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Sears Radial Arm Saw: Egg-shaped Indexing Holes

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Picture of Sears Radial Arm Saw: Egg-shaped Indexing Holes
Sears 10 inch Radial Arm Saws were very popular for many years. The motor yoke is shown below with modifications this Instructable will describe.

The center hole suspends the weight of the motor and yoke from the carriage on the saw arm. The four smaller holes you see in the photo receive the indexing pin to lock the yoke in the crosscut, inrip, outrip and accessories positions.

After years of use the indexing holes become a little oblong or egg-shaped. Some of the holes wear more than others because they get more use. You can align the saw to make an accurate crosscut, but the blade will heel in the ripping positions. I thought for a long time about how I could restore the accuracy of all of the holes. The key was to make each of the three holes used for precision settings (crosscut, inrip, outrip) capable of independent alignment. That can be accomplished with two pieces of strap iron, four 10-32 screws, and four nuts.

For further explanation, imagine you are looking at a clockface in the photo. 12 o'clock is at the top of the photo. The accessory indexing hole is at 1 o'clock. The inrip indexing hole is at the 4 o'clock position. The crosscut indexing hole is at the 7 o'clock position. The outrip indexing hole is at the 10 o'clock position. When you are ready to do the alignment, you will begin with the outrip hole, no matter how much wear it may have endured and how egg-shaped it may be.

Then you will align the strap iron plate you will make that lays above the crosscut indexing hole. Finally, you will align the strap iron plate for the inrip hole.
 
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dpocius5 years ago
I realize this is a bit late, but I just found out about it myself. There is a free safety upgrade kit for many Sears radial-arm saws available that makes the saw much less scary to use. Check http://www.radialarmsawrecall.com/ for details.
I got the kit for my 20-year-old saw. The kit comes with a new blade guard, handle, and as a pleasant surprise, new table boards, which mine desperately needed. It comes with complete instructions that supplement the saw's manual, and installs quick 'n easy. By all means, order and install this kit when you have the saw apart to fix the egg-shaped indexing holes, and it'll feel like a new tool again.
Phil B (author)  dpocius5 years ago
Thank you for the information. My saw was made in 1972, so it is approaching 40 years in age. Although it was sold without a blade guard, the site you gave tells me no kit is available for my saw. That is after entering my serial number.
dpocius Phil B5 years ago
Sorry about that. I'm sure your saw has some kind of blade guard, just not the new, fancy, lawyer-approved one. It even came with an extra part to make it meet OSHA rules for industrial use, but also makes the blade almost impossible to change. I'll only put that bit on if I start a woodworking business and the OSHA inspector twists my arm real hard.
Phil B (author)  dpocius4 years ago
 I should have responded earlier.  My saw has the standardcast blade cover that shields the top half of the blade.  It can betilted so the front rides just above the work piece.  A strong hexrod with anti-kickback paws can be lowered so the paws ride lightly onthe work.  But, it does not have the additional free-moving sideshields of clear plastic or of flat steel.  Those became standard afew years after I got my saw.  As noted below, I keep my hands ahealthy distance from the spinning blade and remain very vigilant whenusing the saw.  I have never had even a "close call."  
Phil B (author)  dpocius5 years ago
Discussions about blade guards remind me of a radio broadcast I once heard about extra safety features on automobiles, like ABS brakes. While these are designed to provide extra safety margins, drivers felt safer and took extra risks as a result so that the drivers were not safer. If an extra blade guard protects against an accidental encounter of a body part with a spinning blade, that is a good thing. But, if people simply use them to justify engaging in more risky practices, that is not good. I try to maintain a very healthy fear of a spinning blade and keep my hands away from any possible way of being injured. So far I am injury free and hope to stay that way.
could you weld those in?
Phil B (author)  sensoryhouse5 years ago
I assume you are talking about welding the strap metal pieces to the yoke and making them permanently affixed. I see three problems with that. 1) Strap iron is mild steel and the yoke on these saws appears to be an aluminum alloy. Those are dissimilar metals that cannot be welded to one another. 2) Anything permanent like welding eliminates the possibility of making further fine adjustments when one of the holes acquires more wear than its neighboring holes and needs to be tweaked. and 3) Even if the metals were not dissimilar and would accept a weld, the process of welding often causes metal to move a little from intense heating and subsequent cooling. Any precision in the adjustment could be lost through expansion and contraction in the welding process.
darkmuskrat5 years ago
sweet instructable man. i dont have a radial arm saw(the only tool i dont have) but this looks like an ingenious fix for a problem :P (carpenters forever!)
Phil B (author)  darkmuskrat5 years ago
Thanks for your comment. A lot of people have these saws. You may find one for sale at a good price one day and decide to get one. Check my Instructable on Jointing Boards without a Jointer to see another use I get from my radial arm saw. I am always concerned that something in an Instructable I authored will not make sense to the reader. I am glad you found it clear enough.
I totally didn't realize you were the same person who did the other instructable (i have it favorited), Im always looking for the older power tools (i got a 20 year old power planer and I just had to replace the brushes...it works better than any new one. lol
Phil B (author)  darkmuskrat5 years ago
I am relatively new to Instructables and want to find really good Instructables from the past. I have experimented with the Randomizer. That works pretty well. I have also clicked on a poster's name when someone has an Instructable I like to see what other things he might have posted. It is a little like going to a movie unknown to you that has some actors you know have done good work in the past. Anyway, thanks for the positive reception you gave the Instructable on using a sanding drum for jointing. I am trying to post some really useful things I came to over the past forty years.