Using a template with a plasma cutter 2

[johnplctech]

Is it possible to use a template when cutting with a plasma cutter? Would it have to be non conductive? For example if I want to cut 16 4" diameter holes can I make a template for that and clamp it to the steel and cut the holes by hand ...

 

[IFRs]

It does not have to be non-conductive. The torch only cuts through what is under the flame. The template has to be thick enough so the body of the torch rides on it. Note that the template is therefore smaller than the desired finished part.

 

[Sciscoe]

It may be more practical to use a non-conductive template. While the torch does cut only what is directly under the arc (flame), it is possible that after the piece you are cutting out is separated that the plasma arc will "ground" through the template to the workpiece. This condition can radically shroten the life of your electrode unless you are using a tip "stand-off". For short runs like your 16 holes, we make templates from quarter or half inch plywood. It is cheap and is expendable after short runs.

When we cut holes, we also use a template that is larger than the desire hole. The stand-off we use on our Miller Spectrum 625 has about a half inch between the cutting arc and the edge of the stand-off. Therefore, we would use a template that has a one inch larger diameter than the hole we want to cut. The plasma cutter would then ride inside the hole template. When the cut is finished, the hole waste falls out. If you use an inside template on a hole, as you cut you will have to move the clamp holding the template in order to cut under the clamp. You will then be holding the template on a hot, fresh cut edge and when the waste falls out, so does your template. This is why we like the outside template for the hole cutting job.

 

[johnplctech]

Thanks for the reply. I was hoping someone had done this before. I'll look into the tip standoff.

Thanks
John

 

[jr32]

You can get precise results by using a simple circle cutting attachment consisting of a torch holding bracket a rod and a pivot. In future if you require smaller or larger holes you can adjust the pivot and cut accordingly.

 

[BillPSU]

In the past the company I worked used metal templates and cut holes in tubing with a plasma torch. The template was an external template which was larger than the hole being cut. The operator simply clampled the template to the work piece, pireced the hole with the hand held plasma and then cut to the template and followed the contour. Accuracy, finish and appearance to the cut was dependent on the skill of the operator. Holes cut were for bosses to be welded in or access holes or clearance holes for assembly.

 

[griffengm]

John,
I've used templates made of metal and some made of plywood. Either works as long as you allow for the offset.
The determining factors on material were complexity and longevity. Plywood tends to scorch on the edges and is short lived but a jig saw can rip out a fairly complex pattern quickly.
Aluminum is light enough to make larger templates easier to use as well as being fairly simple to shape.
We found that life and handling improved if the pattern was made with some risers to keep some space between it and the work. The template did not get as hot and dross had space to clear away from the cut instead of building up on the edges of the template. The buildup made the next pass with the cutter less smooth and caused dragging which affected cut quality.