# How can you tell when a circular saw blade is getting blunt?



## RogerS (30 Nov 2006)

OK - I know the easy answer is 'when it stops cutting' but seriously how can one tell? Are there any visible signs on the teeth? Is there an edge that one can subjectively feel with a fingertip (stationary blade :wink: naturally).

I can see that it depends on what sort of material and thickness it's been cutting. But then I would have thought that that will only determine the rate of wear and so the original question still remains.

I can also see that if you're cutting the same material/same thickness day in/day out then you'd soon get the feel for it and know that it wasn't cutting as quickly/cleanly as it once did. But for those of us like me who (a) don't use it day in/day out and (b) even when we do use it, chances are the material is different etc. it seems more difficult to judge.


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## seaco (30 Nov 2006)

Hi Roger

That's a good question, I find that the lumber gets harder to push through the blade and 
as things get worse the blade will burn the wood sides as it cuts and when it's real bad the wood will smoke... never let it get this far as it will put undue strain on the saws motor ...


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## 9fingers (30 Nov 2006)

The first signs of a blade losing its edge will be seen from the cut. The wood will have an increasing number torn fibres as it starts to blunt. Burning normally happens as the blade gets very blunt and is associated more with the lack of side clearance as the blade loses a combination of set and side cutting ability.

hth

Bob


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## Steve Maskery (30 Nov 2006)

Hi Roger,



Roger Sinden":1bj85kbh said:


> OK - I know the easy answer is 'when it stops cutting' .



Well, quite!

If you are not experiencing problems, carry on as you are. It will be quite apparent when you need to change the blade.

I find that it's the feed rate that is the first give-away. Burning means it is well past its "sharpen-by" date. Sharpening isn't expensive, so my advice is, "If in doubt, get it sharpened".

OK, so it doesn't rhyme.


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## David C (30 Nov 2006)

If Tungsten examine the cutting edge with magnification.

Any feeling of having to force the timber is extremely dangerous, burning is also a bad sign.

David Charlesworth


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## wizer (30 Nov 2006)

Steve Maskery":2wbodxm0 said:


> Sharpening isn't expensive,



Isn't it?

I know we have had this debate before, but is blade sharpening really cost effective? Plus where do you get a blade sharpened?


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## aldel (30 Nov 2006)

I find that tungsten carbide teeth on a sawblade lose their edge very slowly and bluntness sort of creeps up on you. Replacing the blade with a newly sharpened one highlights the smooth and clean cutting action. Try to remember the sound and feel.

When you gently run your finger onto a sharp tungsten tip it "hooks" or catches your skin. A dull blade won't hook but still feel sharp-ish.

:shock: Be sensible of course!!!! No power plugged in and be very gentle or you will cut yourself. 

Cheap blades have smaller and lower quality carbide but still can be sharpened at least twice. Expensive blades will be seen to have much more carbide. It is far better to have them regularly resharpened than wait until it is obviously very blunt when the motor loads and the wood burns. A blunt blade is likely to get hot and warp.


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## scooby (30 Nov 2006)

WiZeR":qqx7w5te said:


> Steve Maskery":qqx7w5te said:
> 
> 
> > Sharpening isn't expensive,
> ...



I was pretty lucky whilst doing my apprenticeship as the company I worked for had a long standing account with a firm called Dentons aka 'The Saw Doctors'  So we could get all our saws sharpened for free. The majority of us had various Disston's but because it was free we'd send anything  On the odd occasion, we send hardpoint disposable saws which they would recut and sharpen. They didn't last long but were useful for taking old window frames out, etc.

Now I'm self employed, I only use hardpoint chuck aways. We still get table saw blades resharpened (usually at J&B) think it costs £10 or so.


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## Barry Burgess (30 Nov 2006)

Roger I visited a friend who had a 12" Sheppach TS and could not believe the saw wanted to stall even feeding the wood slowly. We tried 4 further blades that showed the same effect. Took his 5 blades and a 40 tooth one of mine that I thought was not as effective as a new 60 tooth. The saw guy said mine was 50/50 so I got it sharpened anyway. The 40 tooth cost £6 and a 106/108 tooth 12" cost £16.75 and the rest depended on the number of teeth. 
I will collect them from Southern Counties Saw Co tomorrow. 
I feel that putting on a new blade in is the yard stick as to how much the blade has deteriorated. 
Barry


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## ProShop (30 Nov 2006)

You can usually tell by the sound of the cut, that's my first indication that the blade wants sharpening.


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## Steve Maskery (30 Nov 2006)

WiZeR":3yil4rp9 said:


> Isn't it?
> 
> I know we have had this debate before, but is blade sharpening really cost effective? Plus where do you get a blade sharpened?



OK. How much is a new blade? That's not a rhetorical question, it's a long time since I've bought one. £20? But I pay £5-6 to have a 10" rip blade sharpened at my local (4 miles away) sharpening service. [I used to have one within walking distance, but the owner retired, the business closed and the building the business occupied (a Victorian Mill) is now transformed into bijoux apartments for the up-and-coming (as opposed to the likes of me who are down-and-going!).]

I have mine sharpened 2 or 3 times a year, so I don't consider that to be expensive.

Yes, if the East Midlands Saw and Tool Company go pop then I'm in trouble. I don't know where the next nearest service is.

I suspect that Yellow Pages, rather than Google, is your friend.


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## engineer one (1 Dec 2006)

silly question roger do you change blades for ripping and cross cutting on the saw.

reason i asked is having FINALLY built the wooden box under my dewalt 744. i cut some mfc for a re-organised cupboard from the wardrobes i 
took apart. then cause it was there i cut some old cr*p and the smell was
awful but i was ripping it on the same blade as i cross cut the mfc.

still cross cuts the mfc properly and cleanly so what do i know???

but in principal, we should change the blade for the different jobs shouldn't we??????

paul :wink:


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## RogerS (1 Dec 2006)

Good question, Paul. I do if I'm cutting MFC as I want as clean a cut as possible but if I was cutting MDF I'd probably use the same blade as I'd use for ripping off the waney edge on some oak...maybe that's wrong? Perhaps a coarser tooth blade would be better ..if available for the Festool TS55.

The original question is still valid and I appreciate the responses.


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## garywayne (1 Dec 2006)

What is MFC :?:


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## ike (1 Dec 2006)

Also, sometimes the blades cuts less efficiently when there's resin buildup on the sides of the teeth. I've found resin cleaner can help a bit.

cheers,

Ike


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## aldel (1 Dec 2006)

Most joinery workshops have a weekly visit from 'Saw Doctors'. 

Why not seek out the nearest one and ask if you could include your blade with their collection? A weekly turn-around, no delivery costs and trade charges. New and resharpened planer blades, router cutters, bandsaw blades made up etc

Worth a small inducement to the joinery owner. Get friendly and offer to take some of their plank ends and scrap wood away. They normally have to pay for it to be removed! They are very pleased to have scrap MDF taken away which always comes in useful for jigs etc.

Tis wot I do.


Aldel


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## engineer one (1 Dec 2006)

sorry gary, mfc melamine faced chipboard. or in other words old mfi wardrobes.
:lol: 
paul :wink:


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## garywayne (1 Dec 2006)

Cheers Paul.


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