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Zero Clearance Insert

3K views 31 replies 13 participants last post by  joeyinsouthaustin 
#1 · (Edited by Moderator)
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I don't use any kind of dust collection above the saw blade and have found that I get less dust in the face when I use the standard kerf insert that came with my tablesaw versus when I'm using my zero clearance insert. I might be imagining it. I now only use my zero clearance insert when I am cutting thin strips.

I have also found that if I leave the gullet of the blade slightly below the surface of the wood I also get less dust in the face. Of course it may all be in my imagination. My saw is not used for production so any heat build up with the blade lowered is not a problem for me.

What are your thoughts? Has anyone found the same?
 

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#2 ·
I don't use any dust collection above the blade either. I have my zci on most of the time and do get dust. I made some bevel cuts today with the standard insert and did not notice any difference. I adjust the height of my blade so that it's about 1/4" above the stock being cut, so the gullets are below the surface of the stock.

I've learned the hard way to always wear my safety glasses and live with the dust.
 
#3 ·
I agree with DKV. Since I got my zero clearance inserts for my Rigid4512, I have way more chips flying ABOVE the blade than before, so much that for general cutting, I put back on the insert that came with the saw. I now use the zero for small boards, since it is much safer than losing a piece down below.
 
#6 ·
I drilled a 1" hole in my zero clearance insert just behind the teeth on the side away from the fence, at the front. The teeth still cut through for reduced blow out, and the fence side is still good for thin rips, but the extra air flow pulls down about %50 more than without it, and more than the standard insert. It is an airflow thing, I will post pics in the am. (texas time)
 
#8 ·
What I found is the larger chips and dust follow the blade right around almost to the front of the blade. You will notice they don't go straight up, they come straight at you, or pile up on the table by the front of the blade. I experimented a bit before I came up with this. That particular location actually catches them right where they get "knocked" off the blade, or as they are flinging off. Also on material where you have just a smaller amount of material off the non fence side, it catches quite a bit of the dust. This is on modern uni saw with 1.5 hp dust collection. So the saw cabinet is fairly well sealed. A hole at the back of the blade did not work as well, And, as you have seen, the standard insert allows material to fall in occasionally. I would be interested in the swiss cheese experiment, but i think it won't catch as much of the larger chips. I may even do a video of it at work.. That said, it does not do as much as overhead, but compromises between the best of the zero clearance, and what folks have noticed with the wider factory insert.
 
#10 ·
Yes, but this height varies blade to blade. Your manufacturer will give a recommendation. and I have always been taught at least gullets fully visible for cooling. some encourage up to 3/8" above. I am glad to see this has annoyed others… It annoyed me enough to try a solution. Pics will help so I will follow up with a post.
 
#11 ·
I haven't used my standard insert for so long I'm not sure. I also don't have above the table collection. If I am only taking off <1 />t know how to help lol. But your not alone! I would like to try the swiss cheese idea though…or maybe add a kerf(slit) or 2 on the sides of the blade…
 
#14 ·
I have had the same experience with the ZCI and dust. Because of that I built an above blade guard/vacuum port that I saw in one of the magazines (I cannot remember which one). Interesting comments about the gullets. I had always heard they needed to be just above the wood for both safety and cooling. Cooling issues aside are there any safety issues with having just the teeth through the wood? The cleaner cut aspect is as beneficial as the dust issue.
 
#15 · (Edited by Moderator)
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B.

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C.

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Here are the results from today's test. A pic with the blade well above the gullet had the least smooth cut and the most dust. B pic with the gullet just below the surface of the wood had about the same smoothness of cut and less dust. C pic with only the tops of the teeth above the wood had the smoothest cut and almost zero dust.

All tests were done with my dust collection on and as shown in the last picture a series of holes drilled in the ZCI. I think I am where I should be. I could drill some more holes but I'm happy with test C. Unless someone can tell me why I might be risking my life by keeping the teeth so low I will continue to cut this way.

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#17 ·
One last picture. I made another row of holes and sealed underneath the table around the dust collection shroud. Everything is near perfect now… Thanks to all that contributed. BTW, I don't think I'll ever suffer another kickback or nicked finger since I now religiously use the Grrripper.

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#20 ·
DKV " Unless someone can tell me why I might be risking my life by keeping the teeth so low I will continue to cut this way." Only the DUDE might think you are risking your life, but I could think of what the level of danger is. The distance the gullets and teeth should be above the work piece are a function of the blade design, and there are manufacturer's recommendations having to do with "best results" The only downfalls I see are these: Blade life… too low will lead to overheating, especially on high tooth count blades. Safety… Depending on the rake of the tooth, lowering the blade increases the upward force at the back of the blade, by elongating the path the teeth are traveling through the workpiece. (this happens at the front as well but is negated by the table) And also increases the pushing force towards the front of the saw, for the same reason. What this means is a higher probability of the piece riding up the blade, and a higher chance of kickback. This is minor with safe technique, meaning you just should be aware that a greater downward force, and force countering the pull away from the fence that is needed. I might argue that the increased risk might not be a good trade off just for dust control… but really you should balance those risks on your own, and make the last statement for the newer woodworkers reading.
 
#22 ·
Joey, I like your solution. Well done. Your comment concerning kickback and newer woodworkers is true. Both kickbacks I suffered happened when my saw and I were just getting acquainted. One missed me and the other left a good bruise on my arm. Both times I wasn't paying attention to the cut but thinking about the next steps in my project. Since then (over 5 years) I have studiously paid attention through the entire cut and used the grrrripper. I hate to say this but until a kickback hits you and wakes you up most new woodworkers don't consider it a problem. I had read about kickbacks but didn't consider them a threat. Thanks for the info and contribution to the thread.
 
#23 ·
My only kickback so far actually came from my push stick. I was putting a 45 champfer on some 1×1stock and when I got to the end of the cut I let the push stick hit the back of the blade. I def pay more attention now. Luckily I didn't get hurt. Bounced off my chest and landed about 15ft on the otherside of the garage….my first thought was thank god that didn't hit me in the eye!!(wasn't wearing goggles). Thanks for all the tips. I think I will try to make a grrripper. Always thought it looked like a great tool, but never wanted to pay the price.
 
#24 ·
In the interest of those new reading this…. check out post #16 above to see what a good push block looks like. don't like the word push stick. Any thing that only touches the back of the piece, YES and I mean the thing shipped with the saw, in most cases, is dangerous. You need contact at the back of the piece and and forward to provide downward pressure as the piece is sliding past the back of the blade.
 
#26 ·
shelly and others… here is a simple version I use. I use the blade as context, because it is important for it to be longer than the blade. To use, you must focus the pressure to the front of the push block, not the lock at the back, and, not to bring back images of your accident, should be placed closer to the blade, than the fence. This one is 1/2" baltic birch ply, for thinner, but the shape is important.

now to get back to woodworking.

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