# Scary Time Ripping Maple



## DustyM (May 16, 2016)

So, I thought I would post this as an anecdote/question:

After reading some great posts here about making your own carbide tools, I figured I'd give it a go. Ordered some bar stock and cutters, and picked up some maple (it was the best looking turning stock they had) at the local woodcraft to make the handles. I started by ripping the 2" maple stock in half to rout a square channel for the bar stock, and expected some resistance due to the hardness of the wood and lack of power on my saw (Delta 36-725). But I've got a nice sharp Freud blade (only a couple months old, and lightly used) and made sure my riving knife was installed correctly, so I was surprised when the wood felt like it was completely jamming. As in, it wouldn't move at all, and I could feel the blade trying to throw it back at me. As soon as I felt that, I shut off power to the saw.

After powering down and unplugging the saw (this freaked me out a bit, so I wasn't taking any chances), I removed the stock, and found that the partially split stock was pinching inwards horribly and binding up on the blade. I've never seen wood warp like that while ripping, and wanted to know if anyone else has had any harrowing experiences with such. I still consider myself a novice and a hobbyist, so what could cause this? Is this due to improper drying, so a differential in moisture content causes this immediate bending upon being cut?

Also, if this happens again, what would be the safest way to proceed without throwing out the stock? Would it be safe enough to rip roughly half the depth, then turn it over and rip from the other side?

This was the most nerve-racking thing that's happened to me in the roughly 5 years I've been doing this, and it rattled me pretty good.


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## DrDirt (Feb 26, 2008)

By any chance do you have a standard riving knife (1/8 inch).... and were using a thin kerf blade?

Trying to get a thin groove to go around the fat knife doesn't work well.


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## CharlesA (Jun 24, 2013)

I've only had that happen cutting construction lumber from a big box store.


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## DavidTTU (Dec 3, 2013)

Wood has internal stress, some of which you will never know until you cut into it. I have the same Delta 36-725 and have in fact had the same thing happen to me. If I have good control of the work piece, I will place a small wedge behind the saw blade kerf to make sure the kerf will not pinch, and then finish running the piece through the cut. Might not be the safest way, but it has worked for me.

The safest thing you could do would be to rough cut it on a band saw perhaps.


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## HokieKen (Apr 14, 2015)

I would recommend using a bandsaw as well to rip it in half or try another piece of the stock, could just be some internal stress in that one piece.

Was there burning on the cut? Are you sure your fence is set properly and the fence isn't pinching the wood against the blade?


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## DustyM (May 16, 2016)

Thanks for the response, folks.
Dr.Dirt, the riving knife wasn't the problem (I actually tried it without the knife, though I know that wasn't the smartest idea: same problem). The wood was visibly pinching inward so severely that after the first attempted cut (about halfway through the 30" piece), the end that had been cut was pinching in enough to touch.
David, a bandsaw is on my list of tools, but my shop is still relatively small. This was a single work piece for making two lathe handles, so I don't have anything else to compare it to.
Kenny, there was next to no burning on the cut. And out of fear of binding, I keep my fence a few thousandths farther out at the trailing end. It is worth investigating, though, as I'm afraid the cheap aluminum face that comes standard on the fence may be deflecting, causing this and potentially other problems (though it hasn't affected other projects thus far). Either way, maybe about time to add an auxiliary fence to eliminate that possibility.


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## Unknowncraftsman (Jun 23, 2013)

For me that's what I'd expect from maple.Esp flat sawn.
I use my bandsaw for deep cuts.Cut over size face and joint side square to the face then rip.Its a extra step but much safer and more predictable.

Aj


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## DrDirt (Feb 26, 2008)

Dustin - I would say you have some wood that was either cut with stress, or was not kiln dried correctly.

I would do like Hokie Ken and cut it with the bandsaw to rough shape.

You will need to mill it flat, and let it set for a day or so and see if it wants to move/cup/twist etc once cut - - or if it had stress but will stay put.

Since you are cutting a channel to make tool handles - the movement may not affect you. But if you were making a frame for a floating panel cabinet door… I would say get different wood


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## GR8HUNTER (Jun 13, 2016)

no doubt ….... it is hard maple ….. that does seem to bind …...... I would add a shim and keep cutting ….....that if you don't own a bandsaw …..... good luck to you sir


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## johnstoneb (Jun 14, 2012)

This happens occasionally usually due to internal stress in the wood. The purpose of the riving knife is to keep the wood from closing on the blade and throwing it back at you. Before I got a saw with a riving knife I would drive a wedge in the kerf if it was starting to close. Some times the wood will close tight enough on the riving knife that you experience what you did. Either wedge it or cut it on a band saw.


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## brtech (May 26, 2010)

I'd first try lowering the blade and see if you can cut say 1/3 of the way through the blank. Then raise and do another third and then cut through. If you will plane the surfaces before you join them back, you could flip the blank around after the first cut so that the last cut is the middle third.

The wedge might work well, but you probably can't use it with the riving knife, and you might end up having a split where you don't want it just before the end of the cut.

This is the kind of a cut where a Grrriper is just what you want (with the gravity heel).


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## hotbyte (Apr 3, 2010)

Like CharlesA, I've had it happen with construction grade SYP 2X material. And, similar to DavidTTU, I was able to get rip past back side riving knife and put in a small wedge into the kerf to hold it open.


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## Stewbot (Jun 7, 2015)

I've got the same saw and have had this happen with both construction lumber and hardwood. I'm not necessarily advocating this as a safe solution (I don't know what the safest solution is only what I've done) but what I've done in this instance is once I feel the wood binding too much I'll power down the saw remove the piece and run it through again leaving the fence in place. Usually it removes enough of the material to clear the riving knife to finish the cut, otherwise I run through that same process again further down the board. After that I'll rip it to my desired width without a large off cut (although unfortunately sometimes I won't know a board will react this way until I'm already set-up to cut my final width). I only do this with longer pieces which I feel I can handle safely, anything too short that I think will too easily shoot back at me, I cut my losses.


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## DustyM (May 16, 2016)

Wow, thanks everybody for all the thoughtful replies!

(Gotta say though, you're killing me here. How do I justify a new table saw to the boss if it could be argued that I can make do with what I have?)


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## oldnovice (Mar 7, 2009)

Ditto on what *CharlesA* said!


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## cebfish (Jan 15, 2011)

lie to the boss she probaly does it to you when she wants shoes or a dress


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## sawdustdad (Dec 23, 2015)

That's called reaction wood, most likely from a tree limb or a leaning trunk where internal stresses have built up in the wood through the growth process overcoming gravity. It's pretty common in many types of wood which is one reasons a riving knife is recommended. It is probably the no. 2 cause of table saw kickbacks, No 1 being lodging the cutoff between the blade and the fence.

Reaction wood can also be caused by improper drying, but that is much less of factor.


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## wormil (Nov 19, 2011)

> *it was the best looking turning stock they had *
> - Dustin


What most people believe is internal stress is really moisture. Internal stress does exist but 99% of the time when wood is binding it's too wet. Turning blanks are not kiln dried because wet wood turns easier and you get less tear out. This has nothing to do with internal stress per se, it's just there is too much moisture left inside the wood. When you cut, the sudden exposure to air and heat from friction dry up some of that moisture and what happens when wood dries .. it shrinks. So the inside of your kerf shrinks causing it to pinch the blade and eventually lead to kickback (if the saw has enough power). The only solution is let the wood come to equilibrium for months or however long it takes (or dry it in the oven). Even if you get it ripped before the blank reaches equilibrium, the moisture loss will cause the wood to change shape even if only slightly and the halves will not glue back together without gaps. I ran into exactly this situation awhile back trying to make handles on some air dried turning blanks and no matter what I did, I could never get the ripped halves to mate because they were constantly changing shape. It's suprising how fast it happens but moisture is your problem.


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## tnwood (Dec 13, 2009)

Most likely case hardening due to poor drying in the kiln. I've had it happen with maple more than other woods but it can happen with anything. If you have a riving knife in place it should prevent it from pinching the blade but it could still be impossible to continue the cut without opening it with a wedge of some type. Very frustrating as the resulting narrow pieces may not be usable for their intended purpose. I once bought nearly a hundred board feet of soft maple and every single board did the same thing. I never went back to that lumber yard again.


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## HokieKen (Apr 14, 2015)

> Wow, thanks everybody for all the thoughtful replies!
> 
> (Gotta say though, you re killing me here. How do I justify a new table saw to the boss if it could be argued that I can make do with what I have?)
> 
> - Dustin


Dustin, You MUST get a new table saw NOW in order to ensure your own safety. Continued use of your current saw for any type of cut in any kind of wood will almost certainly result in fatality or permanent, crippling disability. In fact, even when you're not in the shop, your model table saw has been know to become sentient and stalk through the entire house wreaking havoc on anyone in it's path. If you love your family and your life, sell it on Craigslist immediately and purchase a new one.

Print the previous paragraph and show it to your wife without the rest of the thread. Hope that helps…


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