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Rupes LHR 21ES Random Orbital Polisher - Features & Benefits

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#1 Kevin Brown

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Posted 09 November 2012 - 01:13 AM

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I have run the Rupes® LHR 21ES Random Orbital Polisher (herein referred to as Bigfoot) through its paces. As expected, it performs wonderfully! I am looking forward to selling the trio of Bigfoot-branded products (the LHR 15ES, LHR 21ES, and LHR 75).

This write-up is essentially a brief, outlining my thoughts about the Bigfoot. I have also included information regarding some of the latest products and techniques being used with random orbital polishers today, and a bit about how their popularity came about. My hope is that after reading this document, you will better understand why I appreciate the development of the Rupes® LHR 21ES so much.

Bigfoot Versus the Competition.
Bigfoot's price point is expected to be high relative to other electric random orbital polishers, so it will likely face an uphill battle on the sales front if compared only to other electric random orbital machines. I wouldn't be overly concerned about this speculation though, because Bigfoot's capabilities and build quality will have it contending for the paint polisher's dollar whether they happen to be shopping for a random orbital, forced rotation orbital, or rotary-action machine.

Since many of the most popular forced rotation orbital and rotary machines typically sell for $200.00 to $525.00, the Bigfoot should have no problem stealing away dollars from other available brands. Some of the most popular polishing machines are:

Random Orbital Polishers
Meguiar's® G110v2 Professional Dual Action Polisher ($149 typical)
Griot's® Garage 10765 6" Random Orbital ($99-$149 typical)
Porter Cable® 7424XP 6" Random Orbital Polisher ($119-$149 typical)

Dual Mode Orbital Machines (switchable or forced rotation)
Flex® XC 3401 VRG Orbital Polisher ($299-$349 typical)
Festool® Rotex RO 150 FEQ ($525)
Makita® BO6040 ($261-$319 typical)
Bosch® 1250 DEVS ($239-269 typical)
Dynabrade® 61379/61384 Dual Action Buffing Head ($57-$140 typical)

Rotary Polishers
DeWalt® DWP849 ($167-$225 typical)
DeWalt® DWP849X ($179-$250 typical)
Makita® 9227C ($195-$253 typical)
Flex® PE 14-2-150 6" compact Variable Speed Polisher ($359-$399)
Flex® L3403 VRG Lightweight Rotary Polisher ($240-$299 typical)
Festool® RAP150 ($400)

Sales Potential of the BigFoot.
The potential for USA-based sales of the Bigfoot is immense. Veteran paint-polishers will surely consider adding the Bigfoot to their arsenal of machines, but I believe that people new to the polishing scene will as well. After all, the enthusiasts among this group tend to heed the advice given to them by experts in the field, and they’ve grown up accepting the fact that a random orbital is a very capable cutting and finishing machine.

Although most experts will not normally recommend a rotary polisher to a beginner for obvious reasons, they do not hesitate to recommend a forced rotation orbital or dual mode orbital machine. But, will the experts heartily recommend the easy to operate random orbital? A search of the forums for the answer to this question tells an interesting tale.

Within the past five years, the random orbital has gained acceptance as being a tool capable of removing sanding marks and harsh defects. It is also capable of final-polishing paint to the highest degree. Prior to this time, its correcting abilities were called in to question, especially when compared to what an expert could accomplish wielding the mighty rotary.

It was generally accepted throughout the high-end detailing scene that the random orbital would almost certainly create haziness upon an otherwise perfectly polished surface. In short, the random orbital was opined to be for weekend warriors, whereas the rotary was the only real choice for true paint correction. As such, most experts relegated the random orbital to one-step polishing duties, or for final waxing of light colored paints. I believe that lackluster results were not the fault of the machine, but rather were in large part caused by:

  • Backing plates & buffing pads paired for the advancement of polishing safety, rather than for ultimate polishing performance.
  • The use of buffing liquids optimized for hand or rotary application.
  • Performance limitations of D/A specific buffing liquids (due to their design or the unavailability of technologically advanced abrasives).
  • Procedural recommendations that were not properly vetted.

The topic of how to best optimize performance of the random orbital is one that I could write pages and pages on (and I have: link). To the original question, and more specifically in regards to the Bigfoot: Will polishing experts recommend a random orbital with as massive a stroke as the Rupes®? I believe they will.

To back this claim, one need only look at the rising popularity of the Dynabrade® 61379 Dual Action Buffing Head Kit (now available in kit form only as model 61384). This unit features a 3/8” spindle offset, and allows the user to choose between random orbital and rotary modes. Spindle offset is not adjustable, so rotary action is also off-center 3/8”, and therefore creates a 3/4" diameter stroke:

Dynabrade Dual Action Buffing Head. Mounted atop a Makita 9227C Rotary Polisher.

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In March 2009, I wrote a small article about the 61379, which I posted on a few of the more popular detailing forums. Not too many forum guys jumped at the chance to try this tool, primarily because it appeared to be heavy and bulky. Besides- it cost as much money to buy the 61379 as it would a typical random orbital machine.

This component, designed to mount to a rotary polisher, originally sold for $115.00-$145.00. For reasons unknown to polishing enthusiasts, Dynabrade® decided to sell these units via their own online discount store for the incredible price of $59.00.

Dynabrade® has recently introduced the 61318 Dynalocke® Sanding Head, a rotary-mount unit that features true rotary action, and converts to a 3/16” stroke random orbital ($157.00). Perhaps this all-new unit was the reason for the price decrease on the 61379. Could there be an all-new large stroke buffing head on the way?

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Regardless, once the prices dropped on the 61379’s and 61384’s, guys started purchasing them at a rapid pace. The buffing heads are being mounted to all sorts of rotary polishers, ranging in price from $39.00 (Harbor Freight) to over $500.00 (Fein® 12-27E). Not only have the 61379’s gained acceptance, they’re now being used to polish some of the most expensive cars available today. Case in point: Three top-tier detailers polish a McLaren MP4-12C (link):

Attack of the Dynabrade Dual Action Buffing Head- McLaren MP4-12C:

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Barry Theal, Eric Witt, and Dave Purser (January, 2012).
All three chose to use a long-stroke random orbital to polish the McLaren.

This is fantastic news for Bigfoot users, because it will outperform the 61379 (when used in random orbital mode), as its maximum recommended speed is 3,200 RPM. If the same arm speed is used to move both machines along, 31.25% more actual polishing of the surface will be accomplished using the Bigfoot, thanks to its 4,200 RPM capability.

Note: the 15mm-diameter stroke LHR 15ES features a 5,000 RPM top-end speed, which was likely bumped upwards to compensate for its inability to generate an equal amount of centripetal force (which is what makes the backing plate randomly rotate)

When used in forced rotation mode, the 61379 gains a performance edge over the Bigfoot assuming the goal of the polishing session is severe defect removal. However, the added RPM capability of the Bigfoot and larger stroke (21mm versus 19mm, or 10.5% more) help to negate this edge by creating more random rotation of the backing plate at maximum speed (perhaps as much as 10-14 turns per second when a spacer is placed between the mounting pad and backing plate).

There is no need for concern, because the Bigfoot has a huge advantage over the 61379 when comfort of use is taken into consideration. The Bigfoot is lighter, lower in height, and features a far superior balancing mechanism.

Not only will the comfort of the Bigfoot be a HUGE selling point against the 61379, it will be the deciding factor for people that would like to but literally cannot use a random orbital because of its inherent vibration. I must say- no currently available machine beats the Bigfoot when performance and comfort are taken into consideration.

The Bigfoot is incredibly well balanced.
Bigfoot is so well balanced, that I was able to control it using only one hand. This allowed me to use my other hand to apply additional polish, or mist the surface with water (to aid in extending the buffing cycle). Although this is not a technique I would recommend to others, it is an impressive feat nonetheless. While I am also able to accomplish this using traditionally designed random orbital machines, it is not at all easy to do.

The Bigfoot offers improved leverage over traditional designs.
Bigfoot offers more leverage due to its long length, giving it a feel similar to that of a traditional rotary polisher. Familiarity of the Bigfoot’s layout (speed setting, trigger, lock button, handle length, and ability to install a side mount or bail-style handle) will make rotary users feel right at home using the machine. The added length also means that minute unintended vertical movements of the handle will not transfer as readily to the head of the machine.

Length comparison: Rupes® LHR 21E versus the Meguiar’s® G110v2

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The Rupes® LHR 21E measures 16-1/2”, not including the cord.
The added length increases leverage and comfort.
Rotary users will appreciate the familiar feel of the machine.

The Bigfoot features a low profile… 4-3/4” !
Bigfoot’s low profile increases its stability. If a guy is not careful when polishing, a tilt of the machine to the left or right can cause the pad to flip onto its side. It is rare but does happen, especially when using small-diameter pads or high operating speeds. Large stroke machines are more susceptible to this occurrence, especially when used to polish oddly shaped panels, or when the machine is tilted in hopes of allowing a smaller portion of the buffing pad to contact the paint surface.

Bigfoot’s low profile can also increase user comfort, and allow the machine to fit in confined areas (such as when trying to polish the dash area of a boat, directly behind a windshield or wind screen).

The Bigfoot’s low profile can improve high-speed stability.

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To the left: the ever-popular Meguiar’s® G110v2 Dual Action Polisher.

To the right: the Rupes® LHR 21E Bigfoot Random Orbital Polisher.

The Bigfoot features a variable-speed trigger.
If this were the only feature distinguishing the Bigfoot from the rest of the pack, it would be enough to get me to make the switch to the Bigfoot! Luckily, this is not the case. Bravo on this point!

The Bigfoot is relatively lightweight.
Typical weight for a random orbital machine is approximately 5 pounds. The Bigfoot tips the scales at 6-1/2 pounds. Not bad, considering its added length, counterbalance mechanism, and hi-torque motor. This is still two to four pounds lighter than an industry standard rotary polisher outfitted with a Dynabrade® Dual Action or Random Orbital Buffing Head.

The Bigfoot has tremendous cutting ability.
Isn’t this what it’s all about? Compared to a machine featuring a shorter stroke, the Bigfoot moves compounds and pads a farther distance for every rotation the backing plate, which means things are also moving at a more rapid clip. The extra motion and speed can cause abrasive particles to readjust as they move, effectively extending the buffing cycle. This is readily apparent to anyone that has used the 3" Air-Powered LHR75 Mini Random Orbital Polisher; its cutting ability is hard to believe, yet scouring of the surface is kept to a minimum.

The Bigfoot’s 21mm stroke creates loads of centripetal force at speed, and its spindle bearings allow the backing plate to spin along unabated. Consequently, random rotation of the backing plate should be out of this world! However, a purpose-built shroud not only covers the driveshaft-mounted rotating components, but also slows backing plate rotation via drag-induced friction.

Marco (the Rupes® engineer that developed the machine) explained that excessive rotation could cause scouring of the polishing surface if the backing plate and buffing pad were allowed to freewheel spin prior to contacting the polishing surface. He also mentioned that excessive rotation was considered to be a safety hazard in some parts of the world. Understanding his reasoning, I nevertheless decided to install a spacer between the backing plate and mounting pad in hopes of restoring a maximum amount of backing plate rotation.

A metal, plastic, or phenolic washer will work. Cut and sand to size.
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The height of the spacer needs to be enough so that the backing plate will no longer contact Bigfoot’s shroud. The spacer shown is approximately 3/16” tall and was taken from a backing plate featuring a 5/16”-24 mounting stud.

The spacer was placed between the backing plate and mounting pad.
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The pad still mounts safely and securely. If desired, a minimally longer bolt can be installed to compensate. The bolt is 8mm. The shape of the platform and spacer is known as a Double-D cutout.

The resultant gap is nearly unnoticeable.

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With the spacer installed, backing plate rotation and cutting speed were dramatically increased.
The difference was apparent, even when low speed settings were used.

With the spacer installed, backing plate rotation increased immensely. While I was not able to verify exactly how big an increase occurred in terms of backing plate rotation or cutting power, I can say that it was a LOT. My best guess: backing plate rotation increased to 10-14 times per second, and cutting speed increased by about 50 percent.

If a rotary buffer outfitted with a wool pad had any sort of performance advantage over the Bigfoot, the advantage was nearly or completely negated after this easy to implement modification. This newfound cutting power elevates the Bigfoot to superstar status. I hope that Marco will not be overly upset by the addition of the spacer, and I am sure he is aware of the tremendous rotation potential of this machine (otherwise there would have been no need to design the shroud to contact the backing plate). Regardless, I plan on using my machine with a spacer installed.

Note: For the record, I used Meguiar’s® M101 Foam Cutting Compound and Meguiar’s® M105 Ultra-Cut Compound while conducting this test. The Bigfoot was outfitted with a Meguiar’s® 6” DA Microfiber Finishing Disc.

Whereas a machine such as the Meguiar’s® G110v2 Dual Action Polisher (8mm stroke, 6,800 OPM max) requires that a 5” DA Microfiber Disc be used in order to maximize polishing performance, the Bigfoot delivered equal or faster results using the 6” discs. Compared to a 5” disc, a 6” disc offers up more surface area, increased stability, longer working time, and higher rotational speed along the edge of the disc.

In the end, it’s likely that most guys won’t add a spacer between the backing plate and mounting pad. I’m not even aware of whether such a thing will cause a warranty issue. Regardless, as long as the balance or motion created by the Bigfoot is not negatively affected by the design or weight of the buffing pad, the Bigfoot will perform on par or better than a typical random orbital that has been outfitted with smaller diameter pads.

Pad Diameter Comparison Chart

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Most paint polishing guys do not realize how big a difference pad diameter can make.
As an example, a 6” buffing pad features 43.9% more surface area than a similar 5” pad.

The Bigfoot can create a dazzling finish.

Although most guys will be surprised to know that a large stroke machine can create a sparkling, haze-free finish, I have thought this to be the case for years. It sure would have been nice to meet Marco three or four years ago, as I felt my thoughts about cutting and finishing using a large stroke machine had to be incorrect. As it turns out… they were not.

I have found that as long as a proper polishing technique is used and the following guidelines are adhered to, a fantastic finish can almost always be achieved.

  • Use the lowest speed setting that allows continuous but slow rotation of the backing plate (see diagrams below for clarification).

  • Avoid angling the machine in a manner that causes the buffing pad’s edge to be driven into a panel’s surface.

  • Make sure that backing plate rotation is never stalled, or excessively rapid.

  • Keep the buffing pad clean (microfiber pads must be kept fluffy as well, in order to keep the fibers separated from each other).

A long stroke machine used with a low speed setting creates the ideal setup for the final polishing of any surface. While there may be some exceptions to this statement, the amount of exceptions is likely very low. I believe that the following data supports the premise (many of you may have seen this information before).

To better understand backing plate motion, I built this device.Posted Image[

To illustrate how oscillation speed, pad rotation, and user controlled movements affect the pattern created by a random orbital, a random orbital polisher was outfitted with a backing plate using four modified ballpoint pens in place of a buffing pad.

This particular machine (the Meguiar’s G110 Dual Action Polisher) creates a 5/16” (8mm) diameter stroke. However, the pattern it generates is dependent upon a large group of factors. Note: the circle created by the rotating pens measures 4-3/8” (111mm) in diameter.

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This pattern was created using the machine on speed setting 1, which equates to 2,560 orbits per minute.

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This pattern was created using speed setting 6, which equates to 6,700 orbits per minute.

The pen markings tell an interesting tale. When the machine was adjusted to speed setting 1, the pattern revealed a backing plate motion that was curlicue in shape at the orbit transition point (the small “loop” which forms as one orbit ends, and another begins). This pattern verifies that there was a smooth movement of the backing plate. However, as machine speed was increased to speed setting 6, the curlicue transition loop tightened, eventually creating a spiked point instead of a loop.

The net result of these patterns may be difficult to envision, but imagine if the blade of an ice skate created these lines as it traveled across an ice rink. Whereas the curlicue, slow speed pattern would show a smooth movement of the blade with little or no uneven gouging of the ice, the pointed, high-speed pattern would certainly create gouges in the ice at the transition points.

Upon consideration of the patterns, one might conclude that although a higher speed setting can increase cutting power or accomplish more work in a shorter period of time, the paint finish may suffer because of it. This is especially true when the random orbital is used to sand paint prior to polishing. Should gouges or deep pigtail marks occur during sanding (and excessive machine speed is determined to be the culprit), a lowering of the machine speed may reduce or prevent creation of the markings. Precise measuring of the pen marks help to validate the premise:

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There’s more to this story!
Typically, a buffing pad can more readily contour to a panel shape if the pad is moving at a slow rate of speed. (this is true regardless the type of machine). However, a potentially BIG problem arises when a low speed setting is used with a random orbital: rotation of the backing plate suffers, especially if the machine features a short stroke. Things get even worse if the buffing pad is soft and pliable, because its cushioning action can absorb some or all of the machine’s motion, causing backing plate rotation to slow, or stall altogether. To combat stall, machine speed must be increased in hopes of restoring pad rotation via centripetal force. Unfortunately, repetitive scrubbing of the surface sans at this point can create micro marring, as the abraded paint residue saturates the buffing liquid and pad.

Pad stall won’t happen all that often with the Bigfoot, because its large stroke generates a massive amount of centripetal force (which is what makes the backing plate rotate in the first place). Consider that fact for a moment, and take into account the long and gradual sweeping motion created by the machine.

As the diagrams have shown, a slow speed setting creates a softly curved pattern, enabling the pad to easily contour, avoiding edge digging in the process. In addition, the abrasive particles instilled throughout the buffing liquid are scuttled along longer distances per oscillation with the Bigfoot, allowing said particles to adjust positioning as they move. This aids in keeping the particles clean, and helps to minimize clumping.

The Bigfoot works well with a variety of pads and liquids.
I spent quite a bit of time using a variety of buffing pads and liquids with the Bigfoot. While the supplied Rupes® foam pads and buffing liquids worked very well, I was able to achieve impressive results using the Meguiar’s® DA Microfiber System. I had expected this would be the case, as I have spent hundreds of hours using the discs and liquids in prototype and finalized forms.

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Rupes® pads and liquids were expected to work well with the Bigfoot.
I was able to achieve excellent results using other brands of pads and liquids as well.
Machine comfort was very good, regardless the pad.

Why am I so excited about the existence of the Bigfoot?

Bigfoot’s design is mechanically superior & wonderfully unique.
Although buffing liquids and pads are now being tailor made en masse specifically for use with random orbital polishers, machine manufacturers continue to plod along by mimicking the design of the ever-popular Porter Cable 7424.

As far as I know, Bigfoot is the first machine on the market to offer a rotary-style layout, variable-speed trigger, and a formidable 21mm stroke! This is 2.625 times larger than the typical 8mm industry-standard large stroke machine. The fact that a machine such as the Bigfoot was built at all vindicates my thoughts about machine stroke, which are outlined in an article I wrote (available here). Summarized, I believe that there are numerous benefits that come with using a large stroke machine.

Bigfoot is the machine that I’ve wanted AND needed… for years!
As a person that has worked for over two decades to become proficient using a rotary polisher, I’ve come to accept that due to the progression of technology (and a better understanding of how to optimize machines for maximum polishing performance), the random orbital is capable of delivering results that equal or surpass those created by a rotary.

This realization was slow in coming, but as I continued to spend time experimenting with the random orbital, I thought more about the mechanical aspects of the machine, shelving any preconceived notions of its abilities in the process. Whereas the philosophy of learning by doing had served me well in so many areas of detailing, advice given to me regarding the polishing process had not. So, why not learn by thinking about the mechanical aspects of the machine, as opposed to just using the machine and then analyzing results?

Taking thoughts of the mechanical process to extremes helped a lot. As an example, if I were pondering the effects of backing plate weight on random rotation, I would consider extremely light plates as well as extremely heavy plates, their diameters, densities, mass placement, and so on. I also gained knowledge through the testing of prototype products, and consequent discussions regarding those products. But, how best to share this newfound knowledge, without inadvertently sharing trade secrets?

An understanding of what was occurring at the mechanical level was key to writing explanations that would allow readers to create extraordinary polishing results, using already available products. What a difference this made; visualizing what was happening as opposed to wondering what might be occurring.

In closing.
I look forward to selling the Bigfoot and other Rupes® products. The Bigfoot is not a perfect machine, but it comes close. It is apparent that the Bigfoot is a well thought out machine, and heartily built.

I am wondering if the weight distribution of the machine is a bit too forward biased. I cannot confirm this to be true, but this was the first time I recall ever having a strained feeling throughout the muscles of my forward-positioned hand. For now, I’ll chock this up to the fact that when this occurred, I had spent a couple hours polishing the side of my pickup truck, and I was running the machine through the ringer, swapping pads, and generally getting accustomed to the machine.

I see a great opportunity to sell a foam cushion or gel-filled hand pad. It could sit atop the head of the machine, and mount using the threaded holes that already exist for installation of either a side-mount or bail-style handle. I did not see that a handle of any type existed for the Bigfoot, but I suspect this was simply due to an omission in the literature.

Finally, I do not believe that the Bigfoot will be the best choice of machine for every job. On areas such as those that are unusually skinny, or for times when the area in need of polishing is in close proximity to delicate or protruding objects, or if polishing needs to be confined to a specific area, a small stroke random orbital or rotary machine may be a better choice:

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All this being said… in most cases, I think the Bigfoot will be the machine that guys will reach for first.

Edited by Kevin Brown, 03 March 2013 - 11:28 AM.


Paint polishing is a learned craft, not an art form.
Realizing this is the most important step one can make towards becoming a better paint polisher!



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Posted 09 November 2012 - 03:47 AM

Aw crap, I'm going to have to get to the big screen for this one! Brb :)
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#3 C. Charles Hahn

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Posted 09 November 2012 - 04:23 AM

Kevin Brown strikes again!

As if I wasn't looking forward to this machine enough already....
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#4 Garry Dean

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Posted 09 November 2012 - 05:15 AM

After speaking with you last night, I was under the impression you were extremely busy. Now I see why, lol. You are a detailing mastermind. I truly appreciate the well thought out, educated effort you put into your posts. Very well done and thank you, Sir, for sharing.
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#5 Accumulator


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Posted 09 November 2012 - 07:25 AM

Kevin Brown- Ah, another clear, well-presented batch of info! No surprise there... ;) Bet that post took a little time to put together!

Given the LHR 21E's proprietary backing plate design, just what sizes are available?

Assuming larger plates are offered, how do the larger plate/pad sizes perform? I.e., is the effective (RO) use of, say... 7.5" pads now possible?
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#6 drew935


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Posted 09 November 2012 - 08:17 AM

Kevin, another thing is the distribution of weight. When I tried it, I thought how light it feels.
The length is a little longer than I want it to be but whatever. ( I guess that would be nice if a woman said that to guys lol) :har:
It does not feel 6.5lbs! :D

Edited by drew935, 09 November 2012 - 02:19 PM.

#7 Miracle


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Posted 09 November 2012 - 08:37 AM

Hi Guys,

The Rupes bigfoot system is truly second to none compared to other machines, I thought I would never leave the rotary, but now I dont even use it at all!

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#8 SilvaBimma


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Posted 09 November 2012 - 09:03 AM

Well time to start purchasing cases! What pads have you found work best with this type of buffer? Flexi/Rupes/MF?

How does the 15 compare to the 21? How about the LHR75?

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#9 Miracle


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Posted 09 November 2012 - 09:17 AM

Rupes pads work the best I have found, the 15mm is the one I use the most, but the 21mm is awesome for big panels and fast correction, but I love my LHR75 the most, purely an amazing machine, but all three have there place. And as Kevin said, this system produces more gloss than any other system, and I have tested this thoroughly with this machine - http://www.rhopointi...0°/60°/85°.html on all colours as well.

Kind Regards

#10 RaskyR1


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Posted 09 November 2012 - 09:17 AM

Awesome info Kevin! It's information like this that sets you apart from all other retailers and it's just one of the many reasons people should buy from you! :thx

#11 BigAl3


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Posted 09 November 2012 - 12:02 PM

thanks to kevin for his thorough explanation and paul for his input, much appreciated!
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#12 Auto Concierge

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Posted 09 November 2012 - 12:40 PM

Awesome info Kevin! It's information like this that sets you apart from all other retailers and it's just one of the many reasons people should buy from you! :thx

Nuff said..............................
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Posted 09 November 2012 - 06:53 PM

Kevin, I thoroughly enjoyed your article and appreciate the effort, passion, and thought you put into it and everything else you do. I must say I had no plans to purchase another machine as I am quite thrilled with my 3401 and feel it suits me. Furthermore I don't NEED another machine. When I heard you would be offering these awhile back I figured at some point in the nebulous future that the next machine I purchased would be one you will be offering. After reading this article I am very tempted and can confidently say this tops my Christmas wish list and will certainly be the next machine I purchase even if I talk myself out of it in the near term. I will say if I was using a machine daily I would buy one the second you had it ready to ship to me. Your point about comfort and lack of vibration is paramount to me. I used a GG very briefly before my 3401 and was disturbed by how it was not at all enjoyable.

I had a few thoughts and comments not necessarily related to this machine.

your analogy of an ice skater....

Does it actually apply? What I mean is for an ice skater to change direction it must put downward force into the ice. Where as a d/a does not change it's downward force. Rather it is being driven by a force from above and doesn't push off with it's pad to generate this change of movement.

The change of movement with a d/a is the affect while change of movement with an ice skater is the cause if you know what I mean.

I submit (with the full knowledge that I am likely wrong) that the point changes vs. curly changes are all the same depth of cut into the surface. Does that change anything for you if you would agree with it? Or are you saying this theoretical gouge is a horizontal dragging scar rather than a deeper one?

This bit about the longer sweep per oscillation allowing the particles to re-adjust or flatten out is a brilliant thought imo and I can definitely see it.

Finally, your theories and the article on the Kevin Brown method contradict some of the things I do with my Flex 3401 particularly during the finishing stage. In other words I believe I keep the speed much higher than you but my final result is excellent even when studied under sunlight or led. Of course, products, pads and all are different so I know that changes everything. Getting to the point... Your writings are based on smat tech specifically. Is that correct? I almost always finish with diminishing abrasives and wonder if the tool, polishes, and pads I use would change the rules to some of your theories.

Thanks again for the great article and I agree 100% with Chad! I look forward to purchasing my next machine from you.

Edited by CEE DOG, 10 November 2012 - 07:14 AM.

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#14 Perfections


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Posted 09 November 2012 - 08:41 PM

Here's the only question I have, and is the bottom line for me. What advantages does it have over the flex 3401? There's very limited cars I can't finishes down perfect with this machine, I can think of 2 ever.. What would be the benefit of having a rupes?

Currently I own, griots 6", pc, flex 3401, and Milwaukee rotary, with the flex being the majority stock holder of usage.

#15 Peachstate Detail LLC

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Posted 09 November 2012 - 08:55 PM

Nuff said..............................

Truth here

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#16 Accumulator


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Posted 10 November 2012 - 11:51 AM

... There's very limited cars I can't finishes down perfect with... [the Flex 3401]..., I can think of 2 ever.. ..Currently I own, griots 6"...

Not to threadjack, but I'm surprised you can get the same finish with the Flex 3401 that you can achieve with the Griot's. I can't get my Flex to finish out *QUITE* as nicely as with my Cyclos or the Griot's.

Back on topic, I do hear you on the Flex 3401 vs. Rupes question though...I'm kinda in the same position. I can understand the Rupes being great for people who either a) don't have something like the Flex 3401 or B) don't like it, but for those of us who are happy with the corrective abilities of the Flex I'm guessing that the Rupes offers *quicker* correction and a more user-friendly experience. Now just how much those diffs are worth, well, I guess that's between the user and his wallet.
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#17 Kevin Brown

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Posted 10 November 2012 - 06:32 PM

... Your analogy of an ice skater.... Does it actually apply?

Not literally, just a visual that came to mind at the time.
The original intent of the analogy was to relay how the abrupt motion might affect the finish.

For the analogy to be accurate, the skater would have to be towed along at a constant clip, his legs in casts or supports for rigidity; the skate blade would have to be shaped as a point, sphere, or an abrasive particle of some sort, and its up & down positioning would have to be controlled so as to eliminate pressure changes.

...I submit (with the full knowledge that I am likely wrong) that the point changes vs. curly changes are all the same depth of cut into the surface. Does that change anything for you if you would agree with it? Or are you saying this theoretical gouge is a horizontal dragging scar rather than a deeper one?

Pads do change shape as they work, which is no big surprise.

As the pad-face flexes while dragging across the paint (scuttling liquids and abrasives in the process), any single portion of the pad will likely have a varied pressure or force placed upon it. If the pad's face has any sort of ability to conform and change shape via resiliency (foam) or the stacking of its fibers (wool & microfiber) or its design characteristics (Surbuf Microfingers), any particles in the vicinity will be under pressure. This pressure will force the abrasive particle against the paint, causing it to continually scrub the surface. If it so happens that an abrasive particle once again drags across a specific path (without changing its positioning), it'll slice a deeper gouge into the paint on its return trip. This won't happen if something limits the particles ability to conform or stay planted to the paint surface, but when it comes to polishing paint... we generally use pads that have some sort of "suspension" built in. I suppose this is why we see tick marks or pig-tails; these scratches or voids in the paint are likely deeper, wider, or both.

Let's continue to use the ballpoint pen's line of travel for a moment.

If the abrupt transition is not actually a "twist-point" that sees the ball momentarily spin in place, but instead is a path that creates what is essentially an extremely tight and small ovaloid circle... wouldn't the marks on the paper appear to be wider? This assumes that the pen's body is perfectly rigid, so too the backing plate. If either component had an ability to flex or distort, there's a high probability that the ball would travel on its outbound trip in the valley it created as it traveled inwards (towards the mounting spindle). Perhaps the photo is not a true indicator of what typically occurs.

Interesting thought: if the slices in the paint were close enough to each other, wouldn't the paint residing between the slices eventually be removed (via friction, pressure, pad motion, paint shifting & twisting, or whatever force), creating a void in the paint surface? To our eyes, would the void simply resemble a deeper or wider scratch?

Let's remove the ballpoint of the pen, and replace it with a sharp metal cutting tip.

Immediately after running the ballpoint pens across the grid paper, I was thinking about how a single abrasive particle (perhaps attached to a sanding disc) might interact with the paint surface. Would the particle continue to move in a curlicue motion, albeit minute in size? Would the stress placed upon the particle (mostly due to speed & directional change) cause it to detach from the disc?

...Finally, your theories and the article on the Kevin Brown method contradict some of the things I do with my Flex 3401 particularly during the finishing stage. In other words I believe I keep the speed much higher than you but my final result is excellent even when studied under sunlight or led. Of course, products, pads and all are different so I know that changes everything.

I never claimed that the "KBM" is the end-all, be-all polishing method.

At least, I've scribbled down and posted up plenty of support material explaining why I believe certain sanding and polishing methodologies work. From what I've seen, there's very little explanation as to why some guys have huge success polishing using high-speed settings, or short-stroke machines.

The lack of information pertaining to machine stroke in general is the reason I started to write about machine stroke and machine speed in the first place. As an example, I just could not accept without verifying why short stroke machines were always considered as being best for fine sanding, while large stroke machines were supposedly best for coarse sanding. While there is some validity to these set-in-stone recommendations, I never was able to locate any reasoning behind the premise. After much thought and discussion, I now absolutely understand why the recommendations do and do not hold merit.

By the way... a group of us recently used the Rupes® LHR75 Mini-Random Orbital (15mm diameter stroke on a 3" machine) outfitted with 3000 grade sanding discs with no drama whatsoever. We watched for edge-digging, kept our speed low, kept things clean while we worked.

Getting to the point... Your writings are based on smat tech specifically. Is that correct? I almost always finish with diminishing abrasives and wonder if the tool, polishes, and pads I use would change the rules to some of your theories.

Regarding clumped and non-clumped abrasives... a lot depends upon the things already discussed.

Regardless the structure or design of the abrasive particle (diminishing or clumped, non-diminishing or non-clumped)... if the particle has attached itself to the pad or it is rolling between the pad and paint, it makes a difference. If the pad is apt to allow particles to attach to it or not, it makes a difference. If the abraded paint residue inherently ties or binds strings together or not, it makes a difference. If the pad generates a tremendous amount of heat via dragging action (increasing evaporation of buffing liquids, or causing gumminess, or advancing heat build-up in the paint), it makes a difference.

In my mind, if you're using ANY abrasive-laden compound, maximum cut is likely if the particle is traveling at maximum speed (the speed of the pad via attachment or scuttling). If abrasive particles and pads become overly-laden with paint residue, cutting speed and ability will diminish. If the goal is final-polishing, in my mind optimal polishing is accomplished if the abrasive particles can continuously roll about, cleansing themselves as they roll, adjusting positioning all the while.

Things get a bit complicated when we're dealing like a material such as microfiber, because in my mind I don't want the microfiber material to be inconsistently coated with abrasive. This is why I'll generally prime a fresh pad, them blow it clean using compressed air, or run the primed pad against a microfiber towel. The goal is to have every portion of every microfiber string coated with a single abrasive particle, so that the cut will be consistent in depth and width. I don't "work" or "jewel" the area. I cut it slow and steady, using consistent pressure, with an eye towards keeping the fibers planted but separated.

Knowing all of this, how do things differ when using larger, clumped abrasives versus small and non-clumped abrasives?

I suppose that for clumped abrasive to work optimally, they've got to continuously break down to their smallest point. Even if they don't, the pad being used will dictate the depth of cut to some degree. After all, if you were to fully coat a foam pad with clumped abrasives, then place the pad onto the paint surface, the larger particles would not automatically dig into the paint. Instead, they would push into the pad for the most part, correct? Once you started polishing, THEN you would likely see inconsistent cutting of the surface, which hopefully would end up consistently cut after the diminishing cycle had run its course.

In the end, do we even need abrasives to cut away paint if the pad can supply ample friction? I think I know where you'd stand on this idea; SVR15 Matt in Australia is a big proponent of using buffing liquids featuring no abrasive (claimed, I have no data on the subject), and you sell the same pads (or pads very similar) to the type he uses.

I've used Meguiar's Ultimate Paste Wax for cutting via random orbital and microfiber disc. Sure, I know that there's tremendous masking ability with this product, but nonetheless, I was able to eliminate some pretty serious scratching and haziness from a particularly finicky paint job. To confirm, I simply had to wax the area, then polish only a portion of it. Where I polished, no visible marring remained. Again... pretty confident that under all the wax, there was some micro-marring. But this paint was so finicky that it could not be stripped using diluted Glass Cleaner or IPA, otherwise etching would occur. Yup, ultra sensitive paint!

Polishing theories destroyed?

In the end, you are correct that tools, polishes, and pads make a difference, but I don't feel that there are any holes blasted through my "polishing theories". All along I've tried to be fair-minded when considering stroke size, machine speed and type, applied pressure, pad diameter & type, abrasive design, backing plates, and all sorts of other parameter, for several years now.

I will say that microfiber has offered up some interesting twists; whereas I basically considered foam pads to play second fiddle to them, the experience gained with the latest slough of large stroke machines has proven that foam can be a hero when paint cutting and polishing are accomplished at a rapid clip. These large stroke machines work quickly, and are for the moment at least... a blast to use.

I appreciate a good polishing conversation, CEE DOG.
Let's keep it up..! Great for autopia.org.

I hope others will chime in to keep the discussion rolling.

Paint polishing is a learned craft, not an art form.
Realizing this is the most important step one can make towards becoming a better paint polisher!

#18 Chris Larson

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Posted 11 November 2012 - 07:42 AM

Mine is on its way.

#19 Paul Sparks

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Posted 11 November 2012 - 09:03 AM

Just a couple of laymen questions 1. Is there a limit on the stroke of a da where it would be of no additional benefit ? How much stroke is considered the optimum for paint correction. 2. Will this stroke requirment change with the onslaught of new materials being brought out for da paint correction ? Denim ,rayon and the orange peel removal pads come to mind.
I have no idea how you find the time to research all of the information that you share with the detailing community plus your day to day detailing supply business and other numerous activities. I am very thankful you take the time to share with us your findings.
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#20 Kevin Brown

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Posted 11 November 2012 - 12:54 PM

Is there a limit on the stroke of a da where it would be of no additional benefit?

I think it comes down to whether or not the stroke is too large to reasonably use on a particular polishing project.

If the task at hand requires you to polish scratches from a rare pair of eyeglasses, and the lenses are not to be removed from the frames, we would likely not reach for a 21mm BigFoot with a 6" pad! If such a tool existed and you wanted to use it for this task, a 1mm-stroke random orbital outfitted with a 12mm diameter pad might be best. It would have to be a high RPM unit in order to generate an ample amount of random backing plate rotation.

If you had the need to polish the side of a cruise ship, I suppose a random orbital could be designed to be held by two guys; it might feature an ultra-lightweight chassis, use a 6-foot diameter pad and feature a 2-foot diameter stroke. This machine would require very low RPM capability (by comparison), as that amount of throw would create a LOT of centripetal force.

Then again... if you were hired to polish a very delicate antique trinket of some sort, you might not want to use a machine that featured a large stroke because if you happened to hook an edge or a protrusion, the object might be torn to pieces!

It's also important to realize that if held in place, a rotary machine focuses all of its polishing energy and motion onto an area the size of its buffing pad, whereas the random orbital can polish an area exceeding the pad size (dependent upon its stroke):

Posted Image

Why is this relevant? Well, if you happen to be polishing a car panel that requires a lot of edge work, and there's not a whole lot of paint thickness left on that panel, you'd really need to focus all of the polishing only on the exact areas needing polishing attention. In this case, a rotary machine might be the optimal machine. If not a rotary, then a small stroke random orbital would be the next best bet. A large stroke machine would only polish the outlying areas part of the time. I hope this makes sense.

How much stroke is considered the optimum for paint correction?

A lot could be written about this topic (I've written my fair share here). In short and other things being equal (everything about the machine except for its stroke, pad type and size, buffing liquid, machine speed, backing plate, applied pressure, etc.), some points to consider:

• A short stroke machine will focus its polishing energy onto a more confined area.
This has been covered, see above diagram.

• A short stroke machine will move everything attached to its backing plate mounting pad at a slower pace.
The RPM that it is spinning will remain the same, but since everything is whirling around along a smaller circular path, it'll be traveling at a slower rate of speed (MPH).

Posted Image

• A short stroke machine will create less centripetal force and consequently, less backing plate rotation.
Since everything mounted to the motor shaft (counterbalance, bearings, backing plate mounting spindle, backing plate, buffing pad) is moving at a slower rate of travel (just covered this point, see above diagram) it will create less rotational or centripetal force, consequently creating less backing plate rotation. Don't be confused: the motor speed will remain the same (remember, we are not changing any parameters other than stroke size, for simplicity sake), but random rotation will slow. This means that you'll not only see less rotation of the backing plate, but less measured speed of motion along the edge of the buffing pad. This means you may see a loss of cutting power along the edge of the pad.

• A short stroke machine will not maintain its backing plate rotation as well as a large stroke machine.
Since it's common to see manufacturers using lighter weight counterbalances with short stroke machines, there's less mass spinning along. So, if the buffing pad encounters an obstacle or added friction or pressure (causing drag), rotation of all the spinning parts will slow more rapidly. I noticed this exact thing happen while comparing two Mirka CEROS machines (5" and 6" machine 6mm diameter-stroke models). The only variable between the two units was the weight of the counterbalance (one optimized for the weight of a 5" backing plate, the other for a 6" backing plate). The difference was dramatic.

• A short stroke machine moves pads and buffing liquids less distance per rotation.
This is a big deal. With less motion per rotation comes less speed, less rolling about of abrasive particles, and less potential cleaning of the buffing pad, as particulate, debris, and paint residue are more apt to stay attached to or remain underneath the face of the pad. Anyone that has used the Rupes® LHR75 3" 15mm-diameter stroke Mini-Random Orbital can attest to the fact that foam pads stay cleaner longer, and very little scouring occurs (comapred to when a small stroke 3" machine is used).

Will this stroke requirment change with the onslaught of new materials being brought out for da paint correction (denim, rayon, and the orange peel removal pads come to mind)?

Large stroke machines tend to roll the edges of buffing pads under the pad itself. Use of a backing plate that supports the full width of the pad helps control this. If very tall or pliable pads are used, the outer edges will roll under more readily when using a large stroke machine. I've also noticed that very short or firm pads become "jittery" or "darty" as they glide along. Basically, there's not a lot of built in suspension travel if the pad is overly rigid or short. I think these issues could be controlled to a large degree by simply designing pads that have a rolled edge (or a backing plate that was curved upwards at its edge, and Velcro held the pads so that they rolled at the edge).

I have no idea how you find the time to research all of the information that you share with the detailing community plus your day to day detailing supply business and other numerous activities. I am very thankful you take the time to share with us your findings.

All I can say is thanks, and I hope it all makes sense.

Paint polishing is a learned craft, not an art form.
Realizing this is the most important step one can make towards becoming a better paint polisher!

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