Getting Accustomed to the Table Saw

terrydowning · Post by **terrydowning** » Fri Apr 08, 2011 3:32 pm

The length of the board perpendicular to the blade and fence makes it very easy for an uneven feed of the cross cut material to snag on the fence mid cut. When this happens, the blade binds in the cut and the result quite often is a kick back. Remember the definition of Cross Cutting is cutting across the grain.

Snags of this type while possible during ripping operations (usually dude to misalignment of the fence to the blade) are in fact rare as the grain of the wood is moving in the same direction of the cut.

It is the end grain that get snagged against the fence. That combined with the longer lever against a pivot point (blade/miter gauge) makes it really easy to get that board crooked and cause disaster.

michaeltoc · Post by **michaeltoc** » Fri Apr 08, 2011 3:40 pm

Underdog wrote: If that's the case, how do you accurate measure between the fence and the teeth of the blade? I've always run a measure directly between the two. Should I be measuring my spacer, adding that width to my desired measurement, and then setting the fence to that "new" measurement???

I made an "L" shaped spacer with a t-nut that rides in the top track of the rip fence. To set the cut, I slide the spacer close to the blade so I can measure the distance between the spacer and the blade, then slide it back to set the piece for cross cutting.

Underdog · Post by **Underdog** » Fri Apr 08, 2011 4:38 pm

michaeltoc - what you describe I can actually picture.

While I think I'm finally starting to grasp the concept, and what causes kickback, etc... I'm still unclear on how the wooden jig shown earlier works...

terrydowning · Post by **terrydowning** » Fri Apr 08, 2011 4:50 pm

michaeltoc wrote:I made an "L" shaped spacer with a t-nut that rides in the top track of the rip fence. To set the cut, I slide the spacer close to the blade so I can measure the distance between the spacer and the blade, then slide it back to set the piece for cross cutting.

I do do something similar with a clamp and a block of scrap wood on my Mark 5. No T Tracks for those old fences, but we make do.

keakap · Post by **keakap** » Fri Apr 08, 2011 6:15 pm

tomsalwasser wrote:... I used this handy setup to crosscut some long stock down to rough size. ...

If I worked for Shopsmith I would immediately send tom a set of 5' connector tubes to see what he could do with 'em!

Great, fun setup!

JPG · Post by **JPG** » Fri Apr 08, 2011 6:33 pm

Underdog wrote:michaeltoc - what you describe I can actually picture.

While I think I'm finally starting to grasp the concept, and what causes kickback, etc... I'm still unclear on how the wooden jig shown earlier works...

Re: cross cut vs rip -
Consider that when crosscutting with a miter gauge or sled that if the end on the workpiece binds against the fence, further motion(feed) of the workpiece will result in the workpiece rotating since one end is 'bound'. That rotation will bind the blade in the kerf and a pinch will occur on the back side of the blade. The blade may grab the workpiece and fling it!
When ripping the feed force is directly in line with the direction of BOTH the feed and the cutting. If the workpiece 'gets stuck', the feed force is still in line and no rotation is likely to occur...

RE the spacer measuring. - Position the spacer against the fence even with where you will be measuring. While holding the spacer tightly against the fence(clamp it) and measure from the blade to the spacer just as you did with no spacer. After securing the fence, move the spacer to the front of the fence and clamp in place. Now you can butt the workpiece up against the spacer, align with miter gauge/sled and feed off the spacer and into the blade.

Re the jig with the 'fluted' knob.

I be waiting for a first hand explanation there also!

keakap · Post by **keakap** » Fri Apr 08, 2011 6:36 pm

Confused me at first too. So I looked at it a bit differently. Kick back occurs because a cutting skews relative to the blade, the rear up-travelling teeth catch it and whammo. If you are cutting a square the odds are equal to happen. But think of a 4" x 24" piece: crosscut, long support is at the miter gauge, board unlikely to skew going "thru" the blade (oh, the language!).
Same board on a rip, long support at the rip fence, unlikely to skew away from it.

Contrast: 4" x 24", 4" side (end) at the rip fence, trying to crosscut. Chances of not skewing are in The Lottery Family of Numbers.
[or ripping with the end on a miter gauge]

JPG · Post by **JPG** » Fri Apr 08, 2011 6:41 pm

keakap wrote:Confused me at first too. So I looked at it a bit differently. Kick back occurs because a cutting skews relative to the blade, the rear up-travelling teeth catch it and whammo. If you are cutting a square the odds are equal to happen. But think of a 4" x 24" piece: crosscut, long support is at the miter gauge, board unlikely to skew going "thru" the blade (oh, the language!).
Same board on a rip, long support at the rip fence, unlikely to skew away from it.

Contrast: 4" x 24", 4" side (end) at the rip fence, trying to crosscut. Chances of not skewing are in The Lottery Family of Numbers.
[or ripping with the end on a miter gauge]

Using the fence to control length of a cross cut is bad enough, but ripping to width using a miter gauge?:eek::eek::eek::eek:

keakap · Post by **keakap** » Fri Apr 08, 2011 6:45 pm

JPG40504 wrote:...Re the jig with the 'fluted' knob.

I be waiting for a first hand explanation there also!

can I guess?
laminate a turning block, say 4" sq.;
drill 5/16 thru holes in a 3" circle;
turn block to the 3" radius
??

keakap · Post by **keakap** » Fri Apr 08, 2011 6:46 pm

JPG40504 wrote:Using the fence to control length of a cross cut is bad enough, but ripping to width using a miter gauge?:eek::eek::eek::eek:

Makes a dang good graphic example, don't it!

[This image occurs to me whenever I see people discussing cutting extreme bevels/miters and trying to figure out which one they (or me) are actually making.]