Cross cutting using the rip fence is a no no - Woodworking Talk - Woodworkers Forum
 1Likes
Reply
 
Thread Tools Display Modes
post #1 of 52 Old 12-24-2010, 07:30 PM Thread Starter
where's my table saw?
 
woodnthings's Avatar
 
Join Date: Jan 2009
Location: SE, Michigan
Posts: 25,032
View woodnthings's Photo Album My Photos
Cross cutting using the rip fence is a no no

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....

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)
woodnthings is online now  
Sponsored Links
Advertisement
 
post #2 of 52 Old 12-24-2010, 08:02 PM
Senior Member
 
Join Date: Jul 2008
Location: Florida Panhandle
Posts: 11,479
View GeorgeC's Photo Album My Photos
I would not have my hands where the operator has his without push sticks, now would I reach over the blade to retrieve anything.

However, I am not sure that I would classify this as crosscutting. If it was a piece of plywood it would not be crosscutting. Then again I did notice the second cut until I watched the video the second time. That second cut does smack of crosscutting.

The fact that it is plexi does present a problem. Maybe the best way to do that job would be to use a sled.

George
GeorgeC is offline  
post #3 of 52 Old 12-24-2010, 08:40 PM Thread Starter
where's my table saw?
 
woodnthings's Avatar
 
Join Date: Jan 2009
Location: SE, Michigan
Posts: 25,032
View woodnthings's Photo Album My Photos
Crosscutting

Quote:
Originally Posted by GeorgeC View Post
I would not have my hands where the operator has his without push sticks, now would I reach over the blade to retrieve anything.

However, I am not sure that I would classify this as crosscutting. If it was a piece of plywood it would not be crosscutting. Then again I did notice the second cut until I watched the video the second time. That second cut does smack of crosscutting.

The fact that it is plexi does present a problem. Maybe the best way to do that job would be to use a sled.
George
If there is no formal definition in woodworking terms, mine would be cutting across the length of a board, length being a greater dimension than width. The type of material does not matter in any case. Cross cutting with little or minimum bearing surface against the fence, equal to or less than the exposed blade dimension, like in the video is asking for trouble since any deviation will cause a kickback. Use the mitergauge or a sled. bill
See this video ....crosscutting using the fence at 2:51

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)

Last edited by woodnthings; 12-26-2010 at 10:30 PM.
woodnthings is online now  
Sponsored Links
Advertisement
 
post #4 of 52 Old 12-24-2010, 08:48 PM
Member
 
Microtus's Avatar
 
Join Date: Jun 2010
Location: Dixon, Ca
Posts: 42
View Microtus's Photo Album My Photos
As a complete and total newbie to woodworking this is the kind of stuff I like to see and learn. Heck I don't even have a saw yet (wife bought me a cabinet saw for xmas and is in shipping). I learned NOT to cross cut using the rip fence from this forum.

and for a visual reminder...

http://www.metacafe.com/watch/910584...demonstration/
Microtus is offline  
post #5 of 52 Old 12-24-2010, 08:59 PM Thread Starter
where's my table saw?
 
woodnthings's Avatar
 
Join Date: Jan 2009
Location: SE, Michigan
Posts: 25,032
View woodnthings's Photo Album My Photos
Cabinet saw for xmas????

Quote:
Originally Posted by Microtus View Post
As a complete and total newbie to woodworking this is the kind of stuff I like to see and learn. Heck I don't even have a saw yet (wife bought me a cabinet saw for xmas and is in shipping). I learned NOT to cross cut using the rip fence from this forum.
and for a visual reminder...

http://www.metacafe.com/watch/910584...demonstration/
OK which saw, you can't just say that and then leave..... bill

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)
woodnthings is online now  
post #6 of 52 Old 12-24-2010, 10:19 PM
Old School
 
cabinetman's Avatar
 
Join Date: Jul 2007
Location: So. Florida
Posts: 24,062
View cabinetman's Photo Album My Photos
In this particular video, I wouldn't consider the second cut a cross cut. Imagine the piece one inch wider than the cut. IOW, it was a 1" trim off the left edge of a piece. If the concentrated pressure and control of that piece in the video is on the section between the blade and the fence, it's a safe cut.

The problem that comes with crosscutting is when there is a long section and part of the left end is cut off. In a case like that, some control of the long section can interfere with the stock staying on the fence throughout the cut.

That second cut can be made with just controlling the "saved" piece, without controlling the "waste" piece. There's the issue of not using the guard, and that's up to the operator. Some do, and some don't.

I will say I prefer a much higher blade adjustment when cutting. It helps to hold down the stock, as the cutting angle is more vertical. a higher blade clears debris more easily, and provides less blade/stock contact which reduces friction...easier cut. A higher blade cutting acrylics produces a cleaner cut and less melting. This I also find holds true for solid surface countertop materials, like Corian.










.

Last edited by cabinetman; 12-26-2010 at 01:34 PM.
cabinetman is offline  
The Following User Says Thank You to cabinetman For This Useful Post:
Rick C. (12-28-2010)
post #7 of 52 Old 12-24-2010, 10:31 PM
Member
 
Microtus's Avatar
 
Join Date: Jun 2010
Location: Dixon, Ca
Posts: 42
View Microtus's Photo Album My Photos
All she would say is it is an ugly green and has a granite top so that makes it a General 50-240gt?
Microtus is offline  
post #8 of 52 Old 12-26-2010, 08:58 AM
Member
 
Join Date: Oct 2010
Posts: 93
View nijabhaava's Photo Album My Photos
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?

Last edited by nijabhaava; 12-26-2010 at 09:05 AM.
nijabhaava is offline  
post #9 of 52 Old 12-26-2010, 09:02 AM
Old School
 
cabinetman's Avatar
 
Join Date: Jul 2007
Location: So. Florida
Posts: 24,062
View cabinetman's Photo Album My Photos
Quote:
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 up against the fence because with the grain is a smooth movement.

But against 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.

I think this has more to do with it?

How would YOU classify cutting plywood, since there is variable grain directions?










.
cabinetman is offline  
post #10 of 52 Old 12-26-2010, 09:20 AM
Member
 
Join Date: Oct 2010
Posts: 93
View nijabhaava's Photo Album My Photos
Well I guess I wouldn't, because I didn't know that it had variable grain directions. So each ply can be in a different direction?

I learn something new everyday

Quote:
Originally Posted by cabinetman View Post
How would YOU classify cutting plywood, since there is variable grain directions?










.
nijabhaava is offline  
post #11 of 52 Old 12-26-2010, 10:20 AM Thread Starter
where's my table saw?
 
woodnthings's Avatar
 
Join Date: Jan 2009
Location: SE, Michigan
Posts: 25,032
View woodnthings's Photo Album My Photos
Since no one asked, here's what I think...

We generally cut "wood' on the table saw, although I have cut aluminum and acrylic plastic, and Lexan.

There are 2 kinds of wood, man made and lumber from trees
.
Man made, plywood, MDF and other composites are the safest to cut, since there are no internal stresses. Lumber from trees does have internal stresses, some woods more than others and some grain directions a lot more than others, depending on where in the tree the wood came from.
Ripping or cross cutting man made wood is all the same as far as the physics of the wood, it doesn't care which way it's being cut. Yes, there will some tear out cutting across the grain on plywood, but the correct blade will take care of that issue.
Ripping, cutting down the length parallel with the grain for the most part, using the rip fence is what the table saw does better than any other tool with a circular blade. And they have been doin' it for many years. When ripping lumber from trees, the internal stresses can close the kerf behind the blade and it will ride up at the rear,since that's the rotation direction and KICKBACK. Not so with plywood, no internal stresses. Kickback on plywood occurs when the workpiece is not held tightly against the fence , either because of insufficient bearing surface or operator error or both. 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.



Crosscuting using a miter gauge,( mine has an backer extending out on both sides of the blade above) or a crosscut sled is the safest way to deal with shorter workpieces. Some miter gauges have clamp to hold the work securely. I used to use mine, but not any more. Crosscutting using the miter gauge, even with an entended backer board has it's limitations when cutting longer (more than 6 feet) pieces, since any "wiggle" out at the end translates to a lot more at the blade end resulting in an inaccurate cut. Simple physics.
When possible I crosscut my work on the RAS or the sliding miter saw, but I won't hesitate to use the miter gauge on the table saw.
For larger/wider panels (more than 20" or so) the miter gauge become useless since it won't reach, you then use the fence, with proper technique...as above. So, sheet goods or panel work is a little different than lumber from trees, mainly in that lumber is a lot thicker...up to 3" maximum, one pass on a 10" table saw. ...and not every 10" table saw will make that cut in one pass, but that's another issue entirely....blade, horse power, etc.
This may be info already known to some, but there are newbies who should understand that there is a lot of simple physics involved in woodworking. Hope this helps! bill

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)

Last edited by woodnthings; 12-28-2010 at 06:13 PM.
woodnthings is online now  
post #12 of 52 Old 12-26-2010, 12:39 PM
Senior Sawdust Producer
 
Leo G's Avatar
 
Join Date: Oct 2006
Location: Windsor Locks, Connecticut
Posts: 4,274
View Leo G's Photo Album My Photos
I don't see that big of a problem with what he was doing. He was cutting a square, now if he brought the fence out another couple of inches then it might be a bit dicey. Another thing is experience. If this guy had 3 minutes of TS experience then I would say he should have used a sled or miter gauge to have backup. This is something I wouldn't hesitate to do just like he did in the video.

Measure Twice Cut Once -- It's a lot easier to cut more off then it is to cut MORON.
Finishing is 3 parts chemistry and 1 part VooDoo http://lrgwood.com
Leo G is online now  
post #13 of 52 Old 12-26-2010, 12:56 PM
Senior Member
 
Join Date: Nov 2007
Posts: 5,465
View knotscott's Photo Album My Photos
Quote:
Originally Posted by Microtus View Post
All she would say is it is an ugly green and has a granite top so that makes it a General 50-240gt?
That'd be a very good guess as to what the saw is, and I'd guess that you were a very good boy this year to get such a gift!

Nice....get it setup right and put a good blade on it. Congrats.
knotscott is offline  
post #14 of 52 Old 12-26-2010, 01:00 PM Thread Starter
where's my table saw?
 
woodnthings's Avatar
 
Join Date: Jan 2009
Location: SE, Michigan
Posts: 25,032
View woodnthings's Photo Album My Photos
Yeah Leo, but that's you with 100,000? cuts!

Quote:
Originally Posted by Leo G View Post
I don't see that big of a problem with what he was doing. He was cutting a square, now if he brought the fence out another couple of inches then it might be a bit dicey. Another thing is experience. If this guy had 3 minutes of TS experience then I would say he should have used a sled or miter gauge to have backup. This is something I wouldn't hesitate to do just like he did in the video.
Yeah, I've done it that way too, but the more I see "show me the damage photos" the less I want to appear in that thread.
I'm just saying for those who don't know that could be a problem and who don't have the experience, better safe than sorry. We already cured one member of this potential problem who posted above, and anyone else would be great!
bill

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)
woodnthings is online now  
post #15 of 52 Old 12-26-2010, 02:05 PM Thread Starter
where's my table saw?
 
woodnthings's Avatar
 
Join Date: Jan 2009
Location: SE, Michigan
Posts: 25,032
View woodnthings's Photo Album My Photos
I disagree with almost everything you say here

I don't know the background of your "instructor" at Woodcraft, but I would rather trust the knowledge on this forum than him after reading this. Collectively we have 10 of thousands of hours of experience so you be own judge.
I've underlined the parts I disagree with.

Quote:
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.

This is true IF the piece has directional grain, not true for sheet goods. Any time you use the the "rip fence" you are ripping. If the work has insufficent dimension to bear safely against the fence, then you ought not be using it.

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.


The wood grain is being severed at a rate that it has little voice in the matter. The dimension of the stock placed against the fence definitely has to do with the physics, the fence acting as the short distance fulcrum, the less the span/bearing against the fence the greater potential for it to rotate. Grain has no bearing it, only distance/length.

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.

Ripping lumber releases stresses which can not be controlled or know ahead of time, and therefore a splitter should be used. The saw manufacturers have provided splitters for the last 50 years for a reason. The newer moving riving knives are an improvement.

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.

It is easier to cut across the grain then with it. Try a hand saw both ways and then tell your instructor. Cross grain has less resistance to cutting, but not to splitting, but saws don't split, they cut.

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.

The little tearout slivers offer no resistance to the blade, they are a result to the downward force of the teeth as the blade enters the piece. They are inconsequential or nonexistentant with the proper blade.

I think this has more to do with it?
I don't think so. bill

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)

Last edited by woodnthings; 12-26-2010 at 07:47 PM.
woodnthings is online now  
post #16 of 52 Old 12-26-2010, 07:41 PM
Member
 
Join Date: Oct 2010
Posts: 93
View nijabhaava's Photo Album My Photos
Well it was probably me that misheard all this, I doubt they would put such a badly informed instructor out.

I guess I can happily rip ply sheets any way I want now. Ive been using the circular saw instead of my TS for all across the grain cuts, regardless of width.

Thanks for teaching.

cheers

Quote:
Originally Posted by woodnthings View Post
I don't know the background of your "instructor" at Woodcraft, but I would rather trust the knowledge on this forum than him after reading this. Collectively we have 10 of thousands of hours of experience so you be own judge.
I've underlined the parts I disagree with.



I don't think so. bill
nijabhaava is offline  
post #17 of 52 Old 12-26-2010, 09:58 PM
Senior Member
 
Join Date: Jan 2010
Location: Rochester, NY
Posts: 195
View cheese9988's Photo Album My Photos
I trust that you guys know your stuff. But I also have some questions. From what it looks like, the 2nd cut is more dangerous than the 1st cut because the chances of accidently cocking the piece are higher. The first cut doesn't really look like a cross cut to me. I would also think he would have his hand more toward the center of the plastic to apply equal pressure to the fence. I was never taught with a blade splitter or a guard, so I'm guessing thats a matter of preference? I was taught never to stand directly in front of the piece though, I don't like putting both hands, or my body around the blade personally. And last but not least...I would think a higher tooth count would be safer?

Whats your experience with that?
cheese9988 is offline  
post #18 of 52 Old 12-26-2010, 10:18 PM Thread Starter
where's my table saw?
 
woodnthings's Avatar
 
Join Date: Jan 2009
Location: SE, Michigan
Posts: 25,032
View woodnthings's Photo Album My Photos
You are right

Regarding the video above.
The second cut is the problem in my opinion. Not really enough contact with the fence for me. His hand position would be bad news in the event of a kickback, and it would be drawn over the blade. See video at 2:51 crosscutting.....
The splitter will keep the piece from rotating to the left over the blade.
You should stand where you can best control the work.
Not where you can best avoid a kickback which would be behind the saw.....
More teeth are better for Plexi. I don't really like Plexi. I prefer Lexan...less brittle and doesn't melt back together easily.
http://www.amazon.com/gp/product/B00004T7AL/ref=pd_lpo_k2_dp_sr_1?pf_rd_p=486539851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B0002TUFXQ&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=0GX39BQT5TNESA12MM4A


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)

Last edited by woodnthings; 12-26-2010 at 10:28 PM.
woodnthings is online now  
The Following User Says Thank You to woodnthings For This Useful Post:
cheese9988 (12-26-2010)
post #19 of 52 Old 12-27-2010, 07:59 AM
Old School
 
cabinetman's Avatar
 
Join Date: Jul 2007
Location: So. Florida
Posts: 24,062
View cabinetman's Photo Album My Photos
Quote:
Originally Posted by woodnthings View Post
More teeth are better for Plexi. I don't really like Plexi. I prefer Lexan...less brittle and doesn't melt back together easily.

IMO, polycarbonate (Lexan), is more brittle than cast acrylic sheet. You would notice a difference when each shatters when being machined.

I use a 60T blade when cutting acrylics until getting into thicker stock up to Ĺ". Stock ĺ" to 1ľ", a 32T works for an easier cut.

In the video for the second cut on the acrylic, I would only use my right hand to guide the piece against the fence. For that particular type of cut it's necessary to have the concentrated control of just the right edge of the stock against the fence. Using the left hand in unison with the right could cause a skew. After the stock clears the blade at the front of the cut, the waste piece will just stop and stay at rest, while the right piece (the saved one) is passed out to the rear clear of the blade.

CAVEAT: I feel comfortable cutting in this manner as I feel it's the safest way to control stock for this particular procedure. I'm not suggesting that it be done this way if it doesn't feel safe.









.
cabinetman is offline  
post #20 of 52 Old 12-28-2010, 05:33 PM
Senior Member
 
Rick C.'s Avatar
 
Join Date: Dec 2008
Location: Eastern Ozarks
Posts: 468
View Rick C.'s Photo Album My Photos
[QUOTE=cabinetman;170741] A higher blade cutting acrylics produces a cleaner cut and less melting. This I also find holds true for solid surface countertop materials, like Corian.


C'man, thanks I needed that piece of advice.







Rick C. is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Woodworking Talk - Woodworkers Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
Cross cutting long boards on a TBLsaw dribron General Woodworking Discussion 30 12-16-2010 02:31 PM
SCMS Fence / ZC Cutting rrich Tips, Tricks, & Homemade Jigs 3 08-27-2009 02:57 PM
Cross Cutting full 4x8 plywood sheets. Sleeper General Woodworking Discussion 26 05-27-2009 02:30 PM
For Sale: TABLE SAW FENCE - SHOP FOX CLASSIC (fence only) knotscott Classifieds 0 05-11-2009 06:36 AM
recommend a miter fence & replace fence ? msentissi Power Tools & Machinery 0 07-31-2007 03:10 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 
For the best viewing experience please update your browser to Google Chrome