RS King BS Blade Broke into 2 Pieces

[Dick Mahany]

I Just had my Laguna Resaw King blade resharpened and had about 45 minutes of use on it when I heard a LOUD BANG! Scared the bejeepers out of me big time. I immediately shut the saw off to remove the blade and hoped it could be rewelded, but the blade was actually in 2 pieces. Apparently when it snapped, a tooth caught on the upper blade guard and caused the the blade to lift off the upper wheel and jam itself into the top of the upper housing. This left a separate broken piece about 30 " long and had a sharp kink in it.

I'm running a 3/4" x 105" blade on a Delta 14" saw and I believe I had the blade tensioned correctly. The saw seemed to be tracking perfectly and was producing beautiful cuts. Oddly enough, I was just trimming a pen blank of all things even though I had recently cut up a number of burls for turning. Any ideas on what could have caused this ? That blade was incredible but I'm afraid to buy another as it was pricey. Are the 14" wheels too small in diameter and causing work hardening of the blade stock? I don't know of a smaller blade such as a 1/2" blade that would have the same tooth form factor as the RS King. I have had pretty good luck with the Woodslicer, but prefer the carbide tipped blades.

Any suggestions would really be appreciated.

[David Kumm]

How old was the blade? They can develop hairline cracks behind the gullet and eventually go bang. Makes you never want your hands anywhere near the table. The Delta could not overtension although a spring fully compressed will not act as a shock absorber and speed the development of the cracks. I've broken several Trimasters but the RK uses a thinner band that should cope with the smaller wheels. Dave

[Dick Mahany]

The blade is about 3 years old and had probably been under full tension for no more than about 4 months total. I do have an aftermarket cobra coil tensioning spring, but didn't think the Delta could overtension that blade. I was just reading some old threads about the trimasters but figured that without the vari-pitch tooth spacing that they might not be the way to go.

[David Kumm]

Trimasters are too hard to tension for your saw so you made the right choice. Since the spring was not bottomed out did it break at the weld? If not it was just one of those things. Most breaks are welds that aren't quite right. Dave

[Nick Lazz]

I have had a laguna blade...or at least one I bought from them, break before. It was at the weld and it was not the RS King... however, you say the blade was under full tension for 4 months. Was that consecutive months or am I misunderstanding? I de-tension my blades everyday. Maybe that is overkill but I never leave it in the saw under full tension, unless of course the saw is in use.

For the record, I have not had good luck with the RS King anyway. I have the Laguna 14 SE and they sold me a 1" RS King...maybe my saw couldn't tension it but they said it could...anyhow I'm getting off subject, but I like the Wood Slicer.

[Dick Mahany]

Trimasters are too hard to tension for your saw so you made the right choice. Since the spring was not bottomed out did it break at the weld? If not it was just one of those things. Most breaks are welds that aren't quite right. Dave

Thanks Dave,

Neither break appeared to be at the weld. So, I'll just chalk it up to "one of those things" The real problem is going to the CFO and expalining to her why I need a new blade after she just received the resharpened package for me :o.

[Dick Mahany]

I have had a laguna blade...or at least one I bought from them, break before. It was at the weld and it was not the RS King... however, you say the blade was under full tension for 4 months. Was that consecutive months or am I misunderstanding? I de-tension my blades everyday. Maybe that is overkill but I never leave it in the saw under full tension, unless of course the saw is in use.

For the record, I have not had good luck with the RS King anyway. I have the Laguna 14 SE and they sold me a 1" RS King...maybe my saw couldn't tension it but they said it could...anyhow I'm getting off subject, but I like the Wood Slicer.

Nick Thanks,

Yes, I de-tension my blades also. Now I get to explain to the CFO why the Carter quick release I spent money on still didn't keep this one from breaking. :rolleyes:

[David Kumm]

Thanks Dave,

Neither break appeared to be at the weld. So, I'll just chalk it up to "one of those things" The real problem is going to the CFO and expalining to her why I need a new blade after she just received the resharpened package for me :o.

Tell her how happy you are it missed your fingers. She should be OK. I'm a CPA and we are not bad- just dull. Dave

[Mike Leung]

I have a 1" RK on my 14" saw. I have had it for over 6 years now and it was resharpened once. I just used it earlier today and its still cutting well. I also de-tension my blade after use whenever I remember to. You should give Torben a call and see what he can do since it was just in their hands recently for the sharpening. Thinking back now... Laguna did sell me an additional blade a few years ago and the band was thicker than the one I have so I returned it. I think the thinner band works well for smaller wheels like our saws. I'll measure my band thickness later and let you know.

[Dick Mahany]

I have a 1" RK on my 14" saw. I have had it for over 6 years now and it was resharpened once. I just used it earlier today and its still cutting well. I also de-tension my blade after use whenever I remember to. You should give Torben a call and see what he can do since it was just in their hands recently for the sharpening. Thinking back now... Laguna did sell me an additional blade a few years ago and the band was thicker than the one I have so I returned it. I think the thinner band works well for smaller wheels like our saws. I'll measure my band thickness later and let you know.

Thanks Mike,

My band measures 0.019" thick with tooth width 0.042" (after 1 sharpening). The weld is still perfectly in tact. You mention that you have a 1" wide blade on your 14" saw. I don't see how to do a 1" wide blade on mine and keep the gullets behind the teeth anywhere near the center of the wheel becasuse the guides would run out of travel..

[Mike Leung]

0.022" and 0.042" here
I didn't know they have a 0.019 band as well. It should be good for your saw.
I cannot see any hairline cracks on mine like I have on other blades for my 10" BS. Do you see hairline cracks anywhere?

[Mike Heidrick]

Will Laguna replace it. Seems kind of fishy so close to resharpen. Id let them send you a new one and try again.

Still a fairly small saw for that blade IMO.

[Dick Mahany]

Do you see hairline cracks anywhere?

Upon closer inspection under a magnifier, about 2/3 of the teeth have micro hairline cracks developing like this in the gullets. But still can't figure out what caused it with so little use.

254552

[Chris Fournier]

Your blade had tooth left but the actual band was worn out or fatigued, this happens on BS blades especially when they take a trip around a 7" radius. We rarely saw this type of failure with carbon or bi-metal blades because they were dull before they were fatigued.

BSing makes TSing look like a bargain when you look at the true cost of blades. I have TS blades that are sharp and serviceable that are 20 years old. If I have a BS blade that is old it is because it is a specialty blade that gets little use or because it has been forgotten on the blade rack amongst the others.

[Mike Leung]

Upon closer inspection under a magnifier, about 2/3 of the teeth have micro hairline cracks developing like this in the gullets. But still can't figure out what caused it with so little use.

254552

How does your blade sit on your wheels? The teeth on mine overhangs over the front edge of the wheels.

[David Kumm]

Upon closer inspection under a magnifier, about 2/3 of the teeth have micro hairline cracks developing like this in the gullets. But still can't figure out what caused it with so little use.

254552

That really seems like a lot. Surprised the sharpener didn't call you and tell you the blade wasn't worth fixing. Wonder if Laguna has changed their bands since then and if they will tell you if they did. Dave

[Dick Mahany]

How does your blade sit on your wheels? The teeth on mine overhangs over the front edge of the wheels.

On mine, I had it set so that the teeth were as close to the crown of the wheel as I could get. So the teeth were riding on the tire but did not touch the metal wheel rim.

[Mike Leung]

I think that is the problem. The design of these blades are different than standard blades. The gullet section cannot handle the strain you put on them riding near the crown. We put a tremendous amount of force tensioning a wide blade like this so the force needs to be applied on the solid part of the band. If you cannot have the blade overhang on your saw, I wouldn't recommend buying another RK. I agree with the statement about Laguna sharpening a blade with hairline cracks. They should have caught that and not have sharpened. Its so dangerous to use a blade with cracks as you have just experienced. Thank God your hand was not near it when it happened.

[Chris Fournier]

Where those cracks propagate from are stress risers as they would say in the metal working world! The failure by the tooth in the centre is CLASSIC and in my opinion was partially caused by the actions of the sharpener. Look at how the gullet shape has been ground into in plane with the bottom of the tooth, the result being a sharp corner not a more gentle arc like the same location in the gullet to the right. Sharp corners are a serious no no when it comes to avoiding stress risers. Check out all of your gullets and see how many of the cracks start at an "over grinding" location as I have pointed out.

I'm no expert in the metal world but I've played there long enough to have seen this before.

[David Kumm]

I think that saw can not tension enough to cause the problem but those teeth brazed on to a thin band and then curved around the small wheels and then stressed with cutting can really fatigue it. I've also found that running the band against the back bearing heats it up and accelerates the wear as well. Since I began tensioning enough to keep the blade from contacting the guides I've increased their lives a lot. Dave

[Ronald Blue]

The blade should only touch the back roller when cutting. When there is no load against the blade there should be no contact.

[Andrew Joiner]

Where those cracks propagate from are stress risers as they would say in the metal working world! The failure by the tooth in the centre is CLASSIC and in my opinion was partially caused by the actions of the sharpener. Look at how the gullet shape has been ground into in plane with the bottom of the tooth, the result being a sharp corner not a more gentle arc like the same location in the gullet to the right. Sharp corners are a serious no no when it comes to avoiding stress risers. Check out all of your gullets and see how many of the cracks start at an "over grinding" location as I have pointed out.

I'm no expert in the metal world but I've played there long enough to have seen this before.
Exactly my thoughts as well Chris. The cracks started at the spots where the grinding wheel overshot the mark. Show Laguna the photo, they were good to me on a similar problem.

[John Coloccia]

Exactly my thoughts as well Chris. The cracks started at the spots where the grinding wheel overshot the mark. Show Laguna the photo, they were good to me on a similar problem.

Ditto you guys. Exactly and precisely my first thought. That particular crack, at least, is almost certainly caused by the bad grinding. You could hardly do better if you where trying to crack it. The gullets on either side look awful too. Does the entire blade look like that??

[Dick Mahany]

I really appreciate all your helpful insights on this so thank you all very much!

My guides are only in near contact and don't touch the blade when it isn't cutting, including the thrust bearings, so I don't think it was from heat. Many of the gullets on the entire blade have that profile and also have similar cracks. I did send a note and the photo to Laguna asking for their help. Laguna did the sharpening and the blade cut as good, or better than new. They also turned it around in only a few days. I am surprised that if they had noticed the cracks during sharpening, why they didn't contact me. I'll see if they can help.

[Howard Acheson]

Keep in mind that a 14" band saw should not be used with a blade wider than 1/2". That is Delta's and most manufacturer's recommendation.

[David Kumm]

I agree that bearing heat did not cause this problem. I just believe that if you have a saw that will do it you are better to tension so as not to use the back bearing with a wide resaw blade. They are so expensive every precaution you can take to make it last is good. I don't think Lenox recommends sharpening their Trimaster blades. I wonder if what we see here is the reason. Dave

[Chris Fournier]

Keep in mind that a 14" band saw should not be used with a blade wider than 1/2". That is Delta's and most manufacturer's recommendation.

That may well be their recommendation Howard but I used a 3/4" blade on my Delta 14 with a riser block and without it I could not have cut the widths of exotics that I needed to for mnusical instruments. I did feel sorry for the machine when we were on the ragged edge together. It never complained or skipped a beat though. That was a good saw.

[Dick Mahany]

Keep in mind that a 14" band saw should not be used with a blade wider than 1/2". That is Delta's and most manufacturer's recommendation.


Howie,

Thanks for the reply, and I also thought 3/4 inch was possibly too wide, but my Delta manual (28-280) p.11, expressly states "Always use the widest blade possible................For cutting wood..........we can supply them in widths of 1/8.......3/4 inches". My saw has a 1hp motor and that 3/4 blade, while seemingly large, worked wonders on that saw which I bought in 1998! Go figure:confused:.

[Chris Fournier]

If you look at the blade tensioning mechanism on a Delta 14" saw (the model I had anyways) it clearly has a tension setting for 3/4" on it - cast in the mechanism.

[Morey St. Denis]

Strikes me that the radius and sweep of that gullet does not quite appear uniform, especially where this particular crack formed. To my eye, the shape of those gullets looks considerably rougher and more irregular than usual. Cannot tell from that side angle of your image, but does the recently reground surface extend down into the gullet, potentially altering the profile? Microscopic scratches or minute digs to an otherwise smooth profile will cause tremedous stress concentration to that locale. Any possiblity that the grinder may have reshaped a small portion of the gullets? You may want to pursue this notion a bit futher with the manufacturer or firm who did the recent resharpening...

[Erik Loza]

....the grinder may have reshaped a small portion of the gullets?... That is EXACTLY what it looks like to me. Never seen new blade stock with gullets which look that rough. Cannot see how it is anything other than caused by the re-sharpener. Hopefully, they will get you taken care of for this.

Erik Loza
Minimax USA

[John Coloccia]

That is EXACTLY what it looks like to me. Never seen new blade stock with gullets which look that rough. Cannot see how it is anything other than caused by the re-sharpener. Hopefully, they will get you taken care of for this.

Erik Loza
Minimax USA

You know, after I saw that picture I ran downstairs and checked my own blade. It almost looks like it's stamped but it's nothing like that picture.

[Mike Wilkins]

When I had a Delta 14" BS I used the Highland Wood Slicer with great success. I think running a 3/4" blade on a 14" BS is too much, but the bandsaw 'experts' would probably dissagree. You could research a back issue of Fine Woodworking for an article by Michael Fortune on bandsaw tips. I believe he only uses a 1/2" blade on his BS with great results.

[John Coloccia]

When I had a Delta 14" BS I used the Highland Wood Slicer with great success. I think running a 3/4" blade on a 14" BS is too much, but the bandsaw 'experts' would probably dissagree. You could research a back issue of Fine Woodworking for an article by Michael Fortune on bandsaw tips. I believe he only uses a 1/2" blade on his BS with great results.

The ResawKing has a very thin backer. It's not quite like a Woodslicer, but almost. Either way, it won't contribute to any breakage. A thick blade with small wheels can cause problems, but not a wide blade.

[Dick Mahany]

UPDATE 2/18/2013

Laguna tools was quick to answer my email and said the cracks are classic signs from overtightening / over feeding ( of which I don't believe I really had either), but since the failure was so closed to the resharpening, they offered me a substantial discount on a replacement bade. I believe it was a fair solution. They also recommended to release the tension when ever the blade was not being used even if it was 30 minutes or longer just to be safe. I explained that I never tensioned it beyond the 3/4 mark that is cast into the tensioner. From the image I sent them, they agreed that fracturing caused by guide contact or heat was not existent, but didn't have a lot more they could say.

So in all, I'm pleased with their response, but will keep a watchful eye (and magnifier ) on this one. Thanks again for all of the suggestions.

[Andrew Joiner]

Upon closer inspection under a magnifier, about 2/3 of the teeth have micro hairline cracks developing like this in the gullets. But still can't figure out what caused it with so little use.

254552

Dick, I just looked at 2 of my resawkings that have never been resharpened. The gullets are uniform. Before have them resharpened by Laguna I'll send your picture in and ask if they can sharpen without this problem.

[Alan Schwabacher]

If you look at the image, one of the two gullets has a pretty sharp curve ground into it, and the other does not. The one ground sharply has the crack, and the gentler curved gullet looks fine. If you look over your blade and all the cracks originate from the more sharply curved gullets, that would indicate that the problem definitely was caused by the sharpener, who ground in those sharper curves.

[John Coloccia]

UPDATE 2/18/2013

Laguna tools was quick to answer my email and said the cracks are classic signs from overtightening / over feeding ( of which I don't believe I really had either)

On your little 14" Delta? Oh, come on. ROFL. I'm mildy impressed that you can tension it properly to begin with...must be a good saw...but over tension it?

Glad they're getting you a new blade a good discount, though. That's very fair. You've gotten a lot of use out of that blade...just not the entire life you paid for.