The Rupes BIGFOOT LHR 21E is heading to the USA!!!

C. Charles Hahn & gmblack3- Hey, thanks for the info on how the Rupes' 21mm stroke lets it cut better than the GG 6". Ah yes...I'm now vaguely remembering Kevin's other posts about that.



Any downside to it? I'm thinking about, say....finishing; my Cyclos finish out a bit better than my GG does, though it might be some user-related factor I haven't considered.
 
Accumulator said:
C. Charles Hahn & gmblack3- Hey, thanks for the info on how the Rupes' 21mm stroke lets it cut better than the GG 6". Ah yes...I'm now vaguely remembering Kevin's other posts about that.



Any downside to it? I'm thinking about, say....finishing; my Cyclos finish out a bit better than my GG does, though it might be some user-related factor I haven't considered.



They finished down very well at the NXTi class...and that was using MF pads and D300!!! :)



Only downside I could see was tight areas, but I have other tools for tacking those as I already do now.
 
Accumulator said:
C. Charles Hahn & gmblack3- Hey, thanks for the info on how the Rupes' 21mm stroke lets it cut better than the GG 6". Ah yes...I'm now vaguely remembering Kevin's other posts about that.



Any downside to it? I'm thinking about, say....finishing; my Cyclos finish out a bit better than my GG does, though it might be some user-related factor I haven't considered.



Well, Rupes makes both a 21mm and 15mm stroke version of the machine; I would imagine the 21mm is mainly intended to be used for the cutting/compounding stage, and the 15mm (or other smaller stroke machine) for better finishing.
 
RaskyR1- Ah, thanks for the "finishing down" observation.



Eh, I'd better get off this thread before I start thinking about yet another polisher!
 
Dave- the Rupes LHR 21E is a random orbital. It does not use any sort of mechanical or forced or driven rotation.



Charlie- In general and for the most part, a large stroke machine will cut faster AND finish better than a short stroke machine.



Certainly a short stroke machine could be made to deliver a similar cut and finish result, but barring modifications to the machine (which might clean the pad as it worked, or exchanged the compound via a slurry & pump system), most of the advances would come via methodology changes. Diligent cleaning of the pad and compound could be the equalizer; However, the time spent to keep the working area clean would certainly be some sort of commitment.



This is a large topic to cover, which is why I wrote this article quite some time ago (way before any of us even heard of a Rupes BigFoot):



Machine Stroke - How it Affects Sanding and Polishing Performance



I could write a massive post about large stroke machines, but most of it is covered in the above listed article. Here are the benefits I could think of right now, as I write, without listing the reasoning (feel free to read the article or call me for the info, if needed).



All other things being equal (machine, backing plate, buffing pad and liquid)... a large stroke machine will:



• Create more centripetal force. What does this mean in the real world?

The backing plate will spin more rapidly (and it will be more difficult to slow the rotational speed because large stroke machines usually have heavier rotating assemblies)



• Power through resistances more easily (such as paint, surface oxidation & contaminants, uneven or scratched surfaces, panel contours, drag caused by abrasive compounds, etc.)



• Keep pads cleaner (particularly foam pads), as they do not have an ability to become tied or knotted or clumped together the way fibrous pads might (wool, microfinger, microfiber, felt, etc.)



• Deliver a smoother polishing pattern, especially at the curlicue transition point



• Keep compounds and polishes moving at a more rapid pace per revolution



• Essentially do more "work" per revolution, which means that machine speed can either be lowered to achieve the same result (thus potentially increasing user comfort), or more work can be accomplished in the same period of time, or the pad can be used longer before it "loads up" and requires cleaning



• Allow you to use a larger diameter pad and achieve similar or better performance than you might see when using a smaller diameter pad on a typical 8mm diameter stroke random orbital ("performance"= cutting speed, finishing ability, user comfort, etc.)






Use a short stroke machine:



• When you are working on items that may be fragile, such as delicate or thin or old objects



• When you wish to confine sanding or polishing to a very specific area



• When you are working in tight spaces or on small parts



• If the item you are working on benefits from a minimum amount of backing plate rotation
 
From the Rupes website about the Bigfoot: "The antispinning feature prevents the high speed rotations avoiding scratches"



What does this mean in practice? Does the pad spin or not? Is the spin kept down or eliminated completely?



Robert
 
WhyteWizard said:
From the Rupes website about the Bigfoot: "The antispinning feature prevents the high speed rotations avoiding scratches"



What does this mean in practice? Does the pad spin or not? Is the spin kept down or eliminated completely?



Robert





Does anyone have an answer to this? I can see some real advantages to not letting the pad spin, particularly if you want to use the machine - blasphemy follows - to remove polish. We could move the machine in a squeegee sort of pattern keeping the most contaminated edge moving into the polish and the least, or trailing edge just wiping up the residue. Of course, as the pad moves over the paint less and less residue will make it to the very far trailing edge.



So?



Robert
 
WhyteWizard said:
Does anyone have an answer to this? I can see some real advantages to not letting the pad spin, particularly if you want to use the machine - blasphemy follows - to remove polish. We could move the machine in a squeegee sort of pattern keeping the most contaminated edge moving into the polish and the least, or trailing edge just wiping up the residue. Of course, as the pad moves over the paint less and less residue will make it to the very far trailing edge.



So?



Robert



The pad still spins, and it spins well, but Rupes designed it to slow it down a little, which Kevin has a fix for. ;)
 
WhyteWizard said:
From the Rupes website about the Bigfoot: "The antispinning feature prevents the high speed rotations avoiding scratches" What does this mean in practice? Does the pad spin or not? Is the spin kept down or eliminated completely?



Robert



WhyteWizard said:
Does anyone have an answer to this? I can see some real advantages to not letting the pad spin, particularly if you want to use the machine - blasphemy follows - to remove polish. We could move the machine in a squeegee sort of pattern keeping the most contaminated edge moving into the polish and the least, or trailing edge just wiping up the residue. Of course, as the pad moves over the paint less and less residue will make it to the very far trailing edge.



So?



Robert





RaskyR1 said:
The pad still spins, and it spins well, but Rupes designed it to slow it down a little, which Kevin has a fix for. ;)



backing-plate-scrubs-speed2_zps0135a02d.jpg


 
Kevin Brown said:





Using the above mentioned modified Rupes 21mm machine right now(Well I am posting so technically Richie is using it on a Black M3) even at the slower machine speed setting the cut with D300 and a cutting microfiber disc is really quick, removing some serious defects from the finish.



Viva La KBM.....................
 
C. Charles Hahn said:
Well, Rupes makes both a 21mm and 15mm stroke version of the machine; I would imagine the 21mm is mainly intended to be used for the cutting/compounding stage, and the 15mm (or other smaller stroke machine) for better finishing.



This is my question. From what I have read, the 21mm would not finish as well as a smaller stroke.
 
WhyteWizard said:
A 50% increase in cutting as a result of letting the pad free float seems like a lot. Is there a way to test that? Can we have two machines set up to try side by side?



Robert



I should have said I saw a best guess of 50% increase in speed of cutting. Me.



Can't vouch for anyone else or how they buff.



One thing you've got to know Bob... If I write it I regards to theory, methodology, or polishing results, I was diligent in verification of my opinion.



Nothing to lose or gain by the claim, give it a try if you get your hands on a machine. All you need to do is try it as built, then add the spacer, try it again. Sometimes it takes a few back & forths to notice the difference.



For me, the difference was immediately apparent.
 
Kevin,



Awhile back I suggested a test of the actions of different machines. Trying to standardize for the actions and trying to keep everything else equal. Different people will of course get different results because of different skill levels and techniques. I, for example, almost never tape an edge because the way I work, the pads and backing plates I use, the way I vary speed and pressure based on the size of my contact patch makes taping no longer necessary. To someone watching it on video, it looks scary, in reality, the results speak for themselves.



The test I was suggesting goes like this.



I would put the backing plate of the machines on a scale and hold the machine in place, two fingers on the cord or back of the machine to keep it level, maybe a block of some sort to hold the non working end up. Then, add weights to the head of the machine - probably a bag filled with shot in the correct amount - to make sure all the machines had the same downforce.



Then, figure out a pad and an amount of product to use and run the machines, all flat out, for a given time taking the temperature of the panel before and after. My thinking is, the heat generated lets us know where the machines stand in terms of how much Friction/work is being generated.



This test wouldn't show which machine was necessarily best, because in practice, different people will get different results with each and someone who's very skilled with a random orbital might get a better result in less time than, for example, someone like me who uses two different machines and might be less skilled. I'll be at SEMA again this year but I'm not doing demonstrations so maybe I can drop by the 3D booth with my machines and we can collaborate. I would of course expect to use 3D products.



What do you think?



By the way, you should understand, I'm very interested in the machine, it looks great, I like the simplicity of the design, and I'm always looking for better, faster and easier ways to get work done. If I didn't think you could be helpful in that regard I wouldn't be talking with you.



Robert
 
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