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Old 04-18-2013, 09:50 PM
bakka bakka is offline
 
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Default tear outs

So yesterday I go some tear out on a cross cut with a relatively new blade (40 Teeth). Could it be my anti chip inserts. I have a straight cut slop cut into it as well as a bevel (45) cut
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Old 04-18-2013, 10:00 PM
Burt Burt is offline
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How about a little more explanation. I don't understand.


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  #3  
Old 04-18-2013, 10:31 PM
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Philphoto Philphoto is offline
 
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Default More data needed

We need more information.
  1. What it the material thickness?
  2. What is the material -- MDF -Particle Board - Plywood?
  3. What is the blade size?
  4. What is the blade bevel? Triple Chip? High ATB? ATB?
  5. How deep were you setting the depth of cut?
  6. What is the clearance from the furthest out tooth to the board? (trying to find out if you have your blade set with too much clearance. Every blade style has a hook angle and the depth will change the geometry of the blade.
  7. Have you checked for blade alignment?

That will be a good start to find out if there are other problems like run out on your saw bearings which will do the tear out as well.

Phil
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Old 04-18-2013, 10:45 PM
Billy Shaw Billy Shaw is offline
 
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Quote:
Originally Posted by bakka View Post
So yesterday I go some tear out on a cross cut with a relatively new blade (40 Teeth). Could it be my anti chip inserts. I have a straight cut slop cut into it as well as a bevel (45) cut
40 tooth blade,not always the best for crosscut.. Especially on multi ply , or material with a "heavy grain" veneer.. What type of material??,,, Pushing too fast maybe??? What kerf ,and degree of blade teeth???
In my experience, speed of cut,more than blade,determine tear out..
You can cut CDX plywood ,,without A.C.E.,,, and a 24 tooth "framing" blade,with minimal "tear out",or "chipping" if you slow down just a little. The slower ,and more deliberate the speed,,,the less chance of a problem.
As I'm sure you know. If you scribe the top ply,or veneer with your utility knife before cutting,also helps.
Doubt it's the inserts,but maybe not understanding the problem..
Not positive,but thinking maybe you should have a separate ACE, for bevel cuts. As every bevel % will set ACE "Bottom surface", in a different spot. For instance: If you've already made a few 45% cuts with a particular ACE. If you make a 30% cut with same ACE. Your blade will be a little farther away from ACE ,at bottom surface.
Not much farther. But in materials described above,and a duller blade,or too fast of a push,,,,might make a difference..

Anyone else??

Hope I could help,
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  #5  
Old 04-18-2013, 11:05 PM
bakka bakka is offline
 
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Thanks Billy. You made some important points that I will take into consideration this weekend when doing some more work.
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  #6  
Old 04-18-2013, 11:11 PM
bakka bakka is offline
 
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What it the material thickness?
What is the material -- MDF -Particle Board - Plywood?
What is the blade size?
What is the blade bevel? Triple Chip? High ATB? ATB?
How deep were you setting the depth of cut?
What is the clearance from the furthest out tooth to the board? (trying to find out if you have your blade set with too much clearance. Every blade style has a hook angle and the depth will change the geometry of the blade.
Have you checked for blade alignment?

That will be a good start to find out if there are other problems like run out on your saw bearings which will do the tear out as well


Plywood- 3/4*
Blade size 7/14
45 bevel
The Blade alignment is fine
Why would the " blade hook angle and the depth will change the geometry of the blade" really I just buy the blade that goes with the day' Don't pull this out of the cloud to ask me..
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  #7  
Old 04-18-2013, 11:13 PM
sean9c sean9c is offline
 
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Making bevel cuts your blade is likely nowhere near the ACE. There is no anti chip protection on bevel cuts. At anything but small angles your blade has cut through the sloped section of the AC-2 so it's not helping. You could take an AC-1, screw a piece of 1/2" ply to it, so that's what is running on your material. Once you've set the angle on your saw plunge that through the AC-1, so you've made an anti chip piece for that specific angle.

Quote:
Originally Posted by Billy Shaw View Post
40 tooth blade,not always the best for crosscut.. Especially on multi ply , or material with a "heavy grain" veneer.. What type of material??,,, Pushing too fast maybe??? What kerf ,and degree of blade teeth???
In my experience, speed of cut,more than blade,determine tear out..
You can cut CDX plywood ,,without A.C.E.,,, and a 24 tooth "framing" blade,with minimal "tear out",or "chipping" if you slow down just a little. The slower ,and more deliberate the speed,,,the less chance of a problem.
As I'm sure you know. If you scribe the top ply,or veneer with your utility knife before cutting,also helps.
Doubt it's the inserts,but maybe not understanding the problem..
Not positive,but thinking maybe you should have a separate ACE, for bevel cuts. As every bevel % will set ACE "Bottom surface", in a different spot. For instance: If you've already made a few 45% cuts with a particular ACE. If you make a 30% cut with same ACE. Your blade will be a little farther away from ACE ,at bottom surface.
Not much farther. But in materials described above,and a duller blade,or too fast of a push,,,,might make a difference..

Anyone else??

Hope I could help,
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  #8  
Old 04-19-2013, 12:38 AM
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Philphoto Philphoto is offline
 
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Posts: 627
Default Blade information to help.

Quote:
Originally Posted by bakka View Post
What it the material thickness?
Plywood- 3/4*
Blade size 7/14
45 bevel
The Blade alignment is fine
Why would the " blade hook angle and the depth will change the geometry of the blade" really I just buy the blade that goes with the day' Don't pull this out of the cloud to ask me..
"Don't pull this out of the cloud to ask me"
Not pulling it out of a cloud! You asked for help and that is what I am trying to do. I was not trying to embarrass you or cause any offense , I am sorry if I offended you.

Every blade has a tooth type and the tooth has a bevel. If you use the wrong type tooth you will tear out no matter what you do. Every blade has a tooth type and each tooth has a hook angle. Some angles are positive and some negative -- all relative to the arbor hole. If you are cutting too far outside of the materials you will change the angle at which the "chisel" cutting edge meets the stock. This will be further complicated by the angle cut, which is a deeper cut -- think of a hand plane with an improper bevel or cutting edge set wrong for the cut. The following rules (generally) apply for blade selection.
Find the tooth spacing -- the circumference divided by the number of teeth will give you an approximate blade tooth count needed. A 7.25" blade X3.14 = 22.765" divided by the tooth count of 40 = .569" You will need at least one tooth in the material, but more teeth will be carrying sawdust and that will cause tear out on thicker stock. On a bevel cut you are cutting a lot of surface and trying to clear the cut without raker teeth. You will have tearout, too much sawdust to clear and no place to go, so the cutting teeth have to do the work, which will further complicate the cut -- tearout problem. Following are generalized rules for blade selection (and they are general).
  1. Always at least one tooth in the material. Go by tooth spacing for a starting point.
  2. For hard or strong materials, more teeth.
  3. For soft or less strong materials -- fewer teeth.
  4. For thick materials, fewer teeth.
  5. For thin materials, more teeth.
Plus: Just like on a table saw, you do not want the blade all the way up. Clear the material enough to have at least one full gullet above the stock. You will lower the blade the same way for a circular saw. This will keep the hook angle at it's best presentation to the stock. IF you are pushing the limits of your depth of cut, on that bevel, you may not be clearing the cut enough to discharge the sawdust, and that is packing the kerf and causing your tearout. A negative hook may be of help in that case.

I have attached a blade alignment drawing to help with alignment diagnosis of the cut.

Also attached is a tooth grind chart to help with a proper match to the materials you are trying to cut.

The "blade of the day" may be part of the problem, and that is why I asked. Many of the mass market blades are coming to the shelf at the store with very substandard manufacture. You can do everything just right and the blade may be the problem. Sometimes the problem is the woodworker, sometimes the saw, many times it is the blade selected for the task.

I hope that gives you some places to look for your solution.

Phil
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  #9  
Old 04-19-2013, 12:50 AM
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Philphoto Philphoto is offline
 
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Default Billy is correct

Quote:
Originally Posted by Billy Shaw View Post
40
In my experience, speed of cut,more than blade,determine tear out..
You can cut CDX plywood ,,without A.C.E.,,, and a 24 tooth "framing" blade,with minimal "tear out",or "chipping" if you slow down just a little. The slower ,and more deliberate the speed,,,the less chance of a problem.
As I'm sure you know. If you scribe the top ply,or veneer with your utility knife before cutting,also helps.
Doubt it's the inserts,but maybe not understanding the problem..
Not positive,but thinking maybe you should have a separate ACE, for bevel cuts. As every bevel % will set ACE "Bottom surface", in a different spot. For instance: If you've already made a few 45% cuts with a particular ACE. If you make a 30% cut with same ACE. Your blade will be a little farther away from ACE ,at bottom surface.
Not much farther. But in materials described above,and a duller blade,or too fast of a push,,,,might make a difference..

Anyone else??

Hope I could help,
The speed of cut you refer to is formally called "feed rate" and you are absolutely correct. The typical 24 tooth has raker teeth and the typical 40 tooth does not. The slower feed rate will match cut of the higher tooth count blade but without tear out because you have raker teeth. The 40 tooth count is for thinner material, and for special materials, like MDF. It is hard to remember at times because we are a more is better culture, but the higher tooth count with a fast feed rate makes no more cuts than a lower tooth count at a slower feed rate. The advantage is the raker teeth.

Phil
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  #10  
Old 04-19-2013, 01:03 PM
Billy Shaw Billy Shaw is offline
 
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Red face

Quote:
Originally Posted by sean9c View Post
Making bevel cuts your blade is likely nowhere near the ACE. There is no anti chip protection on bevel cuts. At anything but small angles your blade has cut through the sloped section of the AC-2 so it's not helping. You could take an AC-1, screw a piece of 1/2" ply to it, so that's what is running on your material. Once you've set the angle on your saw plunge that through the AC-1, so you've made an anti chip piece for that specific angle.
Yes that's right sean. My bad. Forgot I'm using the leftover,old style ace's here.
They are about 1/4" wider,but still only work when bevel 30 or so degrees or more. ooop's
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