Making thin cuts on your table saw requires a zero clearance insert so that the stock doesn't get pulled into the table saw after cutting.

Most table saws have an insert that's good for a most applications: it can accommodate the blade at full height, at any angle, and has space around the blade that allows sawdust to be pulled down from either side of the blade. A zero clearance insert has no clearance around the blade, and should only be used when the blade is perpendicular to the table. Making your own zero clearance insert is easy, and we can even use the table saw to make it! Having one on hand is great for the few times you need the right tool for the job. To make this zero clearance insert I used

Because there is zero clearance between the blade and the insert there is no space for sawdust to be pulled away from your cut, however this is an easy compromise since without a zero clearance insert you would not be able to make thin cuts.

Ready? Let's make!

Step 1: Take Measurements of Insert

Remove your table saw insert and take the overall measurements: length, height, and depth.

To get accurate readings I used digital calipers. Make sure your saw insert housing is clear of sawdust so you can get the best readings. Most saws have height adjustment screws so you can level out the insert after if your readings are a little off, but it's better to get accurate measurements before starting.

<p>Made from a really nice piece of scrap hardwood! :)</p>
<p>Wow, <em>very </em>nice scrap :) Thanks for sharing your insert, Sam!</p>
<p>i make mine very similar but finish on router table. i make them in two parts because my inserts are very thin to give it more heft. thanks for sharing</p>
<p>The extra heft and support is a great idea! Thanks for sharing pictures; enjoy the Pro Membership!</p>
<p>Very good Instructable, but I think you missed a couple things. One of the advantages of a zero clearance insert is decreased tearout, especially when cutting plywood. You also have to remove the riving knife before you can cut the slot in the insert or use it. (It took me a minute to figure out why the insert was being pushed up by the blade - a blonde moment ) I also had to do some routing on the underside of the insert because my Kobalt saw only has 0.98&quot; between the table surface and the adjusting screws and the thinnest stock I could find was 1/8&quot; melamine board. (see second picture). It works fine, but I think I'll add some tabs to secure it before I use it very much.</p>
<p>Thanks for sharing pictures of your build. Enjoy the Pro Membership!</p>
<p>Isn't it dangerous now without the anti-kickback protection?</p>
<p>Depends if the anti-kickback device is American or European in design. European riving knives are designed as part of the blade arbor mechanism, so they curve around the blade with approximately 1/4&quot; clearance and move up and down with the blade height adjustments. American style riving knives are fixed in place, and therefore have to be removed in order to make any cut that doesn't go all the way through the stock. Plus, that makes them a fixed distance from the blade which is usually far enough back to create other problems. This is why many people end up taking them off entirely. Add to that, the &quot;anti-kickback&quot; pawls that are often part of the blade guard are, IMO, more dangerous than not using them. All the safety mechanism in the world are a poor substitute for proper technique. That said, I strongly advocate for well-designed safety equipment, the most important of which are proper technique and a clear head. </p>
<p>Warning: 1/8&quot; stock, whether plywood, melamine, or tempered hardboard, has way too much flex in<br> it to be safe as an insert. You'll note that the factory made insert is made <br>out of steel. They didn't do that because it was the most economical <br>material to use. Even manufactured table saw inserts made out of <br>aluminum are usually at least 1/4-3/8&quot; thick.</p>
<p>I know I'm missing something here but &quot;zero tolerance&quot;? That doesn't make sense to me. Are they just called that even though it's impossible?</p>
<p>What they mean by &quot;zero clearance&quot; is that the slot for the blade is just the width of the blade compared to the stock inserts that usually are about 3/8&quot; to 1/2&quot; wide to allow for the blade to be tilted. Obviously the blades are not exactly &quot;zero clearance&quot; since just the vibration of the motor (even in the best saws) causes run-out of the blade by a few thousands of an inch. I've been making these for almost 20 years, since my first shop saw was one that no one made inserts for. Now I even have inserts for my stacked dado blade in 1/8 inch increments as that gives me cleaner dados.</p>
<p>It's zero clearance, not zero tolerance. Those words mean two different things. A zero clearance insert is a term used in woodworking for one where you only have a minuscule gap between the side of the blade and the kerf on the insert. When you don't have the normal gap there, it gives more support on things like plywood, where the blade would normally chip the edges as it pushes the teeth down through the material.</p>
<p>Very nicely Done. I have made these before but I always use a piece of aluminum &amp; and a carbide tip blade to cut the slot. Nor sure if most people are aware but carbide tip blades with a table saw is a great way to cut this stuff. I have cut up to 1 1-2&quot; this way </p>
<p>Have you tried using the Router with a flush-trim bit to cut the New insert from a rough-sized work piece and using the Original Plate as a guide taped to the Blank?</p><p>It's much easier than doing it this way... I think...</p>
<p>an easy way to make these inserts is using 3/8&quot; Baltic birch plywood for the insert. Sabre saw/jigsaw the blank 1/8&quot; larger and then use double face tape to fasten the original to the blank. Use a pattern router bit to finish it to a perfect fit. Because Baltic. Birch is so dense you can tap the set screw holes for adjustment screws. Fine tune as necessary.</p>
<p>Thanks for sharing your incredibly detailed method of making zero clearance inserts. It seems hard to find the specific blank for a particular saw and they aren't very cheap. I only have one that I purchased and I could use about 6.</p><p>After seeing your article, I'm wondering if I can't make them with my 3D printer. It should also be possible to add the &quot;hold down&quot; clip. I will probably use Nylon as the print material for strength.</p><p>Also, my blade does not retract much below the surface of the insert. When I cut the slot in my &quot;store-bought&quot; insert, I had to dangerously hand-lower the insert to get the slot started. Then, I could use the board and clamp method you show. I think I could work around this problem, if necessary, with a 3D printed version by simply making the insert a little thinner near where the slot will be.</p>
<p>For the situation where the blade will not retract below of the insert before cutting, sumply use a smaller blades make the initial cut, like a 7-1/2&quot; circular saw blade or one of your dado set blades for example. Then replace the blade you plan to use and finish raising the blade. If the circular saw blade is too narrow, you may need to mount 2 of them to make the initial cut. You just have the initial cut to be high enough so you can safely mount the full sized blade.</p>
<p>or you could use a router to make the area near the blade thinner.</p>
You are correct. Although I am still a &quot;newbee&quot; with respect to 3D printing, one idea is to make the part without much additional work. Since all 3D printers are not the same, I have found that dimensions are not always as specified. For example, hole diameters are often (for me, anyway) a little smaller than I specified. So, I often print a &quot;test&quot; piece where I do not commit to the whole part, just to some feature that I'm interested in to test the results.<br><br>With respect to &quot;thinning&quot; an area, that seems pretty easy to specify once you have somewhat mastered the CAD program used to generate the part. My first trial will be basically just the &quot;outline&quot; of the inset. That way, I can find out if my measurements are close enough. There's always the &quot;is it English or Metric&quot; question. For 3D work, I work in metric. But, older things, like my 30 year old Sears table saw, are probably English.<br><br>With 3D printing, as it seems to be the case with woodworking, the more you do, the better results you get. (So, can I live forever?)<br>
<p>I used a piece of plexiglass. To cut the zero clearance slot I reversed the blade. This reduced the amount of debris flying all over. I used a straight cut router to cut the rough shape and then sanded it down using fine sand paper for metal finishing.</p>
<p>I have made lots of them basically using the same technique. You can also use a router with a ball bearing and use the steel plate as a pattern. And you can use a lot of different materials as well. Plexiglas can be used as well.</p>
<p>Cutting the zero clearance slot in a Plexiglas with a table saw would likely shatter the Plexiglass. <br>Maybe if you use a Melamine blade. I don't think general purpose blades will be delicate enough.</p>
<p>I actually cut Plexiglas on my table saw. While it does send Plexiglas particles all over the shop, It cuts surprisingly easy and smooth as well. I also cut Plexiglas on my 12&quot; DeWalt chop saw as well. It too sends particles everywhere, no no worst then cutting wood. Just make sure you have eye protection on as you should cutting anything. </p>

About This Instructable




Bio: I'm Mike and I make crazy things at Instructables HQ in San Francisco. Follow me and try a few of my projects for yourself!
More by mikeasaurus:Fix a Hole in Drywall DIY Zero Clearance Table Saw Insert Easy Table Saw Sled 
Add instructable to: