Broken tooth

[LCHIEN]

I think I found the bent tooth. 0.015 above the others. I found another tooth .003" high.
Most of the teeth were within +/-0.0015 above the others surrounding it.

Bent tooth.



Typical good tooth


would it be hard to break that tooth off completely at the brazing?
Can I use diamond files to take a few thou off a tungsten carbide tooth?

I've never considered grinding on TC before,

I think that's the only one on this side. I found it by running my finger lightly on the carbide edges and finding one that seemed higher than the others, and checking with the dial gauge. I don't want to have to measure all one hundred tips tho.

Essentially this blade is trash otherwise unusable so some experimenting might be in order if its only the one tooth causing distress.

[capncarl]

If you just want to see what happens, put a piece of cardboard on the saw top and raise the blade through it. Now you can grind on the blade without getting grindings down in the saw guts. A couple of swipes with a 5” grinder should knock off the .15 . If you have a soft metal polishing disk thats better. I bet you will be surprised with the results.

What did you learn from this experience? Just because they say you can cut metal on a table saw doesn’t mean it’s a good idea. This woodworking stuff is just too light duty!

The first time I saw a demonstration of a metal cutting blade in a cheap Skil circular saw, they announced they would be cutting 1/4” steel plate. Every one in my group ran! Nobody got hurt! It turned out to be a great blade, I bought 3 so I would get a free saw and sold 2 blades to co workers!
Alternately, I’ve seen a few attempts of cutting metal with woodworking saws end miserably!

[capncarl]

It’s funny that this discussion on saw blade teeth has drawn in Ads for toothpaste and tooth pain

[LCHIEN]

I learned don't use your good HiATB blade to cut even just one piece of aluminum. Don't be lazy! Change to a more suitable blade like the one that came with the saw or one made for cutting non-ferrous metals.

[LCHIEN]

It's not a radial error, its a lateral error the tooth protrudes 0.015" from the side as it cuts. 0.015 high in my view when I lay the blade on the side and use a dial indicator.

[LCHIEN]

I was refunded the amount without a question by Ace Hardware without them checking with the sharpening service. The cashier wanted to keep my blade but the clerk told her no.

I spent 35 minutes cajoling two teeth, one .003" out and the other .015" out of alignment

Before:



So it wouldn't move around, I Clamped it to the bench supported with a can up to the edge where the tooth met the plate so it would bend there and I bent them with long nose pliers just to the side of the carbide tip (to avoid cracking it) and with a skinny block of wood and a mallet positioned over the one tooth I was working on.





After:



Got them to 0.000 and -0.0005 so that's pretty good. All the other teeth I checked measured between +/-0.0015" (1.5 mils) on the good cutting side of the blade. Used "calibrated" efforts so it went a few mils at a time.

The kids are knocking at the door for trick or treat.... Have to test it later tonight when the vampires and ghouls are gone.

[dbhost]

Here is wishing you the greatest of success with your testing!

[Black walnut]

It seems to me that you have more time invested in this than the blade is worth. Curious to see how good it cuts now.

[capncarl]

They say that we learn from our mistakes. Lchien, is a smart man, he must have made a lot of mistakes,

[LCHIEN]

Yes Capncarl. I have certainly made my share of mistakes.

[twistsol]

I should be a lot smarter than I am then.

[LCHIEN]

I declare success. This blade is now usable as a backup blade.

Before:


After bending teeth straight:


I think I fixed the cut smoothness. There is still a bit of tearout on the backside that my new blade does not do. In the end, this blade has one broken tooth ground off, has been sharpened, and the shop found and straightened or ground down one or more teeth bent to the left, and I straightened 2 teeth that were bent to the right.


I am not sure what you can do to make the rehabbed blade cut as well as the new regarding tearout... I went through three other quality brand blades before finding this Diablo that has minimal if any tearout on the backside when new.

[LCHIEN]

You know, after a few days messing with this blade, I could find the two bent teeth blindfolded... I could feel the 3 mil and 15 mil deviation running my fingertip along the side of the teeth. One direction hurt where you were encountering the sharp edge but the other way was not painful.

[dbhost]

That is a lot of effort for a damaged saw blade... I know tinkering is part of the fun... I actually transferred the Diablo 80 from my Chicago Electric to the Metabo HPT when I got it, I have a brand new blade at the ready but the old Diably still runs fine, gives nice clean cuts with very little to no tear out. I am curious what caused your blade damage in the first place... Was there metal in a piece you were cutting, or something like that?

[LCHIEN]

That is a lot of effort for a damaged saw blade... I know tinkering is part of the fun... I actually transferred the Diablo 80 from my Chicago Electric to the Metabo HPT when I got it, I have a brand new blade at the ready but the old Diably still runs fine, gives nice clean cuts with very little to no tear out. I am curious what caused your blade damage in the first place... Was there metal in a piece you were cutting, or something like that?

Sometimes its a challenge to try and fix things. And a big thrill to have success.

As to what happened, I am not 100% sure. I do cut a number of old reclaimed 4x4 fence posts for various projects - they tend to have nails in them. I usually scan for nails but I have been known to miss them.

On this blade Either I hit a nail on a board or else I damaged it making a cut on an aluminum bar extrusion 1-1/8" x 1/8" thick. I think it was probably the aluminum which in retrospect using a HiATB to cut was not the best choice but I was lazy and it was just "one" cut. I should have switched to a TCG blade or the cheapo one that came with the saw. That said, it was cutting poorly at a later time and on inspection I found a broken carbide tip.

I figured the carbide tip had a spur causing the rough cut, but also found 49 teeth (not 50?) away a tip leaning .009 mils to the left. Presumably by the same event but I don't understand why it was almost halfway around and why it came to be bent.

I contacted the Shop that does the work and asked - he said for $29 bucks they would sharpen the blade and if they found any broken tips they would grind them out of the way and for any slightly bent tips they would grind it in line with the other tips.

When I got it back it cut horribly so I called them and they said to send it back

When I got it back the second time it cut horribly on the right but OK on the left... When I called I talked to the foreman who is the father of the owner and the grandfather of the guy who does the sharpening. Obviously a family business. He said they are a sharpening business and not a repair business when I pointed out it was halfway OK but I detected 2 bent teeth on the right.

So he offered to refund my money because he didn't want to spend more time on it. I figured I would either toss the blade or try to bend the offending teeth back.

I guess he didn't have to refund my money; I did not realize the blade was so badly damaged with at least three bent teeth and one broken tooth.

So what did I learn:

• should use a proper blade for aluminum extrusions; it can be cut but a HiATB is a bad choice (see posts in this thread)
• Probably not going to use this shop again, that was part of my reason for trying to fix this blade. When my Forrest blade needs sharpening, I am going to send it to Forrest. This shop removed all the antistick red coating from the teeth area, and scrubbed off all the blade labeling. The blade looks like crap and I like to keep my stuff looking nice.
• If I buy another blade maybe think about a full kerf; this one was a thin kerf and I was able to bend the teeth; a thicker plate might have survived.
• I was just able to bend the teeth; I figured it would be more difficult. Working hard I got 1-2 or 3 mils per attempt.

[dbhost]

Yeah, I am too cheap to buy Forrest blades. I get the challenge trying to fix things... Glad it worked out for you. Sorry they kind of did you dirty... They took it in knowing the issues and promsing to repair it, then trying to back out seems kind of lousy...

[LCHIEN]

Ah, well, The blade was more damaged that I thought. Maybe they overpromised but the blade was damaged. In the end they refunded my money voluntarily, so I don't really feel like I was mistreated.

I feel like they didn't check for more bent teeth even though I told them in a note it cut badly on both sides. In the end it took little work to identify two teeth to fix; For them it should have taken almost no time but they didn't on two possessions. They simply didn't want to do a third. I guess they thought it was already too much effort. Or maybe they are not as good as they could be.

I really in the end don't know how the teeth got to be bent. I could see the chipped teeth but not three bent teeth.

[dbhost]

I've only ever done something similar once, to a Diablo circ saw blade. I was levelling up fence posts and apparently there was a nail in a brand new PT 4x4 from Home Depot... Scared the fertilizer out of me for sure.

[LCHIEN]

So anyway after doing something bad to this blade I have a sharp blade, cuts almost like new but with a teensy bit of tearout at the back on my miter saw. I ended up spending nothing but a fair amount of time measuring, complaining then working on it my self over four weeks.



I do have a new blade I bought when this first went south so I basically have a spare for that cost.

[dbhost]

The question really is, would you do it again? Pretty sure the answer is yes, just for the fun of tinkering with it, but I cannot really answer that for you...

[LCHIEN]

At the time I was aware I broke a tooth when the cut went horrible. But I wasn't aware of the other damage. So it was a learning experience you are paying for.
Yeah, I might do it again. I now know thin kerf blades can easily have a tooth(s) bend and you can usually measure and un bend it.
I suspect if I'd just located and unbent the teeth I could have had that blade back in operation in a couple of hours instead of taking 4 weeks and two trips to the sharpeners.

[capncarl]

It’s not the place or time to mention the Harbor Freight saw blade sharpener, but in a case like this, and a bunch of fretting with the sharpener you possibly could have the blade cutting nearly new. I’ve tuned up all of my stack of blades a couple of times, and no it’s not a professional quality machine, but it spins a diamond cutter blade the same way.