Instructables

Radial Arm Saw Table Alignment -- An Easier Way

Picture of Radial Arm Saw Table Alignment -- An Easier Way
This is my 10" Craftsman Radial Arm Saw, 1972 vintage.  It is very important that the arm is exactly 90 degrees to the fence at the back of the saw table.  Note the square.  Pull the motor along its travel and see if the blade teeth follow the edge of the square exactly.  It is quite common that a gap between the blade teeth and the square of a few thousandths of an inch will form as the saw moves back toward the end of the arm.  This will cause inaccuracies in any precision cutting.  The owner's manual gives a recommended procedure for aligning the saw, but it is difficult and does not work well.  This Instructable will show you a much easier, much more precise way.
 
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Step 1: The factory recommended procedure

Picture of The factory recommended procedure
The recommended procedure involves loosening and moving the arm in its mount.  Remove the two screws on the angle scale at the top of the column and remove the aluminum disc on which the angle scale is printed.

Step 2: Loosen the mounting bolts

Picture of Loosen the mounting bolts
Under the aluminum disc inside the column are two bolts.  The heads are 9/16".  With a wrench you are to loosen them just a little.

Step 3: Bump the arm

Picture of Bump the arm
After the bolts inside the column have been loosened a little, you are to bump the saw's arm a little and check the blade travel with the square again.  When the arm is square to the fence, you are to tighten the bolts inside the column.  Put the aluminum disc back in place and everything should be good again.  

But, it is very difficult to bump the arm without bumping it either too much or too little.  There is a much easier way.

Step 4: Adjust the table with precision

Picture of Adjust the table with precision
There is an easy way to move the table rather than the arm and move it just a little so the edge of the table that holds the fence in place is exactly 90 degrees away from the blade's travel on the arm. 
LynxSys28 days ago

What a good idea! Everything in this world should have fine-adjustment screws.

Phil B (author)  LynxSys28 days ago
Thank you for looking. I also used similar adjustment screws when I mounted a circular saw under a piece of plywood to make a pretty precise table saw.

I see you want to learn to weld. I did an Instructable on my experiences with that. The first electric welder I bought was a little 115 volt stick welder made by Century. The manual was written with the expectation that the user would learn independently. A friend mentioned an older man he knew as an excellent weldor. This weldor had learned on his own.

http://www.instructables.com/id/Learning-to-Weld/
LynxSys Phil B28 days ago

Thanks for the encouragement and the link! When I have a bit of time and money, I'll give it a shot.

could you give me the measurements of the table. Ours was destroyed years ago and Now i got the saw and would like to make a new table for it.
Phil B (author)  chesterjohn1 year ago
You can find them here: http://m.instructables.com/id/Setting-Up-a-Radial-Arm-Saw/

Scroll down until you see the drawing.
Thanks Phil.
When I cut with my 1973 sears 10 radial arm saw, my cut is clean across the top surface, but ragged on the bottom side. What adjustments do I have to make?
john hermosa
Phil B (author)  john hermosa1 year ago
John,

I assume you have this problem when you pull the motor carriage toward yourself to make a cut (make a crosscut). If you were making a rip cut (motor turned parallel to the fence and pushing the wood across the table into the blade) you would notice the bottom surface cuts cleanly, but the top surface has some roughness and splintering where the blade exits the wood.

Any circular sawblade on a power saw will do this whether it be a radial arm saw, a table saw, or an electric handsaw (also known as a circular saw). The reason is that when the teeth cut entering the wood the fibers are being pressed down into the rest of the wood as the cut is made. But, on the other surface the teeth are cutting as they exit the wood and they pull some of the fibers with them to cause splintering and a rougher cut.

You cannot eliminate this problem, but there are ways to minimize it by means of strategy and some controls. Most wood projects require a good side and a side not really seen after the project is finished. When crosscutting you can plan your work so the side that needs to be good is cut as the teeth on the blade enter the wood. With your radial arm saw that would mean the good side is on the table facing upward as you pull the motor carriage back on the saw arm.

Make certain your saw is properly aligned so the blade does not heel. If it does heel, there will be a tendency to splinter as the teeth exit the wood, even on a cross cut. (Rip cuts on a radial arm saw are made with the teeth exiting the top surface at the leading edge of the cut. Normal practice would be to have the good surface down when cutting if at all possible.)

Using a finer blade (a blade with more teeth) reduces the splintering you mentioned. So does pulling the motor more slowly for a slower cut. Cutting with the grain reduces splintering while cutting across the grain increases splintering. Using better quality woods with a tighter grain pattern reduces splintering, while cheaper open grain woods tend to splinter more when cutting.

Some sensitive cuts, like cutting across the grain on veneer plywood, can be greatly improved by scoring the cut line with a straightedge and a sharp knife, but this requires aligning the scoring knife mark very precisely with the path the saw blade will cut.

I hope this helps you.
flyingbrass2 years ago
Good solution. Found this while pondering how to accomplish the same thing for the final squaring. The saw I've been working on is real close, but I know manually moving the arm is way too imprecise and would likely leave it even further out.

Thanks for posting this tip.
Phil B (author)  flyingbrass2 years ago
Thank you for looking. You are right. Even thought the manual for my Craftsman radial arm saw has the owner moving the arm in order to square the cut line with the fence, it is maddeningly imprecise.

I think I mentioned, too, that if you ever need to take the saw down to move it, the guide blocks allow you to have the saw in alignment again immediately on the first attempt.
pfred23 years ago
Getting my Radial Arm Saw square was such a pain I don't even adjust it at all now. If I want an angle cut I angle the work on the table! I think the real trick to RAS is once they're square leave them alone and use an auxiliary table if you have to. Plus it keeps the table nice and clean looking with just one kerf cut in it which I find handy for aligning cuts with.

It is sort of tough to tell in this picture but I puttied up the wide kerf and just have the true right angle one:

http://img153.imageshack.us/img153/631/rastable.jpg

I made the sub base out of a piece of MDF shelving I got at a big box store for about $3 and screwed some hardboard to the top of it. To me angles aren't nearly as important as it is knowing I'm getting an exact 90 out of the machine.

Funny my snow brush isn't sitting in its usual place on the top of the arm in the photo. It fits up there just perfect, and is great for sweeping dust off the table. Sort of locks in between the end cap and the cord.
neffk3 years ago
Can I use the photos you have in Step 1 and 2 for my instructable? I didn't get a good shot of this detail.
Phil B (author)  neffk3 years ago
I do not mind. Go ahead.
drawkcab4 years ago
This is a great and easy fix! I plan on implementing this on my vintage Craftsman Radial Saw....Thanks!!!
Phil B (author)  drawkcab4 years ago
Thank you for your comment.  I am glad you can use this idea.   I originally thought of it when I was trying to hang a circular saw under a table.  I finally made an Instructable out of that.  It is at this link, if you have not seen it already.  If you have a vintage Craftsman radial, you might eventually want to look at this when you find the saw can be aligned for crosscuts, but heels on ripping.  It is good to hear from someone who appreciates a radial arm saw.
toni-brian4 years ago
Phil - I also have the identical saw.  I can't stand to part with it, it's made so well.  Motor and brake have been rebuilt, and it works great.  It's a 1973 vintage that I bought used in 1975 for $235, and came with shaper attachment, carbide dado, and hold downs.  what a great saw. 
Thanks for the info here.  I'm always on the lookout for shortcuts to align it, and pretty much just fine tune it with a square as required.  I've built it on an 8 foot table so I can just throw a long board on, and cut it with support.  I've done the same with my compound miter.  I'm getting ready to change the top, and fence unit of the radial saw.  I plan to tear off the top and fence so if you have a great plan on how to get everything square, and lined up, and can direct me to a great site, I would appreciate it.  thanks again for great info.  bh
Phil B (author)  toni-brian4 years ago
Brian,

There have to be a lot of these saws in home workshops.  My motor brake is less effective, but I have not replaced it.  I did replace the motor bearings once and the switch a couple of times.  When the factory switch was no longer available, I got a 15 A pushbutton switch at Radio Shack and it has worked fine for many years. 

The most troublesome aspect of alignment for me was getting the table top (and fence) square to the arm.  The blocks with screws I mentioned in this Instructable make the handiest thing I know about alignment.  I also found it helpful to make two squares of 1/8 inch fiberboard about a foot on a side.  Place them on top of each other and make a crosscut that trims a tiny bit from one edge.  Flip one over so the freshly cut edges are against one another.  Push both pieces against the saw's fence.  Check closely to see if the freshly cut edges are truly parallel, or if there is a little bit of a "V".  Otherwise, you just need to start at the beginning of the steps in the manual and work through them in order. 

Check the Related Instructables listed in thumbnail form at the right side and bottom of this Instructable for a couple of others you should find helpful.  After a few years the yoke holes for the indexing pin wore unevenly.  After a few years I came up with a very workable solution.  You might also like to look at the one on an easier way to make precise miter cuts.

Some people do not replace the top on the saw table, but just fasten a piece of 1/4 inch plywood over it to give the saw a fresh surface.
crapflinger4 years ago
i assume, given the angle dial on the saw arm that this contraption is also supposed to be able to make miter cuts by turning the whole saw arm to either side? if that's the case, doesn't your method of truing the table for square make miter cuts inacurate? since the table is square to the saw and not the saw to the table? obviously it would only be off by a fraction in either direction...or am i overthinking this?
Phil B (author)  crapflinger4 years ago
It is safe to say you are overthinking the matter.  Yes, the arm swings and has positive stops at 45 deg. left, 90 deg., and 45 deg. right.  The initial setup requires the arm to be 90 deg. to the fence.  Once that has been attained, the positive stops for the arm's swing right and left also make accurate miters.  A radial arm saw is a wonderfully versatile machine.  Properly aligned, they are also very accurate, despite what some will tell you.  It is too bad people these days know power miter saws, but are often unfamiliar with radial arm saws. 
well i've SEEN radial arm saws (but much bigger...my grandfather still had one with a 24 inch blade from the shipyard he used to own....he said they used to have two 36 inch ones as well...not sure if they were all custom built or purchased)....and i know that they work the same as a miter saw (give or take)

i guess the reason for my question might make more sense if i up the scale...

let's say your radial saw was set at 20 degrees....and you squared the table up to the blade at 20 degrees...now the measurements on the dial would be completely off, because 20 degrees is now 0...so you'd either have to add 20 degrees or subtract 20 degrees to cut an accurate miter... obviously the scale is much different...but if your saw were .5 degrees off to the left...and you squared the table to the saw...then all your miter measurments would be .5 degrees off to the left if you relied directly on the guage at the top of the saw...so you'd have to adjust .5 degrees + or - any time you wanted to do a miter....this of course assumes you knew the variance before squaring the table...if you didn't know, then you wouldn't be able to compensate for purely accurate miters (i know that's a relative term depending on the project, since a 16th will be gone for the blade anyway, and there could be wobble or any other number of factors that would reduce precision to begin with)
Phil B (author)  crapflinger4 years ago
Perhaps I should have mentioned there is some "wiggle" clockwise and counter-clockwise when screwing down the aluminum disc with the angle scale on it.  Before locking down the screws, you align "0" with the yellow pointer.  I would also say the angle scale at the top of the column is not a very precise way to adjust the angle of cut.  If I need a precise cut other than the fixed stops at 45 deg. right or left and 90 deg. I use a "T" bevel angle finder to copy the angle from a drawing or an original piece and use the "T" bevel to set the angle between the face of the blade and the fence.  I hope this helps. 
maybe add that bit as a step? i rarely use the built in angle finder stuff on any equipment (table saws etc..) for anything outside of a 45
Phil B (author)  crapflinger4 years ago
If someone follows the procedure I outlined rather than the factory procedure, there is no need to disturb the angle scale in any way, so it hardly seems necessary to discuss aligning "0" with the yellow pointer.
jmiller294 years ago
Did you break into my garage because I have a saw and a screwdriver just like that! 

Thanks for the instructable.  I'm going to do this.
Phil B (author)  jmiller294 years ago
Thanks for your comment.  The idea of using wood blocks with adjusting screws for alignment stops is something I first developed and used when I wanted to mount a 7 1/4 inch circular saw under a homemade plywood table to make my own table saw.  A block on the side of the saw base near the front of the saw and another similarly placed near the rear of the saw allowed me to remove the saw from the table and rip panels, etc.  Later I could quickly put the saw back into the table and know it was accurately aligned again. 

Hmmm? Have I been in your house?  (Tell your wife not to run out of cookies again.  And, I prefer chocolate chip over sugar cookies. ;-) ) 
Phil B (author)  Phil B4 years ago
One other thing, I used my saw quite a lot in years past.  Eventually the indexing holes in the yoke wore at differing rates.  If I aligned for a good crosscut, the saw heeled on inrip or outrip, or both.  I eventually found a way to fix the problem.  My Instructable on it is listed below as a Related Instructable.  It is titled "Sears Radial Arm Saw: Egg-shaped Indexing Holes."  If you have the same model of Craftsman saw and make a lot of use of it, that Instructable will be worth your time.