Deep Throat Hacksaw

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Introduction: Deep Throat Hacksaw

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 ...

Sometimes it would be handy to have a deep throat hacksaw for better reach. I decided to make my own. This Instructsble could also be used to make a good bowsaw for pruning trees, but a different blade would be needed.

Materials--

  • 1/2" EMT (thinwall conduit)
  • 1/2" square tubing
  • 1/8" x 3/4" strap iron
  • 3/16" rod
  • 5/16" threaded rod
  • 5/16" wing nut
  • 5/16" washer
  • #6 common nail

Tools--

  • Common hacksaw
  • Dremel tool with cutting wheel
  • File or grinder
  • Angle head grinder with flap disc and cutting wheel
  • Vise
  • Hammer
  • MIG welder

Step 1: Bend and Cut EMT

In an earlier Instructable I made a conduit bender for 1/2" EMT. (See the first photo.) I used it to bend the frame for my deep throat hacksaw. The tricky part was to make the open side of the frame properly fitted for a 12" hacksaw blade. See the second photo. I made the first bend so the stub out needed for about a 12" throat would be present and positioned the bender by rotating it on the EMT to find the needed starting point for the bend. I cut the second leg of the saw frame to length, although not as precisely as I intended. It was necessary to put the finished saw frame into a vise and twist it a little to align both ends of the frame.

Step 2: Corner Bracing

I found it necessary to brace the corners. The frame flexed without the braces and the blade did not remain taut. The simple bracing shown did not reduce open space in the throat, but did very much stiffen the saw frame and the saw works very well without the extra weight of a saw frame made of much heavier material that would also have resisted flexing.

I used a flap disc on an angle grinder to remove the zinc coating in areas where I would be welding. (The fumes are very nasty and the zinc makes really strange porous welds.)

First I cut a short piece of 1/8" x 3/4" strap iron. Hold it in place any way you can to tack it. I used a Vise-Grip. Then finish the welds. Bend and fit 3/16" rod to the extent of the bracing. The bracing should extend to the ends of the bends at minimum. Tack it in place and finish the welds.

I had the frame of the saw already fitted for the 12" blade. Adding the bracing opened the angles of the frame corners a little because welding causes metal to contract when the welds cool. Now installing a new blade requires some wrestling with the frame, but the blade is very nicely taut. (I could also have made the 5/16" threaded rod a little longer, and I may yet do that.)

Step 3: Blade Tensioner

See the first photo. I had a piece of 3/8" steel. I cut a square piece from it and filed it to slide inside a piece of 1/2" square tubing. See the second photo. I did not have 5/16" threaded rod, but used a bolt. I removed the head and welded what remained from the bolt to weld it securely to the end of the 3/8" square piece I cut and filed to fit. I ground away weld bead that was in the way. See the third photo.

Step 4: Securing and Adjusting Tension on the Back End of the Blade

I made an opening in the EMT to fit the 1/2" square tubing,and welded the 1/2" square tubing into place (first and second photos). I cut a slot in the 3/8" square piece for the end of the sawblade (third photo). I drilled the 3/8" square steel for a pin to lock the sawblade in it (fourth photo). I used the head end of a #6 common nail for a pin (second photo). Some thought and care needs to be used so the sawblade fits between the ends of the frame properly when finished.

Step 5: Anchor the Other Blade End

I used a Dremel tool to cut a slot in the other end of the frame to pass the blade (first photo). This slot works against any twisting in the blade. The rest of the #6 nail becomes the anchor pin.

I bent the end of the nail to a radius so it loosely fits the inside of the EMT. Then I bent that piece over st 90 degrees so most of the nail protrudes from the open end of the EMT. It is fairly easy to catch the hole in the end of the blade with the hooked nail when the blade is loose. See the second photo.

Be careful. It is easy for nail pieces to fall out of position and be lost when tension is removed from the blade. But, it is also easy to make replacements. (I carefully avoided drilling holes through the EMT because that would weaken the saw frame.)

Some fabric tape would assist the grip in use, but it is not necessary.

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    4 Comments

    I enjoyed your engineering know how in the design of a light hand tool..

    Your fine welding and fabrication skills are enviable !

    1 reply

    Thank you very kindly. A MIG welder is a big help, as opposed to stick or flux core wire. Still, there are opportunities for numerous mistskes. Someone said we never become weldors, but we are always becoming weldors.

    This solves a problem, in the past I would try to use a mini hacksaw. And usually smacked my hand on the work. Good idea

    1 reply

    Thank you you for looking and for commenting. You could use a variety of materials and tools for this, depending on what you have avaioable to yourself. I simoly wanted to see what I could do with thinwall electrical conduit.