How many teeth is a good number?

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Sturgis

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So, I'm pretty new to the double miter saw thing. My saw came with 80 tooth blades. I decided 100 teeth must be better than 80, so I ordered a couple sets of 100 tooth blades. I seem to be getting more tear-out on the new 100 tooth blades than the old 80 tooth blades.

Can someone give me the Idiot's Guide to Saw Teeth? How do you really know when the blades are dull? Why is there tear-out with new blades? Is there a rough industry standard to how many miters you can cut with a newly sharpened blade?

Thanks,

Bob
 
  • Not all blades are equal (e.g. general quality, kerf width, hook angle, and tooth configuration) - this affects quality of cut, & frequency of sharpening
  • For a saw blade to make a true cut, the teeth must be held rigidly in line with one another. The blade plate needs to be as close to perfectly flat as possible, and it needs to stay that way during the cut. The blade plate should be made of quality, hardened steel. The arbor hole also needs to be sized and placed with extreme precision. The blade plate also has to be "tensioned" for it to remain straight and rigid when it comes up to speed. On a high quality blade, correct tensioning keeps the blade from becoming "floppy" as result of the centrifugal force generated in operation.
  • Generally 80T is good unless you are cutting a lot of tiny mouldings
  • As a general rule the greater the number of teeth the slower the feed rate, although this is probably not significant between 80T and 100T
  • Length between sharpening depends not only on specifics of the blade but also the type of moulding you are cutting
 
It's not always about the teeth. Well.... 80 is a little too few if it's a 16" blade.... but on a 8" blade it's just fine.

What kind of teeth is actually more important. The set wants to be a combination cross-cut. The teeth per inch will usually float somewhere about 2-3/inch. 4-6 for aluminum.
Some others will come along with their preferences of where and who to buy from. . . and none of them like who and where I buy from and from none others. But then, most think that paying $280 for a blade is stupid. Personally, I happen to like Czechoslovakian steel, Israeli carbon tips and being able to shake the hand of the pretty lady who grinds my tips and her wife who does the final sharpening.
 
Since you admit to being new to a double miter saw, I might make a suggestion that you make sure that you have the blades on properly. I had an employee that once but on one of the blades backwards. It still cut but did so with a cloud of smoke.

Assuming that you are using a 12" blade, I would think that 80 or 100 would be fine as long as they are sharp.
 
Brief Frankenthread

Baer Charlton said:
Personally, I happen to like Czechoslovakian steel, Israeli carbon tips and being able to shake the hand of the pretty lady who grinds my tips and her wife who does the final sharpening.
Click to expand...
While your steel is Czech, and your tips Israeli, it sounds like your sharpening team is
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(wait for it)
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"Lebanese".

:icon11: Rick
(Not that there's anything wrong with that.)
 
Give us the type of saw and size of blades. Also the HP of the motors on the saw. What is the grind on the blade teeth. Are they carbide tipped.
 
Thanks for all the good info. I'm using 12" blades on an MN200. The new blades came from Quinn. Although I've only bought 4 blades from them, it was a superior online buying experience. As I recall, I had a tracking number within 30 minutes of placing the order.

The blades I'm using are not combination blades, but wood only. I'm a little unclear on "blade tensioning". I hope that's something done by the blade manufacturer, because it sounds like a good way to lose a finger. :cry: I might investigate doing a slower cut, but the saw drops pneumatically, so I will have to see if there is some drop-down speed adjustment.

Thanks,

Bob
 
Slow your blade feed rate. The added teeth are not allowing the wood debris to clear from the cut as quickly as the 80 teeth blade did.
 
Jeff Rodier said:
Give us the type of saw and size of blades. Also the HP of the motors on the saw. What is the grind on the blade teeth. Are they carbide tipped.
Click to expand...

Jeff, It's a Pistorius MN200, 12 inch blades, 1 1/2 hp motors. Blades are 100 tooth, .118 kerf 4+1 ATB carbide tipped.

Thanks,

Bob
 
If you follow the linkage down beneath the blades, you'll see a brass cylinder. There is a dial on that cylinder that slows how fast the blades descend. You could slow that down and see if the tear out diminishes.

Another critical thing to look for is a phenolic insert as well as a phenolic scrap support. They could be worn and in need of replacing. My machine didn't come with the scrap support system and I always had a bad tear out on the mouldings. Once installed the problem went away.
 
Dear Bob:

Thanks for the kind words on our service. As far as the blades go, your 2 sets of blades are a 4+1 alternate top bevel tooth form which should produce excellent cuts for wood moldings. These blades are tensioned to run at your machines RPM's so unless you get the blade into a bind and so hot that they would bend, then that should not be a factor.

The tear out issue typically is related to the support of the molding as the blade exits the cut. If these new 100 tooth blades have a thinner kerf than your prevous 80 tooth blades, then there may be more space between the blade and the table.

To answer some of your other questions:
1. Saw Teeth: The shape of the teeth correspond to the material to be cut.

The 4+1 ATB (alternate top bevel) teeth alternate left, right, left, right and then a flat tooth to clear out the cut. These pointed teeth are for cutting wood only and cut the wood fibers like a knife through celery.

The TCG (triple chip) teeth have one "high tooth" that has chamfers (angles) on both sides and a "low tooth" which is just flat. The high tooth cuts just the middle third of the kerf then the low tooth cleans up the cut by cutting the outer 2/3's of the kerf. This geometry is for man made materials without a grain and for non-ferrous metal cutting.

2. How do you know when the blade is dull? When the cut quality diminishes and the force to push the blade through the cut increases. You can look at the cutting edges of the teeth and start to see a rounding over. You don't want the blade to get extremely dull as then we will have to grind off more carbide to re-establish a sharp cutting edge.

3. How many cuts to expect is as CAFramer said, dependent on the type and size of molding you are cutting.

Just some thoughts, but please feel free to give me a call with any other questions.

Thanks,

Bill Zickel
www.quinnsaw.com
 
triplechip said:
Dear Bob:

Thanks for the kind words on our service. As far as the blades go, your 2 sets of blades are a 4+1 alternate top bevel tooth form which should produce excellent cuts for wood moldings. These blades are tensioned to run at your machines RPM's so unless you get the blade into a bind and so hot that they would bend, then that should not be a factor.

The tear out issue typically is related to the support of the molding as the blade exits the cut. If these new 100 tooth blades have a thinner kerf than your prevous 80 tooth blades, then there may be more space between the blade and the table.

To answer some of your other questions:
1. Saw Teeth: The shape of the teeth correspond to the material to be cut.

The 4+1 ATB (alternate top bevel) teeth alternate left, right, left, right and then a flat tooth to clear out the cut. These pointed teeth are for cutting wood only and cut the wood fibers like a knife through celery.

The TCG (triple chip) teeth have one "high tooth" that has chamfers (angles) on both sides and a "low tooth" which is just flat. The high tooth cuts just the middle third of the kerf then the low tooth cleans up the cut by cutting the outer 2/3's of the kerf. This geometry is for man made materials without a grain and for non-ferrous metal cutting.

2. How do you know when the blade is dull? When the cut quality diminishes and the force to push the blade through the cut increases. You can look at the cutting edges of the teeth and start to see a rounding over. You don't want the blade to get extremely dull as then we will have to grind off more carbide to re-establish a sharp cutting edge.

3. How many cuts to expect is as CAFramer said, dependent on the type and size of molding you are cutting.

Just some thoughts, but please feel free to give me a call with any other questions.

Thanks,

Bill Zickel
www.quinnsaw.com
Click to expand...

Thanks for the good info Bill. I'll probably order a few 80 tooth blades, plus something for my tablesaw as soon as I can figure out what I need on the tablesaw. And I'll be sending some back for sharpening.

Here's a question that I've been wondering about. What is the effect on these precision saw blades when sawing through 18 gauge brads? Or is that question just too stupid to deal with? Here's why I ask. A good part of our business is barnwood frames. A local fellow has made a good business by supplying the midwest with these beautiful frames. For us, he supplies moulding in length and we make our own. The moulding is two pieces: 1) the barnwood 2) quarter moulding trim. In HIS operation, he attaches the trim with 18 gauge brads, THEN it goes to the Pistorius. He says it doesn't hurt a thing when he hits a brad. But he hits nails all the time in this barnwood, so a little brad probably doesn't mean much.

For me, I haven't had the nerve to saw through these brads on my new Pistorius, so I glue the trim first, then saw, then brad nail the trim. But, my way takes 10 times more time. So, I hope with this background my question makes sense.

Thanks,

Bob
 
Just takes the sharp edge off the teeth and maybe knoch a tooth off every now and then. Try using the 23 gauge pin nailers to reduce wear. You'll use more of them but less blades and sharpenings.
 
Bob:

The blades for your Pistorius are specifically designed for wood cutting only. Since the tips are very hard - to provide long blade life, they are also very brittle. Jeff is right on target that you will run the risk of breaking tips.

Your supplier of the barnwood may be using a different type of blade. There are specific tips designed for nail cutting which are more shock resistant, but at the expense of blade life.

Thanks for the question.

Bill Zickel
www.quinnsaw.com
 
Just an update: I'm getting perfect cuts now after a few minor adjustments. I slowed the downstroke a small amount. I also noticed a small part of the fence was a tiny bit out of adjustment. While I had the tools out, I adjusted the insert support (with the help of a fellow Pistorius owner).

Anyway, after all that, I don't think I could expect a better cut from the saw. Thanks for your help.

Bob
 
Bob, what is the condition of your insert support? I turn it around every time I change my scrap support piece.

Does your machine have a phenolic scrap support too? You may want to have a spare in your shop for when it becomes necessary to change. You can order a new one when you install the one you have.
 
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