12 Aug
12Aug

Getting Accurate Crosscuts


Many projects we are called upon to do require numerous pieces of the same length. Everything from boxes, to framed cabinet doors, to shelves and picture frames need two or more pieces cut to the same length. 

And it doesn't matter how well you measure and mark and try to cut the pieces the same exact length, they are going to vary in length, even if it is by just a smidgen. 

But that smidgen can mean the difference between joints that fit nice and tight and those with gaps. So much effort is put into getting the angle just right when cutting crown molding with a miter saw, but what is often forgotten is that the lengths of opposing sides being exactly the same is as important as the angle being just right. 

We can not get that length good enough by just trying to split a line marked onto the pieces, even a line made with a sharp blade. But, we can get exact duplication of length using a stop block.


The most dangerous thing a new woodworker can do is to use both the miter gauge and the rip fence to make through cuts on a piece of wood. It just seems so obvious that one can make duplicate cuts by locking the rip fence at the appropriate distance from the blade, then setting the workpiece against the miter gauge, sliding the end up to the rip fence, and pushing the piece through the blade using the miter gauge.

POW!


The horrible thing we've all heard about, KICKBACK.


You can use the rip fence to index a cut, but you must use a stop block to hold the end of the work piece off of the fence. The pic below shows how to do this.


This method works very nicely,

but be sure to clamp the block to the fence

. I neglected to do that once and was cutting some panels to length and was watching the cut instead of the fence. I didn't notice that the block was sliding along the fence with the workpiece, and just as the piece was cut through, the block kept one end in place while the other end slid toward the fence. 

This brought a corner of the piece into contact with the blade and the whole thing went flying by my arm and struck my miter saw hard enough to knock it out of alignment. It also ruined a nice piece of ash.

I have an auxilliary fence attached to my miter gauge about 99% of the time. This fence is taller than most of my cuts and extends several inches past the blade. This provides me with a zero clearence backing for all of my cuts and also pushes the cut off piece past the leading edge of the blade, keeping it straight as it does so. And since it extends to the left also, it acts as a base to which I can attach a stop block as shown in the picture below.

As I said, I have a sliding miter table (SMT) on my table saw as is shown in the pic, but an auxilliary fence can be attached to any miter gauge and it will improve accuracy immensely. With the stop block in the position shown, it will be nearly toughing the blade after you have completed your cut, making it unsafe to retrieve with the saw running as any sideward movement can push it into the blade possibly causing a kickback.

Making Repeated Narrow Rips on the Table Saw


Many time we need to make narrow stock out of wider stock and as long as we are talking about the finished widths being over an inch or so, it is generally alright to simply set the rip fence the proper distance from the blade and use a push stick or something similar to hold the stock down and push it through the blade. 

But what about making a number of 1/2" wide pieces, or some even smaller? I don't care to be repeatedly doing that and having my push stick getting chewed up a little more with each pass. So, this little trick will allow you to keep the wider stock between the blade and the fence and still give you very accurate cuts on the cutoff side of the blade.


My Table Saw happens to have a sliding miter table with a very nice sturdy fence. It also is capable of being locked in position so that it doesn't slide. But this can be done with any sort of table saw without a problem. Before you start setting up, though, you need to get clean, straight parallel cuts on the stock you are going to cut into narrow strips. Once you have done that, attach an auxilliary fence to your miter gauge. 

A simple piece of plywood or MDF will do nicely. You mostly need something to clamp a stop block to, it is doesn't have to be fancy. Now slide the miter gauge with the fence attached up even with the front of the blade on the saw and clamp a stop block to the fence such that the edge is the finished width of your work piece from the near side of the blade tooth. 

For example if you want to rip pieces 3/8" wide, clamp the stop block so that its edge is 3/8" from the near side of a tooth on the blade. Now slide your miter gauge back toward the operator side of the saw so that the stop block is well in front of the blade, and lock it in place in one manner or another. That is going to depend upon your particular saw. You do this because you don't want the miter gauge to follow the workpiece as you start cutting as this could cause a nasty kickback.

Now set the leading end of your workpiece onto the table so that the front edge is adjacent to the stop block. Unlock you rip fence and slide it over so that the other edge of the piece contacts the stop block and lock the rip fence down in that position. Now turn the saw on and make your cut indexed against the rip fence. 

Push the piece between the blade and fence all of the way through and retrieve it from the other side. Now, again place the workpiece against the stop block on the miter gauge in front of the blade, unlock the rip fence and slide it over to make contact with the workpiece and lock it back down. Make your next cut and repeat the above until you either have all the narrow pieces you need, or until the workpiece is too narrow to safely push it through between the blade and fence.


Crown Molding the Old Fashioned Way, Well Almost


Crown molding in homes is again becoming very popular. Crown is also a must for certain styles of furniture. Compound miter saws and Radial Arm Saws are often used with varying levels of success to make the neccesary compound miter cuts. But applied crown molding has been around used in furniture and in homes well before we had power tools. 

And if you come across an old house with its original crown molding in place, or an antique furniture piece with beautifully applied crown molding on top, you will more than likely find that the work is excellent. No gaps or putty fills in those. 

And those folks did that work by hand, without even a compound miter hand saw setup. So why is it that the fancy dancy power compound miter saw gives less than perfect joints, even after consulting a chart or some foot long math equation? 

Simply because it is real tough to set that saw at 38.439 degrees and to tilt it to some similarly discreet angle to get the cut just right. So, what's a body to do?


The old times figured it out. If you look at the finished joint from a plane parallel to the ceiling, the angle at which the two pieces come together appears to be 90 degrees (or two 45 degree pieces) for a 90 degree turn. Likewise, the joint appears to be any other simple angle when viewed from the proper perspective. 

So the trick is to make your cuts from that perspective and this is simple enough to do, simply lean the workpiece against something in the same orientation as it is going to be when installed. 

This can be done on a non-compound miter saw (or a compound one that is not tilted) or on the table saw. The cut can then be made using the simple angle required for the stuff applied flat. That's how simple cutting crown molding can be.


The drawing is for a miter saw, but a similar setup can be used on the table saw with a tall fence added to the miter gauge. Note that in the drawing the piece is placed with the top edge down, and with the face of the molding out where you can see it. That is because that is the perspective from which the piece was viewed for the plane angle.


A Little High School Geometry


This is a good place to put this in since you may still not get that perfect fit with crown or other molding, especially if you are installing it on someone else's work, like the walls in your house. 

We are tempted to look at that square corner and say, "Well, that looks like 90 degrees, we'll just set the saw at that and cut." But there ain't no square corners. So break out the sliding bevel and get the actual angle. 

Then bisect the angle and set your saw to that to make your cut. You will be amazed at how much easier it is to get nice tight joints in your molding if you do it right.

You could break out a protractor and measure the setting on your sliding bevel, then divide by two, then set the saw to the angle thus derived, but you may end up interpolating for 1/2 degrees. 

Or you could use the protractor to set the cutting angle on the sliding bevel, then set the saw using that. I prefer to skip the protractor thing and bisect the angle like we learned in geometry with a compass, a decent compass. 

Once you have gotten the original angle on the sliding bevel, draw it on a piece of paper or on some scrap stock. Then use the method in the pic to bisect the angle.

Once you have drawn your angle, open your compass to a comfortable width and strike an arc from the juncture of the angle to a point on both legs (arcs BD and BE in the drawing). Now, using points D and E as centers strike two arcs using the same radius for each inside the angle. 

Now a line connecting the juncture of the two lines through the point of intersection of the two last arcs will be a bisector of the original angle. Simply set your sliding bevel to that angle and use it to set your miter angle on your saw, and you're ready to cut.

 

Article Sources (Thank You!)

Wikipedia

Hack Yourself


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