Friday, February 24, 2023

You should buy a radial arm saw.

Reason?  They are very cheap and plentiful on eBay. 

In the old days, when I was a kid, most fathers had a shop, somewhere, the basement, the garage, and other places.  In those days, before chop saws, the shops had either a table saw or a radial arm saw (RAS).  The benefit of the RAS was it could be pushed up against a wall of the shop and work just fine.  Table saws, if they were to cut long stock, needed to be in the middle of the shop with clearance all around.  Both RAS and table saw cut with a disc shaped blade with teeth on the edge turned by a motor bolted to the blade center.  

To trim a 9 foot 2by4 stud to length on a table saw you have to brace the long stud to the miter gage which is only 6 inches long.  It’s very easy to let the long stud slip a tiny bit, and the trim cut is now longer a good square cut, it becomes a little bit off, and the whole project does not fit together a well as you would like. 

   With a RAS, I locate a work bench, the same height as the RAS table right next to the RAS table.  I lay the long stud on the workbench and push it up against the 4 foot RAS fence. With four feet of fence to guide it, the cut will comes out square in both directions.

   Some time in the 1980’s the safety gurus looked at the RAS and declared it too dangerous to use.  The blade could be in many different places, which made it easier to loose track of it and cut yourself.  Half the diameter of the blade was exposed and could do a very nasty cut if the used did not pay attention closely.  The safely gurus were so effective (destructive) that homeowners just stopped buying RASs.  By now I don’t know of any company that still makes them and sells them.

    But there are a lot of used RASs, in good shape, on Craigs list and other places for pennies.  I have seen RASs go for as little as $50.  Table saws will cost you more like $400.  They come in various sizes, from a big 16 inch blade down to a tiny 9 inch blade.  The big 16 inch blades are quite expensive, and unless you are doing timber framing, I would go for a smaller one.  I have a 10 inch RAS which is big enough for everything I do in my shop.  And 10 inch blades are widely available.

   Looking at a used RAS, trying to decide if it is good enough for your shop.  Plug it in, see if the motor runs and the blade turns.  Look for an iron casting for the arm.  The lightweight stamped sheet metal and plastic arms bend out of place during use yielding a cut that does not go where it ought to.  You want a round column with plenty of beef to it supported by a large and beefy bracket holding the column upright from the RAS frame.  The frame should be steel “C section” beams.  Check that the power head rolls smoothly all the way to both ends of the arm.  Check that the auto stops at 90 and 45 degrees are working.  Swing the arm back and forth and make sure the autostop clicks in and locks the arm in position.

    So far so good.  You want to check out the seller’s place.  You want the RAS manual, the blade guard and the anti kickback fingers.  If the seller cannot find, or does not have these items, no sweat there are other places.  Other things you might be able to obtain from the seller is a dado set, extra blades, or a chuck for router bits or twist drills.

   When you get your used RAS home to your shop you want to give it some tender loving care.  Wipe it down with a rag moistened in paint thinner or charcoal light to get the dirt and saw dust off it.  Rub down the guide grooves in the arm in which the power head rolls.  Sawdust gets in there and then gets flattened by the rollers into a bump.

   If the RAS needs one, you want a nice new sharp carbide blade.  I use an ordinary blade with 20 degrees of hook, the normal amount.  The safety gurus claim the RAS wants a blade with zero hook.  I don’t believe the gurus, the ordinary 20 degree blade works just fine in my shop.  You can clean the black stickum off old blades by soaking them in a solution of laundry borax in water.

   Quite likely you want to make a new table and a new fence, since the old one will have all sorts of saw cuts in it.  Make the new table 4 feet long.  Make the width match the old table.  Particle board ¾ inch thick makes a good flat smooth table.  Counter sink all bolts down til the blade won’t hit them

   After installing the new table, you need to align your RAS.  If the have the manual, read up on alignment.  First thing is to make the new table flat to the blade.  With power off, lower the blade until it just scraps the new table.  Swing the arm as far as it will go in either direction.  If it swings and just scrapes you are good, if the blade digs into the new table somewhere and sticks, you have a problem.  The RAS manual ought to give guidance for this predicament. Then you need to check that the arm at right angles cuts square, and the blade is at right angles to your new table/ 

    Now to use the RAS safely.  Keep fingers (and hands and everything) at LEAST 3 inches away from the blade.  If the work is too small to hold and keep 3 inches back, throw that piece in your scrap box and find an bigger piece.  Make sure to maintain 3 inch clearance when you move the blade from behind the fence out to the end of the arm.

   That’s for cross cutting.  For ripping there is a bit more.  The teeth of the blade are moving towards the feed side.  If they grab and stick, the blade will hurl the work back at you at a scary speed.  Never stand behind the blade when ripping, stand to one side, so if it does kick back and throw the work it will just hit the shop wall, and not you. To begin a rip, tilt the blade guard down so that it only admits the work to the blade and blocks any fingers that might be riding on top of the work.  After the blade guard is set, then set the anti kickback fingers to stop the blade from throwing the work.  I use a push stick to push the last part of the work into the blade, rather than my fingers.      

    Good luck with your new RAS purchase. 

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