Radial arm saw question

[Brian Effinger]

I recently got the Mr. Sawdust book, and am through most of it, but there is one question that I've had. He mentions that the saw should never be used for a left-hand miter, but he really gives no good explanation. There is a photo on page 29 that shows him making one, but the carriage is rotated 180 degrees, so the saw blade would be pushing the work away from the fence. I can see why that photo shows a dangerous operation, but why the heck would you rotate the blade??? Later on in the book, he makes a left-hand miter jig so that the work held perpendicular to the fence (parallel to the arm) and the saw is set for a right-hand miter, but again, why???

So, my real question is, why shouldn't I rotate the arm of the saw to the left to make a left-handed miter? I've been thinking about this off and on for several days, but just can't come up with an answer. Of course, I'm not the sharpest tool :rolleyes: so the answer may be staring me right in the face.

Thanks.

[Myk Rian]

Mainly because the USUAL table doesn't go too far to the left. No support.
Other than that, no reason not to.

The miter jig is good for making picture frames. I just turn the stock over and make a right side miter.

[Erik Christensen]

I think Myk has the best answer - most saws have the blade to the left of the rear column so the left side of the table is not as wide as the right - OK when cutting a 90 but maybe not so cool with a left miter. On my saw when I replaced the table I made one that extends as far to the left of the blade as the stock table did on the right - equal support for miters in both directions.

pretty simple fix and gives better support for long stock. of course not applicable to many who are into the RAS as they have built extended tables for their saw that offers many feet of support on both sides of the blade

[John TenEyck]

I can't see why you should never miter on the left side, but I can see why you should never miter towards which ever hand is holding the work piece, whether left or right. So maybe the fact that most people are right handed means they hold the work piece with their left hand regardless of which way they are mitering. All would be fine when miteriing to the right, but the saw would be coming at your hand if mitering on the left side. Just a guess. Otherwise - no clue.

[johnny means]

He mentions that the saw should never be used for a left-hand miter, but he really gives no good explanation.

Yes, mitering one's left hand is never a good move:D

[Neil Brooks]

Yes, mitering one's left hand is never a good move:D

I think you'd be all right if you did ;)

[david brum]

I scratched my head when I read the same info in the Mr Sawdust book. I figured it had to do with the near impossibility of getting complementary, repeatable miters by going back and forth between miter settings. Heck, it's nearly impossible with a miter saw. The beauty of the 90 degree fence is that the miters will be complementary wherever the miter setting ends up.

[Brian Effinger]

I can almost believe that it wasn't recommended because of the lack of space to the left of the blade, but when you look through the instruction manual that came with the saw, it mentions making left miters. What it doesn't mention is turning the saw around 180 degrees. Here is the photo, and the page, from the Mr. Sawdust book:
190792 190793 190794

This photo was only in a sales brochure, as was the third photo above. I found these brochures and the instruction manuals on the OWWM website.

Bizarre.

[Joseph Tarantino]

when the motor carriage is rotated 180* , isn't the blade now backwards? how does it cut? that third pic from the sales brochure looks backasswards to me.

[Terry Beadle]

A simpler and excellent solution is to use a jig as detailed by Curtis Erpelding in his video http://www.amazon.com/Radial-Arm-Saw-Joinery-VHS/dp/6301918797.

The core idea is to keep the RAS set for a 90 degree cut. The jig is simply two pieces of narrow ( about 1 to 1.25 inches wide and about 3 foot long ) ply or straight hardwood that are anchored together by a bolt pivot. On piece is mounted in the fence hole and clamped. The other arm of the jig can pivot almost 180 degrees and has a stop block. You put your piece you want to cut a miter angle against the pivot board and swing it to the angle you want to cut. The jig can cut on either side of the jig by simply sliding it from one side of the blade to the other and re-tightening the fence bolts. You can dial in a very accurate cut with minimal adjustments until you nail the angle just right. You clamp the end of the pivoting arm to the table top and you are ready to repeat cuts etc.

Jig cost is minimal. A bolt and wing nut and some scraps. Washers optional...hoot!

[Robert Rolfe]

While were on this subject, I Love my radial arm saw, thou it seems like a dead tool now, at least in the woodworking mags and even at the tools stores. Mostly it seems the tablesaw rules the shop now. I feel a lot more in control making cuts with the radial than leaning over the table saw. I saw some debate on the head not being square or easy to go out of adjustment, well i have as much problems with my cheap fence on the tablesaw. So since i can't afford a good one I make due, and on both I recheck the angles before i cut.

[Brian Effinger]

A simpler and excellent solution is to use a jig as detailed by Curtis Erpelding in his video http://www.amazon.com/Radial-Arm-Saw-Joinery-VHS/dp/6301918797.

Do you have a photo of your jig?

[Larry Edgerton]

I don't get it either.

I am more uncomfortable the other way when I have to operate the saw with my left hand and holding the piece with the motor in the way. I try to do all my miter cuts on the side in the picture, so I am curious myself why I should not do that. If it is for accuracy I say Pssst.... If there is a safety reason that is escaping me I would like to know. I have an OMGA, but I can't see how that would make a difference.

curious....

[Terry Beadle]

To Brian Effenger : Here's a couple photo's of the jig as you requested. If I get time today, I'll mount it and show a sample piece being cut.

[Lee Schierer]

When you rotate the saw to the right to make a miter cut you can get your hand close to the blade without the danger of teh saw kicking forward into the hand holding the work against the fence. My take is that when you rotate the saw to the left side and the cut off is to the right of the blade, the part you want is to the left, that your left hand holding the work is going to be in the path of the blade. Your right hand will also be in an awkward position holding onto the saw handle to prevent it from moving forward. If the saw catches in the wood, then your left hand would likely be hit by the saw as the blade moves forward.

[Mike Schuch]

Pretty close to 50% of the miters I cut on my RAS are left hand miters. I have never had a problem and can't see where there would be a problem. My body is always pretty much perpendicular to the arm not the table. So when the arm is rotated my body naturally rotates with it so I am making a straight pull and don't have an arm crossing in front of the blade.

I do have my table offset to the left... but this is just because the finished piece is usually on the left and the off cut on the right. I also have a large table (Scratch'n'dent solid core door $5 covered with a sacrificial mdf sheet). A good size table really increases the usefulness and safety of a RAS! The turret arm style of my Redstar (Delta) also helps keep miters more centered on the table.

Here is my picture framing jig. Adjusted for perfect 45 degree miters even though my saw is pretty much spot on with its miter stops it is much quicker to make the cuts without having to swing the arm between every cut. It is even more important to have the opposite sides of a picture frame the same length than it is to have a perfect 45. I use stops on the frame of the jig to get perfectly repeatable lengths.
http://www.hitechengineering.net/DNN/Portals/0/MyShop/PICT8114.gif

[Lee Schierer]

Pretty close to 50% of the miters I cut on my RAS are left hand miters. I have never had a problem and can't see where there would be a problem. My body is always pretty much perpendicular to the arm not the table. So when the arm is rotated my body naturally rotates with it so I am making a straight pull and don't have an arm crossing in front of the blade.

I do have my table offset to the left...

Your offset table makes plenty of room to the left side. Most radial arm saws have a short table on that side and you would be reaching into an acute corner to hold the stock. It is inherently more dangerous to the left side of your saw than the right because the motor and carriage prevent your hand from getting close to the blade on the right and don't on the left. When cutting on the right side you are going to grip the board with your right hand and the saw with your left. On the left side you will grip the saw with your right and the board with your left. With no drop down blade guard your hand is exposed to the potential of the blade making contact. It is much harder to do that on the right side.

[J. Ed taylor]

A simpler and excellent solution is to use a jig as detailed by Curtis Erpelding in his video http://www.amazon.com/Radial-Arm-Saw-Joinery-VHS/dp/6301918797.

The core idea is to keep the RAS set for a 90 degree cut. The jig is simply two pieces of narrow ( about 1 to 1.25 inches wide and about 3 foot long ) ply or straight hardwood that are anchored together by a bolt pivot. On piece is mounted in the fence hole and clamped. The other arm of the jig can pivot almost 180 degrees and has a stop block. You put your piece you want to cut a miter angle against the pivot board and swing it to the angle you want to cut. The jig can cut on either side of the jig by simply sliding it from one side of the blade to the other and re-tightening the fence bolts. You can dial in a very accurate cut with minimal adjustments until you nail the angle just right. You clamp the end of the pivoting arm to the table top and you are ready to repeat cuts etc.

How is the stop block used?

[Rick Potter]

Turning the motor around like that looks pretty iffy to me...kickback city. You have lost one of the main safety features of the RAS, IE the blade pushing the work against the fence. If you don't hold the work somehow.......that workpiece could become part of you.

Rick Potter

[Myk Rian]

That picture takes stupidity to the max.

[Roy Turbett]

Mainly because the USUAL table doesn't go too far to the left. No support.
Other than that, no reason not to.

I agree with Myk that there's no reason not to other than a lack of support on a standard top. I've read the Mr. Sawdust book and he contends that the early DeWalt RAS design allows a properly tuned saw to be returned to perfect 90 degree allignment after making a miter cut. I'm in the process of restoring a 1957 DeWalt GWI and am wondering if anyone with experience with a GW or MB series can confirm this. Can I expect a significant difference in the accuracy of the 1957 GWI over my 1979 Craftsman?

[Myk Rian]

Can I expect a significant difference in the accuracy of the 1957 GWI over my 1979 Craftsman?

Yes. The C-man has points that engage in slots to set up the 90 cut. Not a very good way to do it, IMHO.

[Roy Turbett]

Rotating the saw 180 degrees isn't recommended. There is a warning label on the guard that says "Do not rip or plough from this end".

[J. Ed taylor]

Terry, how is the stop block on the jig used? I just can't visualize it in an actual cut.