TRASH to Angle Grinder Mitre Saw

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About: Hi I'm kent. I am a maker with a lifetime of experience in electronic systems and automation design. I am also developing skills in 3D printing, carpentry and welding.

For years I've been using my handheld angle grinder with a zip disk to cut metal stock. I manage to make fairly good cuts but when a true 90 deg or 45 deg are required it is near impossible by hand.

So, let me introduce you to my latest creation... the Angle Grinder Mitre Saw.

I found plenty of inspiration on the web for similar projects so thanks to the many makers who have shared their solutions to the same problem. I starting sorting through my junk bins gathering material for the project and came across some chrome shower curtain rods which I thought could be turned into a slider mechanism enabling the cutter to have horizontal travel - handy for cutting plate.

I also had some 1 1/2" PVC conduit which I envisioned using as guides for the slider bars...

So will it work??

Step 1: Making the Angle Grinder Bracket.

I decided to use my Dewalt D28402 hand held grinder because it has two opposing threaded holes to accept a threaded handle. I used these threaded holes as anchor points for the bracket.

There are many ways to approach designing a bracket, it depends a lot on the type of grinder you decide to work with - critical measurements are necessary to layout a functional design allowing the grinder to be detached easily for hand work.

I used Sketchup to design the entire project, the files are attached and show all the parts.

Once the bracket design was finished I gathered up some scrap metal and cut it up. Five pieces of 1" x 1/4" flat bar were required for the assembly. Welding them together created the custom bracket as illustrated.

I also welded a short length of 3/8" rebar as a stem to attach a wooden handle. I sanded up a piece of oak hardwood then drilled a hole down the center and used the hot glue gun to attach it to the rebar stem.

Credit is owed to Asril Anwar for posting his Grinder model on Sketchup, it saved me a lot of time not having to draw the grinder.

Step 2: Ski Boot Engineering

I knew my old ski boots that should have been thrown out long ago may serve a purpose some day and today is the day...

I removed one of the buckle sets and attached them to short length of webbing then fastened the main clamp to the upper arm of the angle grinder bracket. This clamp will hold the grinder handle firmly against the head of an adjustment bolt, described later.

Step 3: Making the Slider Mechanism

Now for my biggest challenge... can I turn a couple lengths of 1" chrome shower curtain rod and 1 1/2" PVC conduit into a slider?

I fixtured the PVC conduit on the drill press and drilled four 1" holes along its length then cut it into two 6" lengths. The pipes fit snug and with a bit of lithium grease they slid quite smoothly. So far so good.

Next a foot needed to be attached to the front end of the rods to fasten the grinder bracket to, incorporating a hinge function enabling the grinder to pivot down to the cutting table.

See images for details.

I needed the ability to adjust or calibrate the travel of the cutting wheel so it wouldn't dog-track. Any offset in the travel of the two rods will skew the wheel angling it inward or outward resulting in the cutting wheel not running dead true to the track. To accomplish this I added a plate at the tail with a bolt mounted through each rod and a third hole with a slot in it. By pivoting or rotating the plate across the width of the slot I could fine tune the grinder wheel track at the other end. A bolt then would lock it into position.

Now to create a base for the whole apparatus.

Step 4: Making the Base.

I needed a base that would support the slider mechanism and a cutting table. I decided that PVC 'U' clamps would suffice to fasten the PVC guides onto the frame.

I built a simple frame using two lengths of scrap 1" tubing and bridged them at 6" apart with two pieces of 1" angle iron. I then cut two 1 1/4" angle irons 9" long and welded them along the sides of the rails. These formed a flat platform to attach the slider mechanism using PVC pipe clamps. Note the platform sits 1/4" up from the base, this gives a bit of extra clearance for the slider to travel over the fence and material being cut.

I welded 1/4" nuts under each of the 'U' clamp mounting holes to ease assembly.

I also cut a slot in the forward cross piece to allow the cutting wheel to drop slightly below the table without obstruction.

Step 5: Assembly

  1. Mount the grinder to the holder bracket
  2. Insert the chrome rods into the two PVC conduit guides
  3. Fix the PVC conduits to the frame using four 1 1/2" PVC 'U' clamps (align the chrome rods to the center of the frame before tightening the clamps)
  4. Attach the foot at the front of the chrome rods that support the grinder holding bracket
  5. Attach the alignment plate at the back of the chrome rods and align the cutting wheel for tracking true along the line of travel, tighten rear plate.

After the assembly was complete and I was happy with how it functioned I disassembled the whole thing and spray painted all the metal parts. The next morning I reassembled it again.

Upon final assembly I applied lithium grease to the PCV conduit where the chrome rods travel through, this resulted in very smooth travel of the slide assembly.

Step 6: Adding the Cutting Table

The cutting table is comprised of a light gauge steel plate that I riveted into place near the front of the frame.

With all pieces assembled and cutting path aligned I then aligned the vertical face of the cutting wheel to be perpendicular to the table. To do this I lowered the grinder wheel to rest on the cutting table and set a small square on the table while pivoting the grinder handle and adjusting the offset adjustment bolt on the grinder bracket accordingly. Once aligned the ski boot buckle holds the grinder handle firmly against the offset adjustment bolt.

With the cutting table fastened in place and all alignments done I plugged in the grinder and proceeded to cut a travel path through the light gauge table being sure to leave some material at the front and back of the table.

I then created a fence from a scrap of aluminum bar (1" x 1/4" x 10") and bolted it in place at exactly 90 degrees to the cut line. I created a second anchor hole to bolt the fence at exactly 45 degrees.

Step 7: Final Testing

With the table and fence complete it was time to run some tests and do any final tweaking on the alignment. I was extremely happy with the results, perfect cuts every time.

And that's how I turned a pile of rubble into a very useful tool!

I look forward to getting on with my next metal project knowing I finally have a decent cutoff tool!

Enjoy the video and thanks for checking out this instructable.

Step 8: Materials

Obtainium (everything in this project was gathered from various junk bins at the FrontierShed)

  • two 6" pieces of 1 1/2" PVC conduit
  • 4 PVC 1 1/2" 'U' clamps
  • two pieces of 24" x 1" chrome shower rod
  • approx 24" of 1" x 1/4" bar to make grinder holder bracket and pivot
  • two 22" pieces of 1" square tubing x 1/8" wall
  • two 9" pieces of 1 1/4" angle bar x 1/8" wall
  • two 6" pieces of 1" angle bar x 3/16" wall
  • two pieces of 1/8" plate 4 1/2" x 2 7/8"
  • one piece of light gauge plate for table 8 1/2" x 9 1/2"
  • one piece of 1" x 1/4" x 10" piece of aluminum bar
  • one Ski Boot buckle
  • 8" of nylon webbing x 1"w
  • one 5" x 3/8" bolt and nut to form pivot point of bracket to base
  • one 4" piece of oak flooring

Step 9: Tools and Safety

    Tools

    • Square
    • Tape measure
    • Wrenches
    • Angle grinder with cutoff wheel and grinder wheel
    • Welder
    • Drill press and various bits
    • Hand drill
    • Center punch
    • 1/4" and 5/16" taps
    • Sander

    Safety

    The tools used in this project are powerful and dangerous if not used properly. Know your tools and how to use them. Always wear safety gear:

    • Safety glasses
    • Face shield
    • Hearing protection
    • Welding helmet
    • Heavy, non-flammable clothing and foot wear
    • Gloves

    Share

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      33 Discussions

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      dsgreene71

      7 months ago

      A very nice build, and excellently presented. Cheers.

      1 reply
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      Mihsin

      7 months ago

      I love your plan. However, I'm not sure I can trust I could insure tight sliding fit between the chrome bars and CPVC tubing holes. Therefore, I'll look into the seat mechanism and railing of an unused rowing exercise machine I have laying around for years. Thanks for the inspiration.

      1 reply
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      ogriver

      7 months ago on Step 1

      I think you have come up with a brilliant idea. I have also made a bracket for my grinder but it has a few limitations. Your setup will overcome those shortcomings. I will definitely make one when I get some time away from my other projects. I only see one problem in your bracket and that is the grinder sparks are sprayed back onto the shaft and the PVC slider. I suggest a guard of flat sheet metal to stop or reduce this from happening, otherwise its a great job. Well done.

      1 reply
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      FrontierShedogriver

      Reply 7 months ago

      Ha ha, you're totally right about the sparks. I did end up building a sheet metal deflector for that exact reason. Cheers and thanks.

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      valveman

      7 months ago

      This is brilliant! I am really digging the slides.

      Great idea!

      1 reply
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      FrontierShedvalveman

      Reply 7 months ago

      Thanks. It took a bit of head scratching before it all came together.

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      Lorddrake

      Question 7 months ago

      I may be mistaken but it looks like you have only only one back and forth direction of travel. in order to make mitered cuts on angles other than 90 degrees, what do you do? replace the straight 90 degree fence with an angled fence?

      3 more answers
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      LorddrakeLorddrake

      Answer 7 months ago

      To: FrontierShed - the downside of checking out IBLEs at work .. youtube is blocked so I don't get to see any of the videos. I'll have to check this out when i get home :)

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      FrontierShedLorddrake

      Answer 7 months ago

      The fence can be set at 90 deg and 45 deg (illustrated in the video). Anything in between I use a clamp to lock the fence. Thx

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      RayJN

      7 months ago

      Look great! Another project to add to my list.

      1 reply