed and dependent on type of board by hardness_.


I guess you answered your own question, That is what I would have said.

Mine don't seem to wear out as I am a hobby user. 

Carbide cutters last longer than HSS cutters and most can be resharpened.

Is it cost effective? This also depends on 1) original cost. 2) cost of sharpening 3) are they quality cutters or cheap cutters 4) Do you have to send them away 5) how often do you use that cutter 6) professional user or hobbyist?

Just MHO....


----------



## JOAT (Apr 9, 2010)

Depends. I had a bit that lasted me for years. And not too long ago bought four new ones, to use doing the same thing I used the old bit for. Of the four bits, I had three self-destruct in 30 seconds or less each. I changed brand, and have had no issues since. But usually more along the lines of what James said.


----------



## wbrisett (Feb 12, 2011)

In Fine Woodworking #191 they did a "torture test". It was interesting because some of the bits made the same way did well while others didn't fare so well. You can read about it here: 

http://www.whitesiderouterbits.com/ToolTestRouterBits.pdf

I wonder if the folks doing the router bit test here will discuss this in their results on the bits (how the bits wore after some use). 

Wayne


----------



## neville9999 (Jul 22, 2010)

Mark, the thing about router bits, don't cut to hard, don't cut to deep, if your router has speed control then slow them down a bit if they cut OK slower, keep the waste out of the trench as this stops the cutter getting hot and heat is a cutter killer, clean them when they get crap all over them, buy good quality cutters, they are more expensive but they have better and thicker carbide, and if you buy good quality cutters then get them sharpened when they need it as they will come back like new and work like new, are you seeing my train of thought? Buy cheap cutters and treat them like you don't care and they will break, OH and stuff does happen, good cutters do break but follow these rules and they don't break that often, I have not broken one for years. Neville


----------



## paduke (Mar 28, 2010)

The bit test article confirmed my own conclusions. I buy Eagle online and Whiteside at my local Woodcraft Store.


----------



## Blooch58 (Jan 1, 2014)

What's the worst material , in respect to wear or router bits? Laminate? 

I finished some laminate gunstocks that were fully inlet tend but rough finished. Wow, talk about tough.


----------



## Quillman (Aug 16, 2010)

Cutter wear is quite dependent on how you use the tool and the material your're cutting.
To be sure, in wood, wear lines show up in <300'.
And at 20'/min that is not long.
For precision work (joinery) your stuff may not fit together if the wear lines are pronounced.
But that cutter could still go on wasting MDF, e.g. for hours!
Some figures of merit.


----------



## Blooch58 (Jan 1, 2014)

I think I understand why duplicated gunstocks I buy are so rough. By the time you run a small bit all over the outside of a one piece rifle stock, the bit is long past it's sharpest.


----------



## Tom King (Jan 22, 2014)

paduke said:


> The bit test article confirmed my own conclusions. I buy Eagle online and Whiteside at my local Woodcraft Store.


Whiteside makes the better quality Eagle bits.

We get about 4 hours out of one before it needs sharpening. A year or so ago, we had to mill 3/4" off of a couple of hundred square feet of old Heart Pine flooring. Dirt played a roll too, but I'm guessing we got about half a day out of one before we had to send it back for sharpening. I kept a bit going back to Whiteside, and one coming throughout that whole job.

I was surprised that we didn't burn up a router, or at least a set of bearings, but the 20 year old 7539 is still going strong, and recently was put back to work under a table to cut faces on window muntins, and did a flawless job.

I'll be able to post pictures from my website once my post count gets to 10. Try now. Look on my "Woodwork" page: www.HistoricHousePreservation.com


----------



## Joey Jarrard (Feb 14, 2014)

It is all about the chip load. I have a good chip load calculator in excel format. I can not load it here as this forum does not allow this type file. But if anyone wants it they can email me at info @ routerboyz.com and I will email it to you.

with a good chip load you remove heat from the bits. The bits staying cool will keep the edge sharp and make the life of the tool last a whole lot longer. 

I think of the chip load as a triangle. It has 3 sides or components that change it.

RPM of the bit
Feed rate 
Number of flutes

If you change any of these factors the chip load will change. Most people tend to slow the bit down or the feed rate down when they have a poor cut quality. This is a misconception. In fact you more than likely need to speed the machine feed rate up or slow down the rpm. You want the bit to take more of a bite. This will transfer the heat of the friction to the chip and then remove it.

If I can help anyone just let me know.


----------



## subtleaccents (Nov 5, 2011)

As mentioned, feed and spindle speed are the governing factors to the life of any cutting edge. The grade of carbide as well as the type of material you are cutting will also dictate life expectancy.

I use to cut many lineal feet of solid surface (Corian etc) and that type of material is extremely abrasive to router bits and saw blades. I helped many guys by slowing the spindle speed they used and increased their cut feed rate to reduce the heat build up.

One of my biggest problems was finding a sharpening shop that would do a final clean up with atleast a 600 stone in the harpening process. I could get as many as 4 resharpenings out of one bit so long as I didn't chip it. Many shops used only a 200 stone and give you the cutter back. These would last less than 10 lineal feet of cutting before they were dull again. It was all about how fast they could get the product out the door and how much they could make in the least amount of time.

I have had good luck with Onsurd bits for my CNC router and when it comes to the hand routers I had very little problems with CMT, Whiteside, Bosch and Amana.


----------



## Mike (Nov 22, 2004)

We have had no reported bit failures in the bit test. Keep in mind that these bits are being tested by typical home users and not tortured in a failure test.


----------



## MAFoElffen (Jun 8, 2012)

I go along the lines of Pat. Bits seem to last me a while longer than others I've worked with. But I watched how it was cutting, my feed rate and the depth of cut.

Heat buildup really kills an edge. Good extraction helps keep waste away, which in turn helps keep the bit cooler. If I have a problem keeping heat down, then I coat the bit with Hylo Cool. And if you use a little wax (like I use those wax sticks for double cutters), then it helps lube the cutters and keep things from sticking to the cutter.

If you keep the bit clean, without residue, they don't seem to retain as much heat and stay sharper longer.

After use, if you use a good diamond hone on them to touch them up... they stay sharp and last longer.

Like was mentioned, if you use an appropriate speed for the bit size and material...

And yes, laminations and MDF wear a cutter's edge faster than normal, real wood. Besides the paper fibers in MDF... the glue has a lot to do with that. It sticks to the bit, retains heat and if it sticks near the cutting edge (as it does), then it doesn't cut as well. Things go downhill fast if you don't catch that.

Same things seem to hold true for shaper cutters, molding cutters and saw blades. I think the most important is to watch the cutting surface, feel for any change in how it cuts and keep cutters clean.


----------



## Quillman (Aug 16, 2010)

One other strategy if'n top quality cuttings are paramount.
Do 90+% of the cut with router A using the next smaller cutter.
Then with router B use the finish cutter, to net depth, taking the last 10% of the cut.
The cutter in router B will yield up to 4+x its life if used singly.
Can also be done with 2 routers and 2 different diameter collars, albeit close in O.D.


----------

