More is better? Amps - Watts - Volts and Rupes Polishers

[Mike PhillipsMike Phillips is verified member.]

More is better? Amps - Watts - Volts and Rupes Polishers


On page 8 of the below thread the discussion turns to a talk about Amps & Watts as it relates to more powerful tools.


SEMA Release of Rupes - Page 8


I'm not an electrical engineer and don't care to become one and I also don't have the time or inclination to solve the issue of whether more is better when it comes to power tool.

That said, in Post #85 of the above thread I did say I would share what Marco D'Inca told me at SEMA on the topic of trying to determine the correction power of a tool by simply or only going by the tools rated power needs as rated by Amps and Watts.

And to preface this discussion, my Auto Shop Teacher in High School tried his hardest to explain this to our class using some weird Dirt Bike jumping over a ditch analogy and his explanation didn't help back then and I still don't know what he was talking about even to today.


Here's what Marco said and this of course is a paraphrase and I'll use a picture below to try to help make the point.



Marco said,

The amount of amps or watts a tool uses does not automatically equate to the efficiency of the tool.




Let's look at that again,

The amount of amps or watts a tool uses does not automatically equate to the efficiency of the tool.





Then he used a miles per gallon analogy with cars to explain tool efficiency which I found easier to understand than the dirt bikes jumping a ditch analogy my high school shop teacher tried to use with the class.


If you have two cars and one is large and has a big powerful engine and one is small and has a smaller, more efficient engine, the smaller car will go further on a gallon of gas than the larger vehicle.

For the owner of the larger vehicle to tout that their car uses more gas to go the same distance or for one tool to use more power to do the same work is not a benefit. It's s sign of an inefficient motor.

At least that's how I remember the conversation and keep in mind, it's very busy when working inside a booth at a show like SEMA.


Now here's the picture, Nick's car can go further on a gallon of gas than my truck.

I think what Marco is saying is that he can get his tools to do the same type of work without having to use as much power as the design of electrical motors in other tools.

Or Nick and I can travel certain number of miles down the road but Nick can arrive at the same destination, going the same speed but he won't need as much gas or power as I will.

Don't know if that helps or hurts but I said I would post what was explained to me at SEMA and I kept my word.

You guys can hash out the electrical details...

Hey Nick? Want to race?

 

[FUNX650]

Thanks for sharing this information.
Makes perfectly good sense to me.

(Question to self):
Would Nick's: Little Car..."out-pull"...Mike's: BIG TRUCK?



Bob

 

[JSou]

Makes perfect sense to me.

 

[c8n]

All I can say is that you will be able to load more pizza pies in Mike's truck which I am sure Ray will be happy about.

 

[Rsurfer]

I understand the point being made. However, if you Mike wanted to get there faster, would you not have the power to do so?

 

[Squiigii]

I am a certified electrician. The best way to explain electricity or current is by examining a water hose. When the water is on and flowing out the hose there is 0 resistance or pressure. This is the current. By putting your thumb over the opening, causing the pressure or resistance to increase. This is called amps.
A polisher running at full speed touching nothing has 0 resistance, but as soon as it touches an object to polish increases resistance, therefore needing to work harder to spin. Hope this helps.

Sent from my Prism II using AG Online

 

[swanicyouth]

I understand the point as well. But, you have to realize the engineers designing these machines are all striving for the most efficient use of power. The machines are constructed of similar materials and the drive mechanisms are similar. While efficiency of machines is not equal, I think its pretty fair to say the power consumption can give you a BALLPARK idea of how well a DA machine can spin a pad on a complex panel, instead of bogging down.

Of course, similar efficiency and design does not mean they are the same. Larger stroke machines, like the Rupes, likely have more correction power do to there large stroke. However, it's no secret that people have reported the Rupes 15/21 bogging down on complex/concave panels - panels that a machine like a Griots Garage 6" has no problem spinning a pad on.

I have both machines (GG6 & Rupes 15) and I can tell you the GG6 pad is almost impossible to stop spinning during normal use on higher speeds. On the other hand, the 15 can take some tweaking to keep the pad spinning on complex panels.

So if none of these numbers matter, to me that would mean that by some act of serendipity the engineers of the GG6 created a machine that has a ton of pad spinning power that just coincidently draws more current than all other free spindle DA that I know of - the GG6.

You can't create power from nothing. A quality DA machine that draws 4 amps and 500 watts LIKELY isn't going to be able to spin a pad better than a quality DA machine that draws 7 amps and 850 watts. Sorry, I don't believe it's likely.

Just like if you had two light bulbs of similar construction and build materials, both engineered for peak efficiency and one is a 25 watt bulb and another 50 watt bulb. It's likely the 50 watt bulb will be brighter. That analogy isn't perfect, I know. But neither is comparing an older, heavier, RWD truck with huge wheels and tires to a newer compact FWD car. When we are comparing these machines, we are comparing machines of similar size, drive mechanisms, weight, and construction.

But I understand the point and do feel the Rupes machines and products are very good.

 

[swanicyouth]

I am a certified electrician. The best way to explain electricity or current is by examining a water hose. When the water is on and flowing out the hose there is 0 resistance or pressure. This is the current. By putting your thumb over the opening, causing the pressure or resistance to increase. This is called amps.

I'm not an electrician, but I know resistance in a circuit is ohms. Amperes (amps) is the AMOUNT of current (electrons) that passes through a circuit over a certain time, not adding resistance to a circuit.

 

[2old2change]

It sort of boils down to the fact if you want a large stroke Rupes machine , buy one. If not the all the discussion in the world won't change your mind. This poor horse has been beaten so bad I thought it was a dust pile.

 

[SR99]

I pulled together some info that may help this discussion. To review, the "Dual Action" of a DA polisher refers to:

Action #1: the orbital motion of the motor driveshaft driving the offset spindle assembly (this leads to the OPM (Orbits Per Minute) specification, and it typically can be selected by the user via a control dial to cover a range of OPM's (e.g. 2500-6800 OPM for the GG6)).

And

Action #2: the rotation of the pad via the free-spinning bearing that is part of the offset spindle assembly (I called this assembly the "orbital assembly" in the photo below, but there are different names for it). During operation this Action #2 is typically 1-3 pad rotations per second, but could be as low as zero under load/friction, and quite a bit higher on some DA's especially if free-spinning in air. Manufacturers do not specify this, since it is affected by the usage conditions (e.g. applied pressure, panel contours, pad and liquid choice). It is not directly driven by the motor (there is no electrical connection to Action #2; it's a bearing-mounted spindle so it doesn't require electrical power).

To give some perspective on the motions in the machine, here are some photos of a PC7424 with the backing plate and counterweight removed. You can see the free-spinning part (the nut on the "orbital assembly," annotated in red) which is surrounded by a bearing. The backing plate screws into this nut. The rest of the "orbital assembly" is fixed together, and moves as a unit (independent of the free-spinning nut), driven by the motor driveshaft, but at an offset to it (the offset is the "throw radius," which is 1/2 the often quoted throw "diameter," and is annotated in purple).

The outer shroud (see the orange annotation in the photo above) gives a frame of reference for the motor drive shaft. It would be centered within this circular shroud, and is shown as a small orange circle in the photo, just as a reference, since it is buried a layer below and you cannot see it.

You can turn the orbital assembly with your hand to see how it is linked to motor rotation as it orbits the drive shaft. You can also move the free-spinning bearing to see that its rotation is independent of the orbital motion and motor.

I drew alignment marks with a silver Sharpie so you can follow what moves from photo to photo below. The free-rotating spindle, the bearing, and the offset/orbital assembly are all aligned the same direction in the first photo. As the motor drive shaft turns the "orbital assembly" moves in an orbit around the drive shaft.

The 4 photos below show the orbital assembly moving 1/4 turn counter-clockwise in each successive photo (note the position of the silver marks), to show a full turn of the orbital assembly. Note the nut for the free-rotating spindle is in the same location in all photos (just showing that its movement is independent of the orbital motion).

And the next step (photo not shown) would be another 1/4 turn to complete a full turn of the orbital assembly (it would look the same as the first photo). If the motor were set at 3000 OPM via the speed dial, the orbital assembly would make 3000 of these full turns in one minute. The free-rotating spindle (and the backing plate/pad, when attached) may or may not rotate at all, depending on e.g. applied pressure/friction.



To summarize:

Action #1 (orbital motion) is motor-driven. Action #2 (free rotation) is not.

Action #2 can be stopped completely, with the motor continuing to drive the orbital motion (Action #1) while consuming full power (or whatever power setting the user has set)). In that case it then essentially becomes a "Single Action" machine (orbital motion only).

There is no rotation of the backing plate/pad if there is no motor-driven orbital motion first. The orbital motion induces (via centripetal force) the rotation of a pad attached to the free-rotating spindle. The pad rotation can be slowed or stopped when the applied pressure/friction counteracts the centripetal force.


So to say this more simply, the free-rotating "Action #2" component of the Dual Action happens because of physics (centripetal force), not electricity.


For the record, I've measured the AC power consumption of my GG6, and under heavy load it tops out at about 540 watts. At the same max speed selection but no load, it measures about 470 Watts. At the lowest speed setting on the dial, it measures about 140 watts unloaded and 165 watts loaded.

Maybe the 850 watt number in the GG6 specification sheet is derived from the peak inrush current on motor start-up or mechanically-induced stall; don't know. Vacuum cleaner manufacturers publish those sorts of non-operational measurements of power to win the "horsepower wars," so it's not unprecedented.


I don't suppose the information above is going to sway the "flat earth society" that wants to believe the AC power consumption figure can be used for some meaningful machine comparison, but hopefully others found this helpful, and will just ignore that number when making comparisons.

There's just no concrete or reliable, quantitative use for that number, so it's a waste of your time trying to force it to be something it's not. As noted above, the claimed power consumption numbers are questionable anyway.

Another thing worth noting:

Not everyone even uses the max orbital speed setting on DA's, and some well-respected detailers I know use their Rupes 21 at around the 3.5-4.5 setting when correcting paint. In that case the motor is operating well below its maximums anyway.

 

[Mike PhillipsMike Phillips is verified member.]

It sort of boils down to the fact if you want a large stroke Rupes machine , buy one. If not the all the discussion in the world won't change your mind. This poor horse has been beaten so bad I thought it was a dust pile.

Wel said Paul The thing is though, forums invite discussion from all points of view. As long as they are polite and repsectful then it's all good...

I pulled together some info that may help this discussion. To review, the "Dual Action" of a DA polisher refers to:


I don't suppose the information above is going to sway the "flat earth society" that wants to believe the AC power consumption figure can be used for some meaningful machine comparison, but hopefully others found this helpful, and will just ignore that number when making comparisons.

There's just no concrete or reliable, quantitative use for that number, so it's a waste of your time trying to force it to be something it's not. As noted above, the claimed power consumption numbers are questionable anyway.

Not everyone even uses the max orbital speed setting on DA's, and some well-respected detailers I know use their Rupes 21 at around the 3.5-4.5 setting when correcting paint. In that case the motor is operating well below its maximums anyway.

All good information and great photography work...


Me? Whatever the tool I'm using, I just make sure I'm getting good results during my Test Spot... then get to work.

I never spend much time on trying to figure out the technical stuff as to why my polisher is enabling me to get good results.

 

[Pinpoint_Precision]

Great point Mike. I would love to get the Rupes machine in the future but for now I will just wait until the time is right. So let me get this straight, the Rupes ( hyper machine ) that's what I call it, it's like for me the
Nissan GT-R which not only is well built and fast for a big and heavy car but also it can beat porsches and ferraris on a heart beat? pretty much what I am trying to say is this .
Rupes is a more well balanced machine all around unlike others, is that correct Mike?

Now of course with wrong techniques and products, I don't care how good the machine is, you won't get the results.

I like my flex3401 and it does wonders, I just don't want to jump into something which I can get the same results.



sorry my english is slow. lol

 

[Mike PhillipsMike Phillips is verified member.]

pretty much what I am trying to say is this .

Rupes is a more well balanced machine all around unlike others, is that correct Mike?

Franscisco, you need to peel away from work this Thursday with your wife's blessings of course and come to Autoeek and test these cool new tools out yourself...

How to detail a Muscle Car Class



Terry's Mean 1956 Chevy Bel Air!

Come on... you'll have a great time!



:dblthumb2:

 

[Pinpoint_Precision]

You are killing me Mike. Hopefully I can get done with work sooner then for sure I will start heading over there. It's kind of a long drive.