Table saw question, I need answers, opinions are fine, information is better

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Forum topic by 30yearluthier posted 11-19-2018 05:45 PM 1782 views 0 times favorited 9 replies Add to Favorites Watch
View 30yearluthier's profile


2 posts in 983 days

11-19-2018 05:45 PM

Topic tags/keywords: table saw shop luthier woodworking business safety shop safety kickback spreader splitter riving knife anti-kickback ripping rip fence saw alignment spreader alignment spletter alignment hardwood hardwoods internal stresses pressure physics craftsman 10 blade 10 saw blade craftsman table saw craftsman speader poor spreader design home business family business wood grain table saw set up table saw alignment scrap bubinga alder cocobolo purpleheart wenge ash mahogany padauk basswood cherry maple walnut zebrawood

I’ve been working with my hands, and my brain, since I was 14, and worked in several fields. Started carpentry in high school, rough for residential and commercial though I was trained in fine cabinet making. In my early twenties I worked in finish carpentry, fine cabinetry and high-end construction and remodeling, but went into biotech after getting an opportunity to return to school in my late twenties. I did that until the early-mid 2000’s when I went back to school again for machine tool technics, CNC and manual machining, CNC programming, quality management, and process engineering (which I probably enjoyed the most, and I enjoyed all of them, honestly). I had worked in that field, working up from entry level operator, into set-up, then programming, then process engineering, process management, and into being production manager until I got sick three years ago.

I’ve been a luthier (builder of electric guitars and basses, primarily), and performed modifications, repairs, and instrument tech tasks for over thirty years. Since I wasn’t being allowed to return to work for medical reasons for the foreseeable future, and I am NOT the type to sit around and do nothing, my wife and I decided to start a company which performs all of these musical instrument related activities.

Believe it or not, in all these years, I have run a table saw probably three times since leaving the fine carpentry arena around 15 years ago, and though most of it has been retained I am needing input and advisement, and quickly because I have deadlines I NEED to meet SOON.

When running a table saw, and mine has a splitter or spreader (I’ve heard both terms), where within the kerf should that spreader be, if the spreader is approximately 70% of the kerf width? Should it be flush with the right side or face of the blade, closest to the rip fence,? Should it be in the middle? Should it be on the left, away form the fence, allowing any narrowing of the kerf to reduce pressure on the fence? I can see how each situation could be potentially increasing risk of kickback (or damage to the expensive exotic and domestic hardwoods (often figured, spalted, or burl, hardwoods, even more expensive), but I can see the opposite side of the argument as well. Eventually I will make my own riving knife and anti-kickback device, but until then I am asking for feedback on these questions ASAP!

Very much appreciated!

9 replies so far

View jimintx's profile


934 posts in 2743 days

#1 posted 11-19-2018 06:02 PM

Most any information you get will be offset with information that differs.
Such is woodworking.

My own information for you is this:
- First, you are most likely overthinking this topic, but sometimes that is how most all people operate, including me of course.

- Then, with the fence on the right side of the blade, the splitter should contact the left side of the kerf slot.

You will get opposing info that provides you one of these propositions:
a) the splitter should press the work to the right, and thus maintain its contact with the fence.
b) the splitter is to keep the kerf from closing and should thus be in contact with the left side of the kerf slot
c) the splitter is to keep the kerf from closing, and you don’t know which side of the kerf cut is most likely to close, the most, so it is okay in the middle.

As you can see, the info that I offered, based on a few decades of table saw use, is aligned with the b) option. However I also have plenty of in-use evidence that the c) option is most often correct. And the c) option suggests that it doesn’t matter where the splitter sits in the kerf.

Further, for the last ten years or so, I have chosen to work with no splitter or riving knife at all, and am very content and happy with the way this works, FOR ME.

Good luck with your table saw adventures.

-- Jim, Houston, TX

View AlaskaGuy's profile


6698 posts in 3467 days

#2 posted 11-19-2018 06:15 PM

I have two saws. One has a riving knife that is the right width for the blade so I don’t worry about it. My other saw has no knife so I don’t have to worry about it on that one either.

-- Alaskan's for Global warming!

View jonah's profile


2136 posts in 4457 days

#3 posted 11-19-2018 06:51 PM

The riving knife or splitter should be towards the fence side (the right, 99% of the time), but not necessarily directly in line with the right side of the blade. You always want to allow for the wood to pass by the splitter without hitting it. If you hit the splitter, it could bump the wood into the back of the blade and cause the very thing you’re trying to avoid.

I’d put it close to the middle, but closer to the right than the left side of the saw blade kerf.

Most importantly, I’d be sure to use a sharp blade, align the fence parallel with the blade and miter slot, and be sure to check those things regularly.

View HokieKen's profile


18417 posts in 2297 days

#4 posted 11-19-2018 07:17 PM

I put my splitters (which I make and install in ZCIs which I also make) on the right side which is next to the fence. I do this because that’s where the arbor sits and is a constant. I use full kerf blades in some situations and narrow kerf in others. By locating the splitter adjacent to the arbor, I know I’m good regardless of blade. If I located it to the off-side of a full kerf blade then put a narrow kerf blade on, it would want to pull the work away from the fence.

Just my $.02.

-- I collect hobbies. There is no sense in limiting yourself (Don W) - - - - - - - - Kenny in SW VA

View jimintx's profile


934 posts in 2743 days

#5 posted 11-19-2018 07:19 PM

HokieKen has made an excellent point.
This is a very logical idea about the topic.

-- Jim, Houston, TX

View Bill White's profile

Bill White

5356 posts in 5119 days

#6 posted 11-19-2018 11:30 PM

Right side of blade. Close to fence.

-- [email protected]

View Bill_Steele's profile


771 posts in 2890 days

#7 posted 11-20-2018 03:14 PM

I agree with the others—it should be positioned so that it is within the kerf.

I have an old contractor saw and I don’t like to use the supplied splitter/blade guard—but I do see the value in using a splitter—so I made a splitter from one of those thin shelf brackets.

It is thin enough that it will fit in the kerf of a thin kerf blade. I cut it down to a decent size and smoothed all the sharp edges. I attach it with a single bolt through the same hole used to secure the factory supplied splitter. I’ve found that I can adjust the spacing of the splitter with washers.

When this saw dies I’ll buy a proper table saw with a splitter that follows the blade when making blade height adjustments.

View AlaskaGuy's profile


6698 posts in 3467 days

#8 posted 11-20-2018 09:47 PM

I don’t know for this post if you can call a riving knife, splitter, spreader are all the same or not. What I’ve always read is a riving knife should be thicker than the blade plate but thinner than the saw kerf. Centered on the blade you should be able to cut from either side. I cut from both sides on my saw with a riving knife and don’‘t adjust anything.

-- Alaskan's for Global warming!

View msinc's profile


567 posts in 1662 days

#9 posted 11-20-2018 10:02 PM

If I had deadlines that had to be met “soon” and I needed answers to this question asap…....I’d take the damn thing off and move on with the immediate program!!! Then worry about trivialities like where in the kerf the riving knife should lie when I had time. I mean, in 57 years I have done 99.9% of my table-sawing on a saw that was completely devoid of any riving knife and I really don’t remember ever being stopped from working.
All that said, I have never gave it a second thought…my Powermatic PM2000 has a riving knife and it works great, so I will now have to go and look and see exactly what the stupid thing is doing…....this is interesting.

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