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This is what drives me NUTS (uneven TS rip cut)

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Forum topic by DanM posted 07-03-2008 05:49 AM 1601 views 0 times favorited 20 replies Add to Favorites Watch
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DanM

90 posts in 2454 days


07-03-2008 05:49 AM

I’ve just ripped a ~3” x 48” board in half. I VERY CAREFULLY marked the EXACT center of the leading edge of the cut with a fine pencil line, and VERY CAREFULLY centered that line visually in the middle of the saw blade teeth when positioning the rip fence. Set up seemed PERFECT. Ripped the board, one half is more the 1/32 wider than the other. This is a board that has been jointed & planed on quality equipment, and cut on a PM2000 TS with a WWII blade. I run into this all the time, despite the fact that I invested the $$$ in quality equipment, and despite having invested the time in setting/tuning it up with dial indicators, digital gauges, you name it. Frankly, it’s beginning to take the FUN out of things. I have a heckuva time getting things to size repeatably, getting gap free joints etc. I’m relatively new at this & no doubt some of it is practice, but come on, we’re talking about ripping a bloody board in half! Doesn’t get whole lot more basic!

Like I said, it drives me NUTS!

Dan


20 replies so far

View John Ormsby's profile

John Ormsby

1281 posts in 2482 days


#1 posted 07-03-2008 06:24 AM

Dan,
There will be good days and bad days with woodworking. There are a couple of things you can do to rip very straight.
You can use a feather board that clamps into the miter slot. I use one that has a roller on a spring. The standard feather board will do just fine.
Your fence might be out of alignment. Either pushing into or away from the blade. If this is so, you will also be subjected to a possible kick back situation.
Using the Grr-Ripper push system will be much safer and accurate than using push sticks.
There are roller hold downs that help guide the board along the fence.
Sometimes you can use these things together.
One more thing comes to mind is that the board may not be perfectly parallel. It may be 1/32” narrower on one end compared with the other.
I am sure with some practice and guidance you will be able to rip a straight board.

Good Luck and have fun with woodworking.

-- Oldworld, Fair Oaks, Ca

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DanM

90 posts in 2454 days


#2 posted 07-03-2008 08:25 AM

John – Thanks for the reply. I did use one of those plastic fingerboards that goes in the miter slot to push the board against the fence. I do have a Grripper, but in this case I used a “push board” for lack of a better term which I made with a nub to catch the end of the board & enough length to exert downward pressure. When I initially got the saw, I set the fence parallel to the miter slot using a dial indicator, I can check it again. I’m familiar with the 2 schools of thought on this, slightly tilted away to avoid kickback or parallel, I opt for the latter. The board in question was jointed & planed & was true. The wider piece is wider along it’s entire length by the same degree. It’s weird, I was very careful with everything as far as I can tell, obviously something’s off, but I sure don’t know what.

View Myron Wooley's profile

Myron Wooley

226 posts in 2641 days


#3 posted 07-03-2008 08:52 AM

Do you watch the blade or the fence during the cut? Watching the blade will allow the workpiece to drift away from the fence. Keep your eyes on the fence, and maintain pressure against it.

-- The days are long and the years are short...

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Grumpy

19693 posts in 2596 days


#4 posted 07-03-2008 09:31 AM

I don’t know what sort of fence you have but some will move slightly when you lock them in place. I often use a test piece if I need accuracy. I have the magswitch featherboard which is invaluable (holds laterally & vertically. See review below. Good luck.
http://lumberjocks.com/reviews/69

-- Grumpy - "Always look on the bright side of life"- Monty Python

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Bob #2

3808 posts in 2766 days


#5 posted 07-03-2008 02:14 PM

One solution is to start with a boards about 1/8” wider than your final width.
Mark the blade to fence distance carefully to allow for and extra 1/16” on the first pass.
You nnow should have two boards of differnt widths so don’t panic. Set your fence at the final width and take a skimming pass off the board at the proper width.
Do the same for the other board without changing the fence .
Use feather boards on the pieces to keep the work against the fence.
If you have a planer this is usually where this matching is done.

p.s. do you do a test piece before running the part?

Good luck

Bob

-- A mind, like a home, is furnished by its owner

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CharlieM1958

15780 posts in 2963 days


#6 posted 07-03-2008 03:46 PM

To recap what I see as the two most important things mentioned:

1) Make sure you are still dead centered on your mark after locking the fence in place
2)Make sure your piece is not drifting during the cut.

That being said, I find it is just EXTREMELY difficult to rip a board into equal halves. Think about it… if your cut is just 1/64 off center, you are taking 1/64 too much from one piece and adding 1/64 to the other. So the net difference in piece size will be 1/32.

-- Charlie M. "Woodworking - patience = firewood"

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hcbph

14 posts in 2363 days


#7 posted 07-03-2008 04:07 PM

Did I miss someone saying it, but has the fence been checked for movement and whether it’s parallel to the blade?

Quick and dirty test: take a short piece of ply – against the rip fence cut in about 1”. Power off and unplug the saw. check it on the front of the blade and it’s tight, mark that tooth and rotate the blade so it’s at the back of the table. Recheck it there against the same tooth. Is it the same?

Now without changing any settings, rip a piece of wood. Is the wood accurately cut? Do the same tests, does it still check out ok?

If these check out then it’s probably technique. If they don’t then something is incorrect in your saw or fence setup.

Hope that helps.

Paul

View Damian Penney's profile

Damian Penney

1140 posts in 2736 days


#8 posted 07-03-2008 05:03 PM

The fence moving when you lock it down is definitely something that can bite you. I thought my fence was broken when I figured out it did this. Test cuts are definitely the way to go when something has to be dead on though.

-- I am always doing that which I can not do, in order that I may learn how to do it. - Pablo Picasso

View brunob's profile

brunob

2277 posts in 2914 days


#9 posted 07-03-2008 05:13 PM

Instead of trying to cut the board in half, my solution is to cut it just shy of half then take the cut off piece and run it through the saw at the same setting. Works for me.

-- Bruce from Central New York...now, if you'll pardon me, I have some sawdust to make.

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bfd

502 posts in 2552 days


#10 posted 07-03-2008 05:31 PM

I agree with Bruce, I avoid ripping a board in half to final dimension altogether. You are better off starting off with a board that is slightly larger then what you need. Set your fence to the width you need and make two cuts. It will take you 30 seconds longer but save you in the long run.

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Betsy

2914 posts in 2641 days


#11 posted 07-03-2008 07:08 PM

It’s hard to eyeball the center of the board, no matter how it is marked, with the center of the saw blade. Especially if you are leaning over the saw trying to do so.

I’m with the others—- start with a slightly larger board and rip it twice. You’ll be much happier with the outcome than the way you have tried it. The good part of this method – is you’ll save your sanity.

-- Like a bad penny, I keep coming back!

View Joe Lyddon's profile

Joe Lyddon

7928 posts in 2797 days


#12 posted 07-03-2008 07:26 PM

One thing that I do, to be sure I’m in the Middle:

Using a piece of scrap of the same width I will be cutting.
Measure & set fence as you are doing.
With saw on, touch the wood to the blade to just cut through top & bottom & pull it back.
Flip the wood over & do the same thing.

If you’re in the middle, the kerf cut will identical for both cuts… If different, adjust the fence & try again until centered.
It may take a little fiddling to get it “Just right”...

Hope this helps.

-- Have Fun! Joe Lyddon - Alta Loma, CA USA - Home: http://www.WoodworkStuff.net ... My Small Gallery: http://www.ncwoodworker.net/pp/showgallery.php?ppuser=1389&cat=500"

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Joe Lyddon

7928 posts in 2797 days


#13 posted 07-03-2008 07:43 PM

... sorry… please delete this one…

-- Have Fun! Joe Lyddon - Alta Loma, CA USA - Home: http://www.WoodworkStuff.net ... My Small Gallery: http://www.ncwoodworker.net/pp/showgallery.php?ppuser=1389&cat=500"

View Slacker's profile

Slacker

178 posts in 2446 days


#14 posted 07-03-2008 10:32 PM

So, its better to be consistent than correct…

-- Adapt, improvise, overcome

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DanM

90 posts in 2454 days


#15 posted 07-03-2008 11:15 PM

Thanks for the helpful replies. I didn’t do a test run, but I will in the future.

As was said, with so much of this, errors add up; one side +1/64, the other -1/64, totaling 1/32, and so on. I was also using a Woodcraft tenoning jig for part of the project, which I am finding out is a piece of junk. When you tighten the locking nut, the section of the jig holding the board skews slightly toward the blade. I was assuming it was doing so uniformly and was compensating based on that assumption, but in fact it’s just the front edge which steps out, given a cut which is at a slight angle to the face of the board. Because of what I was trying to accomplish, this error was also doubled.

So it was a bad day ;-)

I also agree in this pursuit it’s best to aim more for precision (consistency) then accuracy (correctness).

Thanks again.

Dan

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