Pertneer's Blog

I needed some tools to make some calculation for certain areas of the build of my plasma table. I have decided that these tools may be of use to others also as they begin their journey building a CNC Plasma.

Among others I needed an easy way to determine the amount of water that my Plasma Table was going to hold so when I drain in into a reservoir below table it would not overflow.
Below I have attached the spreadsheet that I came up with to do just this. It is in Excel 2007 format, if needed i can also post in an older format.

Gear reduction is a big topic when deciding how to make your table move and do it in an efficient manner. Most often for CNC Plasma machines with stepper motors you want the movement to be one unit of travel for one rotation of the stepper motor. This means that if you are using and inch machine you want to move the machine one inch for every rotation of the stepper motor.

A stepper motor runs about 600 rpm max. You need the reduction to cancel out any pinion setup you may have. the pinion setup is calculated by dividing the pitch diameter by π (3.14159~) . So to cancel the pinion you need a reduction of about 3:1. With a reduction that is equal (one inch travel to one revolution) you will have full motor torque. The Gear Reduction file help with these calculations.

I also am posting a file that I found on a Plasma forum that I go to at times. It is used to quote prices for work completed on a CNC Plasma table. You need to make a couple of changes to have it come out to your specific cost schedule but I changed the “Item Cost” sheet to reflect the changes that I use. You will need to make the changes to the other pages to have it work accurately for you.

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