Questions about welder specs

An 'adjustable tap' machine has a series of discreet taps for voltage (or current depending on the machine) Continuous lets you have an infinite set of voltages. Cheaper machines use the tap style, more expensive use the continuous.

C> Can anyone tell me what the difference is between an "adjustable tap voltage

I'll assume you're talking about MIG/wirefeed welders?

Tap voltage control is where you have multiple taps on the secondary winding of the power transformer. By selecting different taps you select a different voltage. This is the simplest because all you need is a switch that selects a tap to control the voltage.

A continuously variable voltage control is a potentiometer that adjusts the voltage much like you adjust the volume on a radio. This requires quite a bit more circuitry which makes the welder more expensive to operate and repair and probably more prone to failure simply because of the added complexity.

I have a Lincoln SP-170T (same as the SP-175T) and it's a multi-tap machine. I've never used a continuously variable welder so I'm not really qualified to tell you how much it affects your welds but I've never missed it and personally I think I'd have more trouble setting it up with the extra adjustment. :-)

Best Regards, Keith Marshall snipped-for-privacy@progressivelogic.com

"I'm not grown up enough to be so old!"

Taps mean you have a definite number of voltage levels for output. Continuous allows an infinite number of voltages (between 14.1 and 14.2V, there is 14.15, and between...). I would hazard a guess that you won't need an infinite number of taps, that however many the tapped machine has will be fine.

In a way I guess it's like gears on a bike or car. Sometimes one gear is too high while the adjecent gear is too low. I'm glad I have a 24 speed bike. ;)

Tim

-- "I have misplaced my pants." - Homer Simpson | Electronics,

Multiple Tap transformer based MIG welders used to be the most common type. They are much simpler to build since you just have a wire come off the transformer at each voltage required.

The rotary switch just chooses between the taps.

Most modern MIG machines use an electronic voltage control to allow finer adjustment of your output voltage. It makes the transformers a lot cheaper to manufacture.

However... If these infinitely variable transformers were so superior for everything, why would Miller and Lincoln still be selling a 250 amp multi-tap transformer MIG machine?

The answer has to do with arc stability. A multi-tap transformer power supply has a very smooth arc that works much better for sheet metal than a digitally controlled transformer. The digitally controlled transformers tend to have a harsher arc. Lincoln has made progress to improve this and Miller is catching up.

There is enough of a market for them that Miller and Lincoln still offer the older style machine.