Smaller diameter blades have less saw marks?

[Nick Sorenson]

With all else being equal, wouldn't smaller diameter blades show less saw kerfs in a cut? Seems like the larger the diameter the more runout and vibration, would this be true in most cases?

I'm considering ordering a 10" blade instead of a 12" blade for my DeWalt GP Radial. The saw has PLENTY of power to use the 12" blade but I'm guessing I'd have a cleaner cut with a smaller diameter.

[Rick Potter]

My 7790 12" leaves a polished edge on oak..hardly ever see a line unless the wood had a slight bow to it, and wasn't perfect with the fence, then it burns a bit, but that is operator error, not the blade. Also, a 12" will last longer. My blade is 100 teeth, for crosscut only.

If it does not cut clean, recheck your adjustments.
Rick Potter

[lowell holmes]

If you have a proper hook angle on the blade, it should not make much difference. My Forrest blades don't leave marks.

[John McClanahan]

10" blades have a 5/8" arbor. I'm guessing your 12" saw has a 1" arbor.

John

[Peter Quinn]

If the blade is full kerf and well made, I doubt there is much difference in cut quality. My GR spins a 14" blade, the cut looks like it were sanded with a sharp blade. I've found with thin kerf blades a 10" seems to cut cleaner than a 12" all else being equal but those are very thin kerf plates, even less than a tk TS blade.

[scott spencer]

IF all else is equal, there's likely less chance of deflection from a 10" blade, but if the 12" blade has sufficient body thickness, tensioning, and good design, it shouldn't be an issue. I tend to recommend against a 12" thin kerf blade due to the increased span, but a good full kerf blade should be fine.

[Rick Potter]

John,

I think you will find that most 12" RAS use a 5/8" arbor. I assume this is to enable standard dado sets to be used. It also allows use of a smaller blade, if desired. My 12" DeWalt has a 5/8" arbor, and I use a bushing in the blade.

Rick Potter

[Jim Neeley]

With all else being equal.

With "all else being equal", technically, yes. That said...

This assumes things like:
* the blades being made to the same tolerances (and how much they exceed them), which may or may not be true
* that the runout on the motors are identical.

I'd expect to see a larger variance between brands than between sizes, although I'd also expect some amount (since it's almost guaranteed not to be precisely zero) of difference in the resulting runout.

Whether or not it's noticable depends.

This is the same reason why "everything else being equal" a non-slider will cut truer than a slider, because there's one less range of motion.

In my experience, with a good saw (I have a Bosch Glide) and a top quality blade (mine is the 12" Forrest Chopmaster Signature Series) I get a cut like glass. Of course that's also a $170 blade in a $725 saw that I've taken the time to carefully tune to optimize its cut.

While there are likely individual units for which this may not be true, you generally get what you pay for (or at least not more than you pay for). <g>

Jim

[John McClanahan]

John,

I think you will find that most 12" RAS use a 5/8" arbor. I assume this is to enable standard dado sets to be used. It also allows use of a smaller blade, if desired. My 12" DeWalt has a 5/8" arbor, and I use a bushing in the blade.

Rick Potter

You talkin to me? :D

Straighten me out. When I was table saw shopping, 12" saws had 1" arbors,so I found a 10" saw so I wouldn't have to buy new blades and dado set. Is that just true on table saws, not radial arm saws and miter saws?

John

[Rick Potter]

John,

No expert here. I can only speak from my experience, but I had for a short time, a delta 12" turret 33-890 RAS, which had a 58" arbor, and my current 12" DeWalt 7790 is also a 5/8" arbor.

My miter saw is a 12" DeWalt, and it takes a 1" arbor. I use the same blade on my RAS with a bushing, which is very common. I believe RAS arbors go to one inch on 14" saws.

All the 12" table saws I have seen have, as you say, a 1" arbor.


Now the following is all assumption on my part. Take it for what it's worth:

Many 12" RAS's have a 'Contractor' label on them. In the old days when they sold the DeWalt's as portable saws to contractors, and the standard on site table saw was a real 'contractor saw', I would assume that builders would have bought a 12" RAS over a 10, because it would cut a 4X. If they burned up a blade (carbide was rare), being able to slap on a table saw 10" blade to their 12" RAS would be a plus for them since they would have several 10" on the truck. Not too many chop saws around in those days either. Ever see one of those old Comet trailer mounted RAS's? Monsters.

RP

[John McClanahan]

Thanks, Rick! This also answers a question I had asked in another thread regarding a 12" Delta turret saw with a 5/8 arbor.

John

[jack forsberg]

larger blades cut cleaner and do it longer. if all thing are equal than a larger blade has a thicker plate larger teeth. The reason bigger blades cut cleaner is the rim speed is much faster and there fore you get more cut per inch with the same feed rate. coming from a thin kerf 10"blade to what is commonly refers to as a 10" full kerf blade (1/8") might feel like this is a big jump for those that have not used industrial quality saw blades. to me the 10" full kerf look small compared to my 18" table saw blade for the Wadkin PK that cuts a glass finish and takes about 6 months to dull.

10" full kerf blade with a 18" FS TOOL saw blade for the wadkin Table saw.

http://i927.photobucket.com/albums/ad111/tool613/wadkin/18blade002_zpsac9ac202.jpg (http://s927.photobucket.com/user/tool613/media/wadkin/18blade002_zpsac9ac202.jpg.html)

http://i927.photobucket.com/albums/ad111/tool613/wadkin/18blade003_zps63f4202d.jpg (http://s927.photobucket.com/user/tool613/media/wadkin/18blade003_zps63f4202d.jpg.html)

[David Kumm]

As the blade gets larger the guy who sharpens them become more important. People who know how to grind and how to flatten the plate make all the difference. I run 14" most of the time as it is the size I prefer. A good saw with the arbor ground to have no runout helps too. Dave

[J.R. Rutter]

In my experience doing precision miters on relatively cheap chop saws, I found that using a 10" blade on a 12" saw gave a better cut. They were DeWalt saws that used a bushing to go from 5/8" to 1", so it was easy to experiment. This probably had more to do with the arbor tolerances than the blades. The 10" Chopmaster did better than the 12" Chopmaster.

[Howard Acheson]

I know a number of top quality cabinet makers who use a 7 1/4" high tooth count blade for crosscutting. They claim that they get a cleaner crosscut with the smaller blade. They use a standard 10" rip blade for ripping.

[Tom Walz]

Something not mentioned is side clearance variance. How far does each tooth stick out from the body of the saw?

Assume the steel saw body runs straight and true (not necessarily accurate but assume it anyway.) Then he sides of all the teeth should stick out the same amount.

In really good blades you will see variance of + / - .0005" (half a thousandth of an inch.
In other blades you may see variance of + / - 0.010” (ten thousandths of an inch.) If you are cutting and most of the teeth are lined up pretty close to right then the ones that are sticking out quite a distance are going to leave marks.

Side clearance variance can be caused by brazing issues, grinding issues and handling issues.

Carbide tips vary slightly in width. There is usually very, very little variance on tips within a batch. However tips in different batches, that are nominally the same size, can vary by a couple thousandths of an inch.

When the carbide tips are brazed on their typically located in place from one side. So a difference in width of the tip means that it sits off to one side on the saw.

Carbide tips are extremely wear resistant which is why you use them. However this means they are also hard to grind. The term in the industry is pushback. As in the grinding wheel pushes on the blade and the blade pushes back. If the grinding wheel pushes too hard on the tip then the tip can spring back.

If you measure side clearance variance on a saw blade that has expansion slots on the rim you’ll often find that the tip immediately following the expansion slot has more side clearance variance the others. This is because that tip is only really supported on one side with the slot on the other side. This allows that tip to move more.

When grinding the saw tip immediately behind in expansion slot you should take into consideration the effects of the expansion slot. One way to do this is to reverse the direction of the wheel and reverse rotation of the wheel for the teeth, and just the teeth, immediately behind the expansion slot. This is commonly overlooked.


Saw plate is not consistent in its thickness, its physical makeup, its tension or really anything else. Matter how much saw manufacturers try, there is still variance throughout the plate. Some manufacturers spend a great deal more time and trouble correcting this than others.

Grinding the carbide teeth on the saw blade is not really a straightforward operation. You can spend $100,000 to $500,000 on a CNC grinder and still not get perfect lines.

Grinding wheels can load up as they grind. Part of the problem is anti-rust on the steel saw body. Another issue is hydraulic fluid with weeping around seals. These can clog up the wheel. A clogged wheel has to push a lot harder against the tooth to do any good which, of course, causes a lot more pushback.

The number of diamonds, size of diamonds, kind of diamonds and matrix that holds the diamonds can all influence how well the wheel cuts. If you have some time go to Google and look up information on man-made diamonds. There really is a huge variance. You want diamonds that are going to stay sharp.

One way of looking at grinding carbide is to consider it as an extrusion process. The sharp diamond points pull carbide grains out of the carbide tip. So you want diamonds that are going to stay sharp which means they fracture pretty readily which means they wear out pretty fast. You can also get diamonds that round over in use and they last a long time but don’t cut very well.

You get into an issue on machine maintenance and operator skill. If you are in a top-quality saw blade manufacturing operation you will see operators interrupt their task go over make slight adjustments to machines. No matter what they are doing, they are also listening to how the machine is running.

CNC machines have wear issues. As an example, bearings wear and need to be replaced. There will be more variation in grinding with worn bearings than with new bearings.

There is much more but that will give you an idea of the difficulty involved.