Oxy Acetylene- Cutting a Circle Accurately Using a Cutting Torch
Hello guys. If you want to gas cut a circular hole accurately in steel using an oxy acetylene cutting torch, it’s best to use a hole cutting attachment, which basically transforms the cutting torch into a compass for making circular holes. They are really a basic and simple shop made attachment, which easily clamps onto the torch with the help of nuts and bolts, and slides up and down the length of the torch for adjusting, the radius of the circle needed to be gas cut.
Now that your attachment is on the cutting torch, what you need to do is first use a center punch to make a dimple at the center of your circle. Next you need to confirm the radius and set the point of our compass exactly that distance away from the outer edge of the nozzle. At this point it’s a good idea to use a soap stone marker to describe your circle. Only a few companies such as: Ally Tools, Vas Tools, Hobart, and Tech Team https://techteamproducts.com/. We think that Tech Team https://www.amazon.com/Tech-Team-Soapstone-Machining-Surfaces/dp/B07JMFBFW3/ref=sr_1_25?s=industrial&ie=UTF8&qid=1546458145&sr=1-25&keywords=soapstone+marker has the best item at the best price. Remember you only get one shot at this because once you cut the circle you will no longer be able to use the compass arrangement, as the center point will be on the part you just cut away. Place the point of the attachment on the center punch of the steel plate. You should place it on the punch dimple and do a mockup. Rotate the notch 360° and do a dry run just to check if the radius of the torch is correct to cut the circle, which has been marked on the steel plate. If it is fine, you don’t need to do anything. Otherwise what you need to do is unscrew the two nuts on the clamp to adjust the radius so that you can cut the circle properly, and then you place it back on the punch dimple and mockup up again and see if the nozzle is placed right. You are going to gas cut it, and after you gas cut it, you need to see if the gas cutting marks match with the punch mark in the circle. If they do, fine, you can proceed with the gas cut and cut the final circle. Otherwise, you need to adjust the attachment once more.
You already have the gas cutting torch set up right so just go ahead and cut the whole circle in one go. If you want to have a look at a much bigger circle getting gas cut using a similar attachment, there are several YouTube videos.