Cross cutting using the rip fence is a no no - Page 3 - Woodworking Talk - Woodworkers Forum
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post #41 of 52 Old 04-13-2013, 12:03 PM
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Originally Posted by woodnthings View Post
This guys scares me. Plexi is unforgiving and if it heats up, binds and seizes, then a kick back is certain. I wanted to post this a while back but couldn't find it. No blade guard, no splitter, no push stick....scary Sometimes You Tube has good example of bad examples....
YouTube - Cutting Acrylic Sheet with a table saw
if kickback occurs, the plexi might slice through his flesh
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post #42 of 52 Old 04-13-2013, 09:11 PM
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Originally Posted by nijabhaava View Post
I'm mostly new to woodworking, so correct me if I am wrong -

I took some classes at woodcraft and this is what they told me -

Ripping or crosscutting has nothing to do with how long or wide the piece is - it has to do with the grain. Ripping is with the grain, and cross cutting is across the grain.

The issue is not just the physics of having a piece that is longer across up against the rip fence which can cause binding because of the mechanics, but the grain itself.

Ripping with a fence is safe because both the rip fence and the blade are going with the grain. The blade does not stress more and is not left in a potentially binding position, nor is the piece providing frictional resistance at a 90 to the fence because with the grain is a smooth movement.

But across the grain, both the blade has additional resistance that can cause binding, and the grain that is coming into the fence is going to provide too much resistance for comfort that could potentially cause binding and kickback. If a piece tears out, especially from ply, you have a worse situation with the cross grain with all kinds of uneven grain and pieces sticking out into the fence at 90 degrees, which is very liable for resistance, binding and kickback.

Additionally, especially with ply, as you cut, the cut section in a cross cut can be messy and full of burrs, These burrs can be picked up by the spinning blade and grab and throw the wood. In a crosscut with a sled or miter gauge this is fine because there is a solid piece behind the wood, which protects you somewhat and since there is no fence stifling the piece in, the chances are that if it does get caught, it wont be thrown back but will, after some short backward pressure, move off to the side. You dont have this death trap of nothing between you and the wood, and nowhere for the wood to go but back at you because of the fence.

I think this has more to do with it?
This is pretty much how I have always thought of the differences between cross cutting and ripping. Of course I have never run across a piece of wood where the cross grain dimension was less then the along the grain dimension.

Plywood does confuse this whole issue.

George

PS Just noticed I got caught by an old thread again.
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post #43 of 52 Old 04-13-2013, 11:08 PM
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The use of a splitter or riving knife will all but eliminate this issue if proper technique is followed....forward pressure, downward pressure and pressure inward towards the fence.
I just don't agree with this statement. Is the statement to read ..."will all but eliminate", or, "will eliminate"? Not very clear. I'm reading it as that those two devices will eliminate the kickback issue...which I don't agree with.

While those two devices are intended to keep the kerf, wood can "walk" as it's being cut. Wood can, push against the fence towards the blade. In a case like that it's edge can be forced into the riving knife or splitter, and cause binding. What happens then...since it's at the rear of the blade, can be projected up and forward towards the operator.

This is the same complaint I have with the "short fence", that is used in Europe. Makers there decided that once the stock clears the back of the blade, it needs no fence, and hence, lessens the possibility of kickback. BULLPUCKY. As wood gets cut, it can drift either way. So, for example, if ripping a long piece of lumber, with no fence past the blade, you have "legs" as a result of the cut that can go anywhere.





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post #44 of 52 Old 04-14-2013, 08:24 AM Thread Starter
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what's your advice then?

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I just don't agree with this statement. Is the statement to read ..."will all but eliminate", or, "will eliminate"? Not very clear. I'm reading it as that those two devices will eliminate the kickback issue...which I don't agree with.

While those two devices are intended to keep the kerf, wood can "walk" as it's being cut. Wood can, push against the fence towards the blade. In a case like that it's edge can be forced into the riving knife or splitter, and cause binding. What happens then...since it's at the rear of the blade, can be projected up and forward towards the operator.

This is the same complaint I have with the "short fence", that is used in Europe. Makers there decided that once the stock clears the back of the blade, it needs no fence, and hence, lessens the possibility of kickback. BULLPUCKY. As wood gets cut, it can drift either way. So, for example, if ripping a long piece of lumber, with no fence past the blade, you have "legs" as a result of the cut that can go anywhere.





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Would you advise NOT using the splitter?
Do you use a splitter?
When and under what circumstances should you use a spiltter?

I stand by my statement, ...it will ALL but eliminate kickback due to a rotation of the work away from the rear of the fence.

Also when the wood "walks" ...what ever that means.. it can pinch at the rear of the blade as the kerf closes and binds on the splitter.... I've had it happen. When that does happen it becomes difficult to push and you may have to STOP the saw and insert a small wedge in the kerf....BUT you will have no over the top of the blade kickback because you stopped the saw. Without a splitter, you would have had a kickback due to a pinched blade.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #45 of 52 Old 04-14-2013, 08:37 AM
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what's your advice then?
Use the safety devices available for the tool.





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post #46 of 52 Old 06-18-2018, 03:59 PM
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So to be clear, It's ok to cross cut sheet goods (OSB, Plywood) against the rip fence provided theres ample surface area? Say I've got a 4x4' piece of maple plywood and I want to trim it down to 30"x 42" It should be fine use the rip fence instead of busting out the SkillSaw?
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post #47 of 52 Old 06-18-2018, 04:13 PM
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So to be clear, It's ok to cross cut sheet goods (OSB, Plywood) against the rip fence provided theres ample surface area? Say I've got a 4x4' piece of maple plywood and I want to trim it down to 30"x 42" It should be fine use the rip fence instead of busting out the SkillSaw?
As a general rule of thumb it's alright to crosscut against the fence if the material is 10" wide or wider. Now if that 10" piece is 8' long that is a different story. That long and it's difficult to keep the sheet against the fence.

As far as the plexiglass, I've never had any issues with kickback. It's styrofoam sheeting board I find bad to kickback. You can push it against the fence enough to compress and if you let the slightest pressure off it will kick in a heartbeat.
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post #48 of 52 Old 06-18-2018, 04:31 PM
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Thank you for the reply. I'm new to this but I like to learn. I just got a table saw and am making an outfeed table and wanted to cut down a piece of plywood for the top but was curious if I could do that safely against the rip fence.
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post #49 of 52 Old 07-14-2018, 01:15 PM
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At the shop I work at we dont have blade guards or sleds. We just cut it and move on. Never had a problem in 40 years. We do cross cut 12 foot MDF at times removing only 2 inches. It's not hard.
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post #50 of 52 Old 07-14-2018, 03:09 PM Thread Starter
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a 12 foot crosscut?

A "crosscut" that is 12 ft in length would be a "rip" in my book. Typically, a crosscut is made across the width of a board, not along it's length. The thread was started to prevent the inexperience from using the fence as a "stop" where the cutoff piece ends up being trapped between the spinning blade and the fence where it can rotate slightly and get kicked back at the operator. It's a dangerous practice.

Experienced woodworkers would use a small block clamped to the fence at a point just before the blade starts:

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #51 of 52 Old 07-14-2018, 08:32 PM
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Originally Posted by woodnthings View Post
A "crosscut" that is 12 ft in length would be a "rip" in my book. Typically, a crosscut is made across the width of a board, not along it's length. The thread was started to prevent the inexperience from using the fence as a "stop" where the cutoff piece ends up being trapped between the spinning blade and the fence where it can rotate slightly and get kicked back at the operator. It's a dangerous practice.

Experienced woodworkers would use a small block clamped to the fence at a point just before the blade starts:

I meant across the width. It comes 12ft and we need at times a piece 11ft 10" etc. I understand a RIP and a cross cut
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post #52 of 52 Old 07-14-2018, 09:06 PM Thread Starter
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just so I undertand ....

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I meant across the width. It comes 12ft and we need at times a piece 11ft 10" etc. I understand a RIP and a cross cut
You have ripped a 2" wide piece off your 12 ft long MDF. Now you want to crosscut 2" off one end making it 11 ft 10" ...right? Why would you use a table saw with all that length hanging off one side when a miter saw would be easier and safer? And you don't use a stop block on the fence either..? Seems like an accident waiting to happen to me.
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The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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