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Bad TS Cut. What is wrong?

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Forum topic by MichaelMacD posted 01-27-2010 09:53 PM 1807 views 1 time favorited 21 replies Add to Favorites Watch
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MichaelMacD

20 posts in 2520 days


01-27-2010 09:53 PM

Topic tags/keywords: tablesaw

I was dithering around last night and thought I would cut a 2 inch square test block to verify that my TS blade was perpendicular to the table (I think one has to flip the cutoff to see if there is any gap). And lo and behold I got this result—these pics show the wood in the same orientation as it was cut. (first time entering pics… hope it works.) The cut is tight in the back, but the top/front one inch of the cut seems to have a gap.

I have a full kerf, combo blade that came stock with the SS contractors saw. I use a melamine/sandpaper face on my miter, so the wood is not slipping as I cut.

Any idea why this might be? If the blade is angled, it should still how a tight cut before one flips the cutoff to check for perpendicularity (I made that word up). If the miter path is parallel but the miter is not square, then the cut should still be tight. I was thinking this is a result of the blade out of alignment with the miter slot… or perhaps slop in the miter track… (there is some slop in these stock miters) but I didn’t find any difference in distance at front and back of blade. If it a result of arbor run out, then I would think the gap would run through the top of the cut—front to back. I am at a loss. Could it be blade vibration or technique? Any ideas what I should do?

front of cut
back of cut


21 replies so far

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MichaelMacD

20 posts in 2520 days


#1 posted 01-27-2010 09:54 PM

(pictures are truncated halfway though, which cuts off the cut in the first pic… but the second pic shows the full top of the cut. thanks for your help.)

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PurpLev

8523 posts in 3115 days


#2 posted 01-27-2010 10:04 PM

I would check for blade runout.

unplug saw from power

clamp a piece of board to your miter gauge, place miter gauge so that the board is just touching the front tooth of the blade. and hold it in place. then turn the blade by hand and see if you can spot blade runout or blade warp. if all the teech just kiss the edge of that board, then the blade is good, and the arbor runout is negligible.

next plug the saw back up, lower blade, and run some scrap board to make a groove (1/8” dado) along it’s length. push the board against the FENCE (no miter gauge). stop the saw, and check the cut line with a straight edge – if you see a curved line then some vibration is causing your inconsistent cuts.

at least this will give you a starting point.

-- ㊍ When in doubt - There is no doubt - Go the safer route.

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TheWoodNerd

288 posts in 2658 days


#3 posted 01-27-2010 10:44 PM

I would vote for the tightness of the bar in the table. It could be you’re slightly turning the gauge as the wood exist the blade, making the blade turn into the wood and trimming that corner a bit more. Or you’re relaxing once the blade is almost through and allowing it to drift in the slot.

If the bar is solid, you can use a center punch to dimple the bar and tighten it up.

-- The Wood Nerd -- http://www.workshopaholic.net

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Brian024

358 posts in 2867 days


#4 posted 01-27-2010 11:42 PM

Mine just started doing this and its driving me crazy, or more crazy. I’ll have to check it out.

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MichaelMacD

20 posts in 2520 days


#5 posted 01-28-2010 05:37 AM

I tried to accomodate for the miter track slop, and found it helped only a little—or at least appeared to produce a smaller gap. It appears that the blade is not parallel to the miter track by about .004 inches… measured by the same tooth at the front of the blade and the back of the blade. I also measured from the miter tracks on both sides. Perhaps that explains why the top left of the 2-inch block is the part that gets chewed out of square… the blade is angled closer on that side.

I checked out the SS manual. No instructions on squaring the blade. Why do I think this will not be easy?

Just about to embark on a night of research to get this done. I MUST have right shoulder cuts for my tenons.

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MichaelMacD

20 posts in 2520 days


#6 posted 01-28-2010 06:34 AM

So now I have three of the bolts loosened, and I cannot seem to get to the fourth. I assume it is the bracket bolts that hold the trunion brackets to the table top that have to be loose. Anyway, I can’t get a mallet directly on the trunion… so I am putting a short dowel rod against it and making the rod… no movement yet. I probably need to loosen that fourth bolt. Any ideas how to get to it? it is the front left bolt, and it is hidden by the height and angle gears and power switch cables and who knows what else… nuts. I am still looking for any info on the Internet to help with this. I have only found vague references to truing a contractors saw blade… have not found any pics or instructions yet.

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ajosephg

1878 posts in 3028 days


#7 posted 01-28-2010 06:55 AM

Check out this Table Alignment website. It really helped me beat my saw into submission.

If you have three of the four bolts loose you should be able to adjust the trunion. If you can’t, here are several possible reasons.

1. The washers between the trunnion bolts and the trunnions have become dished (bent inward) keeping the trunnions from sliding.

2. The trunnion slots may not be long enough (requires dissasembly and filing them out.)

I also find it difficult to move the trunnions by pounding on them with dowels or whatever, and found a Quick Grip Clamp or equiv. works better because it holds the trunnion in place. What may be happening is that when you tap it with your dowel, it moves, but immediately springs back to where it was and it seems like it didn’t move. The clamp holds it in place so you can retighten the bolts.

What I found worked best on my saw (to reach the front bolts) was to buy a 24 inch long 3/8” drive extension so I could reach up from beneath the saw.

If your misalignment is only 0.004 inch, I don’t think that is your problem, as most “experts” say anything better than 0.005 is acceptable – IF MEASURED ACCURATELY. The referenced website will provide a reality check on how to measure. LOL – now that you’ve loosened it all up you’re committed to fixing it.

If you are interested, I wrote a paper on the exercise I went through to fix my saw a while back. Send me a PM and we can exchange email ADDY’s.

-- Joe

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MichaelMacD

20 posts in 2520 days


#8 posted 01-28-2010 07:27 AM

Well… it is possble that I made a difference. (Though .004” is not much, and I am measuring with a hand-held caliper, not a dial gauge in the miter track. However, each time I measured—perhaps a dozen, using inside blade to inside track as well outside blade to outside track dimensions—I saw a similar different between the front and back of the blade.) So I loosed three bolts and wacked the back trunion bracket a few times. It seemed to make a difference. And when I measure now, it seems only .001 or .002 difference. woo hoo.

But, and here is the rub, no difference in the cut. And now that I think of it, I was probably barking up the wrong tree. If the blade was angled and chewing at the left side of the cut, then the gap would be more consistent across the cut… not just at the front. Isn’t that really odd—only at the front inch of the cut? and only about an inch off the table. The kerf for the first inch seemed fine.

I tried PurpleV’s first suggested test and did not detect any runout. I didn’t try the kerf-straightness check yet with a rip cut… I will do that next.

I also tried raising the blade to max height so the cut would be made more vertically, and I didn’t pass the wood through the back teeth… no real difference in the problem from the way I was cutting before.

Joe—I will check out that ailgnment page. I may tried it again once I have purchased a proper gauge. And I will take you up on your offer of your prior experience write-up.

So all in all, this is a real bummer. I will have to stop bragging to my wife about how sweet this saw cuts. (She didn’t care anyway.) On the bright side, if I keep all my cutoffs to the left, I won’t have a problem.

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Luke

545 posts in 2761 days


#9 posted 01-28-2010 07:53 AM

You really should invest in a dial gauge for your saw. The In-Line Industries Versions are great. Heres the steps you need to take after you get one.

1. Check the arbor for excessive runout.
2. Check the blade for excessive runout.
3. Parallel the miter slot(s) to the blade.
4. Parallel the fence to the miter slot(s).
5. Square the blade to the table top 90 degrees.
6. Square the fence to the table top 90 degrees.
7. If using a miter gauge or sled square that to the blade 90 degrees.

If you do all of this and still get the same results then I would look at your technique or if the saw is vibrating so badly that you can’t get it to go through cleanly. If you buy the gauge from in line there is a bunch of videos on their website for how to do all this and there are instructions in the box.

-- LAS, http://www.abettersign.com

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PurpLev

8523 posts in 3115 days


#10 posted 01-28-2010 07:53 AM

have you tried a different blade? if not – thats another thing you can try.

-- ㊍ When in doubt - There is no doubt - Go the safer route.

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MichaelMacD

20 posts in 2520 days


#11 posted 01-28-2010 10:07 PM

No… I have not tried a diff blade yet. I have been meening to buy a better crosscut blade, so I might do that now. Right now, I am using the combo blade that came with the saw. It looks like I need to buy a proper dial gauge and go through the whole set of steps that Luke (i.e. skywalker01) outlined. I was hoping to find a shortcut to the solution.

I actually cut a 2×6 last night on its side using the miter gauge. I found that the kerf at the bottom front was about 0.128, and at the top of the cut—3 1/8 above the table—the kerf was 0.140. I assume that this result is just not right and I should continue to seek a fix. The blade teeth are about 0.118 according to my calipers. Is the extra .010 at the very bottom of the cut indicatative of the problem also? Should the kerf be the exact size as the blade?

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ajosephg

1878 posts in 3028 days


#12 posted 01-28-2010 11:33 PM

Without doing a lot of thinking, that sounds like excessive run out caused by one or more of: warped blade, bent arbor, or excessive run out on the blade mounting flange.

The kerf should be very slightly larger than the blade, but unless yours is a thin kerf blade I doubt it is only 0.118. I think most blades are right at 0.125. I’m going to the shop in a little while and I’ll check what mine is and report back.

-- Joe

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ajosephg

1878 posts in 3028 days


#13 posted 01-29-2010 01:26 AM

Well, looks like I have to eat a little crow about kerf width.

I measured my Freud Ultimate 80 tooth crosscut blade with a pair of digital calipers and the width from the outside of the left teeth to the outside of the right teeth measured 0.125. Disclaimer – this is a tough measurement to make with a caliper with only 1 inch wide jaws.

Then I made a cut with a depth of approx. 1/4 inch and measured its width a with feeler guage, and the width was 0.117 inch. Made another cut with a 2 inch depth and measured its width at the top and bottom. The width was the same (0.117 inch). (The top and bottom width using digital calipers “could be made to” read 0.125 inch, but I had to use a little more force than I normally use.)

(Again, this is a difficult thing to measure with the tools available to me. Measuring the kerf with with calipers is not easy and the results suspect because of the fact that the wood easily deforms. If you want better accuracy, I think a set of plug gauges would be better.)

At any rate, the bottom line is that a variation of 0.012 inch from the bottom to the top of a kerf as you got is excessive, compared to what I got. My saw is an old Delta clone contractor saw that I’ve spent a lot of time getting it tuned up. I used an Osborne EB3 Miter gauge to make the cuts described above.

-- Joe

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Luke

545 posts in 2761 days


#14 posted 01-29-2010 03:34 AM

Unless your just trying to get through this and move on then I would really consider the Dial Gauge. You’ll use for more than just your table saw and you’ll be amazed how much better your cuts will get when everything is exact.

That said it sounds like you have some sort of wobble or runout issue. I guess you could just buy a new blade and hope that will fix it. Or maybe switch to another blade that you have and see if that fixes it. If you get one and it still happens it could be the arbor which you would then need to check with your Gauge.

Something I missed in my list.

.01 Make sure the wings (if applicable) are flat and parallel to the main table.

-- LAS, http://www.abettersign.com

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MichaelMacD

20 posts in 2520 days


#15 posted 01-29-2010 06:36 AM

OK… so I went by harbor freight and got a dial gauge… and some clamps… and two hold downs. I almost bought a planer. $219 instead of $249. But came to my senses and left with my treasure.

1. Check the arbor for excessive runout.—no run out… sometimes wobbles toward .001, but not consistent. I also check the rim of the arbor washer (is that what it is called?) and it was fine too.

2. Check the blade for excessive runout.—I believe there was too much variance in the blade. It appears to reach .006 across one section on the blade plate

3. Parallel the miter slot(s) to the blade— I thought I did this last night, but the dial gauge begged to differ. So I did it again (but with the bad blade). It looked OK, but I need to check it again with a new blade. I found that if I started tightening with a different bolt, I got a better result. Otherwise, I didn’t seem to have much control, other than watching the dial move as I tightened. But knowledge is power. With the calipers, it was more frustrating.

4. Parallel the fence to the miter slot(s).—I did this and found that the fence had some bumps…I didn’t think it was enought to worry about, though. Not really part of the problem, but I was on a roll with the dial gauge..

So after all this, I decided to try another blade—a freud glue-line rip blade. I didn’t want to use this. As I don’t have a jointer, I am trying to only use this specifically for when I need to create a glue-ready edge. But I didn’t have a chance to buy a new combo or cross-cut blade, and one cross-cut won’t hurt. So I cut a 2×6 like last night. And behold, a fine cut! It appears my problem was the blade. It must really be in bad shape. I assume this is not fixable and I need to just toss it. Or I can save it and use it for rough cuts.

here is a pic of my three cut tests—the stock blade actually did say .118 on it. Not full “full kerf”. The new freud blade just says 1/8. The first two cuts are with the old blade and had identical dimensions (nice—consistency). The kerf of the third cut is from the new freud triple chip blade and is .122 at top and bottom.

cut tests

I haven’t done the rest yet… I want to check the blade once it is at 45 degrees as part of re-testing #3.

5. Square the blade to the table top 90 degrees.
6. Square the fence to the table top 90 degrees.
7. If using a miter gauge or sled square that to the blade 90 degrees

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