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what is causing tapered cuts on table saw?

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Forum topic by jcwalleye posted 03-19-2010 01:22 AM 2183 views 0 times favorited 20 replies Add to Favorites Watch
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jcwalleye

291 posts in 1759 days


03-19-2010 01:22 AM

Topic tags/keywords: taper alignment question tablesaw

I’m going to demonstrate my inexperience here, but today my table saw started cutting tapers when ripping. The saw has worked great since I set it up 5 months ago but today when ripping some poplar I noticed there was a 1/16” taper over the length of a 6’ board. I checked the fence and blade alignments, cleaned the arbor, changed blades, removed my fence face but still get a slight taper. Today was the first time I used a new rip blade but I get similar results after changing to a combo blade.

Photobucket

Do you folks have any suggestions what I should check to solve this? I don’t want to start the alignment process over, but that’s all I can think of to do. I don’t know what would cause a table saw to cut a taper short of a taper jig. I do have to move the saw around a lot.

Thanks in advance.

-- Trees, a wonderful gift --Joe--


20 replies so far

View eastside's profile

eastside

94 posts in 1948 days


#1 posted 03-19-2010 01:25 AM

Just a shot in the dark but check the straightness of the fence. If it hooks toward the blade at the end it will move the board.

-- Mike, Westport MA.

View Michael Murphy's profile

Michael Murphy

448 posts in 1692 days


#2 posted 03-19-2010 01:37 AM

Could it be just the tendency of poplar to contain stresses, reaction wood, and move around a bit? Try a strip of plywood or Particle board. What happens to it?

Is there an abundance of dust shooting up at the back of the blade? Is the fence parallel to the blade or just a hair farther away at the back of the blade?

Nice Saw.

-- Michael Murphy, Woodland, CA.

View jcwalleye's profile

jcwalleye

291 posts in 1759 days


#3 posted 03-19-2010 01:49 AM

Thanks for the reply.

The fence is flat according to two different 4’ straight edges. I checked the blade and fence alignment to the miter slot with a dial gauge. The blade was dead on within .001. The fence was also fairly close over its length, but there were some indentions of about .005 where the auxillary fence holes were punched out. I wonder if something in the fence rails or rail support could be causing this.

I tried with some plywood and get the same results. That was in the picture. Didn’t notice any extra dust, but do use a vac.

Any more ideas?

-- Trees, a wonderful gift --Joe--

View ToddTurner's profile

ToddTurner

144 posts in 2010 days


#4 posted 03-19-2010 02:03 AM

The first thing to do is pack the saw up in its original packaging and send it to me.
The second thing to do is call Rigid directly and talk to their technical support folks. THey are truly great.
What you may want to do is check the alignment if the table top, blade, fence, AND miter slots. If any one of these is out of whack from any of the others, you will get what you are getting now. Been there. Look under the saw and there should be adjustment screws in several places. they are there for a reason-to adjust to different blades, materials and habits. even if they are aligned, move them a bit in a direction opposite of your outage. Believe me, this is a phenominal saw and it will take a while to dial it in. Once you do, you will be in heaven.
Lastly, the last thing you mentioned was a new blade. try the old one and see what results you get. THen, when its all aligned, refer to suggestion #1.

Todd

View Brad_Nailor's profile

Brad_Nailor

2531 posts in 2644 days


#5 posted 03-19-2010 02:21 AM

Truthfully I think your setup might be a tiny bit out of alignment. My saw has a biesmeyer on it and the manual suggests that the fence should lean away from the blade about 1/64 of an inch to help prevent kickback. My fence is a tiny bit less than 1/64. Are you really working wood with less than 1/64” tolerances? And really…who knows if you were holding the piece perfectly against the fence..the slightest movement would cause a variation equal to what you are seeing. 1/16” is unacceptable..but 1/64 is..IMHO

-- http://www.facebook.com/pages/DSO-Designs/297237806954248

View grumpycarp's profile

grumpycarp

257 posts in 2432 days


#6 posted 03-19-2010 02:28 AM

Is the wide end on the infeed or outfeed side of the cut?

Did you join the edge facing the fence prior to the cut? ( I see from the photos that it seems to be fat at the front)

You stated that you installed a new blade. Did you check this blade for parallel to the fence/miter slot or did you go with a previously checked setup? It can change every time you remove and install even the same blade of your arbor washers are not completely co-planar.

1\64th over four feet on plywood isn’t really that huge of an issue. Particularly when ripping thin stock in plywood in the “wrong” way. By wrong I mean against the grain of the top and bottom veneers. It could easily have something to do with the mechanics of your input at the blade.

If I had to hazard a guess I would, (after checking the above) guess that the fence is slightly toe in at the back.

One other thing that sometimes occurs with people using table saws and can result in the cut being skinny at the heel is the following: when pushing the stock through the blade, particularly with a push stick on narrower stock, the “waste” side of the stock isn’t followed through like the fence side is, resulting in a little nib of stock left at the very back of the “off” side. If you then immediately present this face to the fence you will get about half way through a four foot cut before the “nib” contacts the fence and begins to push the stock further over into the blade, resulting in a cut that is tapered unless checked at the absolute extreme end of the stock. There might not even be a noticeable “tab” just a very subtle wane in the sawcut.

It happens when you feed stock through the blade. You’re very mindful of the stock against the fence, maybe following all the way through with the push stick, but the offhand side gets slightly neglected, maybe pulled to the left and clear of the spinning blade. You’re worried about keeping your hands out of the blade and just fade the piece on the left slightly after the piece you’re concentrating on keeping against the fence clears the blade. A little bit of the part that would have become sawdust from the kerf remains on the offside. If you then immediately present this side to the fence without jointing it you will create a tapered cut as has been described.

Not saying this is what is happening, just saying this can happen and it can produce some of the maladies you describe. Your mileage may vary.

View jcwalleye's profile

jcwalleye

291 posts in 1759 days


#7 posted 03-19-2010 02:37 AM

Better idea Todd, how about I ship it off to you for alignment ;-) At a $1.00 a pound USPS that should only cost about $500 which is $100 more than I paid for it. I do like the saw a lot, but it is a bit heavy to be dragging out every time I need to cut something.

That’s a great idea calling Ridgid, I’ll do that tomorrow. I had it dialed in at one time, and hope I can get it back. A friend moved it last time and I don’t know how much force he put on the rails. Also my floor isn’t level so have to adjust the leveling feet often.

It don’t understand how it makes a tapered cut since it’s the front of the blade that does the cutting and that stays the same distance from the fence. Does that make sense? Time to fix up a Ruebin sandwich

-- Trees, a wonderful gift --Joe--

View TimF's profile

TimF

31 posts in 1927 days


#8 posted 03-19-2010 02:37 AM

I had that problem with my Rigid saw. I went back the instructoin manual. Then I adjusted the trunions. No problems since then. Also the way the material is fed through the saw can cause this problem

View Sawdust4Blood's profile

Sawdust4Blood

348 posts in 1708 days


#9 posted 03-19-2010 02:38 AM

1/16 of an inch over a 6 foot run is very close to the same angle as 0.001 from the leading edge to trailing edge of a 10 inch blade.

You say that you move the saw a lot and that looks like the granite top Ridgid saw (I’m guessing roughly 350 lbs). If you’re moving it by holding on to the fence rails, they can pretty easily get puled out of alignment by that amount of mass. I don’t know anything about the trunnion mounts on that particular saw or how solid they are.

-- Greg, Severn MD

View lwllms's profile

lwllms

545 posts in 1968 days


#10 posted 03-19-2010 04:16 AM

It could be a lot of things—stress in the wood, slight misalignment, slightly dull blade, technique or what ever. I doubt you’ll ever get a repeatable and uniform rip of that length. That’s why the shops I’ve worked in always rough cut to over sized rough dimension then joint and plane to the desired size. This, in fact, has been trade practice for hundreds of years, hand tools or power tools. I suspect you have some unrealistic expectations and some help with basic stock preparation would be a benefit.

I wish I had time tonight to write up a quick tutorial on stock preparation but I don’t.

View jcwalleye's profile

jcwalleye

291 posts in 1759 days


#11 posted 03-19-2010 04:18 AM

We’ll thank you everybody. It’s a little clearer in my mind that my problem is mostly technique and a little misalignment. I’ve looked hard at the fence and it’s fairly straight where the fence is on the table. However the ends of the fence, the part that overhangs, does hook a little (.004) toward the blade, on both ends. Not sure how I’ll fix that, sand the ends down, or shim the aux fence.

Grumpycarp, good guess, you are dead on with my ignoring the waste side. It gets completely neglected. I’ll change that. And I am starting with non jointed sides, using rip and flip. Re; your question, the skinny end is at the heel.

I’ve learned there is a lot of places where things can go wrong and I’m not ready to blame the saw. I’ll try some more cuts tomorrow and report back. Thanks again.

-- Trees, a wonderful gift --Joe--

View grumpycarp's profile

grumpycarp

257 posts in 2432 days


#12 posted 03-20-2010 02:19 AM

From the photos you showed you were dealing with 1/32 to 1/64th. That the skinny end is at the heel lends credit to my hypothesis. If you aren’t jointing the edge each time you present it to the fence then you can easily experience the situation you have described.

Like others who have echoed the sentiment that you’re pretty much “good to go”. Well, seems your good to go. Go ahead and make things. 64ths. tend to offset themselves and you learn by doing.

“If you ain’t making mistakes, you ain’t making anything.” (source unconfirmed, but probably one of our grandparents . . .)

good luck!

View Gofor's profile

Gofor

470 posts in 2474 days


#13 posted 03-20-2010 03:27 AM

The biggest problem I have seen using my Ridgid 3650 on getting straight rips on a long board is the out feed support. If the out feed support is sloped any at all toward the left, it will drag the board over as you push it out. It is best to have it exactly level to the table, but a little inclination downward towards the fence is preferable to the opposite. In that case, a longer sacrificial fence will still hold the board true. If the out feed support is trying to guide the board away from the fence, you cannot hold it.

i agree, a 1/16 taper is not good to go for a face frame rip on a bookshelf face or large cabinet. If you have moved your saw at all, you could have caught a little dust or chip under one of the feet.

Check your out feed surface against your saw table.

Go

-- Go http://ncwoodworker.net/pp/showgallery.php?cat=500&ppuser=730

View jcwalleye's profile

jcwalleye

291 posts in 1759 days


#14 posted 03-21-2010 04:10 AM

Thanks everybody, the saw is cutting good again. I shimmed the aux fence a little, adjusted the toe of the fence out a little, and jointed the edge in a few more cases. It was a real obvious fix as the saw cut the wood so much easier.

My real problem is jerking that darn saw around the shop and then expecting it to stay in alignment. Gives some impetus to an expansion. Anyway, the ideas you gave me on LJ helped a lot in figuring out the problem. Thanks again.

-- Trees, a wonderful gift --Joe--

View Routerisstillmyname's profile

Routerisstillmyname

712 posts in 2196 days


#15 posted 03-22-2010 02:53 AM

The boards you are cutting are too thick for your blade. you can prove this by taking a same length board that’s only half inch thick and try cutting that with that same blade, that is if the blade has not been damaged from the stress. no more taper. you can try a thick kerf ripping blade then.

-- Router รจ ancora il mio nome.

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