Newbie Table saw + plywood questions.....

[Christopher Wright]

Hey guys,

I bought a General 50-185 table saw w/50" fence late last year. I'm just getting around to working on my first real furniture project. I have a few questions.

1. My main question is: Is there any reason why I shouldn't cross cut plywood using the TS fence (like I would be ripping) instead of a sled or miter gauge? I cut 4 - 20" pieces out of 3/4" cherry veneer plywood last night for night stand table tops. I'm using a CMT melamine/plywood blade. I got no tear out. Are there any safety hazards to cross cutting using the fence this way?

2. What's the best way to cut 2" squares out of each corner of a 20" piece of 3/4" plywood. It's for a shelf that will wrap around 2" aluminum table legs. See pic below. Should I keep the TS blade where it's basically centered (vertically) on the plywood? This would logically mean the very center would be slightly deeper than the top or bottom, right? Make sense? I'll be covering with veneer edge banding anyway.

3. My belt guard was rubbing so I took it off. I'm sure the manufacturer would warn against this, but is it OK? Using a link belt also.

Thanks in advance for any input.

This is a great forum!
Christopher

[Frank Hagan]

1. My main question is: Is there any reason why I shouldn't cross cut plywood using the TS fence (like I would be ripping) instead of a sled or miter gauge? I cut 4 - 20" pieces out of 3/4" cherry veneer plywood last night for night stand table tops. I'm using a CMT melamine/plywood blade. I got no tear out. Are there any safety hazards to cross cutting using the fence this way?


There's a good chance you will have a problem trying to do this. If you shift the sheet of plywood even a little bit, so that the long edge along the fence past the blade acts like a fulcrum and causes the sheet to bind and pinch the blade, you will get kickback like you wouldn't believe. Not sure I explained it well enough, but the leading corner, against the fence, can exert a lot of pressure against the blade with relatively little movement of the plywood that is still uncut. If you have a good in-feed table, and a good outfeed table that will support the plywood all the way through the cut, its much safer. When I'm setting up, I lower the blade and do a dry run to make sure I won't get in a position where I'm wrestling with the plywood.

Safer still is to have the support on infeed and outfeed, and then clamp a board along the fence about half-way; it should extend to the point just equal with the beginning of the blade. As you push the plywood through, there's a 3/4" gap between the cut-off piece and the fence, which allows for a lot of minor movement without binding.

[Steve Cox]

It is generally considered unsafe to crosscut panels on the table saw without either a sled or a sliding table. The reason is one of friction and balance. If at any point the the edge next to the fence and on the back side of the cut comes away from the fence the saw will grab the panel out of your hands and fling it somewhere (probably into you). This will happen faster than you can see, much faster than you can react to, and you have no hope of controlling it once it starts. The wider (side to side) and shallower (front to back) the piece of wood, the harder it is to control. Once you get to squares, you can either cross cut or rip and it will be equally safe. Try this, take a 6' long 2x4 and put one end of it against the fence (blade down and saw off for this!;) ). Try to keep the board going across the saw without skewing it at all and keeping the end against the fence. Now imagine if you had the pull of the saw blade cutting on the board. This is an extreme example but it illustrates the dangers associated with crosscutting wide panels on the saw.

[Corey Hallagan]

On the corners either a jig saw and speed square or a small hand saw is how I would notch out the corners. On the guard, you should be careful without that guard with your clothes etc. Maybe you need to file the area rubbing or modify it. A modified guard is better than no guard I think. Is it missmolded or just bad fitting. Asking for a new one maybe from the manufacturer?
Corey

[RichMagnone]

No doubt about it. This is a clear situation where you need to go buy yourself a Bosch or Festool jigsaw.

[Christopher Wright]

Frank and Steve,

Makes sense on a piece of wood that has a very short face (that touches the fence)...like a 6' long 2x4 for example. But what about a piece of plywood that is 40" wide x 20" tall? See the pic where I cut a 40" x 20" panel down to 20" x 20" (across the grain).

Here you have a relatively long, solid edge to push up against the fence with. I'm a missing something? In the same scenario what if I cut the 40" x 20" down to 35" x 20".

Thanks for the help...you too Corey.

Christopher

[Doug Shepard]

I personally agree with most of the other comments here. I originally thought you were taking 20" cuts from a full 4x8 sheet, and I think maybe the others thought that as well. I don't see any problem with the 20" cuts on the 20x40 piece in your last post, but that's about the absolute limit I'd personally try without rough cutting oversize with a straight-edge and circular saw first. Just one thought though: You do realize your 2nd pc wont be 20x20, but 19-7/8x20 ??

As far as cutting the corners, I'd raise the TS blade up to max height and clamp a stop block to the fence so that when you hit it the 2" mark on the bottom of the ply is reached. The top face will end up with the blade stopping just shy of the mark, but you can clean up the corner with a handsaw and chisel. Unless you're not concerned about getting tearout on the face side of the ply, you'll have to make 4 cuts, then switch the fence to the other side of the blade to get the other 4 to complete the corner. The safest way would be to stop the saw when you hit the stop block, before trying to pull the piece back.

[Richard Wolf]

Cross cutting ply on a table saw should not be a problem for you, the problem with plywood kick backs is very common with 1/4 inch ply. It is light weight and very flexible and the front edge can climb up the back of the blade if you are not paying attention and cause a nasty kick back that most people will not forget quickly.

Richard

[Steve Cox]

Christopher, I gave you the example of the 2x4 knowing it was extreme but it illustrates the point. 20" x 40"? Not sure, I'd have to try that setup myself. You're correct, there comes a time when you have enough surface bearing against the fence to make the cut. How much is enough is up to you. In order to make things safer, people build sleds to hold the pieces, they use a guided circular saw system, or they get a sliding table for their table saw (or buy one that already has one). I went with the last option. You'll need to do one of them in your shop eventually.

[Jim W. White]

I'm with Richard, the only time I've gotten into problems doing the above illustrated cut is with 1/4" ply; otherwise no problems.

I would highly recommend a Bosch jigsaw for the corner cuts. It's a great saw!! :D ...but if the budget is tight, a $10-15 coping saw from any hardware store will do the job as well. ;)

[Steve Cox]

Jim and Richard, I would respectfully disagree with you. I attended two full time woodworking programs for a total of 3 years. They were programs that emphasized safety above all else and I worked with and around approximately 100 other students in that time. I have seen plenty of sheet goods kickbacks of the type described above whether with 1/4 or 3/4 material. I haven't had one myself but I was hit by somone elses and it didn't tickle. Most of them happened because someone was cutting a board that was wider than it was deep and the back edge came off the fence. There is a very distinctive gouge that is on the board after this happens. It is an arc that is deep near where the blade first caught the board and it gets shallower towards the end as the board is launched. Once you've seen one you can describe exactly what happened when shown a board after a kickback. There were a fair number of them hung on the walls in the shop by the survivors to remind them not to make the same mistake again. I made a big mistake in safety a couple of weeks ago and survived intact. I won't make that mistake again. I would like other people not to have make their mistakes in the firat place though I realize that is probably not realistic.:o

[Scott Berg]

[QUOTE=Most of them happened because someone was cutting a board that was wider than it was deep and the back edge came off the fence. There is a very distinctive gouge that is on the board after this happens. It is an arc that is deep near where the blade first caught the board and it gets shallower towards the end as the board is launched. Once you've seen one you can describe exactly what happened when shown a board after a kickback. [/QUOTE]

Yep, this EXACT thing just happened to me on Friday while cutting 3/4 inch plywood. It was late and I was not paying attention as well as I should have because I did not notice that the edge up against the fence was not square, rather it had a slight ridge in it which kept it from sitting tight against the fence (there is a long story involved in describing how this happened which I will not go into right now!).
When I was almost done with the cut, the board moved, and the back edge got pressed towards the blade. The 20 by 24 inch piece came flying back and caught me in the hip. The bottom had the exact mark on it that Steve was talking about. Luckily I was not hurt, and luckilly I knew not to stand directly behind the board. It woke me up and I called it a night!!

[Doug Shepard]

...There is a very distinctive gouge that is on the board after this happens. It is an arc that is deep near where the blade first caught the board and it gets shallower towards the end as the board is launched....

You'll get the exact same missile behaviour and gouge mark if you're dumb enough to try using the fence AND the miter guide at the same time.
Dont ask me how I know this ....:cool:

[John Lucas]

When cutting panel goods on the TS, you must keep your eyes and hands on the piece bewteen the fence and the blade. The offcut will almost never cause the kickback. The incut will if it is allowed to turn to the blade, particularly near the backpf the blade. No one has mentioned it, but this is an ideal place for a splitter with anti-kickback palls. I also listen to the cut all the time. If the sound changes that may give you a millisecond time to adjust the situation...or better yet, stop and let things settle out. If you try to correct things at that point, you are likely going to be "corrected" yourself.

[Peter Lyon]

I'll throw my $.02 worth in here. Although I think this is an area where one can get into to trouble, I must admit that I've done it on many occasions. I'd say do what's comfortable for you. Conversly, if it makes you nervous, don't do it. If you're careful -- particularly if you use the splitter like John suggested -- I think its OK.

I have no rule of thumb per se but I think the example that you provided (20" x 40") falls within my comfort factor.

[Keith Hooks]

My question probably stems from inexperience, but it seems like a properly aligned splitter would eliminate any chance of this happening. What am I missing? On my TS, the splitter isn't as wide as the blade so I've biased it to the fence face of the blade in order to help keep it against the fence.

[Richard Wolf]

Jim and Richard, I would respectfully disagree with you. :o

Steve you are right that kick backs are not limited to any perdicular size or piece of wood and I didn"t mean to imply that. It all has to do with control of the piece of wood between the blade and the fence. The scar you describe is always the scar that will be on a kick back, thats just the nature of the way it happens.
Bottom line is always being able to control the wood and most importantly, a straight, clean edge thats long enough to run against your rip fence.

Richard

[roy knapp]

everything that has been said by the others is true. i would just like to comment on the link belt and another way to do the 2' cutouts.
i have a dewalt 746x hybrid table saw and run a link belt on it and it runs smoother and i would not put the standard belt back on.

another way to do the cutout would be with a router, guide bushing and a template. make sure the that the template is large enough so when its clamped to your work, the router base will clear the clamps. after you make the cutout just cleanup the corners (a small radius will be left)
when you make the template don't forget the ofset for the guide bushing that you are going to use.:)

[Christopher Wright]

Thanks to everyone for all the responses. As an in-experienced woodworker, it's something I've been trying to wrap my brain around.

I do have a micro-jig splitter.

Sounds like what I'm doing is safe for the most part. I did cut the panels down to managable sizes with a circular saw before going to the table saw.
I do understand that a panel that is a lot wider than it is deep isn't safe.

So here's a dumb question.....is a "crosscut" always considered a cut across the grain, or can it be a cut across the short side of a panel, but with the grain?

Thanks again,
Christopher

[Keith Hooks]

I wanted to bump this to see if anyone had answers to Christopher's and my(above) questions.

[John Hemenway]

OK I'll take a stab at the cross grain question. I bet the term originated way before ply was made. On 'natural' wood cross grain is pretty obvious. Using the term on ply that really has no one grain direction is a stretch. I would consider cross grain in ply to be perpendicular to the face grain direction. There aren’t the wood movement issues w/ ply so it’s not as tricky to cut ‘cross grain’. If the long side is on the fence it’s safe, if the short side is on the fence much more caution is indicated.

Back to the original question, when the piece being cut is a lot wider than deep there is the tendency to push it around the blade and not straight thru the blade. One side drags much more. I would use a miter gage with extension and a block on the rip fence that sets the distance to the cut but ends BEFORE the blade. This is easy to do w/ ‘unifence’ style fence.