0 items in your basket
Total £ 0.00 EX VAT
MIG Gloves
TIG Gloves
Baseball Caps
Armguards
TIG Heat Blockers
Shop 55,000 Products
SERVICEDEPT.
RAPID BLOG
FEEDBACK
HIRE
Harris roller guide for tips 6290 and cutting attachment and torches 142, 62-5, 42-3, 42-4, 49-3, 572, 72-3, 73-3, 242, 273.
90° angle.
Practical answers on using circle cutting guides and roller guides to get cleaner, more accurate gas cuts.
Look at the drag lines on the cut face. A good cut has regular, only slightly sloping lines. If the lines lean well backwards and slag clings to the underside, you are moving too fast and risk losing the cut. If the lines are vertical and the top edge looks rounded or beaded, you are moving too slowly, or using too much cutting oxygen for the nozzle.A circle guide helps because it keeps the radius fixed, but you still control the speed, so aim for a steady, even pace all the way round. Speed depends on the thickness and the nozzle, so use the maker's chart for your equipment as the starting point.
You normally pierce the plate first. Heat a spot inside the circle until it is at ignition temperature, then open the cutting oxygen gradually and hold the torch steady until the jet goes through. Slag and molten metal can build up and be thrown back at the nozzle, so follow the torch maker's piercing method and wear full eye and face protection.From the pierce hole you cut out to the line of the circle, then use the guide to cut round it. Piercing is slower with propane than with acetylene, and thicker plate takes longer to pierce, so allow time and do not rush it.
It can. Propane has a lower flame temperature than acetylene, so piercing the start hole takes longer, although cutting speed once under way is about the same. Propane also tolerates a greater nozzle-to-plate distance, which reduces the risk of molten metal splashing back onto the nozzle and causing a backfire.The nozzles are different too. Acetylene and propane need nozzles designed for the gas, so make sure the nozzle in the torch matches the fuel gas, and set the guide height to the maker's advice for that nozzle. Check the instructions for your torch before changing from one fuel gas to the other.
First mark the centre of the circle with a centre punch. On most guides you then slide the pivot along the shaft, or slide the attachment along the torch tubes, until the distance between the pivot pin and the cutting nozzle equals the radius you want, and lock it in place. Many shafts have markings to help.Remember that the radius is measured to the cutting oxygen hole, not the outside of the torch, so check against a rule or a scribed line on scrap before cutting good material. Also allow for the width of the kerf, because the finished hole will be slightly larger, or the disc slightly smaller, than the radius you set. Always follow the instructions that come with your guide.