Determining Speed Ranges for Atlas Rotary Welding Positioner

Atlas Models XT100 and XT200 Welding Positioners are available in 4 speed ranges. The question often comes up as to what speed range is appropriate for a customer's needs for a particular welding job. A simple formula can be used to determine the required table rotation speed, expressed in rpm's.

Welding Speed (in inches per minute) ÷ Circumference of Part = RPM

If you have a part to examine, you can make an actual measurement of its circumference. If you only know the part's diameter, then multiply that dimension by 3.14 to determine the circumference.

Welding travel speed may have to be determined by actually running a bead during a timed period, measuring the bead length, and calculating the length of the bead to inches per minute. If you are MIG welding, do not use the wire feed speed (indicated on your wire feeder), as arc travel speed. Wire feed speed indicates how many inches of wire you use in a minute, but not how fast the arc passes over the weldment. Most welders know how many pieces of a particular part they can weld in an hour, or a day, but generally don't know the actual speed of arc travel. If you're not sure, setup the welding parameters required for your job, get a watch with second hand and a tape measure, and run a test bead.

Let's try an example. Assume a 3" diameter part welded at 35" per minute.

3" diameter x 3.14 = 9.42" circumference.
35" (speed) ÷ 9.42" = 3.7 RPM

A 4" diameter part would require a slower table rotation speed of 2.78 RPM. The larger diameter of the part, the slower you have to run your positioner, assuming a constant weld travel speed.


Now that you know what speed (in rpm's) you need to turn your part on an Atlas Positioner, you can choose the speed range that best suits your needs. We offer two models (Model XT100 and XT200). Each model is available in four speed ranges. Listed below is the speed range data for all eight available turntables.

Both the Model XT100 and Model XT200 Positioners are powered by DC gearhead motors. Motor speed is controlled by a solid state variable speed controller, which is a voltage control device. When voltage is reduced, the motors turn slower. At the low end of the motors' speed (approximately 20% of the top speed), torque tends to fall off. The speed ranges listed below reflect optimum torque levels. The turntables will operate at considerably slower speeds, but may not have the "lugging power" to turn loads that are near maximum weight, or are out of balance.