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  1. #1

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    Hi guys, 1st time here.



    Ok, here is my problem. I have tar-like tacky stuff on my leather seats. Its the black stuff from Extreme Dynamat. Its not a whole lot, just little spots here and there. BTW, its a 2002 tundra.



    Also, my Oak colored leather seems to attract the dye from my blue jeans. So now, both the driver seat and passanger seat have a blue-ish tint to it. Whats the best way to handle my situation? I am trying to use product I can pick up locally. Thanks.

  2. #2
    Guest
    thats tough... Maybe mineral spirits?

  3. #3

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    In situations like this I whip out my trusty 3M Adhesive, Tar, and Wax remover. Available at most auto parts stores (although I found my last stash at WalMart). Use a soft cloth, test an area for colorfastnest (is that a word?), and go to town. Do a typical leather clean immediately afterwards.



    For good leather cleaners look at a few recent posts. For some odd reason leather care is a hot topic this week at the ol` Carport.
    There are only three things you need to know about me. Gloss, Gloss, GLOSS!!

  4. #4
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    Machine Stroke and How It Affects Sanding and Polishing Performance

    For quite some time I have been working on a paper about the innerworkings of the random orbital. While I have not had a whole lot of extra time this year to devote to completing it, I decided to post a modified portion of it. This section pertains to MACHINE STROKE, and how it may affect overall performance. I hope it is easy to understand and will help those that are interested in maximinzing the potential of their machine. For those of you on the fence regarding which machine to purchase next, perhaps this article will help you decide.



    Machine stroke is a term that identifies the diameter of the path the backing plate travels as it circumnavigates the driveshaft.
    Since the machine`s driveshaft is rarely level with the backing plate, machine stroke actually refers to the driveshaft axis and the backing plate or backing plate mounting spindle axis. The diagram below illustrates this point:





    Machine manufacturers also refer to machine offset, backing plate offset, stroke radius, and stroke diameter. Regardless the terminology, these terms are identifiers of the machine`s movement.


    To clarify:

    Machine offset or backing plate offset or stroke radius
    The distance between the driveshaft axis and the backing plate axis

    Machine stroke or stroke diameter
    The distance between the driveshaft axis and the backing plate axis multiplied by two

    A longer offset or stroke places the backing plate axis farther away from the driveshaft axis.



    If the machine`s driveshaft is rotated once, the backing plate shaft will travel around the driveshaft axis once, creating a perfect circular pattern. This motion is referred to as an orbit. Machine manufacturers often refer to operating speeds using "Orbits Per Minute" or an "OPM" rating. Some manufacturers refer to operating speeds using a "Revolutions Per Minute" or "RPM" rating. This is completely accurate, but can cause confusion because this rating is sometimes thought of as referring to the backing plate`s rotational speed. Since the backing plate rotates independently of the machine`s driveshaft (and does so at a random rate), an RPM rating can be confusing. The diagram below compares orbit speed to orbits per minute:





    A majority of random orbital machines use a stroke diameter that measures somewhere between 1/8" to 5/16" (approximately 3.0mm-8.0mm). It is generally accepted that a smaller stroke leaves a more refined finish, but reasoning and experience tell a different story. After all, if the sanding disc being utilized features consistently sized particles that are evenly placed and proper sanding techniques are used while sanding, a satisfactory result will be realized regardless the stroke. The diagram below illustrates this point:





    Factually, a small stroke machine does confine sanding to a smaller area. This means that for a given amount of time, sanding of any one point will be multiplied. If you plan on using the machine to sand or polish items diminutive in size, a small stroke machine is the way to go. A small stroke machine is also a great choice if you will be using the machine to work on small areas (such as touch-up jobs or similar tasks), or on confined areas that may limit machine movement. In addition, a small stroke machine is generally easier to control because the backing plate orbits around the driveshaft axis along a smaller circular path. This equates to less lateral motion of the machine as it is held in your hand (versus a similarly outfitted large stroke machine), and is therefore easier to grasp while the machine is in use.

    Otherwise, a machine featuring a large stroke delivers increased speed of backing plate motion using the same RPM setting. A large stroke also increases movement of the sanding disc, so "leveling" of the area is more consistent. Increased movement may help abraded residue more readily escape from between the disc and sanded surface, so consistent sanding results and extended life of the disc may be realized. The diagram below illustrates the differences between four of the most popular stroke sizes in relation to spindle speed:





    By now you may be wondering if a small stroke machine could deliver the best of both worlds by simply increasing the RPM of the machine. While this would likely increase random rotation of the backing plate, there would be several drawbacks. Most noticeable would be a decrease in user comfort, as the machine would be more difficult to control. Vibration would also increase, making the machine uncomfortable or unusable for users susceptible to fatigue. It is important to also note that since the backing plate would not have extended movement as would a long stroke machine, abraded residue and sanding debris (such as dislodged abrasive particles) might not clear away from beneath the sanding disc. The list goes on, but the most important issue that might occur due to an increase in RPM has to be a potential decrease in overall sanding performance. The following three diagrams illustrate this point:









    Keep in mind that in terms of leveling a large surface (one that is larger than the diameter of the pad), there is no denying that a large diameter disc will level that surface more consistently than a small diameter disc. Since this article pertains to machine stroke, how best to illustrate the performance differences between small and large stroke machines? A comparison of machine stroke to a typical handheld sanding block helps to illustrate the point:




    What Should You Consider Before Purchasing a Machine?

    There are five important factors to consider when choosing the ideal stroke size:

    Control of the Sanding Area
    Cushioning
    Centripetal Force
    Backing Plate Diameter
    User Comfort


    1. Control of the Sanding Area
    Controlling the size of the area being sanded is accomplished primarily by the user`s movement of the machine. The diameter of the sanding disc has an obvious effect, too. Finally, if the machine is held in place and throttled, a large stroke machine will sand a larger area than a small stroke machine. As an example, a machine touting a 3/32" diameter stroke outfitted with a 6" backing plate will effectively sand an area 6-3/32" in diameter, whereas an identical machine featuring a 5/16" diameter stroke will sand an area 6-5/16" in diameter. Although a 7/32" variance may seem trivial, it might not be considered as such if the 6" backing plate was swapped for a 3" backing plate.



    2. Cushioning
    If a majority of work is going to be done using interface pads for contouring purposes, or if a lot of paint polishing will be done using the machine, it is important to note that much of the machine`s motion could be affected due to cushioning from the interface or buffing pad. This is especially true if the machine is used at a high oscillation speed, as the time frame for the foam to react is dramatically shortened. Machines featuring a small stroke are certainly more susceptible to this occurrence, so this should be considered prior to purchasing a machine.



    3. Centripetal Force
    Be patient reading this section- it can be hard to comprehend.
    Before we discuss what centripetal force has to do with machine stroke size, it is important to understand what it is. Do not confuse centripetal force with centrifugal force- they are different! Centripetal force, loosely defined, is a "center seeking force". This means that any entity that causes another entity to form a circular pattern of motion is placing centripetal force upon that object.

    An easy to understand example of centripetal force has to do with a boy holding the end of string that has a ball attached to the other end. If the boy spins in place fast enough, the ball will take flight, and string tension will direct the ball in a circular pattern of motion. The boy, through string tension, is directing the ball in a centripetal manner. Ultimately, you could say that the string is placing centripetal force on the ball.

    What if the string is lengthened?
    Even if the boy spins at the same rate, the ball will be moving faster because it has to travel more distance in the same amount of time.

    What if the string breaks?
    The kinetic energy of the ball (the energy it has while in motion) immediately forces the ball away from the boy. This reaction is known as a reactive centrifugal force, often referred to as centrifugal force. Centrifugal force is not important for this discussion- it`s just good to know the difference. To increase kinetic energy, either mass or velocity must be increased. A-ha!

    What does all this have to do with stroke size?
    Quite a bit! If the stroke diameter is increased, all of the parts that are mounted to the backing plate spindle will travel at a faster rate of speed because they are traveling a longer distance in the same amount of time. The resultant speed increase also increases the development of kinetic energy. An increase in kinetic energy means that the backing plate (which is mounted to a free-spinning spindle and rotates at a random rate) will rotate more rapidly. Further, more resistance will be required to slow backing plate rotation.

    Bottom line:
    All other parameters being equal (machine, backing plate, disc or pad, sanding surface, applied pressure, and RPM setting), a long stroke machine will spin the backing plate faster or longer than a similarly equipped short stroke machine.



    4. Backing Plate Diameter
    Sanding discs are available in a wide variety of diameters, ranging from 1-1/4" to 12". For the most part, 3", 5", and 6" diameter discs are the most popular sizes. Woodworkers seem to favor 3" and 5" diameter discs, while 3" and 6" diameter discs seem to get the nod for automotive sanding duties. Regardless the job, common sense should be used when pairing specific disc sizes with small or large stroke machines.

    On the small side of the scale, 3" system (backing plate and sanding disc) would likely be used for spot jobs or tasks that require small diameter discs due to space limitations. Small diameter discs work well on complex or heavily contoured areas, too. While it is not unreasonable to use a large stroke machine with small diameter sanding discs (I personally use a 5/16" stroke machine quite a bit with 3" pads for the added centripetal force it creates), most times a small stroke machine is less unnerving to use because there is less side-to-side (or lateral) movement of the backing plate. Therefore, there is less likelihood that the backing plate will come into contact with surrounding parts or surfaces. If the machine is going to be used on surfaces that are not very wide (such as automotive A-pillars, stainless steel body trim, or thin strips of wood), then a small stroke machine will not be so apt to "ride off" the piece, possibly gouging an edge in the process.

    On the other end of the scale, a machine outfitted with a 6" sanding system (backing plate and sanding disc) benefits from a larger stroke if the surface area to be sanded is large, or substantial amounts of material needed to be removed. As previously discussed, increased movement of the backing plate allows abraded residue to more readily detach and then evacuate from the sanding disc, keeping it and the sanded surface clean. A small stroke machine outfitted with a 6" sanding system allows the user to strategically sand and "level" larger portions of a panel compared to a similar machine equipped with a 3" sanding system. An example when this might come in handy? A desire to remove of a long but gradual sag in a paint job without removing paint outside the edges of the sag. Parts or materials that cannot withstand lots of shaking due to lateral movement of the backing plate would benefit from the movements developed by a small stroke machine.



    5. User Comfort
    A short stroke machine does not move the backing plate as much as a large stroke machine. For users that are susceptible to discomfort due to high frequency vibration (such as when a machine is run at a high speed setting), the small stroke machine may cause more discomfort than a similarly equipped large stroke machine. For users that are susceptible to discomfort due to lateral motions (such as encountered when a machine wiggles back and forth due to the weight of the backing plate and items attached to it), a large stroke machine may cause more discomfort than a similarly equipped small stroke machine.


    In general:

    A machine featuring a 3/32" diameter stroke is optimal for sanding small parts, or for sanding areas that are hard to reach due to clearance restrictions. A small stroke machine works exceptionally well on delicate parts because lateral movement of the backing plate is minimized (thus delivering a gentler movement that a large stroke machine). Random rotation of the backing plate will generally be negligible unless the machine is set to a high speed setting (which can be a benefit or drawback, depending upon the situation).


    A machine featuring a 3/16" diameter stroke is ideal for most tasks because it delivers ample movement of the backing plate, but it can still be used in tight or confined areas without a problem. When used for polishing paint with buffing pads and liquids, a machine featuring a 3/16" diameter stroke will usually generate enough centripetal force to keep the backing plate and buffing pad rotating. Of course, a very tall pad will negate much of the machine`s motions.


    A machine featuring a 5/16" diameter stroke is the best choice if there is ample room to use the machine, and the machine is not used regularly on parts or surfaces that are not very wide.
    Kevin Brown
    NXTti Instructor, Meguiar`s/Ford SEMA Team, Meguiar`s Distributor/Retailer

  5. #5

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    Kevin - please pick up your PhD. at PAC immediately!

  6. #6

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    I just got done working 14 hours and you post this! Wow I was planning on going to bed about 15 minutes ago. LOL Kevin this is just another reason why you are a huge assest to our industry! Thanks for sharing your knowledge with us. As always another outstanding article. I will re-read it tomarrow. Its going to take time to comprehend all this. Your an insperation! :thumbup:
    In the words of Mr. T "I pitty the fool"

  7. #7
    Jedi Master
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    Quote Originally Posted by grungy View Post
    Kevin - please pick up your PhD. at PAC immediately!
    Will do. Thanks. :ar!

    Quote Originally Posted by bufferbarry View Post
    I just got done working 14 hours and you post this! Wow I was planning on going to bed about 15 minutes ago. LOL Kevin this is just another reason why you are a huge assest to our industry! Thanks for sharing your knowledge with us. As always another outstanding article. I will re-read it tomarrow. Its going to take time to comprehend all this. Your an insperation! :thumbup:
    Probably not much in there you haven`t already pondered, Barry. Thanks.:smile:
    Kevin Brown
    NXTti Instructor, Meguiar`s/Ford SEMA Team, Meguiar`s Distributor/Retailer

  8. #8
    El Presidente
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    Kevin, if you ever learn anything about polishing paint, you would be dangerous!!!!

    Thanks Kevin

    jk

  9. #9
    AMG Classic Car Detailing Old Pirate's Avatar
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    Wow, I have to frame this and post it near my desk for reference. I would like to thank you for your hard work, your great contributions and your awesome write up`s you do for everyone involved in the Car Care industry. :clap:
    AutopiaForums is the place to be.
    Remember to Shop Autopia-CarCare.com for your Detailing Needs!

  10. #10

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    Looking fwd to reading it again and again!

    Thanks KB!
    Bryan Burnworth - Atlanta Car Detailing - Peachstate Detail LLC

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  11. #11
    bmw5541's Avatar
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    Quote Originally Posted by gmblack3 View Post
    Looking fwd to reading it again and again!

    Thanks KB!
    I agree. This is something that I will have to read a few times so I can comprehend it all. This is great information Kevin.

    Thanks for doing all the leg works for us all!
    Barry Schultz
    Detailed Elegance

  12. #12

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    Wow! :notworthy:

    Thanks for sharing this Kevin! Very well written and I also found easy to understand. That aid of the illustrations and analogies really helped visualize things too!


    You Rock! :thumbup:
    Rasky`s Auto Detailing

    Quote Originally Posted by Auto Concierge View Post
    That finish is "brill" (british slang for tightness) as in "BRILLIANT" great clarity and gloss!!.

  13. #13

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    Wow Kevin, that`s a load of great information. Good thing your write ups have lots of charts, graphs, pics, illustrations etc so I can understand them a little better.......and even then like some of the others I`ll have to read this probably a couple of times to comprehend it.
    Good work.

  14. #14
    imported_Flash Gordon's Avatar
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    All I can say is having A.D.D. + O.C.D. sucks. Makes life twice as difficult

  15. #15
    Jedi Master
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    Quote Originally Posted by Jack View Post
    Kevin, if you ever learn anything about polishing paint, you would be dangerous!!!!

    Thanks Kevin

    jk
    Who has time to polish paint with all the backed up computer work?! You are welcome, Sir Jack!

    Quote Originally Posted by zoomzoom mazda5 View Post
    Wow, I have to frame this and post it near my desk for reference. I would like to thank you for your hard work, your great contributions and your awesome write up`s you do for everyone involved in the Car Care industry. :clap:
    Wow, I really appreciate the acknowledgement!
    I have a PDF copy I can e-mail you... having trouble figuring out how to send it... 3.6 megabytes. ~X(
    Kevin Brown
    NXTti Instructor, Meguiar`s/Ford SEMA Team, Meguiar`s Distributor/Retailer

 

 
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