Chestnut

Another Broken Bandsaw Blade

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Last night my resaw king blade broke after 5 months out of the last 8 of use. This is my 3rd broken Resaw King blade. I've had a lot of blades brake on my saw and I'm starting to wonder, Am I the problem here? How many times do you get blades to break on your bandsaw?

I set the blade tension with the flutter method and it usually corresponds with the lower limit for the blade size on the gauge on the saw (14BX). I typically set the blade towards the back side of the wheel similar to how Snodgrass suggests. I set the guides so they are a hairs width from touching the blade and set the thrust blocks so there is a tiny gap as well. I almost always release the tension on the blade when i'm not using the saw.

I can't keep spending $150 on a bandsaw blade every 9 months. Last night after it broke i need to make a rip cut and felt slightly lost. I glanced over at my table saw with an uneasy look and grabbed a 1/4" 6tpi blade to finish what i was working on. The cut quality was terrible and i'd have had less waste if i used the table saw with an 1/8" blade, but I've found i just like using the band saw for rip cuts a heck of a lot more.

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I have the same saw you have (and have had it about 2 years I think) and have never broken a blade.  I use Timberwolfs mostly and a woodslicer, so I would think my blades would be more likely to break, but I am not sure.  I dont' get into the shop as much as I'd like so it doesn't have a ton of hours on it, but a decent number.

 

I have trusted the saw's tension gauge and it seems ght to me, but never checked it against anything more than the finger pressure test.  Sorry to hear about the broken blades and I hope someone can figure out what is going on!  I certainly have toyed with the idea of a carbide blade like yours.

 

I do take the tension off the blade when not in use, but have read that you don't really need to do that if you aren't over tensioning the blade.  I figure it can't hurt so I do it anyway.

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1 hour ago, Chestnut said:

Last night my resaw king blade broke after 5 months out of the last 8 of use. This is my 3rd broken Resaw King blade. I've had a lot of blades brake on my saw and I'm starting to wonder, Am I the problem here? How many times do you get blades to break on your bandsaw?

I set the blade tension with the flutter method and it usually corresponds with the lower limit for the blade size on the gauge on the saw (14BX). I typically set the blade towards the back side of the wheel similar to how Snodgrass suggests. I set the guides so they are a hairs width from touching the blade and set the thrust blocks so there is a tiny gap as well. I almost always release the tension on the blade when i'm not using the saw.

I can't keep spending $150 on a bandsaw blade every 9 months. Last night after it broke i need to make a rip cut and felt slightly lost. I glanced over at my table saw with an uneasy look and grabbed a 1/4" 6tpi blade to finish what i was working on. The cut quality was terrible and i'd have had less waste if i used the table saw with an 1/8" blade, but I've found i just like using the band saw for rip cuts a heck of a lot more.

Nut, there's a Carter bandsaw setup video on youtube,  It's well worth checking out. They explain that if you go by the indicator on the saw for your tension, it could be either to tight or to loose. There's a better way to set the tension, and Mr. Snodgrass explains it.  It might be helpful to check out.

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First, I assume the blades are not breaking at the weld, if they are this is a different discussion (faulty weld).  

I rarely break a blade on any of my saws, when I do usually the cause is clear (the blade is dull and at the end of its life, hit something foreign in the cut, overstressing a small blade etc).  

While it may be counterintuitive low tension has caused more blade failures than over tension on wood saws. Most wood cutting bandsaws can't provide enough tension to snap a blade.  Under tension increases the stress both side to side and front to back on the blade.  Blades are very good at handling strain, not so good with side loads that produce twisting.   Not sure which width of RK you have but just assuming it is a 3/4" it will need every bit of tension a 14BX can put on it and likely not be at optimum.  The RK and other carbide bandsaw blades like between 28,000 and 30,000 psi to be at their best.  This is just one area where the Snodgrass method can and will fail you.  The Snodgrass method (and all the flutter/finger deflection etc) is a seat of the pants approach and not very repeatable, it works in most situations but is unlikely to ever get the blade optimized.  One of the big issues with these methods is they do not take into account the type of blade.  A carbide or bi-metal blade requires roughly twice the tension that a carbon or spring steel blade requires.  So the amount of deflection will vary significantly on a carbide vs carbon blade of the same gauge and width when each is set at the recommended tension.   While it certainly could be other factors, I am confident your tension is low for that blade and it could be a contributing factor to the breakage. 

I have cut 18"+ veneer in tropicals with a 1" RK on my MM24 using a power feeder for more than an hour straight on numerous occasions, that particular blade has already been resharpened 3 times so it has seen some wood, I run it at 30k psi.  While I certainly can't say under tension is the cause, it can be the root cause of blade breakage and I am confident you are well below optimal for a carbide blade when running at the lower end of the size indication on the saw scale for the width.  

By the way, I assume it broke in a gullet, have you checked the other gullets for fatigue cracks?  If you have fatigue cracks in the gullets it is another discussion.  There have been reports of early fatigue on RKs, it is rare but it has been mentioned.

 

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10 minutes ago, RichardA said:

Nut, there's a Carter bandsaw setup video on youtube,  It's well worth checking out. They explain that if you go by the indicator on the saw for your tension, it could be either to tight or to loose. There's a better way to set the tension, and Mr. Snodgrass explains it.  It might be helpful to check out.

He mentioned he was using the Snodgrass "tap method" for tensioning.  

I know tension is a contentious issue and most authors and video creators tend to make it as simple as possible since the vast majority of people do not own nor will they pay for a proper strain gauge (I also know Duginske's opinion on strain gauges).  Basically, all of the simple methods oversimplify the issue and most result in very low tension especially on bi-metal and carbide blades.  A bandsaw will do a reasonable job even with the blade under tensioned this is why these methods persist, along with being simple and no-cost.  Strain can be measured using a caliper and Matthias Wandell has a good setup on his site.  I always see this part of bandsaw tension as analogous to car tires.  You can get from point A to point B with 15 psi in the tire on your Camry but the quality of the ride/handling and the longevity of the tire is not optimal, it is the exact same way with a bandsaw blade with less than optimal tension, it will wear faster and not produce the cut quality it is capable of.   

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I was in the process of rushing  [something to do with life]  I didn't take the time to read the full post. Just threw out a possible answer to his problem.  I stand chastised.

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5 minutes ago, RichardA said:

I was in the process of rushing  [something to do with life]  I didn't take the time to read the full post. Just threw out a possible answer to his problem.  I stand chastised.

Rick no worries, i appreciate the time you took to reply.

 

11 minutes ago, HuxleyWood said:

He mentioned he was using the Snodgrass "tap method" for tensioning.  

Flutter method is what i used initially and reading your other post has me thinking long and hard about increasing the tension. I think the  time invested to make a tension gauge might be worth it. How would a person be able to tell the difference between an under tension break and an over tension break.

20 minutes ago, Tom King said:

What width blade?

3/4" i think it's a 0.025" backing.

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20 minutes ago, HuxleyWood said:

The RK has a .6mm backer, .025" is close enough for "govment" work.  

Typo meant to hit 0.024, also depends on what government work. I'm doing some government work where ~5' is good enough.

26 minutes ago, HuxleyWood said:

However, the majority of people run resaw blade widths/thicknesses that actually are near or above the tension limit of their saws because they always see "wider is better". 

I don't WANT 3/4" that's just was readily available. I have now changed and am going to go with a 1/2" Lenox Tri-master. When i get it in I'm not going to use it until i make some sort of tension gauge. I'm going to take some pictures of the blade tonight and I'll post them i'd be interested in your opinion. I'm not blaming Laguna for this at this point with this many failures it has to be on me. I have a contact with customer service going atm and they are being quite helpful.

I also wonder if the ceramic blocks don't heat the balde and basically cause the metal to harden and become

1 minute ago, Tom King said:

I think you'd have better luck with a 1/2" blade on any 14" saw.

FACT! I think the new 14" saws are more capable than the old ones but i have a hard time believing wheel diameter and blade fatigue aren't linked in any way.

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11 minutes ago, Chestnut said:

...I also wonder if the ceramic blocks don't heat the balde and basically cause the metal to harden and become

FACT! I think the new 14" saws are more capable than the old ones but i have a hard time believing wheel diameter and blade fatigue aren't linked in any way.

If they are they are to tight to the blade.

I agree with Tom that a 1/2" would be better although I'm not convinced that it has anything to do with your issue. 

I have had a Laguna 16HD for about 14 years and a Laguna 1412 for about 2 years and have never broken a blade on either so I suspect there is a problem that's not the blade related somewhere. FWIW I use the Highland Woodworker resaw set up directions  (on their web site) for the most part and rarely run thicker than 1/2" blade on either. I have a Luguna resaw blade but was never impressed and now use 1/2" wide Woodslicers from for everything cut on the 16HD. 

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2 minutes ago, Chestnut said:
 

 

 

2 minutes ago, Chestnut said:

I don't WANT 3/4" that's just was readily available. I have now changed and am going to go with a 1/2" Lenox Tri-master. When i get it in I'm not going to use it until i make some sort of tension gauge. I'm going to take some pictures of the blade tonight and I'll post them i'd be interested in your opinion. I'm not blaming Laguna for this at this point with this many failures it has to be on me. I have a contact with customer service going atm and they are being quite helpful.

I also wonder if the ceramic blocks don't heat the balde and basically cause the metal to harden and become

FACT! I think the new 14" saws are more capable than the old ones but i have a hard time believing wheel diameter and blade fatigue aren't linked in any way.

The Tri-master is a good choice when you drop down to 1/2" Lenox uses a .025" backer so the tension requirements drop off proportional to the width compared to the RK.  

I doubt you are building near that much heat.  The vast majority of the heat will be from wood/tooth interface friction.  Louis Ittura (and another guy did an article published about 20 years ago) studied the difference in heat based on different types of guides and materials, neither were able to create blade temps high enough to get close to affecting the structure of the steel.  

In general, the 14" steel spined saws are capable of much more tension than a Delta cast saw, not a lot more than a PM 141 but that is a different class of saw.  They are still fairly limited in spring pressure but they have to be to preserve the integrity of the spine.  Laguna has always maintained the RK was fine on 14" wheels.  Lenox used to recommend at least an 18" wheel for their carbide blades but supposedly "changed" the backer formulation several years ago to help prevent fatigue on smaller wheels.  While it is only anecdotal and I don't know how much you used the blade before it broke there are a lot of people running 3/4" RKs on 14" saws (particularly the 14/12, 14BX and SUV because Laguna and their dealers push them) and have been doing it for years without fatigue breaks.  If it is a fatigue break you WILL find other cracks at the bottom of the gullets.  I have never run a carbide blade on a wheel smaller than 20" so I have no first hand experience.  

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6 minutes ago, pkinneb said:

FWIW I use the Highland Woodworker resaw set up directions  (on their web site) for the most part and rarely run thicker than 1/2" blade on either. I have a Luguna resaw blade but was never impressed and now use 1/2" wide Woodslicers from for everything cut on the 16HD. 

2

The Woodslicer is an excellent blade that comes with one large negative.  

The Woodslicer is a spring steel blade with impulse hardened teeth and curiously comes from the meat cutting industry.  Because the teeth are relatively soft (Rc 48-50 vs Carbon at 63-64 Bimetal M42 65-66 and Carbide at Rc68) they take a very fine edge, but they just dull quickly.  The blade stock is from Atlanta Sharptech and Iturra and Spectrum sale it for much less than Highland, Highland does not weld their own blades so there is another middleman and they were the first to commercialize it for wood and most associated with this type of blade.  The lack of set and thin backer make them excellent for cutting veneer and also don't require much spring pressure to get them to 17-18k psi where they perform best.  Spectrum also carries the 5/8" x.016" stock that is excellent for small saws or when you want to save wood cutting expensive wood into veneer.  When sharp they produce finish basically equal to the RK, and a touch ahead of the Tri-master, the Tri-master is at a slight disadvantage since it is a TCG and doesn't have the high shear angles of the RK.  It will outlast the RK but is MUCH harder to find someone to sharpen it.   Daily saw in Fullerton used to sharpen the Lenox but I don't think they do any longer.  I have never used a blade that leaves a better finish than the RK but it has a slower feedrate than the Tri-master and especially the Lenox Woodmaster CT but the Woodmaster is really a bandmill blade.  The RK is really one of the few if not only carbide tipped blade purpose built for resawing on smaller vertical saws, the Tri-master is really a blade designed for cutting very hard steel alloys and titanium.  

 

Sorry for the stream of consciousness posts, I must have been tapping into my inner Proust or more likely Joyce.  

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2 minutes ago, HuxleyWood said:

The Woodslicer is an excellent blade that comes with one large negative.  

The Woodslicer is a spring steel blade with impulse hardened teeth and curiously comes from the meat cutting industry.  Because the teeth are relatively soft (Rc 48-50 vs Carbon at 63-64 Bimetal M42 65-66 and Carbide at Rc68) they take a very fine edge, but they just dull quickly.  The blade stock is from Atlanta Sharptech and Iturra and Spectrum sale it for much less than Highland, Highland does not weld their own blades so there is another middleman and they were the first to commercialize it for wood and most associated with this type of blade.  The lack of set and thin backer make them excellent for cutting veneer and also don't require much spring pressure to get them to 17-18k psi where they perform best.  Spectrum also carries the 5/8" x.016" stock that is excellent for small saws or when you want to save wood cutting expensive wood into veneer.  When sharp they produce finish basically equal to the RK, and a touch ahead of the Tri-master, the Tri-master is at a slight disadvantage since it is a TCG and doesn't have the high shear angles of the RK.  It will outlast the RK but is MUCH harder to find someone to sharpen it.   Daily saw in Fullerton used to sharpen the Lenox but I don't think they do any longer.  I have never used a blade that leaves a better finish than the RK but it has a slower feedrate than the Tri-master and especially the Lenox Woodmaster CT but the Woodmaster is really a bandmill blade.  The RK is really one of the few if not only carbide tipped blade purpose built for resawing on smaller vertical saws, the Tri-master is really a blade designed for cutting very hard steel alloys and titanium.  

 

Sorry for the stream of consciousness posts, I must have been tapping into my inner Proust or more likely Joyce.  

Fair enough. In my shop I make 3-4 pieces of furniture a year, mostly form rough stock, and go through 1-2 blades a year at $35 a pop I can live with that :)  

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15 minutes ago, pkinneb said:

Fair enough. In my shop I make 3-4 pieces of furniture a year, mostly form rough stock, and go through 1-2 blades a year at $35 a pop I can live with that :)  

I'm not too far off. I feel like I'm chasing my tail. I bought the carbide to minimize how much stock was lost resawing with bi-metal blades and then started to love the cut quality. After goign from a resaw king back to a timberwolf it's like comparing North Dakota to the grand canyon. Even still i snapped some bi-metal blades as well and even breaking a $30 blade twice a year adds up, cheaper than $150 a year though i guess.....

22 minutes ago, HuxleyWood said:

Sorry for the stream of consciousness posts, I must have been tapping into my inner Proust or more likely Joyce.  

No i appreciate this information. it's actually frustrating trying to get information from the blade makes as to how much tension they should have. The more frustrating part is no one wants to simplify the matter and put the whole thing in lbs. The gauge on the saws could be converted to lbs spring pressure. Springs generally have a spring rate and it's very predictable. X compression in the spring equals Y lbs force. Blade manufactures know the cross sectional area of the blades and can take their design tension divide by the cross sectional area and get lbs force. Timber wolf 1/4" 3tpi blade needs X lbs force to be properly tensioned. Heck i can't even get a tension spec most of the time. It's absurd they are taking a SIMPLE engineering formula and making it REALLY REALLY complicated.

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22 minutes ago, Chestnut said:
 

 

 

22 minutes ago, Chestnut said:

No i appreciate this information. it's actually frustrating trying to get information from the blade makes as to how much tension they should have. The more frustrating part is no one wants to simplify the matter and put the whole thing in lbs. The gauge on the saws could be converted to lbs spring pressure. Springs generally have a spring rate and it's very predictable. X compression in the spring equals Y lbs force. Blade manufactures know the cross sectional area of the blades and can take their design tension divide by the cross sectional area and get lbs force. Timber wolf 1/4" 3tpi blade needs X lbs force to be properly tensioned. Heck i can't even get a tension spec most of the time. It's absurd they are taking a SIMPLE engineering formula and making it REALLY REALLY complicated.

 

Carter used to sell a load cell based tension gauge ETG that fit the Delta 14" cast saw and its clones that did not have a quick release.  It read in spring pressure and required some calculations for each blade, they even had a version that would cut power to the saw if the spring pressure suddenly dropped (blade broke or jumped off the tires).  They don't make it anymore.  Someone posted on Indestructables about building one using a Rasberry Pi and a load cell that was quite cool.   With the economy of scale manufacturers could add it to a bandsaw quite reasonably.  Part of the issue is bandsaws are dying in industrial and most commercial settings due to the CNC so there is little chance of trickle down and the reason you can buy old industrial bandsaws for basically scrap prices.  

 

One thing writing the post brought to mind is the tire issue.  Laguna did have some tire issues on one of their 14" saws and supposedly replaced the compound because stretching them in assembly was leaving them too loose.  If the blade comes off the wheel it is possible it will snap and more tension could exacerbate the problem.  I might check the tires to ensure they are very tight on the wheels.

 

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Huxley has blades and tension on lock down, clearly. I will only add that I have a resale king from 2004 that is still in action. 20” ACM saw. 

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2 hours ago, HuxleyWood said:

...One thing writing the post brought to mind is the tire issue.  Laguna did have some tire issues on one of their 14" saws and supposedly replaced the compound because stretching them in assembly was leaving them too loose.  If the blade comes off the wheel it is possible it will snap and more tension could exacerbate the problem.  I might check the tires to ensure they are very tight on the wheels.

 

I agree it sounds like something not related to the blade since you have had multiple failures of what is considered to be a very good blade.

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9 hours ago, Chestnut said:
Quote

Last night my resaw king blade broke after 5 months out of the last 8 of use. This is my 3rd broken Resaw King blade. I've had a lot of blades brake on my saw and I'm starting to wonder, Am I the problem here? How many times do you get blades to break on your bandsaw?

I run 10",  14" and 17" saws.  Resaw Kings, Woodslicer, Ellis and Timberwolf on the 17" machine and have run Carter and Timberwolf's on all the others.  I have never broken a blade.  I have chased a couple off the wheels when doing tight scroll work on the smaller saws so they do get used quite aggressively.  I don't know what would break a blade during resaw but, I do not resaw material that is not dry enough to continue milling.  I also generally joint a face and an edge to give me a reliable feed path so factor that in.

Quote

 

I set the blade tension with the flutter method and it usually corresponds with the lower limit for the blade size on the gauge on the saw (14BX). I typically set the blade towards the back side of the wheel similar to how Snodgrass suggests. I set the guides so they are a hairs width from touching the blade and set the thrust blocks so there is a tiny gap as well. I almost always release the tension on the blade when i'm not using the saw.

 

 

 

I have used the flutter method on all my saws and blades.  I actually run them pretty loose compared to folks on forums that prefer high tension.  I take extra care in setting up the saws and the blades really want to cut straight.

Alex's famous video is on a crowned tire saw.  For crowned tires I set the blade position based more on blade angle than on blade position but . . . 

57007994979ea_BladeTrack2.JPG.efb21469e56660d141c15f678fe96ec0.JPG

57007993915af_BladeTrack1.JPG.efaaba10842257458af550eae84b880d.JPG

697757868_BladeTrack3.thumb.JPG.46929cf49d712965f7712f0ece7fc149.JPG

. . . it may work out the same.  I just haven't paid attention in that way.  My guides are set similar to your settings.

 

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So here are pictures of the break. I only managed to find one area were there was a fracture that was starting. 2874983556648431069.thumb.jpg.535d007e0ad2ecb310b8b075e843dff5.jpg

DSC_1685-01.thumb.jpeg.b3ae0a50122ab3693a6844346baeb1e8.jpeg

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OK, this is nothing you did, those are fatigue cracks and propagating exactly where I would expect. 

 

I am pretty sure I know exactly what caused it.  There is a root cause and an accelerating cause.  Prestrain forces (static bandsaw tension) has basically little to no impact.  The accelerating factor is the high bending load over a small wheel, as the blade passes over the arc of the wheel the bending load is added to the static load plus the blade is subjected to the sudden increase and decrease of the bending load as the blade runs.  Preload is generally only about a 1/3 of this load and the cutting load is very minor, binding twisting and other accidental loads can be very high.  But the bending load can be very high especially on the small 14" wheels.

Now all this adds up to metal fatigue and EVERY band will fail if it is run long enough, however most of our blades get dull long before they fail, this sometimes is not the case with a carbide blade due to their long life and especially if they are resharpened, however you should not have reached this point even on small 14" wheels based on lots of anecdotal evidence of them running without fatigue failures for much longer than you apparently did, some are running fine even with several sharpenings, again based on forum reporting.  

The root cause of this is likely the surface roughness in the gullets.  When the blade stock was originally made by CET (Laguna just does the final grinding) the gullets were probably not finished smooth enough. This surface roughness develops cracks about 10 times quicker than properly finished metal, it is the bane of the high speed bandmill industry.  While you might not see any more cracks I bet if you ran a Magnaflux test you would see cracks forming in many if not all the gullets.

Contact Laguna, show them the pictures of the crack and explain how long it has been in service and how little it has been used and I would expect them to replace it.  The only problem I see with my conclusion (which I am still very confident with) is the multiple breaks you had in what you would expect were in different lots of blade stock OR if not you would expect to have heard more tales of breakage, I have heard of fatigue cracks in RKs but nothing recently.  Did you buy from the retailer (large internet or local) or did you get it from Laguna direct?  Maybe you were just introducing more accidental loads that you were unaware of but still that is not the root cause, I think poorly polished gullets were. 

Let us know what Laguna says.

 

Good luck.

 

 

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I admit to not being a metallurgist ( had to look up the correct spelling), and everything said above sounds true to form and they may have stated it, but I’m guessing that you need to resort to a 1/2” blade. My 14” states 1/2” max and I bet there’s a reason they say that. That sucks that it’s a carbide tip blade. 

5 minutes ago, wdwerker said:

It's a shame you can't use your West Systems on those band saw blades.

Hah, you beat me to it! 

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I guess I just realized you are running this on a 14" saw.  There are a number of posts out there about RSK's breaking on 14" saws.  It could be my "luck" with these blades is the fact that I run a larger bend radius on my larger saws.  I run 1/2" blades now finding no benefit in running wider blades over the years.  Carter and Woodslicer like blades give a pretty good finish and seem to tolerate the smaller wheels OK.  They would not last as long or cut as fast, of course, and would need replacing more often but, are less costly. 

You would have to run a Carter (or other) to the point of replacement and do the math to see if it balances out.  At $150 every 6 months you could buy a lot of Woodslicers.  Doing 'cost of ownership' studies like this are what moved me to insert heads on my jointer and planer.  I also run Cermet II tablesaw blades for the same reasons.  My point is that some things are not inherently obvious but, prove to make sense once you see them in black and white or dollars and cents.

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