Building a circle cutter jig for use with the plasma torch has been on my list of things to accomplish in my lifetime. Since I am not sure how much time I have left I figured I had better spend an evening completing the task before it is too late. I really do not know what is available to purchase when it comes to circle cutters. I admit I have spent no time looking around to see what the standard design is. I have seen some jigs for an O/A set up that has a nice rolling wheel and the works. I decided to go purely from scratch and approach it with no firm plan.

 I started digging through the metal piles looking for something that could be morphed into a useful tool. The plasma torch is a standard 1 inch OD which makes things easy. I had some left over pipe from the metal bender that would do the trick to use as the torch head holder. The rest of the parts were some scrap steel rod, a 3/8 inch coupler nut and some 3/8’ threaded rod.

The build is really not worth writing about. The design was simple. Take a look at the pictures and you can pretty much figure out how the build went. The main reason for using threaded rod is purely for adjustment and flexibility. I can adjust for just about any radius circle I need. If the rod gets too long I can always machine some mid-way support wheels to help with the stability.

Pin should have been mounted on the inside of the circle – oops

 

 At a later date I might machine a centering adapter for the torch head holder. This way I can drop the adapter into the end were the torch head would normally be inserted and then I will set my radius precisely using the adapter first. Basically it would allow me to measure my radius using two pencil tip points instead of having to measure to the torch tip.

 

 The operating instructions are simple. Determine the radius of circle you want to cut and set the distance between the centers. Take the metal that needs to be cut and determine where the center of the circle is and give it a good center punch. Next step is just go to town and plasma out the circle.

 I shot a quick video of the very first cut using the tool. As you will see I still need to develop some coordination in order to use it a bit better. However for the first cut it worked out fantastic. I used a 12” wide section of 10 gauge steel to cut an 11.875” circle. The steel was too narrow to support the height guide on the torch end of the tool but everything still worked out fine. As I am writing about this flaw I just realized I screwed up. I don’t know why I mounted that pin on the outside of the torch holder, I should have drilled the holder and welded the pin on the inside circle. Oh well…I can fix it yet.

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Comments
  1. Chris Muncy says:

    Hey Gord!

    Do you have a drag tip on that cutter? Looks like you were having some issues cutting through.

    CHris

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