Is this correct, mitre gauge set up?

[devonwoody]

My incra 1000SE instruction manual says I should use a square to the blade.

However others say no set it to the mitre slot on table saw.

https://www.youtube.com/watch?v=NrTeFQ0iQ5k

What say you..

 

[MattRoberts]

The idea is that your blade should be completely parallel to the mitre slot, so assuming that's the case, either would do.

It's often easier to square against the mitre slot - no pesky teeth in the way!

 

[devonwoody]

But if the blade is not parallel to the mitre slot does the video link really work?

It is a big job to alter the blade position.

 

[Steve Maskery]

If your blade is not parallel to the mitre slot, make it so. Everything else follow after that. If your mitre fence or any sleds are to work properly, your tablesaw must be set up correctly in the first place.I admit it is a pain, and the bolts are sometimes difficult to get to, but you only have to do it once.

 

[monkeybiter]

Judging by your documented output and quality of work your blade will be 'close enough' to parallel. Any small deviation will have negligible effect. The method detailed in that excellent video will give you square cuts.

 

[katellwood]

If the blade is not parallel to the slot it will still always (well nearly always) cut square

in essence if the gap between the slot and front of the blade is less than at the back then the cut will always be square if squared from the mitre slot.

However, if the gap is smaller at the back of the blade by less than the set on the blade in reality the blade will cut twice, once when you feed the work into the front of the blade and in addition you will also get a slight upwards trim cut when the work passes the back of the blade. Therefore to get a square cut in this situation the work will need to pass both the front and back of the blade.

However Steve is right, take the time to setup the saw correctly

 

[Brentingby]

If the blade is not parallel to the slot it will still always (well nearly always) cut square

That's not exactly correct. If the slot and blade are not parallel then as the work is advanced, it will be travelling across the plane of the blade. As the work is advanced the cut face will be driven into the saw plate. If the work is clamped to the mitre gauge fence, it will cause the saw plate to deflect. If it isn't clamped securely, the plate will cause the work to shift and the cut will drift away from the line. And, yes, when the work gets to the back of the blade, it will be caught by the bases of the rising teeth. At best this will create a poor surface finish in the cut. At worst, it could lift the work and send it back in your direction.

It might be easier to understand if you picture the angle between slot and blade as some larger angle. Suppose 10°.

However Steve is right, take the time to setup the saw correctly

This is exactly correct.

 

[devonwoody]

My Incra. 1000 , the blade is square to the bar on mitre gauge.

However using a long plastic set square the slot is slightly off to the bar.

My four cut mitred corners are square.

Difficult to measure blade to table slot without engineered equipment.

But why worry if it all fits when glued up :wink:

 

[Myfordman]

You can set the blade to slot up by ear. The trailing edge teeth should just touch the workpiece and make a small sound compared to the cut by the leading edge teeth. If you have two slots, one either side of the blade, then you can compare the trailing edge tooth noise for each slot and make hair thick adjustments until both sound levels are equal.
Only once the slots and blade are parallel, should you proceed to shimming the rip fence and tinkering with the mite gauge.
With reference to the post above, two wrongs do not make a right!

 

[katellwood]

If the blade is not parallel to the slot it will still always (well nearly always) cut square

That's not exactly correct. If the slot and blade are not parallel then as the work is advanced, it will be travelling across the plane of the blade. As the work is advanced the cut face will be driven into the saw plate. If the work is clamped to the mitre gauge fence, it will cause the saw plate to deflect. If it isn't clamped securely, the plate will cause the work to shift and the cut will drift away from the line. And, yes, when the work gets to the back of the blade, it will be caught by the bases of the rising teeth. At best this will create a poor surface finish in the cut. At worst, it could lift the work and send it back in your direction.

It might be easier to understand if you picture the angle between slot and blade as some larger angle. Suppose 10°.
.

That's why I referred to the out of parallel being less than the set of the teeth on the blade and utilised the word "well nearly always". in most cases if the work is not clamped then the blade will just push the work back along the mitre gauge and possibly burn the endgrain

 

[deema]

Virtually ever old saw manufacturer, Wadkin, Startrite, Dominion, Cookson set the fence on the RHS and ensured that the blade was a degree or two out of parallel to reduce the risk of kick back. The reason for this is to ensure that the back of the blade does not toe into the fence. If it does it gets exciting.

I would never recommend setting the blade parallel to the fence which is normally parallel to the mitre slots, slightly out in the setting and you end up with a problem. Set the mitre fence with a square to the blade.

 

[katellwood]

Whatever angle you set the mitre gauge too the cut will always be parallel to the slot (as the slot dictates the line of cut) unless as identified the blade is so out of parallel that it pushes the material off on the blade side

As deema has identified the fence needs to be parallel to the blade (or a thou or two tighter at the front ) to prevent kick up as the material reaches the back of the blade trapping itself between fence and blade. however there is nothing to suggest that the fence needs to be perfectly parallel to the table slot and most decent saws have a facility to achieve this

 

[katellwood]

Repeat post, Sorry

 

[devonwoody]

I am cutting picture frames at present so only the one edge of blade goes through the timber and I am getting perfect 45% mitres. If were cutting large sheets things might need that pure set up. (sheets are done on my sled)

 

[katellwood]

One thing to bear in mind when using a sled which utilises both table slots, if the blade is out of parallel with the slots but only slightly then the cut in the sled will be wider than the actual blade subjective to the margin of error the blade is out with the table slots. In addition one edge of the cut in the sled will have been cut by the back of the blade (upcut). If this is the case and you want accurate cuts on both sides of the sled then you will need to feed the back fence of the sled completely through the blade and not just to the front cutting edge.

If the blade is out of parallel by a large amount then the sled will only cut through the blade until it starts to bind on the side of the blade thereby distorting the blade and causing burning to one side of the sled cut

One other thought relating to a blade being out of parallel, the straightness of the cut vertically will not be absolutely flat and may be out of square vertically even if the blade is set square (think of the procedure of cutting a cove on a table saw where you feed the timber at an angle to the blade) the resultant cut is not flat or square (an extreme exaggeration I know but food for thought)

http://www.finewoodworking.com/how-to/v ... lesaw.aspx

The final rule of thumb as already identified is spend the time with a spanner and rubber mallet to get the blade parallel to the slots but in answer to the OP's original question is to in my opinion to set the mitre gauge square to the slot and not the blade.