[dougan]

Hey all,

I am somewhat new to woodworking. I've done some projects basic 4/4 hardwood boards I picked up at Menards. But now I've come upon some nice 8/4 maple and walnut I want to use for a project. I have so far done well with the standard 28 tooth blade on my table saw for ripping 4/4 boards.

I am familiar with table saw safety. But is there anything to know about doing a good job (technique, blades, etc) with these thicker boards? I just don't want to screw these nice boards up. Thanks!

 

[kkalin78]

Tricks are really depended on table saw you are gonna use If it's powerful table saw (3HP or more) I would rip it in one pass. If it's small saw I would do it in two-three passes with thin kerf ripping blade.

 

[Hunter]

Slow down your feet rate.

Hunter

 

[MNsawyergp]

A few factors come into play with thicker wood. Mainly, there is more area of the saw blade in the wood at one time, which, depending on the number of teeth, tooth angle and grind, gullet size and pitch, and horse power of the saw motor, can cause the saw to bog down. Even if you slow down your feed rate, the blade can heat up and warp, the saw motor can heat up, the wood can pinch or bind the blade....causing the saw motor to trip the heat sensor or a breaker in your electric panel, or if the saw has plenty of horse power, a kick back can occur, sending the board past you or through you at rocket speed. 8/4 wood can have some real stresses built up in the board, which, when ripped, can either pinch the saw cut together or open the saw cut up. It is the pinching shut that you need to watch. If the saw kerf closes as the board is being sawed, get ready for problems. I have found that stopping the saw and pounding a shim into the kerf to hold it open allows the cut to be made without pinching the blade. This requires shutting off the saw in the middle of the cut, adding the shim, then backing up the board to take the teeth out of the wood, then holding on for dear life and re-starting the saw and continuing the cut. Some woodworkers may scream and set off sirens when reading this, but in the case I am presenting, I have had to hold boards like wrestling an alligator until the cut is completed because the kerf pinched shut and the board wanted to fly out of the saw. Anti-kick back pawls and the spreader on your table saw guard are your protection from this safety issue. A lot of woodworkers take the guard off (including me), but the hazard I just described is exactly why these guards were invented.

There is a whole science to saw blade design. It is best to go to a saw blade manufacturer or talk to one on the phone and tell them what you are cutting. They will recommend the right blade for thick wood ripping. Here is one link to give you some info about saw blades. There is a lot to learn so study up on the terms and why saws blades work the way they do....
http://www.sharptool.com/PitchVsDepth.html

Here is another link. Look at this blade ... LM71Thick Stock Rip Blades at this link... http://www.carbidespecialties.com/ripping_blades.htm

I would not recommend using thin kerf saw blades for ripping 8/4 wood. It is too easy for the thin kerf saw disk to warp when over heated...in my opinion.

 

[knotscott]

The blade you choose can make a huge difference. The only 28T blades I've used were real dogs....Vermont American and a nearly identical Skil blade. I'd strongly suggest picking up a good 24T ripper like a Freud Diablo D1024, Freud Industrial, Irwin Marples, CMT Industrial, DW Precision Trim, or Infinity. Keep the blade clean and sharp.

It'll also help a lot if the wood is flat and straight.

 

[cabinetman]

The blade you choose can make a huge difference. The only 28T blades I've used were real dogs....Vermont American and a nearly identical Skil blade. I'd strongly suggest picking up a good 24T ripper like a Freud Diablo D1024, Freud Industrial, Irwin Marples, CMT Industrial, DW Precision Trim, or Infinity. Keep the blade clean and sharp.

It'll also help a lot if the wood is flat and straight.

+1. :yes: Keep the stock against the fence. I would run the blade up high at least for the gullets to clear the wood.

.

 

[Midwest Millworks]

Higher horse powere does not increase the chances of kick back. Not enough horse power along with a improperly set up saw and improper tecnique causes kick backs. When only horse power is a factor in a kick back, it is caused by the motor bogging down during the cut allowing the blade to get a hold of the stock instead of cutting through, then sending the stock on a journey in the opposite direction.

It all boils down the the same solution for everything. We need to use the proper tool for the job. Most contractor saws and any other low horse powere saws will do o.k. up to 4/4 stock. Thicker than that and you start having problems.

I work with a lot of 12/4 hardwood stock. I have a 5 horse power saw with a riving knife and run a Tenyru 40 tooth Gold Medal blade when cutting the thick hard stuff. I get glue line cuts and have never had a kick back with that set up. I wouldn't even consider cutting that stuff on a smaller saw. Not to mention once you get used to high quality cuts you won't accept anything else.

Mike Darr

 

[MNsawyergp]

Running the blade high, with a good portion of the blade exposed above the board is best for clearing the gullets and for not having as much of the blade surface and as many teeth in contact with the wood. This becomes a safety issue, though. If anything goes wrong, all that exposed blade is like staring at a shark's mouth in front of you. Using a blade guard is very important if you expose a lot of blade.

When I took shop class in high school the teacher showed a film of accidents in a woodworking factory. One involved a table saw operator ripping large boards. He had the blade low and no kick back pawls or spreader or guard on the saw. Another man was bringing boards to him. The board being fed pinched and because of the low blade angle, the board shot out of the saw at rocket speed and impaled the helper, leaving him dead on the floor with the board and guts coming out his back. Okay, that is pretty gross, but you get the point of safety after hearing that story, I hope.

 

[cabinetman]

When I took shop class in high school the teacher showed a film of accidents in a woodworking factory. One involved a table saw operator ripping large boards. He had the blade low and no kick back pawls or spreader or guard on the saw. Another man was bringing boards to him. The board being fed pinched and because of the low blade angle, the board shot out of the saw at rocket speed and impaled the helper, leaving him dead on the floor with the board and guts coming out his back. Okay, that is pretty gross, but you get the point of safety after hearing that story, I hope.

Now that one deserves some nice color pictures.:yes:

.

 

[d_slat]

I would do it in two-three passes with thin kerf ripping blade.

This is not an operation I would recommend. Multiple passes requires you not to use a splitter, blade guard, and kick back prawls. Single pass with a decent blade is a much better option.

 

[rrich]

This is not an operation I would recommend. Multiple passes requires you not to use a splitter, blade guard, and kick back prawls. Single pass with a decent blade is a much better option.

+ 1 here!

The big trick for ripping 8/4 or 12/4 is big gullets. You can get and use a dedicated rip blade that is designed to make rip only cuts. With the proper blade I have ripped 12/4 cherry on a Jet contractor saw without a problem.

Another solution is to get a combination blade. Typically 8 or 10 groups of 5 teeth, 4 ATB and 1 Raker. These blades are not very expensive and in fact less than a co-pay at the ER.

The blades to avoid are general purpose blades. These are small gullets and all ATB teeth. This type of blade works well for rip cuts up to about 3/4. Beyond 3/4 in thickness the gullets aren't large enough to clear the saw dust and the saw will really bog down.

There is one other thing. Unless you have, and you probably don't, a 3/32" splitter, DO NOT USE A THIN KERF BLADE. The typical full kerf splitter will not pass through a thin kerf cut. It is what it is. A full 1/8" ain't going to pass through a 3/32" slot.

 

[Brian T.]

I don't use my cheap TS much at all. BUT, I bought a top blade (Freud?) for ripping 6/4 birch.
Usually no more than 200-300' at a session.
Must admit, it does quite a nice job. A long time ago, I figured out that having several purpose-designed blades, and very good ones, too, was the practical way to go.

From a wood carving perspective, each saw blade tooth is a chisel/gouge. I try to run them into the wood, of any thickness, at 45 degrees.

 

[GoNavy429]

If your talking about making thinner boards out of your 8/4 then use a bandsaw to resaw boards to a thinner profile, which I assume is what you are talking about, or are you just concerned with cutting a thicker board. If your talking about re-saw, You can get two 3/4 inch boards from 8/4 stock. Bandsaw is sent with a fence and a 5/8 inch resaw blade. I use a feather board just before the blade to keep the stock against the fence. Dependent on the lenght of the board make sure you have adequate support on the out feed side and have a push stick handy for the last few inches of the cut. Set your fence slightly over the final thickness to compensate for sanding and/or planning to final thickness. If I plan to just sand I go 1/16th over add an additional 1/8 if you plan to use a planner as well which use just about all of your 8/4 board. You just have to do the math ahead of time before you cut. But getting two 3/4 boards from a piece of 8/4 lumber is very doable, but I wouldn't do it on a table saw

If you are just concerned with cutting a thicker board, the less teeth the better and get your blade as high as possible to reduce the number of teeth actually in the wood at any time. The more teeth your blade has, the slower you have to go.

 

[kkalin78]

This is not an operation I would recommend. Multiple passes requires you not to use a splitter, blade guard, and kick back prawls. Single pass with a decent blade is a much better option.

Of course single pass is better but it works if you have enough horse-power. Otherwise it's more dangerous (as it mentioned above) than do two cuts.

Not sure why you need to remove riving knife. Modern saw usually have two positions for the riving knife: through cut and non-through cut. Thus the knife just needs to be lowered. If it's not a modern saw then the hand-made splitter is must. There are plenty of example how to make table insert with splitter.

Also I understood when I was saying multiple passes - people can take it wrong. I mean that one cut is done on one side of the board, another cut on another side of the boards. But both cuts don't cut the board completely. And finish the cut with hand-saw. Same technic is used for resawing on table saw.

 

[CNYWOODS]

I agree with the general census here. I too sometimes will use the band saw within a 1/16" then trim again on table saw. Usually there's a little tension if your ripping in 1/2 so I always take it back to the joiner to straighten it back out before that final pass.

 

[Old Skhool]

Of course single pass is better but it works if you have enough horse-power. Otherwise it's more dangerous (as it mentioned above) than do two cuts.

Not sure why you need to remove riving knife. Modern saw usually have two positions for the riving knife: through cut and non-through cut. Thus the knife just needs to be lowered. If it's not a modern saw then the hand-made splitter is must. There are plenty of example how to make table insert with splitter.

Also I understood when I was saying multiple passes - people can take it wrong. I mean that one cut is done on one side of the board, another cut on another side of the boards. But both cuts don't cut the board completely. And finish the cut with hand-saw. Same technic is used for resawing on table saw.

Most early Unisaws were built with a 1 hp repulsion induction motor AKA "bullet motor". No thin kerf blades, and cutting 4/4, 6/4, and even 8/4 hardwoods were done routinely as well as safely. And yes I remember resawing on that saw as deep as was possible from both edges before either finishing with a handsaw, or with the bandsaw which was a 20" Rockwell (Delta) with a 3 tpi blade to finish the cut as the bandsaw was only 1 hp also. (Not enough hp in some cases with resawing wide hard stock.)

I'm sure almost everyone here has cut dados, or non through cuts such as those for drawer bottoms. It is really no different, the problem is a combination of many factors, blade, material hardness, heat developed, knots, depth of cut, ... Splitters, riving knifes generally do not come into play here. Almost any operation can be guarded. Nothing really unsafe here, just doing what was needed to get the job done.

Respect to all of the excellent advice given in the previous posts.

 

[johnnie52]

When I took shop class in high school the teacher showed a film of accidents in a woodworking factory. One involved a table saw operator ripping large boards. He had the blade low and no kick back pawls or spreader or guard on the saw. Another man was bringing boards to him. The board being fed pinched and because of the low blade angle, the board shot out of the saw at rocket speed and impaled the helper, leaving him dead on the floor with the board and guts coming out his back. Okay, that is pretty gross, but you get the point of safety after hearing that story, I hope.

Now that one deserves some nice color pictures.:yes:

.

Thanks men... I just ate!

 

[kkalin78]

... Splitters, riving knifes generally do not come into play here. Almost any operation can be guarded. Nothing really unsafe here, just doing what was needed to get the job done.

Respect to all of the excellent advice given in the previous posts.

I agree that riving knife or splitter are not needed to dado-cuts. But I kinda disagree for normal blade on non-through cuts. It does help to keep a stock straight and prevent side-movements. As result the blade never twist and the cut is smoother. Also the blade produces less heat. This is my experience

 

[Old Skhool]

I agree that riving knife or splitter are not needed to dado-cuts. But I kinda disagree for normal blade on non-through cuts. It does help to keep a stock straight and prevent side-movements. As result the blade never twist and the cut is smoother. Also the blade produces less heat. This is my experience

You're right a riving knife can ride in the non through cut helping to resist the stock from turning and kicking back. However you could also use feather boards to hold stock against the fence AND down on the table. The riving knife is not keeping the cut from closing on a non thru cut unless it's a really deep one like resawing case hardened, or otherwise internally stressed stock. The question is, how many will use the safest possible set ups compared to an easy to use riving knife, especially for just a few cuts? Riving knives undoubtedly are a positive feature.

 

[calwilliams63]

Yeah, I would just cut everything at the bandsaw slightly over sized and then run it through the planer down to the size. A lot safer with better results. Cheers!!!