Pin Router for a Sears Radial Arm Saw

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Introduction: Pin Router for a Sears Radial Arm Saw

About: I miss the days when magazines like Popular Mechanics had all sorts of DIY projects for making and repairing just about everything. I am enjoying posting things I have learned and done since I got my first ...

There are times when a pin router would be handy, and a radial arm saw provides a handy platform with its arm adjustable for height and the motor carriage that can be locked at any position along the arm. And, if necessary, the motor can be tilted for very special needs.

Some radial arm saws, like Sawsmith and Montgomery Ward's Powr-Kraft, came from the factory with a high-speed spindle on the right end of the motor for a router collet chuck.  The Sears radial arm saws have a spindle with 1/2 inch thread for a Jacob's Chuck.  The Sears spindle runs too slowly for use with a router bit. 

Step 1: Mounting Holes

This Sears radial arm saw came with two threaded holes on the bottom of the motor.  The holes were used to secure the motor in the crate for shipping.  The holes are 5/16 inch by 18 threads per inch.   

Step 2: Attaching Angle Iron

I used a piece of 1 inch angle iron 11 inches long.  I drilled two 5/16 inch holes in the angle iron to match the holes on the bottom of the motor.  I used two 5/16 inch bolts about an inch long each and put a nut onto each before threading them into the holes.  The nuts are used to snug the angle iron against the bottom of the saw.

Step 3: Upright Frame Member

I had some 3/4 inch birch leftover from another project.  I cut a piece 4 1/8 x 5 5/8 inch for the vertical piece you see here attached to the end of the angle iron. 

The four nuts and washers seen in the corners defining a rectangle are 1/4 inch threaded rods 7 1/8 inch long each.  They are part of the clamping system to hold the router body.  The center bolt at the bottom fastens the end of the angle iron to the vertical frame member and is a bevel head screw long enough to pass through the lower part of the router body clamp.  That will become clearer in another step.  One longer piece of angle iron would have made this extra bolt unnecessary, but my angle iron was too short.

Step 4: Secure the Upper Portion of the Frame

A 5/16 inch eyebolt fits closely around the saw's motor shaft.  You may have to open the eye just a little to make it slide onto the shaft.  Notice the washers used as spacers between the eye and the back of the upright frame member.  Between this and the angle iron, the router is mounted very securely.  Naturally, the saw's motor does not run when the pin router is in use.

Step 5: Holding the Router Body

My router has a round body with no rack and pinion adjuster, but rather a large threaded ring that fits around the whole body and acts on threads around the body of the router.  I made two squares from the 3/4 inch birch that were 5 5/8 inch on each side.  I mounted them on a lathe faceplate and turned out the center sections to leave an open circle the same size as my router body, which is 3 13/16 inch.  (The image is from Google Sketch-Up.)

Step 6: Make Halves of the Squares

I cut out a portion of the middle of each square to leave two halves.  I drilled a 1/4 inch hole through each of two sides as shown by the red arrows and the red circles.  These will be for the 1/4 inch threaded rods.

Step 7: Assemble

The sets of halves are bolted to the upright frame piece.  On the bottom set you can see the head of a 1/4 inch bolt mentioned earlier.  It is recessed and attaches the end of the angle iron.  I placed the threaded rods through holes in the halves of the squares.  Each half that attaches directly to the upright frame piece has a nut and washer to hold it firmly in place.  The outer halves are secured by wing-nuts. 

Step 8: Insert the Router

Turn the router's threaded adjusting ring as far to the top of the router body as it can go.  Insert the router bit you wish to use.  Slide the router down into the hole made for it.  Tighten the wing-nuts.  You are ready to do some routing. 

Step 9: Pin Routing

A pin router allows you to make a pattern from 1/4 inch plywood or Masonite and reproduce that pattern on multiple copies.  What you see is an example of a possible pattern.  Small brads are usually used to fasten it to the bottom of a piece of wood to be routed with the pattern.

Step 10: The Pin

The guide pin would be the same diameter as the router bit.  A dowel can suffice.  Mount it in a piece of plywood and align the pin with the router bit so the bit is directly above the pin.  Fasten the plywood to the saw table so it does not move.  Raise the saw arm with the crank under the saw's table.  Place the pattern over the pin.  Turn the router "on" and lower the arm so the bit cuts in the work piece at the desired depth.  Follow the pattern below until it is reproduced in the work piece.  

I do not use a pin router often, but this is an economical alternative to a commercially produced pin router and works very well. 

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    35 Comments

    HEY!!!

    THANKS for simplifying my life!

    I have an 8 1/4" and a 10", both Sears.  One is going to be dedicated to 'other projects' now.

    7 replies

    Thank you for your comment.  I hope that works out well for you.  I do not mind using my one tool for multiple purposes, although I spend extra time setting up for a new task.

    I have posted several Instructables related to a Craftsman 10" radial arm saw.  One you might want to check deals with egg-shaped indexing pin holes in the yoke, and how to fix that.  With enough use, you will notice you can align your saw for crosscuts, but the blade will heel on ripping.    

    I am discovering there a quite a few people who have never seen a radial arm saw and do not understand what they are, nor how they work.  I guess electric miter boxes have displaced them.  Meanwhile, there are some radial arm saws available on Craig's List for very low prices.

    The 10" is a new acquisition from habitat for Humanity for $35.  It has some serious problems. The elevation crank is gone, the yoke that disengages the miter is broken.  The power cord didn't quite get pulled far enough out of the way at least once.
    It lived outdoors for quite some time as well.  The table top is shot.
    I can build an adapter for a small router and make if single purpose until I find the parts to fix it right.
    All the swivel and tilt parts seem tight, as well as the carriage track.
    I have a 10" slide miter too, but the radial arm is so much easier for some projects.
    They DO require care and caution when in use though, and not for the careless types.

    It sounds like you did well.  I will have to drop in at our local Habitat for Humanity Restore more often.  Unless I misunderstood badly, the things damaged or missing on your 10" saw do not sound that difficult to put into new condition.  Some could even be improvised at home.  Do you have a manual for your saw?

    I found a link on www.lumberjocks.com.

    A very good site for woodworking tips, tricks, and very talented people willing to help.

    Sort of a woodworkers instructables site.

    I scanned my manual and turned it into a PDF.  I would send it to you if you needed it. 

    When I got my saw new, the motor tilt adjustment knob would not lock the motor in place.  I opened it up and found two nylon plugs had been installed backwards.  I turned each one around and everything has been fine ever since.  That is just a story.  There is no big point, but the manual was helpful in doing the job.

    I failed to mention that the link I posted  was where I found a PDF of the manual.
    Manuals are written by the engineers that designed them.
    The manufacturers should follow up with a new manual that has USERS notes included on the best, easiest, safest manner to use their product.
    Lumberjocks.com is like an online users manual for any woodworking question.  From how to sharpen a chisel to how to keep body parts in their original, attached, condition when working with power tools.

    I appreciate the link to the Lumberjock website.  I have not been doing a lot of woodworking in more recent years, but the site is good to know about.

     Another option may be to make a base for the router that the router screws into.  I have a different radial arm saw but could probably do something similar- interesting project.

    I have a project in the works using a router to make a pocket hole machine- another one I similarly wouldn't use terribly often and really don't need a dedicated machine for.

    4 replies

    Please share your project when it is finished.  Thank you for commenting.

     Will do- I'm on the tail end of moving, so once I get more settled (AND get more done on the project : ) I will put that one up

    I noticed you are in Hixson, Tennessee.  We lived in East Brainerd from '83 to '95.  Are you moving across town or to a new city?

    Moved from Chattanooga to Hixson, so more of a new residence than changing cities.

    I put up an Instructable on the pocket hole jig- I will include pictures of the real deal when I unearth it.  I can't paste a link for some reason, but it should come up with a search of pocket hole jig.


    I can't to step 10 for some reason - it links to the intro. That applies for the link from the intro page, and the "Next Step" link from step 9.

    Weird.

    2 replies

    This 'ible has been getting multiple hits all of a sudden.  Try checking back when things calm down.  It might work better then.

    Works now - now I know why it's called a pin router!

    I like that radial arm saw increasingly, Phil. Seems a very useful and versatile tool. I suppose it must be expensive, I have not seen "personally" any similar. 

    I'm feeling
    desire to make one "poor man's" of these at home, now that I retire from work this 30/12. Maybe for 2011...

    Your instructables are increasingly good.

    3 replies

    Thank you, Osvaldo.  Radial arm saws are still available in the USA, but do not enjoy the popularity they had 30 years ago.  I think the electric miter boxes (miter saws) have taken their place, although they do not do as many things.  Today there are many radial arm saws in the USA collecting dust in people's garages.  With a little cleaning, loving care, and careful adjustment they would again be wonderfully useful and accurate woodworking machines.  In the USA we have an electronic classified advertising page called Craig's List.  (for example: http://seattle.craigslist.org [The name of the city changes for your place of residence.])  Many times a good radial arm saw can be found there (under "Tools") at a very fair and economical price.  A radial arm saw, even new, is not as expensive as a Shopsmith system, if you have seen those in person or on the Internet.  

    Once AMT (American Machine and Tool) produced a kit for making a radial arm saw.  Another manufacturer had a radial arm saw attachment that used a common 7 1/4 inch electric handsaw.  Some radial arm saws were light duty home models.  But, a better radial arm saw designed to stand up to construction needs on the job site is the best choice. 

    I do not know if radial arm saws are available in Argentina.  I was in Germany and they were not sold there ten years ago, although one German friend knew what they are. 

    Enjoy your retirement.  I am hoping to retire in less than 3 years.  Some of my friends have retired already, but sometimes because their company could no longer continue to pay them.  Maybe when you retire you could become a distributor for radial arm saws in Argentina.

    Here in Argentina the miter saws are named "sensitiva" (you can see http://listado.mercadolibre.com.ar/sensitiva [today 1 U$S = $arg 3.81 ===> 1 $arg=0.262 U$S] ) But nobody could explain me why they are called so.

    Besides not having seen in my life a radial arm saw, I have not seen an ad of it.

    I'm bad for business, if I start distribute those saws in Argentina , sure I go broke and lose the house. If I start making bras, women begin to come without breasts...