Sliding Table Saw Safety
From the original questioner:
Not the first I have heard of slider blades twisting and cutting the table. I don't understand why you push the material into the slider fence vs. pushing the slider fence into the material?
From contributor C:
Cutting on a slider is not a speed race. Popular belief is that cutting on a slider is more efficient at high speed. Wrong. While pushing at a moderate rate, a piece can be properly held in place behind/against the fence with a minimal amount of pressure. I caution you to never cut a large piece in a slider with the blade behind it - this is a major accident waiting to happen. The rip fence should always be left in front of the blade when working as a stop, to alleviate the possibility of a jamb and a rocket propelled backfire.
From contributor J:
We use an SCMI slider with the fence in front. The main reason for this is so that you can load the sheets from the back without having to lift them over the fence every time. This makes it much easier for one person to use the saw. Ours has a riving knife behind the blade, which makes it much safer and more kickback resistant than a regular table saw. We have had material bind a time or two, but it has never been thrown.
From contributor E:
Don't ask me how I know this, but... After you crosscut on the sliding carriage, pay attention to where the piece is that is still on the carriage when you pull it back past the blade. If a work piece on the carriage hits the blade from behind, it will launch.
From contributor B:
I get small offcuts between the scoring blade and the main blade, and have got to remember not to reach in and brush them away. The scoring blade will get you.
From contributor P:
I've been using a slider for years; here is the approach I use.
#1 - The crosscut fence is in front of the material. This allows for the loading of larger pieces, but also the operator should be able to see the edge mate up to the fence and see if there is trash holding the panel away from the fence. I know you can still see the joint if you run the fence on the back side, but it's not as natural to look directly down.
#2 - As stated above, cutting on a slider is not a speed race. A slider is faster than a tablesaw but not as fast as a panel saw, so buy according to your workload. The purpose of a slider is to produce square (eliminating the factory out-of-squareness), chip-free panels time after time.
#3 - Most hazards occur when using the rip fence in conjunction with the crosscut fence. Never run the rip fence fully forward when using the crosscut fence or you create a pinch point and material can kick back or jam, forcing the blade into the slide carriage or worse. As a rule of thumb, position the end of the rip fence center of the main blade. This allows the material to open up and decreases the likelihood of binding of the blade. When using the rip fence only, you can run the fence in the forward position.
#4 - Run an overhead guard. I know guys who cut wood hate guards, but if it keeps you from losing a finger, it's worth the trouble. The other reason to run a guard is you are protected when running the blade high. Check this for yourself - place a panel beside the saw blade (with it off) and lower the blade to just where the teeth protrude through the top side. Which direction does the tooth appear to be pushing? Answer; back toward the operator and slightly down through the table. Now raise the blade to the highest position. Which direction does the blade appear to be pushing? Answer; almost straight down through the table. By running the blade at the top most position, you have decreased the likelihood of kickback toward the operator and your blades will last longer because you are in the cut less time.
#5 - Make sure the slide carriage is just slightly above the cast table. Many guys have been hurt because the slide table has not been kept in adjustment. When the slide table settles with normal wear, adjust it or replace wear parts. This is not a daily, weekly or even yearly adjustment that needs to be made on a quality slider, but when you see the panel shining the edge of the cast table that is adjacent to the slide, it needs to be checked. The slide carriage should be .005" to .010" above the cast table. You want the slide carriage carrying the weight of the material as much as possible.
Lastly it's a benefit to switch blades when switching materials.
From contributor J:
I agree with contributor P about the overhead guard. It is definitely worth it. It makes it much safer, and ours is attached to dust collection, so it removes almost all surface dust.
From contributor D:
Try to get in the habit of retracting your scoring blade when you're not using it. Several times guys forgot/didn't notice that the scoring blades were up, and then slid a piece of material into it.
From contributor T:
We have an Altendorf F-45. We used to struggle with the scoring blade until we switched to a melamine blade from Royce Tooling in Canada. The quality of cut on pre-finished plywood is equal or superior to what we were getting with a scoring blade.
For a scoring blade to work, the material has to be exactly flat to the table. From the operator's side it usually looks flat. If you view the cutting operation from the outboard side, you will see the material undulate and twist considerably as you march through the blade.
Sometimes people compensate for this by increasing height of scoring blade, but this can produce a tiny shoulder on the edge of the board which can complicate subsequent PVC on the edgebander.
From contributor I:
The scoring blade is very hard to see. It is easy to accidentally put your hand near it.
From contributor F:
In order to use the slider safely, I did two things. First, I built a pneumatic hold down to keep the piece from moving, keep hands away from the blade, and redirect any kickbacks that may occur. Second, I have an air hose hanging down right at the blade so any small loose offcuts can easily be blown away without getting anywhere near the blade.
From contributor M:
My shop is an all Euro shop. Sliding panel saws (not to be confused with adding a sliding attachment to a cabinet saw) are much safer machines.
We use the saw as it was meant to be used, fence in front. This keeps the saw more versatile and allows it to be loaded properly. When I am cross cutting lumber I put the fence in the rear position of the sliding outrigging and put material on the other side of the fence. This is a lot easier and safer for narrow stock.
Sliders are actually more difficult to use than a cabinet saw; much faster and more accurate but require more skill. The operator has to keep the panel against the crosscut fence while cutting, even though he can't push the panel against it. This usually means pushing the stock down onto the table instead of forward into the fence.
As mentioned by others, the feed rate is difficult to master. If the slider is moving too fast when the blade hits the panel, it will push the panel back (away from the fence). So you must enter the cut slowly, then accelerate as you cut. Finishing the cut with more speed helps the offcut slide past the blade without nicking the corner, as the momentum allows it to slide past the blade. Also you can never push the table; always push the stock. It feels unnerving at first as the panel feels like it is floating and you need to hold the carriage to keep it in check, but this is wrong. Focus on applying pressure down into the table and walk the piece through with your feet, not your body.
Proper setup is a big deal also. I don't mean the obvious stuff (square fence, true table, proper blade height, etc.). I am talking about the location of the fence/outrigging relative to the blade and the positioning of the table locks. Most tables are 10'+ long; most of us cut 8' panels. The fence should be in the forward mounting position and the outrigging table should be positioned so that when a full sheet is loaded, there is about 4" of the sliding table exposed at the end. This way the operator can easily grab the rear handle with one hand and push the panel into the fence with the other.
My saw has three table locks, one in the neutral or home position, one for loading 8' panels and one for loading 10' panels. (If you set up the outrigging as I describe above, there will be two different positions for loading based on the panel size you are cutting.) The lock should be set so that the work piece is about 2" from the scoring blade. This seems crazy to old school cabinet saw users who like to have a good bit of fence and table in front of the blade so we can guide the panel into the blade, but sliders do not need this space. Instead the extra space allows the operator to accelerate the panel too much before it meets the blade. Remember the panel should be moving slow when it meets the blade and accelerate through the cut. If there is only 2 or 4 inches of space between the blade and work piece, there is little chance for the carriage to move too fast. Also this creates a larger area to support the panel as it is being loaded.
I want to repeat that the work is fed with your feet, not your arms or back. Look at the operators on Altendorf or Martin youtube videos. Notice they are standing upright and their arms are pushing down on the work piece close to their hips. They are not bent over at the waist with outstretched arms, which causes you to push too much forward with your hands instead of down. Focus on maintaining this posture and walking with the panel. Not only does this ensure a good cut by keeping the panel in position, it is also a lot easier for the operator after a long day. No stooping and bending.
Finally, dust cutting full sheets is tricky. You have to lift the outside of the panel with your left while pushing down with the right. This keeps the panel from teetering off the table at the opposite corner due to the weight of the panel hanging off the back/left side.
Also keep sawdust off the sliding table, which makes it more slippery.
My #1 thing to get used to was hearing the panel hit the scoring blade before the main blade. Every time it would startle me. Now I can hear if the operators are feeding correctly by the timing of the blades. The #1 cause of injury at the saw is loading. Panels are heavy and awkward to handle. Keep that in mind when you position the stock pile.
From contributor T:
The Altendorf people taught us how to load the saw. If you're picking up the entire weight of a sheet, you are loading incorrectly. The proper way is to drag the material across the floor and roll one edge onto either the butt rest bar or, if you are coming from the side, the roller at the end of slide side. The dominant weight of the panel is either always on the floor or always on the saw. The operator never hoists the sheet at all. Note that the sliding table is in semi-locked position during this loading.
From contributor N:
I thought I was the only one around here that still does Cave Man Cabinetmaking. When we have sheets stacked up vertically behind the slider, I leave one corner on the floor, bring the sheet over to the slider, lower it, and then do a nice flip over onto the saw (this takes some circus skills). All the weight is on the floor or the saw. Most of the time I slide the material from the rack (to the left of the saw) onto the slider, still not lifting, only sliding the material to the saw. If not for the slider I would have worn my back out a long time ago.
From contributor B:
Try this for loading a slider. From a flat stack position, I lift one end and slide it onto a plastic garbage can on wheels. Roll over to the saw and slide onto the table. Never lifted the whole sheet.
From contributor M:
I use the drag and roll method. The issue I have is, outside of the roller is the plastic ledge thing for supporting long crosscuts when the fence is extended. This plastic ledge is in the way of the roller, sort of. I thing you guys know what I mean. Has anyone decided to take it off? I almost never use it anyway.
From contributor E:
I built a cart that is the same height as my saw. I only order sheets as required so they get slid off the delivery truck on to the cart. Cart gets wheeled over to the saw and sheets are slid off the cart on to the saw. I never lift a sheet and it never gets dragged on the floor.
If I had the space, I would probably stock lifts of my common sheets, but I would also then own a forklift. Use the forklift the same way I use the cart, just slide the sheets from the forklift onto the saw.
The cart is beefy with really heavy duty castors and is made of 2x4's with all sorts of cross braces. I routinely load it up with 20 sheets. The top is about 3' x 5'.
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