Saw Blades, Radial Arm, Table Saw, Miter Saw (What's the Difference?)

[John Morris]

Dad is coming down this morning to pick up some saw blades for his Radial Arm Saw.

I have some 10" blades sitting around that I have not used in a while, and he needs them. As I was sorting through my blades, and picking out some that would work well on his RAS, I was thinking what a neat subject this would make here in our community.

 

I am not going to get into the differences between the blades and submit my knowledge of the differences, I wanted you all to contribute your own knowledge on the subject, meanwhile also staying away from linking to outside articles on the subject if you will. I would love to see the opinions and knowledge of our contributors here, for others who may happen onto our woodworking community, to benefit from and read up on.

 

• So, what is the difference between the various types of blades for our Radial Arm Saws, Miter Saws, and Table Saws, and even the hand held Cabinet or Wormdrive Saws?
• Why would you use one blade over the other?
• Why do these blades have different rakes?
• Why does tooth count matter?

 

Thanks everyone for your contributions to this subject, please submit supporting images too if you like, but again, try to stay away from linking to outside sources, lets make this our own topic of knowledge on the subject!

 

[Stick486]

BLADE HOOK ANGLE.pdf

JIGSAW BLADE GUIDE.pdf

 

[Fred W. Hargis Jr]

I can only offer that my early use of an RAS was with high hook angle blades and it made cutting a challenge with it. If you read the opinions of those that think an RAS has no place in the shop it's usually due to two things : 1) the self feed attribute caused by the wrong blade, and 2: the lack of accuracy (that denotes they used a Craftsman saw to me). Eventually I learned that negative hook angle blades make life with an RAS so much easier it's all I use on them. Some of the guys over at the Dewalt forum still rip on the RAS (I don't, but that's because of the mess it makes) and they use a blade that has a positive hook angle, but on;y slightly so. Generally a 5° hook angle and a TCG tooth grind (I guess) allows for a very good rip cut. For my table saw I don't get into much detail on the blade specs. I have 3 types of blades that see common use. The first is a 40 tooth combo, either a WW2 or Freud 410 and those see 90% of the work my TS does. Bit i also have a 24 tooth dedicated rip blade (Freud) for the thicker woods, and an 80 count glass smooth cross cut blade (another Freud) for plywood when i want the smoothest cut possible. I use a miter saw and circ saw so little, and consider them home improvement tools I'm not even sure what blades they have on them. But I do have a track saw, and I bought a dedicated rip blade to go along with the crosscut blade it had.

 

I know a lot less about the other stuff than most guys around here, but I can count on a few things: more teeth almost always make the blade cut more slowly. the combo and crosscut blades have teeth that help shear the fibers where the rip blade is simply chiseling them out. But the question about which blade to use is easy: I try to pick the one that will do the best cut for the job at hand. (Where is Scott Spencer when you need him {knotscott}?)

[Dadio]

I use mainly crosscut blades on my RAS as i don't do any ripping on it. So the combination/rip blades are for the table saw. I like a 80t blade for the RA makes a smooth cut.

TS get the 42t,50t,62t, blades. Don't like the thin kerf blades,too much deflection, in hardwoods and leaves kerf lines. Those work OK for soft woods,and plywood, still leave kerf lines. The 26t blade for particule board cuts it like butter.

Skill saw blades are combination blades.

Herb

 

[knotscott]

On 12/2/2016 at 1:45 PM, Fred W. Hargis, Jr said:

... (Where is Scott Spencer when you need him {knotscott}?)....

 

Does "better late than never" still hold true?!

 

(Below some highlights from my saw blade blog)

 

The Basics:
There are pros and cons with every design parameter.  If all else is equal, more teeth tends to equate to a cleaner cut, but with more resistance, more heat, more chance of burning. Fewer teeth tends to equate to a faster cut, with less resistance, less burning, but a rougher finish. Neither extreme or design parameter is ideal for all situations, and neither extreme or parameter is “better” in all situations…they’re just better suited for different applications. Choosing the correct parameter for the situation is the tough part.   Depending on thickness, it’s recommended to have 5 to 7 teeth in the material for crosscutting and finish cuts in hard wood, and 3 to 5 teeth for ripping operations. Depending on blade diameter, it’s common to see between 10 and 30 teeth on a specialized ripping blade, and 60 to 100 teeth for crosscut blades and blades used for plywood, veneers, melamine. laminates, and other sheet goods. Note that more teeth cost more to make, more to buy, and more to sharpen when the time comes, but more teeth also tend to hold an edge longer because they share the work load.

Hook Angle:
Hook angle (or rake) is the amount of forward or backward lean of the teeth on a blade. The hook angle can range from roughly -7° to as much as + 22°. The steeper the hook angle, the more aggressive and faster the feed rate will be. A steep, or positive hook angle, will have more pull on the material than a low or negative hook blade, which is a feature well suited for ripping operations on a table saw. A low to negative hook blade is well suited for use on a sliding compound miter saw (Miter Saw">SCMS) or radial arm saw (RAS) to prevent “climb” or self feeding of the material, and is highly recommended when cutting metals on any type of saw. The steeper hook angles will feed faster but can also increase tear out characteristics at the exit of the cut. A lower hook angle will have less tear out, but will require more feed pressure and may have a higher tendency for burning to occur if the saw bogs down.

Side Clearance:
The side clearance is another important feature that is essentially the amount of overhang a tooth has relative to the blade’s body. The tangential and radial side clearance angles are the geometry of the sides of the teeth. These features all combine to determine how much “polish” or “burnishing” characteristics the teeth will contribute to the edge of the wood. Tight side clearances and tight angles mean that more tooth makes contact with the edge of the cut, and thus gives a more polished look. The same characteristic can also increase burning if the feed rate slows too much, and/or if the wood is naturally more prone to burning.

 

Gullet:
A gullet is the trough between the teeth. A larger gullet allows for more efficient chip removal, which is one of the reasons that a blade with fewer teeth will cut faster…there’s simply more gullet space on a lower tooth count blade. Ripping operations have larger chip size than crosscutting operations, which makes lower tooth count blades more conducive to ripping operations. Crosscutting operations tend to have smaller chip sizes, so a dedicated crosscut blade can have more teeth around the perimeter of the blade, which allows for a cleaner cut.

Task-specific or general purpose blades?:
Taking the approach of using task specific blades requires owning at least two blades that each excel in a limited operating region, and are typically unacceptable for tasks outside of their intended scope. These blades should achieve the optimum possible results when used within their intended usage range. They also require blade changes for each different task for optimum results. Two task-specific blades (typically a 24T ripper and a 60T or 80T crosscutter) will generally stay sharp longer than a single general purpose blade because they share the work load, but will cost more upfront and will also cost more to re-sharpen when the time comes.

A general purpose blade will neither rip as efficiently as a true rip blade nor crosscut as cleanly as a dedicated crosscut blade, and will be less than ideal in both extremes, but you may find that it’s more than acceptable at doing both tasks for most situations. A valid argument in favor of using one high quality general purpose blade is that the GP blade leaves a cleaner edge than the rip blade, crosscuts faster than a crosscut blade, and does so with the convenience and cost of using one blade. Most higher quality general purpose blades will leave a glue ready edge, which is often as good as it needs to be.

If you want the absolute best performance possible from your saw, look to high quality task specific blades. If you happen to do a lot of specialty cutting of fine veneered plywoods, veneers, melamine, MDF, plastics, etc., a blade made specifically for those materials is definitely recommended. If you tend to rip very thick dense materials regularly, then a dedicated bulk ripping blade is a wise choice for you right from the start. It’s worth noting that a high quality general purpose blade will often outperform a lower end task-specific blade. Sooner a later a decent general purpose blade will be useful, so if you’re not certain what to get it’s always a reasonable starting point IMO, even if you pursue separate dedicated blades later. Regardless of the approach you choose, buy quality blades.

 

Crosscut Blades:
Crosscut blades use design parameters that are optimized for fine cuts across the grain of hard and soft woods, but the high tooth count can make them more prone to burning, so are not recommended for most rip cuts…particularly in thicker materials. The same parameters also make many crosscut blades suitable for lower volume cutting in plywood, veneers, and melamine. Most fine crosscut blades combine a high tooth count (usually between 60T and 80T for a 10” diameter blade) with an ATB or Hi-ATB grind that excels at shearing across wood fibers, with a low to medium hook angle. The resulting cut is smoother and slower than most other types of blades. Depending on thickness, it’s recommended to have 5 to 7 teeth in the material for crosscutting and finish cuts in hard wood.  It’s not uncommon to find crosscut blades for miter saws that feature a combination of ATB and FTG teeth for increased efficiency and edge life. If all else is equal, the steeper the top bevel, the lower the resulting tear out there will be, but note that it comes at the expense of edge life, due to the pointy tips of a Hi-ATB grind being weaker than the tips of other grinds. More teeth tends to equate to a cleaner cut too, but comes at the price of more heat and resistance. Generally 60T to 80T is the sweet spot for cut quality and efficiency of cut for cross grain applications. Some 100T+ crosscut blades do exist, but my experience has been that the added resistance isn’t worth whatever benefits they offer, with the possible exception of cutting veneers or very thin plywood. There are also some crosscut/ply/laminate/melamine blades that feature a triple chip grind (TCG). TCG blades tend to have excellent wear characteristics, but not necessarily the cleanest of cuts….they’re ideal for high volume applications where edge life is a concern, and for very brittle and abrasive materials (melamine, MDF, teak, pressboard, etc) that tend to cause the tips of an ATB or Hi-ATB blade to abrade more quickly than other grind types. An 80T Hi-ATB will be among the cleanest cutting blades on the market, but will have somewhat shorter edge life than a comparable ATB or TCG blade. Depending on your volumes and cleaning habits, most hobbyists should still get very reasonable edge life from a top shelf Hi-ATB blade.  

 

Rip Blades:
Rip blades tend to be the polar opposites of crosscut blades. Their parameters are optimized for clearing the longer fibers of rip cuts with the grain, where tear out isn’t much of a concern.   Depending on thickness, it’s recommended to have between 3 to 5 teeth for ripping operations. Bulk rippers tend to use a flat top grind (FTG), low tooth count (10T-24T), and a steep hook angle often near 20° that’s ideal for efficient ripping, but would tend to leave more tear out in crosscuts. There are also rip blades with a moderate top bevel ATB grind that will do slightly better in crosscuts than an FTG, but aren't really optimized for crosscut tasks. The resulting cut of a low tooth count blade with a steep hook angle is quick and efficient feed rates, less resistance and heat, and a somewhat rougher cut. The better examples of the more common 24T FTG rippers are capable of glue line edges given flat straight stock and a well tuned saw. They’re easier to spin in thick materials, so put less strain on your saw than higher tooth count blades.

There is also a subgroup of rip blades known as “Glue Line Rip” blades…that term can be defined in many ways and is a common marketing phrase, but the most common is found in a 30T configuration with a triple chip grind (TCG) and a moderate hook angle of 12-13°. Since they tend to feature very tight side geometries to provide a highly polished edge, their ability to rip thicker materials is generally somewhat limited compared to a standard 24T FTG ripper. The niche of most of these “GLR” blades is smoother rip cuts in materials up to about an inch thick…if you choose a 30T GLR ripper, you will likely still want a bulk 24T FTG rip blade for thicker stock. Many blades are capable of a glue ready edge….you don’t need to buy a blade that states it as a slogan on the blade for it to be capable of it. It’s also important to recognize that no saw blade can replace the function of a jointer…a clean edge doesn’t flatten the face of a board, and is only one part of a larger equation of flattening and squaring stock.

 

 

Edited January 21, 2017 by knotscott

[John Morris]

Better late than never is always great! Thanks Scott for this wonderful indepth breakdown.

Scott, can you please give us a link to your blog, and if you have the time, please create your link at our "Links Directory" to add to our growing list of links to interesting resources. I would say your blog would fit in the "Member Websites" category on that page.

 

Thanks again Scott, for the entry here!

[HARO50]

Very informative post, Scott. Thank you.

John