Alas ... there is no standard in table saw throat plates. There are some manufacturers that are similar but it seems most all make their own versions. While there are many different throat plates or inserts as they are also called, there are also a variety of ways to make replacement ones. In trying to keep things as simple as possible, I will be showing how to make throat plates in a pretty simple way that will hopefully give others some ideas on how they might best tackle this table saw feature for their own saws.
To clear up some confusions on throat plates, shop made throat plates often have their relief cut made by the blade they will be used with making a very close tolerance between the blade and the throat plate, hence the name "zero clearance", but they can also have a wider tolerance in which case they would simply be called "inserts" or "throat plates". All the term "zero clearance" refers to is the distance between the throat plate and the blade.
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The main reason to ensure you have and use table saw throat plates is a safety feature. Of course, we need access to the blades for changing them, and sometimes when cutting dado or making sider cuts with dado blades, wobble wheels etc, we need to use a throat plate with a wider space to accommodate the blade.
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For my saw, good quality throat plates can be made from good quality 1/2" plywood. All it takes is a bit of shaping, inserting thumb removal hole and another for the hold down screw and that is really all it takes.
My current table saw came with some sort of a resin type throat plate. I could use it for a template but I prefer to leave it a pristine as I can and to make a separate plastic template that I can use that way my original is not going to be subjected to any undue damage that might happen along the way.
The table saw previous to this saw had a metal throat plate and one time when I was using that metal throat plate as a template to make a new blank, and using the templating bit on my router, I inadvertently left the router bit too high and ended up damaging both the router bit and to a smaller degree the throat plate. At that point I determined it would always be best to make a plastic template for future works ... and I have stuck with doing that.
Making a plastic template is really no different than making an actual working throat plate. To make mine, I used an 80 tooth blade in my table saw to cut the rectangle from the 1/4" plastic piece, then used my band saw to rough out the rounded part and working very slowly so as to minimize the plastic chipping, and finally over to the belt sander for some fine tuning and it was done.
To make the plywood inserts, I start off with wood that is exactly the same width as a template. After that, it's a simple matter of making the round part and cutting it out. You can cut the round part out on a bandsaw like I did, you could use a router and router table with a templating or a flush trim bit, or you could even use a jigsaw and make a rough cut and sand it down smooth after the cut.
After the insert has been cut and sized to fit the hole, if possible, you can even size it for height if it is to low. Many years ago I used to use a car body filler called Bondo that was a 2 part mixture but cured in about 5 minutes, and the nice part about it was that it held it's body during the process, unlike any of the 5-minute epoxy glues I have tried that are to runny ... but perhaps there is a version I am not aware of that has more body ... in any case, a great and inexpensive replacement is using the hot melt glue. It works great for this and the only drawback is waiting for the hot melt glue gun to heat up, which in the end is still quicker than the Bondo option.
The last thing to do once the insert is made and completely fitted is to drive the blade up through the throat plate. You can hold it down with a piece of scrap wood but I find just running the edge of the table saw fence over top edge of the new insert works just fine.
Making inserts is easy, and if you are using any kind of a dado blade or cutting widths, you need to have throat plate that is at least close to the width you are cutting, it doesn't necessarily need to be a perfect fit, but it should be close in order to be a safety benefit ...
Copyright Colin Knecht