Square Cross Cuts

[JimD]

The only thing I will add is that table saws don't work well for crosscutting long, particularly if they are heavy, pieces. That is what CMSs, RASs, or track saws are for. Even perfectly set up table saws. But if the pieces you are cutting are small and not terribly heavy, then the saw setup would seem to be the issue.

My crosscutting, even for small pieces is done by the 12 inch CMS up to it's capacity of about 8 inches, the by the RAS up to it limit of about 12 inches and then the track saw. If I already had the crosscut jig on the workbench I would use the track saw on small pieces. It is very accurate and safer to use, I think, than the other tools. Dust collection is better too. For one or two crosscuts wider than the CMS or RAS will handle, I mark and cut with the track saw. I only rip on the table saw.

 

[chris_goris]

I never questioned the idea of squaring the miter fence to the blade until we had the NCWW chat with Mark Duginske back in 2013. He wasn't able to participate live due to some technical issues, but he answered all the questions that we came up with ahead of time. The transcript can be found here: http://www.ncwoodworker.net/forums/content.php?r=150-Mark-Duginske-Bandsaw-Guy-Chat-2013-Jan-17

One question was: "What are some examples of bad information on woodworking that is being distributed on the internet and magazines" One of his responses to this question was "Squaring the miter gauge to the blade"

I didn't understand this at the time, I was really confused by the statement. So much so, that I even tried e-mailing Mark, but I didn't get a response. When setting up a sliding table saw, this concept "clicked" for me and I finally understood what Mark was saying. I just did a quick google search on the topic, and this site (which I have never seen before today) by NCWW's very own Tom Hintz came up. It does a better job of explaining the concept than I did. It even has a video. http://www.newwoodworker.com/squrmitrgag.html


I personally try and have both the miter slot and the rip fence as close as possible to parallel with the blade, without either of them being toed in towards the blade. I find that I get less burning on both the keeper piece and cutoff piece when things are set up as close as possible to parallel, but this is NOT a necessary condition to get parallel cuts when ripping or square cuts when using the miter gauge. This isn't an opinion, this is just the result of physics. The micro-cove that I brought up earlier (and is mentioned by Tom Hintz) is the only non-ideal effect of not being perfectly parallel to the blade and it has nothing to do with the cut being square or parallel.



Kelly Mehler (author of "Mastering Your Tablesaw") talks about the two schools of thought when setting up the rip fence. One schools says make it parallel to the blade, the other school says set it up so it is toed away from the blade slightly. Lots of different ways to skin a cat. We all have our personal preferences, but there is a huge body of evidence to suggest that both ways are acceptable and used by well known successful woodworkers.

I like Howard's setup method. It should give good results and it doesn't require any special tools which is always nice.

What do you suppose is causing burning when cross cutting? Its not the wood closing down on the blade from internal wood stresses, its misalignment. The wood is being forced against the blade either inside or out depending on how misaligned the blade is to the miter slot. The wood is coming in contact with the flat blade surface beyond the teeth as it is fed through pushing the workpiece right or left. Again, I ask you to exagerrate the scenario in your head so you can grasp what Im talking about. suppose the blade was at a 45 degree angle to the miter slot? would it still cut your board? It should if what you are saying is true.

 

[Jeremy Scuteri]

What do you suppose is causing burning when cross cutting? Its not the wood closing down on the blade from internal wood stresses, its misalignment. The wood is being forced against the blade either inside or out depending on how misaligned the blade is to the miter slot. The wood is coming in contact with the flat blade surface beyond the teeth as it is fed through pushing the workpiece right or left. Again, I ask you to exagerrate the scenario in your head so you can grasp what Im talking about. suppose the blade was at a 45 degree angle to the miter slot? would it still cut your board? It should if what you are saying is true.

I have noticed burning when ripping wide boards (when the offcut is wide enough that is doesn't just deflect instead of being pushed into the blade and burning), not cross cutting, but I agree 100% with your description of the scenario. Mis-alignment causes burning. That is the biggest reason I prefer to keep things as close to parallel as possible. You can control which side of the blade burns the wood by steering the mis-alignment to either side, why not shoot for perfect and get burn free cuts on both sides of the blade.

Note that I am not saying that I keep things parallel to make square crosscuts and parallel rip cuts, because parallelism to the blade isn't necessary to achieve those tasks. Cutting at a 45 degree angle to the blade would work fine if you took successive light passes like one does when making a cove. The resulting cut would be no more or less square (or parallel if ripping) than it would be if you were cutting parallel to the blade.

 

[chris_goris]

Jeremy, do you agree that my workpiece will come in contact with the non cutting face of the sawblade (on either side depending on the misalignment direction) if I simply align my miter fence to the T slot as its fed into the blade?.
This condition becomes magnified with a wider workpiece (longer crosscut) and it also depends on blade height , to further muddy the waters here. Blade height is a function of this because more of the non cutting face of the blade is exposed to the cutting face of the workpiece.

 

[Mike Davis]

In my experience a misaligned blade tends to pull the work into alignment causing a tapered cut. Excessive force will counteract the pull keeping the cut straight with burning and rough blade marks. A true, square blade is easier to feed and gives a clean smooth cut.

 

[Jeremy Scuteri]

Jeremy, do you agree that my workpiece will come in contact with the non cutting face of the sawblade (on either side depending on the misalignment direction) if I simply align my miter fence to the T slot as its fed into the blade?.
This condition becomes magnified with a wider workpiece (longer crosscut) and it also depends on blade height , to further muddy the waters here. Blade height is a function of this because more of the non cutting face of the blade is exposed to the cutting face of the workpiece.

I agree with everything you just said. To be clear, I am not advocating that people set up their saws with large mis-alignments. I am only saying that a mis-alignment of the slot to blade by itself does not cause a cross cut to be out of square. A mis-alignment should be avoided for lots of practical reasons that you have mentioned. A crosscut not being square just isn't one of them.

Another way to view this would be to just trim a tiny bit off the edge of a wide cross cut piece with the miter slot at a large angle to the blade. It would work fine and the cut would be square. As you try and crosscut a piece with a large offcut, things get trickier due to the effects you mentioned above. This is the exact reason why I stated in my previous post that you would have to take successive light pass (just like one does when making a cove on the tablesaw) if the miter slot were at a 45 degree angle to the blade. This is really impractical to do and nobody in their right mind would set up a saw this way, but it illustrates the point that the parallelism of the miter slot to the blade is not strictly necessary for square cuts.

 

[Mike Davis]

That would only be true if the offcut is away from the leading edge of the blade (blade angled toward main piece of wood). If the leading edge is away from the main piece of wood (leading edge toward offcut) the wood will be pushed away from the teeth by the plate of the blade until the rear teeth start cutting.

 

[bluedawg76]

That would only be true if the offcut is away from the leading edge of the blade (blade angled toward main piece of wood). If the leading edge is away from the main piece of wood (leading edge toward offcut) the wood will be pushed away from the teeth by the plate of the blade until the rear teeth start cutting.

exactly. so when in doubt, just square it up -miter slot to blade, fence to blade

 

[bluedawg76]

cross cuts are much easier with a sled. well worth the effort IMO. you can eliminate board slippage and repeat cuts are more consistent if you incorporate a stop block.

 

[chris_goris]

That would only be true if the offcut is away from the leading edge of the blade (blade angled toward main piece of wood). If the leading edge is away from the main piece of wood (leading edge toward offcut) the wood will be pushed away from the teeth by the plate of the blade until the rear teeth start cutting.

Exactly... and this by definition, at least mine, is NOT a clean, straight true cut and this is what happens when leaving blade parallelism to the miter slot out of the equation.

 

[Gofor]

Need Some Help

Having a problem getting square cross cuts. Boards have been jointed so the broad and narrow sides of the board are flat against the table and the miter. Each side of the blade appears to be parallel to the edges of the throat-plate recess, at both the front and back positions. Miter gauge is square to the blade.

But when I put a square on the end of the board after I make a cross cut, the leading edge of the board (the edge that enters the blade first) is off by a bit less than 1/32” of an inch compared to the back. Not exactly square. I’ve even allowed for some minor play in the miter gauge to the miter groove by holding the miter tight against one side or the other of the miter groove.

Have checked for wobble in the blade as it circulates but either I'm not noticing it or the movement of the blade is fine. Wondering if the source of the problem is the blade trunnion – haven’t tried to adjust that yet because I’ve never done it before.

Table saw is a Ridgid 10-inch TS3650.

Any ideas?

I have had the same thing happen a time or two on my TS3650. Every time, the problem has been the splitter. If its skewed a little either way, the back end will force the board left or right as it progresses through the cut. On a long cut, it will actually cause a curved cut.

Check the splitter alignment for the entire length of the splitter.

I like everything about my TS3650 except the splitter, which is aggravating at its best, and really frustrating at times to set properly. If using thin kerf blades, the difficulty in setting it right is really a pain because the splitter is as wide as the blade, which is one reason I mainly use full kerf blades now. When it really gets me aggravated, I remove it and use other means of kick-back prevention (i.e feather boards on the fence and/or along side the work)

Go

 

[Jeremy Scuteri]

Exactly... and this by definition, at least mine, is NOT a clean, straight true cut and this is what happens when leaving blade parallelism to the miter slot out of the equation.

Once you start adding addition descriptors and requirements such as clean, true, burn free, etc, then the game changes completely. If the only properties are square crosscuts and parallel rips, then it is a much easier task and parallelism doesn't matter (there are caveats though which have been described in detail in previous posts).

I don't think we are actually disagreeing with each other here. I suspect we are actually talking about slightly different things. You are talking about pretty much all aspects of the cut; burning, cleanness of the cut, whether or not that is any kind of micro-cove on the cut edge, etc. I am *only* talking about whether the cut edge will be square for crosscuts and parallel for rip cuts. I won't say any more on the topic.

 

[Mike Davis]

Jeremy, your theory holds true as long as the pitch of the blade does not exceed the overhang of the teeth past the width of the plate.

Once the pitch exceeds the width of the teeth then the plate will push the material in one direction or the other.

 

[Jeremy Scuteri]

Jeremy, your theory holds true as long as the pitch of the blade does not exceed the overhang of the teeth past the width of the plate.

Once the pitch exceeds the width of the teeth then the plate will push the material in one direction or the other.

I agree Mike. Raising the blade a little at a time and taking successive light passes like one does when cutting a cove would alleviate this limitation. I said i wasn't going to comment any more on this, but I really have a hard time keeping my big mouth shut (in case nobody has already noticed).

 

[Raymond]

, but I really have a hard time keeping my big mouth shut (in case nobody has already noticed).

Say it ain't true, Jeremy. :wwink:

 

[chris_goris]

I agree Mike. Raising the blade a little at a time and taking successive light passes like one does when cutting a cove would alleviate this limitation. I said i wasn't going to comment any more on this, but I really have a hard time keeping my big mouth shut (in case nobody has already noticed).

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