Correction Power Differences

**Zubair** · 03-09-2016, 06:28 AM

Hi

Am hoping Todd or Dylan or both could answer these 2 questions:

1: Between the MKII 15 and MKI 21, which has more correction power?

2. We know the MKII's have 30% more correction power over the MKI's, however what is the percentage power difference between the MKII 15 and the MKII 21?

**RaskyR1** · 03-09-2016, 10:05 AM

All other variable being the same the 21 should have more correction power.

**Dylan@RUPES** · 03-09-2016, 11:48 AM

Excellent question, and one that's been posed more and more lately.

1: Its closer than most would think. The 15II clearly has a speed and torque advantage, but the 21ES has the larger orbit. Going after a very specific scratch in a very compact area the 15II has the edge due to higher pad speeds, but the more important question in the equation is what are you correcting? If all you're doing is big flat panels then the 21 will cover more area, the additional torque of the MKII on flat areas is a non-factor so it would be faster thru that correction scenario of a panel. If you're working in the real world, cars have curves... that's where the 15II is going to run away b/c the pad size and stroke are less prone to stall on deep valleys and edgework.

2. Simple answer, from a straight mechanical standpoint: NONE. The 15II and the 21II utilize the same 'motor' (rotor/armature assembly) what creates the difference between the two tools is created in the electronics module (brain) of the tool and how that module regulates delivery of power based on feedback. Each tool is specifically tuned to deliver the optimal amount of power in each specific range for its orbit size.

In terms of 'correcting power' its a lot of the same as what you would see in point 1, just a smaller gap. Large flat panel, huge area, the 21II wins simply because of its footprint (pad and orbit being larger), but in the real world when you get to edgework the 15 will power thru and hit more areas than the 21will, plus it closes the gap on orbit size by having a higher speed. Not to mention you're forced to go to a second tool with the 21 for edgework and ultimately the goal is time to completion.

We (everyone as a whole) tend to get caught up in the 'correcting power' bullet point on tools... but if we really think about it the more important thing to think about is situational application of power. I've said many times on this forum that I've never seen the DETAILING related application where the 15II wasn't completely capable of getting the job done as well as the 21II and with less complication related to the need for secondary tools for edgework.

**WRAPT C5Z06** · 03-09-2016, 12:19 PM

21 MKII with 5" BP. Cuts down the pad size a lot, therefore, you can correct smaller areas.

**Zubair** · 03-09-2016, 12:33 PM

Thanks for the responses guys, however let me rephrase. Same size 5" BP on both, and lets say trying to correct deep defects on flat panels say hood/trunk etc. I assume the 21 with 5" BP would be noticeably more powerful in the level of defect removal?

Were I targeting a specific very deep swirl/rid/defect on a flat panel, which one will get me results the fastest?

**WRAPT C5Z06** · 03-09-2016, 03:40 PM

Originally Posted by Zubair

Thanks for the responses guys, however let me rephrase. Same size 5" BP on both, and lets say trying to correct deep defects on flat panels say hood/trunk etc. I assume the 21 with 5" BP would be noticeably more powerful in the level of defect removal?

Were I targeting a specific very deep swirl/rid/defect on a flat panel, which one will get me results the fastest?

On a flat panel, the first generation 21 for sure.

**WRAPT C5Z06** · 03-09-2016, 03:42 PM

Originally Posted by WRAPT C5Z06

On a flat panel, the first generation 21 for sure.

On a side note, I'm wondering if Rupes made 5" backing plates balance on the MKII 21 as well? This wasn't the case with the first generation.

**Zubair** · 03-09-2016, 04:25 PM

I'm looking at the MKII 21 with 5" BP as my next purchase, but just need confirmation its noticeably more powerful on spot defects compared to a MKII 15.

**WRAPT C5Z06** · 03-09-2016, 05:04 PM

Originally Posted by Zubair

I'm looking at the MKII 21 with 5" BP as my next purchase, but just need confirmation its noticeably more powerful on spot defects compared to a MKII 15.

Without a doubt, IMO. Let's see what Dylan has to say.

**Dylan@RUPES** · 03-09-2016, 06:06 PM

The 15II v the 21II in their stock form - we don't endorse the plate swaps specifically so I won't go down that road - you're going to see much less separation between them than you'd think.

Again, you have to remember that the 21 gets the edge in stroke length, but the 15 is operating at a higher speed.

The 21 gets a +40% advantage in orbit size in both generations, which is a good amount.

The 15 gets a +/-13% speed advantage over the 21II and a +/-26% advantage over the 21ES which is nothing to sneeze at.

Now you can't draw a direct correlation between 1% increase in speed overcomes XX% increase is stroke, but speed can make up for a lot. Jason and I were just talking about his question in the office and pretty much we agree that the 21 gets an advantage in overall correcting power, but its not by a wide margin.