How To Avoid Kickback On The Table Saw

I'm making this talk about saws in particular that don't have a riving knife so it's not even a consideration for this talk right here also I think that it's better to know how to prevent the kickback then rather than let something else try to do that for you if you know more about the material you're working with and how it's going to react you'll better be able to prevent it regardless of the safety equipment you have on yourself the first thing I want to talk about with regards to kickback is you need to learn something about the stuff that you're going to be cutting all right I have here is your standard 2x4 and these are notorious for kickback or jamming up mainly because when these are cut from the forest they're of course green and then they go and they get milled down to some rough sawn I don't know the exact process these days but eventually it gets sent through a kiln that rapidly pulls the moisture out of there and it gets it down to around fifteen sixteen percent sometimes as low as twelve I've measured these as soon as I've taken them from the big-box store and they've been as low as say ten percent if they're sitting around for a long time and as high as say eighteen percent so there's quite a bit of variability there now it's not the moisture per se that's the problem it is the stresses that build up in the wood when you rapidly dry it of course wood is a natural product and it has things like knots and other grain variations in it that cause the density of the wood to be different in different places and it's these density differences that cause the internal stress to build up so that when you cut it you're releasing these stress it wants to bend inwards or bend outwards almost anyone that's cut one of these things has seen that so what I'm going to do is I'm going to take this one I'm going to cut it this 2x4 has been down in my basement for months on end so it's fairly dry and when you leave wood that's kiln-dried for months on end to dry what happens it naturally releases those stresses that build up although there might be some here now the things to watch out for when you are cutting a 2x4 like this or not okay you've got two knots here and what may happen is as you cut down the middle here this may try to close together and it'll pinch on the back of the blade and try to kick back all right I'm gonna rip this right down the middle and we'll see if it actually you know reacts first thing I do is set the height of my blade up to just slightly higher than the wood that I'm cutting through I'll set my fence to one and three-quarters and I'm gonna start my cut [Music] okay I had to stop there and show you what's going on it probably would have been a lot more dramatic if the wood had been less dry if I hadn't got this maybe two or three months ago after I bought it from the you know the Home Depot but it started to pinch together and you can see it here I'll get a picture and put in here and it's these two knots that are causing this pinching to happen the stress is built up around these knots and it's causing that wood to turn inwards like that when I was cutting this I was aware of that situation so I was following the work firmly I was listening for a change in the tone of the saw I had you know good contact with the wood here so I could feel if it was starting to bind and I just stopped the saw to show you what's going on here now under normal circumstances I would just continue cutting this as long as it's not stalling the saw or binding up so badly that it's actually pushing back at me I would press on and would continue cutting until I you know got through the cut that I need to make but just to show you what you can do if it starts to happen you want to stop the saw pull the work off you can make that cut again I actually start the saw and recut that curve so widens out and now the lesson the chances of it kicking back the other way to deal with the closing up kerf like that is to have a wedge and stick in there to push it open after it starts to bind push the wedge in make sure it's a wooden wedge not stealing and you can see that the blade passes easily through the kerf now and that'll stop it from binding pinching on the saw the other thing that can happen you know other than that pinching so you're cutting the standard 2x4 here again is that it may curved you know as you're starting to cut it it could curve both pieces actually curved away from the saw this way and then what will happen is that'll press up against the back side of the blade and that'll start to kick back as well the solution for that is also the wedge if you can get the wedge in there also if you can stop the saw and recut the kerf that'll help a lot as well okay that's basically it for solid wood the things that you should look out for there are other things that I can't think of at this moment but all these things come with actually you know using the saw making these cuts practice is where you'll learn a lot about how to cut wood safely plywood this is a piece of maple veneer particleboard core plywood so we call it and plywood generally doesn't twist or warp when you cut it because it's usually you know not under any stress it's made it's a manufacturer product and once it's put together it's it's basically stable it doesn't you know expand or contract or twist or warp too much earth it's usually not a factor when you're cutting it but there are some things that you need to be aware of when you're cutting sheet stock or panels like this you can say that the really big one is not to make this cut right here say eight inch piece and you need you know you need this piece to be eight inches and then try to cut it this way the problem with making this cut if you're not experienced is that there's a better chance of it rocking into the blade as you're pushing it through all it takes is a little bit for this to come off the fence at the back push into the side of the blade and kick back at you the other problem is that as you're completing your cut what can happen you since you're pushing on both sides of the work as its passing through the blade you could push that kerf together and pinch it at the back and that will cause kickback and if you and this is something that can happen if you've never done this before it can really make you your pants that's basically because it's totally unexpected but that's what can happen and I'm going to try to demonstrate that a little bit and the safest way I possibly can here [Music] okay that's it coming off the fence and you actually you can see the blade pushing sideways I had a really firm grip on it I knew that I could kick back but I didn't go far enough to make it actually happen now the next thing I'm gonna do is to and I don't know if I actually actually do this try to make it pinched at the back [Music] [Music] [Music] okay I got my heart restarted you can see how quickly that happens if you're doing that and you don't know what can happen like that would ruin your day you would walk away from this thing and never return type thing but those are the two things you have to be aware of when you're making this particular cut on the table saw now if you're cutting okay this you need two pieces that's eight inches wide the best thing to start off with is something that's just a little bit wider than that and then firmly pass it through the blade like this that way you don't have this big massive piece out here to try to worry about so the best solution for this kind of thing is to rough cut it with either circular saw or miter saw or something like that rather than try to make this cut on a tabletop the other way to do it is if you have a sled and you know the slab what the sled does is it supports the stock all the way across at the back as you push it through there's still it still may pinch but there's quite a lot less probability of that happening okay so I'll make that clean up cut to get rid of this ragged edge here and talk about something that I talked about in the previous video on push sticks and that's it's gained more dangerous to try to cut this size piece with a push stick then using your hands in all circumstances you want to hold onto this piece and guide it through what your fingers will do that this push to can't is feel what the wood is going to do your fingertips will also grip the surface and you'll be able to push it into the soft of her talk people talk about their hand got pulled into the blade a lot of times what happens there that's a failure of technique whenever I'm pushing wood through the saw my hand is always going that way I'm pushing not straight through or towards the blade I'm pushing straight through and towards the fence so I'm holding the stock up against the fence you got to imagine that it's going this way and that's the way you always want to be pushing your stocks with a saw and I'll take it and push it forwards you push it sideways type [Music] I'm letting the sauce spin down because this is another thing that I see quite often now notice what I did there I let the saw stop I didn't mess around with this piece right here I see guys trying to move that out of the way with a push stick or whatever and you don't have to kick back only happens between the blade and the fence that's the only place where kickback can happen between something that's spinning and something that doesn't move and these pieces that fall off on the side here they can be in the way but they're never a danger so leave them where they are until the saw stops don't get in there with your push stick trying to mess around pushing out of the way what happens if the blade is still spinning or spinning down is the tip of the push that can get in this in the saw there and you know come back at you type thing so you get a kickback type thing with that so leave those things there where they're at and don't worry about them okay I talked about using a sled to make you know panel cutting safer and I said that a can possibly pinch the blade at the back and the reason for that is if your stock is not absolutely straight on the edge where it goes up against the fence if you put it up against the fence and you notice a gap between the stock and the fence where the blade is that's gonna pinch if it's supported on both sides and a gap in the middle it will close together as you complete your cut and cause a kickback I chickened out the last second there I was gonna try to make the cut but I said that it's not worth it because I'm holding the slab with my thumbs basically only you know keep them pushing it forward and that can kick back violently enough and with enough force you sprained your thumbs or even break them so you'll have to use your imagination I've got my mini table saw sled what am I saw here this is the one I mostly use to point out something else and that's situations where you're cutting many pieces the same length and you want to set up a stop block so I'm gonna quickly kind of stop walk here [Music] see I broke my own rule I push this block out of the way and I also use my stick here to break the blade anyway so here's my stop block and I'm gonna put a clamp on it so it doesn't move flap down there nice and tight so that you know I can cut several pieces the same length right now that length is arbitrary now when you're making this cut and I see this all the time - and not only on the table saw with a sled like this on the miter saw as well when I said about kickback only happening between the spinning blade and the fence as in a spinning blade and the thing that doesn't move the same thing can happen here in this circumstance I see guys holding the piece that's not constrained in any way and the other piece that's up against that stop is loose between the blade and that stop so you've got a kickback situation there so you push it through the blade and then when you pull it back what happens is the piece that you've cut off tries to drag a little bit against the table or against the blade and gets jammed between the blade and the stop here and causes a kickback you always always always want to hold that piece that's being cut off between the blade and the stuff now if the piece is bigger you can use your hands like I'm using here and if it's small you can use a pencil or a small stick whatever it takes to hold that piece in place so that they can't move as it passes through the blade I should point out that it's always a good idea to complete the cup by pushing it all the way through the blade rather than trying to return it you double your chances of kickback that way okay that about wraps this one up there are things that you can do with your equipment to ensure or trying to safeguard against kickback as well and the things that you should do immediately after you get your table saw it doesn't matter if it's new used whatever straight out of the box right from the place wherever you bought it brand new you should make these checks to make sure that it's lined up properly you got to make sure that the blade is in line with the miter slots that's the first test the miter slots are what guides jigs and you know t-squares and all the stuff through the saw so these two have to be parallel the blade has to be absolutely in line with these miter slots then your fence has to be in line with the miter slots as well so parallel parallel parallel there shouldn't be any I've seen this before people set their fence so that there's more of a gap at the back you don't want to do that you want to have your fence set so that it's absolutely in line with the blade with no you know offset and definitely if you want to avoid kickback of any kind do not set the fence so that's tighter at the back then at the front [Music]

Channel: John Heisz - Speakers and Audio Projects

Views: 181,248

Rating: 4.8593202 out of 5

Keywords: woodworking, how to, diy, make, maker, making, i build it, john heisz, table saw, kickback

Id: ecCORCUnRW4

Length: 17min 7sec (1027 seconds)

Published: Wed Oct 11 2017