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I snapped a tooth off my carbide saw blade. My fault or ?

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Forum topic by Dan posted 1235 days ago 2146 views 0 times favorited 19 replies Add to Favorites Watch
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Dan

3543 posts in 1486 days


1235 days ago

Yesterday I went to change blades on my table saw. I change and swap blades out pretty often and I have always done it the same way by wedging a piece of scrap wood against the blade. Well I went to change the blade yesterday and as I went to tighten the new blade in the saw I heard a small snap. The piece of wood that I was using to wedge or stop the blade actually snapped the carbide tip right off my blade. Now this happened as I was tightening the blade so I know what happened. The scrap piece was wedged at the back of the blade and the pressure I applied when tightening caused the wood to snap the tooth.

My question is whether or not this is my fault for poor placement of the scrap piece or was it due to a bad or faulty blade tip.

The main reason I ask this is because I actually just had this blade sharpened by a professional sharpening and carbide service place. When I brought it in to get it sharpened there were a couple of broken teeth to which they were able to replace for me. Part of me wonders if the replaced tooth is the one that snapped off. I have changed the blades so often and I have never had a tooth break before when using the wood block as a wedge.

The blade is also a Woodworker II so it is not a cheap made blade.

Has anyone had this happen before while changing a blade? Should the carbide tip of this blade snap off so easily? I also want to add I was not putting an extreme amount of pressure either. I always just tighten the blade in with a snug fit, I didn’t over tighten it.

I don’t want to bring the blade back to the service place and complain unless I am more sure that it was not my fault. If you guys think it was my fault then I wont bother complaining. I just want some input and or advice..

Thanks!

-- Dan - "Collector of Hand Planes"


19 replies so far

View Pop's profile

Pop

419 posts in 2552 days


#1 posted 1235 days ago

Saw blades are suppose to cut wood not be damaged by it. I think your guess about the broken tooth being the one that broke is a very good guess. I would take the blade back and have them check. If the other replaced tooth is not put on correctly it could come off during operation with a damaging or lethal result.

Pop

-- One who works with his hands is a laborer, his hands & head A craftsman, his hands, head & heart a artist

View GregD's profile

GregD

608 posts in 1742 days


#2 posted 1235 days ago

Bummer.

I think it was either a Forrest representative or the instructions that came with one of my WW II blades that recommended holding the blade with a rag in one hand while snugging the arbor nut with the other when reinstalling the blade. That method would pretty much eliminate the chance of messing up a tooth when putting the blade on, and it’s my understanding that you don’t need to put much torque on the nut because firing up the saw will tend to tighten it up anyway. As I recall, gripping the blade with a rag also worked OK for removing the nut. A short time after I got this advice I upgraded to a saw that has 2 wrenches and that was over a year ago so my memory is a bit fuzzy. But I seem to recall using my leather-palmed work gloves as the “rag” – a bit more substantial than the T-shirt material I typically use for rags.

-- Greg D.

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Greedo

465 posts in 1566 days


#3 posted 1235 days ago

did the carbide part came off entirely, or did a part broke off?
the weld is supposed to be tougher than the carbide, just like glue is supposed to be tougher than wood. so when a joint comes loose at the glued part, then it wasn’t done properly!
so if the carbide tooth came off entirely then i think it was not welded on properly.
now the tricky part is proving that tooth had been replaced or not.
modern european saws (maybe american aswell?) have a hole in the table in wich you insert a steel rod that completely blocks the arbor, so you can replace the blade fast and easy.

View ajosephg's profile

ajosephg

1840 posts in 2167 days


#4 posted 1235 days ago

First off, using a block of wood like you did, should not have caused a tooth to break off. Actually you were fortunate that it did, or else it would have let go when the blade was at speed and it could have greatly damaged you, or something else!

Secondly, you don’t need to be tightening the nut that tight. The method Greg described is good. I don’t even use a rag, I’m just careful to keep my fingers away from the sharp edges. The reverse threads on the arbor/nut will tighten the blade adequately when it is running, and you don’t have to worry about trying to loosen an excessively tight nut when it’s time to change blades again.

-- Joe

View wasmithee's profile

wasmithee

55 posts in 1299 days


#5 posted 1235 days ago

I use two wrenches with my Steel City table saw… never thought to use a rag or a block of wood.

I’d be glad that the tip broke off the way it did and not under high rpm… I think I might wear protective gear now when I approach my saw…

View Roger's profile

Roger

14177 posts in 1410 days


#6 posted 1235 days ago

Being that there is no way to tell if it was one of the teeth your sharpener replaced, I’d just take it back to him and let him fix it. If it wasn’t too long ago when you had it in there, maybe, if he’s a good guy, he’ll cut you some slack.
It sounds like you didn’t do anything wrong, sh__ happens. :)

-- Roger from KY. Work/Play/Travel Safe. Kentuk55@bellsouth.net

View knotscott's profile

knotscott

5374 posts in 1981 days


#7 posted 1235 days ago

It’s possible that you tightened too much. If you block the wood when tightening the teeth don’t have the benefit of the steel should to hold them in place…it’s strictly the binders against your pressure. I block the blade in the front when loosening but not in the back when tightening…it only needs to be snugged up a little, and shouldn’t be overtightened or you risk distorting the body of the blade.

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

View Bertha's profile

Bertha

12951 posts in 1299 days


#8 posted 1235 days ago

I’ve always hooked a very small dowel under the hook. I figure if I’m applying enough pressure to break a small dowel, then I’m applying too much pressure. I’ve seen tools at Lowe’s designed to grip the blade but it always seemed a bit silly. I bet Forrest would replace it at any rate.

-- My dad and I built a 65 chev pick up.I killed trannys in that thing for some reason-Hog

View Dan's profile

Dan

3543 posts in 1486 days


#9 posted 1235 days ago

Greedo – The whole tooth broke and it is actually still attached to the blade by just a thread of weld. My first thought was that it was a bad weld but I just wanted someone else to say it before I went in to ask the service place to replace it for me. The sharpening place I use has a good rep and I know many of the local woodworking factories use them to sharpen their blades. Even our local woodcraft store uses this place for their service and for the customers who bring there stuff to woodcraft to get it sharpened. I guess stuff like that just happens..

I also just called the place a few minuets ago and told them what happened. The guy said to just bring it in and they would take care of it free of charge.

Joe- I really don’t think I over tighten the nut at all. I just get it kind of snug but maybe what I think is kind of snug is too tight idk. I have used my hands before to hold the blade but I got poked a few times so I switched to wood block.

-- Dan - "Collector of Hand Planes"

View knotscott's profile

knotscott

5374 posts in 1981 days


#10 posted 1235 days ago

It’s definitely possible that there was a bed weld, and that you did nothing wrong, but since the whole tooth came dislodged, it’s also possible it was due to the pressure exerted on the back of the tooth, which is not where Forrest (or any blade manufacturer) really intended there to be much pressure. In my haste in my intial reply, I mistyped “shoulder” and erroneously typed “should”...I wanted to point out the when the blade is cutting, the teeth are supported heavily by the steel “shoulder” of the blade’s body, which is a very important structural component, along with the brazing. If you put pressure on the opposite side, there’s nothing but the brazing holding the tooth in place, which is asking a lot. One reason that carbide blades should never be run backwards.

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

View Sawkerf's profile

Sawkerf

1730 posts in 1674 days


#11 posted 1235 days ago

From your description, I would say that it’s on you. First, I think that you were trying to tighten the nut way more than you need to (I hold the blade with a rag and just make the nut snug. Anything more is overkill.)

You were applying all the tightening pressure on the back of the tooth and the brazing let go.

-- Adversity doesn't build character...................it reveals it.

View JasonWagner's profile

JasonWagner

523 posts in 1786 days


#12 posted 1235 days ago

Sorry to reiterate what others have said but I agree with the rag/towel method. I can hold the blade to take the nut off and barely torque it back on when installing a blade.

-- some day I hope to have enough clamps to need a clamp cart!

View rance's profile

rance

4126 posts in 1766 days


#13 posted 1235 days ago

Sounds like a product defect. Call them, but don’t be arrogant. First ask them how they suggest changing blades. Then ask about your current method. Ask if your method voids the warranty. Getting a tooth replaced at a good sharpening shop should not be a problem.

-- Backer boards, stop blocks, build oversized, and never buy a hand plane--

View kpo101's profile

kpo101

32 posts in 1235 days


#14 posted 1235 days ago

This is my virgin entry at LumberJocks and this blade thing really made me respond to this. The blade tip should not have come off with the pressure you can put unless its a 5’ cheater with a butt load of torque. The only time I use any thing to hold the blade is in the removal process. All of the table saws that I have used in the past have reverse threads on the shaft. Try this next time you install a new blade: 1) Put blade on shaft alone with the washer and the nut holding the blade with your fingers. 2) After hand tight wiggle blade with your fingers side to side (or left to right) to make sure the blade is seated and hand tight the nut again. 3) plug saw into the power and without the guard on, run for about 5 seconds and shut off. Done. The next time you have to remove the blade you WILL need the assistance of a piece of wood. The nut tightens itself as the saw is running.

-- When the problem becomes just too much, There is always the directions!! Karl O. of Louisiana

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dennis mitchell

3994 posts in 2920 days


#15 posted 1235 days ago

Not your fault. Period.

showing 1 through 15 of 19 replies

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