Rupes LHR15 Mark III vs Rupes LHR21 Mark III

Do you know the differences between these two almost identical polishers?

Don’t worry, you’re not the first person to wonder which one is the better choice and why. People have been struggling to decide between Rupes long throw polishers since the LHR 15ES and 21ES days.

It’s easy to confuse the two when some retailers are even using the same image for both polishers.

As with most things in life, the devil is in the details and then it comes down to how you plan to use the polisher.

As you can see, they both have the same motor, body, and weight.

The motor on both is rated at 500watt with a min speed of 3000 orbits per minute and a max of 5200 OPM on the LHR15 and 4500 on the LHR21.

The body is the same with both having the rounded forward hand hold, rubber tool rest on top, pistol grip, trigger, and trigger lock.

Rupes LHR 15 MKIII vs Rupes LHR 21 MKIII: The Differences

Not a lot of physical differences in the product specs huh? To sum them up:

• The LHR15 comes with a 15mm throw (also known as a spindle orbit) and a 5″ backing plate for running 5.5″ and larger pads.
• The LHR21 comes with a 21mm throw and a 6″ backing plate for running 6.5″ and larger pads.
• The LHR21 weighs slightly more, about 1/4 lb difference.

So what does that translate to as far as real world usage?

The longer throw on the LHR21 MKIII allows the pad to cover more area with each orbit. It also increases the leverage the motor has on the pad when it’s whipping it around in circles allowing for more powerful polishing of flat surfaces.

The larger backing plate on the LHR21 Mark III allows for running larger pads, again to benefit covering more area in less time.

It’s not all sunshine and roses though. The longer throw also makes the machine more susceptible to stalling out (stopping the pad from spinning) on tightly curved and angled surfaces.

Combined with the larger pad the polisher has a harder time polishing smaller areas too.

This is where the LHR15 comes in. As you’ve probably deduced the LHR 15 with it’s 15mm throw and 5″ backing plate gives up a little aggressiveness and area of coverage for more versatility in smaller and more curved / angular areas.

It’s true that you can put a 5″ backing plate on the LHR21 and meet in the middle of area of coverage and ability to polish in tighter spaces but you’re talking about adding $20 to a tool that’s already around $30 more expensive.

Another thing to consider when putting the smaller backing plate on the LHR21 is that the counter balance in the motor is designed to run smooth with the 6″ backing plate and accompanying pads. You risk increasing the vibration of the tool. It might not be a meaningful amount but one of the reason’s you’re considering buying a $400 Italian designed polisher in the first place is how smooth and refined of a tool it is.

The Rupes System Explained: What Sets the Rupes Apart

Rupes polishers have three things going for them that sets them apart from other mainstream polishers. They are Italian designed and USA made (in the case of the LHR15 and 21 in the US) by an actual tool manufacture with years of experience and positive reputation behind them.

They are built with impeccable build quality, smoothness, and quietness.

They are the corner stone to a full polishing system that includes the Rupes BigFoot polishers, Rupes Pads, and Rupes Compounds and Polishes, all of which were designed to work together.

While you can get great results mixing and matching these polishers with your favorite pads and polishes you’ll have the most complete and fool proof experience if you stick with the system.

It’s easy to overthink it but it really is as simple as that. My honest opinion is that when in doubt, buy the LHR15 Mark III.