Zero Clearance Throat Plates?

[Paul Zonneveld]

I have a General International 360 table saw and need to make some zero clearance throat plates for it. I made an attempt today, but found that the half inch MDF I was using was a little too thick to fit flush with the table. What methds can I use to get the MDF to the correct thickness to fit flush with the table top? Also what methods are there to make sure the throat plate stays in place?

Any help on this would be appreciated.

[Joe Chritz]

Rabbit the back, thickness sand it with a drun sander, use 3/8 MDF or some other material.

1/2 Baltic birch would probably be just about right.

I used a material called ridgelight for mine. Its for commercial cutting boards but any material that is flat works well. Toss in a couple small set screws for leveling and you are good to go.

I had mine made on a CNC so it has a tab to hook under the table but just a brad nail would work.

Joe

[jonathan snyder]

Paul,

I too have made ZCI's out of 1/2" MDF. I ran mine through the planner to thickness them (if you dont have a planer how about a hand plane). I'm sure MDF is heck on planer blades, but it was only a couple of passes! I use the rear spring off my factory insert and a finish nail at the other end to hold it in place. I also drilled and tapped the MDF for set screws to level it with the saw table.

Hope that helps
Jonathan

[glenn bradley]

I found 1/2 BB ply to be just right for my hybrid. Used 1/4 hex set-screws as levelers and a finish nail at the back along with the factory screw at the front to secure.

For the one(s) already made a rabbet to allow it to drop in further would be my choice. I fear running MDF through my planer but it could be done. For what a knife sharpening job would cost I could buy a full sheet of 1/2" BB ply and just start over.

[Luciano Burtini]

I have the 350 and make my ZCI's out of whatever scrap baltic birch (usually 3/4") I have readily available. After they have been fit to size, I simply sketch in the 4 little pads (and the splitter mount), set a trim router to the proper depth and free hand the cutouts. Not as difficult as it sounds and you don't need to be perfect as long as they are slightly oversize. Of course, if you wanted to be more precise you could make a 1/4" hardboard template to follow - actually, maybe I will do that as well.

ZCI's total cost $0.00 (and a few minutes of work on each). I generally make 3 or 4 when I need one to ensure that I have several avaialble for different blades, dados etc. BTW, a 8" skilsaw blade works well to cut the starter slot.

[Paul Zonneveld]

Just wanted to thank everyone for the responses I made up 5 1/2 and 5 3/4 inch MDF inserts. I used a hard board template to route the edges of all the inserts so I have a perfect fit. I then used a router to drop the insets down to just below the table surface. I plan on finishing with some of those threaded brass inserts that you then can put a screw into. These screws can then be used to make the template level with the table.

One more question however, I have heard of using a small nail in the front of the insert to hold the back edge of the plate in place. Are there any other methods you may have used to keep the throat plate in place? I also noted that the edges of the throat plates made from MDF have a tendency to begin to separate. I brushed some yellow glue onto the edge of one of the throat plates to see if that would help to preserve the edges of the MDF. Does this sound like a good idea to help prevent the MDF edges from comming apart.

[jonathan snyder]

[quote=Paul Zonneveld] I plan on finishing with some of those threaded brass inserts that you then can put a screw into. These screws can then be used to make the template level with the table.

Paul, You dont need to use threaded inserts, just drill and tap holes for the set screws. The ZCI doesn't weigh very much, so the threads in the MDF will hold up just fine. I haven't had any trouble with my MDF ZCI's splitting, maybe you just got bad piece.

Jonathan

[Luciano Burtini]

One more question however, I have heard of using a small nail in the front of the insert to hold the back edge of the plate in place. Are there any other methods you may have used to keep the throat plate in place?

I use a small screw (approx. #4 x 3/4) screwed into the edge of the baltic birch at the back. With the head just protruding it locks the back of the ZCI down quite nicely. If you've made the insert snug, it doesn't want to move in any case.

Luciano

[glenn bradley]

I'll second jonathan; i drill holes and thread the hex screws right into the wood for levelers, no problems. As for the glue on the edges, couldn't hurt. I'm curious about the MDF failing; is it terribly wet where you are?

When I am finishing something and have a bit of shellac or whatever left in a rag, I'll rub it on inserts and the like. Once fully coated after "cleaning" a few rags on them, I will wax down the inserts.

I also write on the bottom with a felt open what blade they are for. I use MJ Splitters so I write the 0, +, ++ or +++ setting next to the holes for the splitter position as well.