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Discussion Starter · #1 ·
Hey there,
I recently built a tenoning jig and was sure to square everything before glue up. I built it to be able to cut the 22.5 degree miters for a memorial flag case. I have noticed that the height of the waste piece is taller by 1/8" on the leading side gradually getting shorter towards the back of the piece as it is cut. I am trying to figure out why this is happening. From what I can tell everything is square. I have also noticed that my table saw blade is 1/16" close to the miter slots at the teeth than in the middle of the blade. I don't know if that is normal or not. It's a Ridgid R4512 10" table saw. I was able to create a mock up of the flag case but since the 22.5 degree corners are not a perfect fit the 45 degree miters at the top does not butt up properly leaving a gap. I'm attaching photos to illustrate each of these issues. Can anyone tell me why this is happening and whether it is normal for a table saw blade to be at different distances from the miter slot?
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Edge of blade (at the teeth). 5 and 9/16ths
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Center of blade. 5 and 5/8ths
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Homemade Tenoning Jig
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22.5 Miter. This doesn't seat the same across the glued surface.
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45 degree Miter at the top not seating correctly.
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Height of waste piece across the cut. The longer side is the leading edge when being fed to the blade.
Any help would be greatly appreciated.
Thanks,
 

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Discussion Starter · #2 ·
Apologies. The distance on the first saw blade picture should be 11/16ths instead of 9/16ths.
 

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The blade and arbor are attached to a cast iron carriage that has "trunnions" at either end. These are bolted to the bottom of the table with slightly enlarged holes.
The trunnions permit the carriage to be tilted for cutting bevels, but have stops at 45 degrees and 90 degrees, which are adjustable.

What you need to do is loosen the 4 retaining bolts just slightly, determine which way to "bump" the carriage to make the blade parallel to the miter slot and then snug the bolts, rechecking for parallelism and finally tighten them. The saw may have not been properly aligned from the factory, but more than likely it got severely bumped during it's life span.
Good luck on getting it adjusted so you can enjoy it!

BTW, this not a "fun" project if you are elderly, because it means laying down under the saw to reach the bolts, getting back up to check the alignment, laying down again to snug them, getting back up to make sure it's still aligned and finally laying down again to tighten them ..... just sayin'
An easier way, and the way I do it is to lay the saw on it back, removing the motor first so you can reach around to get to the bolts and measure at the same time.
 
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Discussion Starter · #4 ·
Would this misalignment cause the kind of miscuts that I have outlined or could it be something else as well?
 

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where's my table saw?
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Would this misalignment cause the kind of miscuts that I have outlined or could it be something else as well?
I recommended the proper way to fix your issue.
 

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Would this misalignment cause the kind of miscuts that I have outlined or could it be something else as well?
Frankly, the answer to the question does not matter. A misaligned table saw will be the root of many mysterious woodworking problems until you get it fixed. Worse yet, a misaligned table saw can be very dangerous.

Check your table saw alignment. If your table saw is not properly aligned, then stop and fix that first.
  • Align the blade with the miter slots.
  • Align the fence with the miter slots. After you do this, the fence will be aligned with the blade.
    • Note: If you always cut with the fence on one side of the blade, then some woodworkers "toe out" their fence away from the blade by a few 1000ths of an inch, comparing the front and back of the fence. Otherwise, leave it perfectly parallel to the blade. Never allow the fence to toe in. A toed-in fence is dangerous.
  • Optional, but Recommended:
    • Check and adjust the blade tilt stops and indicator. Make sure that 90 degrees is perfectly square to the table.
    • Check and adjust the fence tape measure indicator for your favorite blade.
Do a web search for "R4512 alignment" and you will find many resources to guide you.

After that, test the tenon jig and see what happens.
 

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In addition to the comments already made, I highly recommend buying John White's "Care and Repair of Shop Machines" for a great description of aligning your table saw (and setting up other ww'ing machines, as well). I'd use a dial indicator (the HF one works fine) to check alignment; reading off your speed square rule markings won't cut it. As far as your poorly matched 45 and 22.5 degree cuts, it could be: 1) fence (and jig) not parallel to the blade; 2) jig vertical support block (the one attached with knobs) not exactly perpendicular to the table; and/or 3) blade tilt not exactly 45 and 22.5 degrees from vertical- don't trust the saw's tilt gauge. Good luck!
 

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Discussion Starter · #9 ·
In addition to the comments already made, I highly recommend buying John White's "Care and Repair of Shop Machines" for a great description of aligning your table saw (and setting up other ww'ing machines, as well). I'd use a dial indicator (the HF one works fine) to check alignment; reading off your speed square rule markings won't cut it. As far as your poorly matched 45 and 22.5 degree cuts, it could be: 1) fence (and jig) not parallel to the blade; 2) jig vertical support block (the one attached with knobs) not exactly perpendicular to the table; and/or 3) blade tilt not exactly 45 and 22.5 degrees from vertical- don't trust the saw's tilt gauge. Good luck!
I just used my MHC dial indicator magneted to the top and wound the blade all the way up and down. There is somewhere between 55-60/1000ths of an inch of a difference. It is worst when the blade is all the way up. I'm going to have to spend a while this weekend tuning up my table saw for sure. Thanks for all the advice. I'm only 37 but i feel old enoughto not look forward to the up and down of making all of the adjustments and checking them. Good stuff to know though.
 

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I have the same saw, and I've never had to adjust the trunnions, only aligning the fence and blade. Obviously, since you have a fence mounted jig, make sure your fence is aligned with the blade. The owners manual has pretty good instructions for this, but I would add, keep the bolts as tight as possible, but still loose enough to shift the fence, and push the locking handle down before you check alignment and tighten the bolts.

I suspect you have a combination of the fence not being aligned with the blade, an imperfect jig, and you're not perfectly setting the blade angle precisely enough.

You have to have everything right on for those long miter cuts, flat, square wood, perfectly square ends on the workpiece, aligned saw, perfect jig.

From what I see, you're trying to hold a piece vertically in the jig, while the blade is angled?

From the problem you describe about the cutoff getting smaller, that could mean that the fence is is slightly angled towards the blade (to the left). As you push the jig along the fence, the jig moves slightly towards the blade, which puts more blade into your waste piece at the end of the cut, making it smaller.

Also, really take a look at that jig. You won't get a perfect cut if that jig is:
  • not holding the workpiece perfectly 90° to both the saw table (tilted left or right)
  • Not holding the workpiece perfectly 90° to the path of the blade (tilted forward or back)
How do you set the blade angle? Are you using the Wixey I see in the picture? If so, make sure you have it on the flat part of the blade. Even then, it may not be good enough for that type of cut, since the Wixey only measures to 1/10 of a degree, so if it's 1/20 off, that adds up over more cuts.

Good luck, and let us know how it goes.
 

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I just used my MHC dial indicator magneted to the top and wound the blade all the way up and down. There is somewhere between 55-60/1000ths of an inch of a difference. It is worst when the blade is all the way up. I'm going to have to spend a while this weekend tuning up my table saw for sure. Thanks for all the advice. I'm only 37 but i feel old enoughto not look forward to the up and down of making all of the adjustments and checking them. Good stuff to know though.
Leave the dial indicator in the case, that particular measurement isnt going to help narrow down anything, if for no other reason than youre measuring off a very inaccurate surface. Table saw blade bodies are seldom perfectly flat or straight, and once you add together all the possible sources of inaccuracy in that particular measurement, its completely useless

If you want to use the indicator for something, use it to check the alignment of the blade to the miter slots. Fix the indicator to a miter gauge, push the miter bar gently to one side of the miter slot to take up any slack, then zero off a tooth. Move the miter gauge to the back side of the blade, then rotate the blade so that youre measuring off of the same tooth, note the difference. Measuring off the same tooth is important, as if you try to measure off a different tooth you bring possible sources of error like warp in the blade into play. If you get more than about .010" difference front to back, you need to work on aligning your trunnions: Table saw alignment
 

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I agree an alignment is in order but I think there are other factors - blade deflection (thin kerf), securely holding material (I assume you are clamping piece to jig), feed rate, sharp blade.

That said, a properly aligned fence is 3-5 thou wider at rear of blade. I’ve never seen a noticeable issue with jig that rides along the fence, but I wonder could this be magnified when making bevel cuts?

I recommend using a full kerf blade, both for the alignment and the cut.
 

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, but I wonder could this be magnified when making bevel cuts?
Agree, any little thing off is magnified on that type of cut. Good call on potentially using a full kerf blade. I've actually never used one on my R4512. I only use the thin kerf Freud Industrial blades.
 

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Discussion Starter · #14 ·
Agree, any little thing off is magnified on that type of cut. Good call on potentially using a full kerf blade. I've actually never used one on my R4512. I only use the thin kerf Freud Industrial blades.
I’m using the same blade on this saw and it is brand new. I have only made about a dozen cuts with it and the were all made using the tenoning jig.
 

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Discussion Starter · #15 ·
I have the same saw, and I've never had to adjust the trunnions, only aligning the fence and blade. Obviously, since you have a fence mounted jig, make sure your fence is aligned with the blade. The owners manual has pretty good instructions for this, but I would add, keep the bolts as tight as possible, but still loose enough to shift the fence, and push the locking handle down before you check alignment and tighten the bolts.

I suspect you have a combination of the fence not being aligned with the blade, an imperfect jig, and you're not perfectly setting the blade angle precisely enough.

You have to have everything right on for those long miter cuts, flat, square wood, perfectly square ends on the workpiece, aligned saw, perfect jig.

From what I see, you're trying to hold a piece vertically in the jig, while the blade is angled?

From the problem you describe about the cutoff getting smaller, that could mean that the fence is is slightly angled towards the blade (to the left). As you push the jig along the fence, the jig moves slightly towards the blade, which puts more blade into your waste piece at the end of the cut, making it smaller.

Also, really take a look at that jig. You won't get a perfect cut if that jig is:
  • not holding the workpiece perfectly 90° to both the saw table (tilted left or right)
  • Not holding the workpiece perfectly 90° to the path of the blade (tilted forward or back)
How do you set the blade angle? Are you using the Wixey I see in the picture? If so, make sure you have it on the flat part of the blade. Even then, it may not be good enough for that type of cut, since the Wixey only measures to 1/10 of a degree, so if it's 1/20 off, that adds up over more cuts.

Good luck, and let us know how it goes.
Yes I’m using the Wixey and I am putting the pieces through vertically. I will be checking the fence alignment when I do the tune up of the saw this weekend. The readings I was getting on the dial indicator were from the miter slot.
 

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I just used my MHC dial indicator magneted to the top and wound the blade all the way up and down. There is somewhere between 55-60/1000ths of an inch of a difference. It is worst when the blade is all the way up. I'm going to have to spend a while this weekend tuning up my table saw for sure. Thanks for all the advice. I'm only 37 but i feel old enoughto not look forward to the up and down of making all of the adjustments and checking them. Good stuff to know though.
The table saw blade is a flat, round plate or in geometry terms a "plane". If you have aligned that plate vertically, for parallel to the the miterslot that's one step. The other step is to tilt the blade over to 45 degrees, fully up and see it it's still parallel to the same miter slot. If not you will need to shim under one of the mounting bolts that secure it to the table and recheck it. There are videos for this process on You Tube, but it's relatively simple.

I like the Stump Nubs version because he speaks in plain English and does not overly complicate the process. For a contractor type saw the process starts here:
 

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The blade must be parallel with the miter slot. This is the section of the manual covering that adjustments.
The fence is also aligned to the miter slot.
Actually if you set the fence 3-5 thousand wider towards the back of the blade (IOW slightly toed out) it does make a difference in the cut quality and the way wood moves through the saw.
 

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Actually if you set the fence 3-5 thousand wider towards the back of the blade (IOW slightly toed out) it does make a difference in the cut quality and the way wood moves through the saw.
Mean while, the rest of us that have no way of measuring "3-5 thousand wider towards the back of the blade" can aline our fence with the miter slot.
 
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