Bowl steady tips?

Discussion in 'Woodturning Discussion Forum' started by Zach LaPerriere, Jan 23, 2017.

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  1. odie

    odie

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    There are only three possible scenarios where the OBS wheels will run true and without interference with various issues resulting from the rubber wheels compressing on the surface of your bowl: Anywhere along a parallel line to the spindle.....and with convex and concave surfaces, only a single point where it will intersect perpendicularly with a parallel line to the spindle, at only one single point. Ideally, these are the theoretical points where the OBS wheels should be located for best results, and should be maintained as close as possible.
    IMG_2534.JPG
    At the moment, I only have one real world example of a convex, or concave surface where it illustrates the point where the OBS wheels should be located for best results. The photo illustrates where the wheels should be positioned on a concave surface, similar to the middle example in the above drawing. Note that the further the distance from the spindle to the outermost point of the bowl rim, the more tendency to vibrate.....so that should be taken into consideration when positioning the wheels. This is the point where the wheels will run as true as can be had, and will have the most influence on dampening any vibrations. (In the photo, if the wheels were positioned just to the right and on the very narrow parallel surface of the rim.....that would also be a good place to position the wheels.)
    IMG_2532.JPG
    This all brings to the forefront another incongruity, which is not consistent with what is logical.......specifically because the width of the scissor arms themselves results with the two wheels not running true to one another. In order to solve this problem I have made up a special jig for positioning the two wheels so that they are running true to one another:
    IMG_2527.JPG
    In this photo below, it shows that longer bolts have been substituted for the shorter bolts that came with the OBS as supplied by the manufacturer. This substitution allows for multiple washers positioned strategically.....with the specific purpose of bringing the two wheels in perfect alignment with each other.
    IMG_2530.JPG
    There is an ascribed line on the jig that allows you to see exactly where the wheels make contact, and align with each other. Use this visual indication to add and subtract washers to accomplish the goal of both wheels running in alignment with each other, as close as possible.
    IMG_2528.JPG

    ko = burning the midnight oil.....! :rolleyes:
     
    Last edited: Jan 28, 2017
  2. Doug Rasmussen

    Doug Rasmussen

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    Interesting thread....

    If chatter is the main concern in using various steadying methods there may be another way to help with the chatter. Automotive machine shops that surface brake drums wrap a giant rubber band around the outside of the drum to dampen chatter. I've only tried it on a small diameter bowl with thin walls and it helped quite a bit.
     
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  3. Mike Johnson

    Mike Johnson

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    Funny you bring up rubber bands, I was considering heavy gauge o-rings wrapped around a guide pulley
    on several sides of the ways encompassing the item being turned. With 3 or 4 of these equally spaced around the billet you would provide support for the billet and it would be easier to apply and remove the "rubber bands"
    from the billet. Adjusting inline skate wheels around the billet can be a pain sometimes trying to get them
    adjusted for the diameter of the billet and equal pressure from each wheel on the billet.

    I can see where a large diameter rubber band would work on a thin walled vessel when turning. Rubber inner tubes are a cheap and easy way of finding the different diameters needed for wood turners needs. These also
    work nice when putting segmented rings together.
     
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  4. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Rockler Hardware used to sell bags of large rubber bands that we're about 3/4" wide, very thick and different diameters. Originally I used them for holding glue ups, but then discovered that they were also useful to wrap around hollow forms to help dampen vibrations. I don't know if they are still available, but my local store was getting rid of them.
     
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  5. odie

    odie

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    I have modified the profile of the OBS wheels into a "V" shape, so that the original "fat balloon tire" shape didn't interfere with some shapes I've been using......such as this one:
    IMG_2532.JPG
    If I hadn't reshaped the wheel profile, I couldn't have snugged up so close to the flared rim. Because of this, the rubber on the tip of the "V" seems to have been altered in how "spongy" the wheel surface is (because it's less wide). This may have led to better results with eliminating vibrations overall. Anyway, I'm not completely sure of that, and regardless, the "V" shaped wheels are more suitable to negotiate more intricate bowl shapes.

    The wheels are easily altered by using a 60gt sanding disc while the wheel is spinning against the wheel spacing jig I mentioned in the last post.....like so:
    IMG_2531.JPG

    ko
     
    Last edited: Jan 29, 2017
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  6. Leo Van Der Loo

    Leo Van Der Loo

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    The nice thing about using my single wheel when set at center height, it can be set at any angle to flat concave or convex surface, even when not at right angles with them.
     
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  7. Zach LaPerriere

    Zach LaPerriere

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    So far I've managed to avoid pulling out my steady rest on most thinner bowls since starting this thread. I improvised on Bill's idea about the leather gloves. Since I can't stand wearing gloves, I've been sanding the outside of the bowl to 4-600 before finish cuts on the interior.

    The rubber band idea is interesting. Part of the reason it seems we get vibration in thin forms is from the varying densities of wood between side grain and end grain.

    Great thread, everyone. Thanks for all the ideas, especially you, Odie—you've really gone the distance here.
     
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  8. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Should we make Odie an honorary member of the herd for his contributions. :)
     
  9. odie

    odie

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    OK, Bill......you made me LOL......! :D
     
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  10. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Moo. Moo-o-o-ooo! :D That's the secret herd password
     
  11. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Zach, I found these pictures taken on the last basket illusion piece that I did. They don't show me gripping both sides with the glove while beading, but you kind of get the idea of what I was doing with the gloves here to dampen the vibrations while cleaning up the surface with a scraper.

    Celebration Basket2.jpg

    And the view from the other side.

    Celebration Basket5.jpg

    Why buy a new face seal for your respirator when you can use tape. I was out of duct tape so I had to make a substitution.
     
  12. Zach LaPerriere

    Zach LaPerriere

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    Thanks for the photos, Bill. Worth at least 2,000 words! :D That's a heck of a nice profile on the piece you're turning. Just right.

    Yes, that left thumb is vital for guiding your tool into the bowl, especially with a gouge of course. I'd always done that with no glove, but you inspired me to sand the outside of the bowl first. Much better control and feeling, and not quite as warm.

    I come from a long line of men who just never felt right wearing gloves. My dad was a journeyman machinist...heck even for welding, he never wore gloves. I make an exception when commercial fishing, but that doesn't mean I like it!

    And nothing wrong with blue tape... I hear it's all the rage, now that everyone has run out of room for tattoos and piercings. :)
     
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  13. Zach LaPerriere

    Zach LaPerriere

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    If I can give myself permission to go further off topic, I just heard a great comment from Swedish turner Ulf Jannson over on Instagram.

    I mentioned that a bowl can be both beautiful to the eye and functional and still be a mediocre bowl—it needs to feel right in the hands.

    Ulf replied, just go read up on the cortical sensory homunculous for the answer why. I had forgotten all about the crazy looking illustration of the man with giant hands and big lips. The short version of homunculous is that our hands take up a large percentage of brain real estate.

    I'll venture to say that's a big part of why we love to work with our hands...that tactile feel, especially of turned objects. It says a lot about why a finished bowl or other turned object brings such satisfaction, even to those who aren't the turner. And it also answers in small part why gloves drive me crazy.

    Boy, that's a long way from bowl steady tips...and yet, weight (and thickness) of a bowl is equally important to the feel of bowl.
     
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  14. Bill Boehme

    Bill Boehme Administrator Staff Member

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    I would rather burn some anamal's hide than my own and save my ability to appreciate feeling things with my hands for occasions where it isn't a destructive appreciation.
     
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  15. odie

    odie

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    That's ok, Zach......I've always been one who appreciates conversation with other turners on these AAW forums......no matter where the topic goes. There are those who maintain that threads MUST stay on topic, but that isn't like real life is. When engaged in a discussion, face to face, the topic nearly always shifts to tangents. The official policy on that is more appropriate for someone like Bill to comment on.....but, from my point of view.....this isn't a formal gathering of woodturners........it's better as a casual interaction.

    To my thinking, if someone wants the subject to shift back to the main topic in a thread.......he needs to add some input to the thread, so that it does......! :p
     
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  16. Bill Boehme

    Bill Boehme Administrator Staff Member

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    I think that you summed it up quite well. Of course, we don't talk politics, religion, or hot rods ... and whatever else is liable to start an argument if it isn't woodturning related. Difference of opinion is to be expected when it comes to woodturning. Just recognize that other people's opinions are just as valid as your own ... or at least act like they are. The line between facts and opinions is sometimes rather fuzzy.
     
  17. Leo Van Der Loo

    Leo Van Der Loo

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    I totally agree with the notion that a bowl or HF can look very nice and yes you can use it as you like, but the moment you pick it up, that feeling of the wrong balance makes it a flop.

    Ok to bring this back on topic, It might not be because there was no steady used while making them, but o_O :confused: ;)

    I have had this happen on a couple of occasions that stand out for me, one was a very good looking Hollow Form, at someones house, then as I had to pick it up of course, found that whomever made this, didn’t bother to make the inside bottom anywhere near the thickness of the rest of the piece, it just felt so bad and heavy to me, and I will always remember that, mind you it will collect dust as well as any very nice and thin walled HF ;).

    Another one was a turner that came to one of our get togethers, and we would bring some of our pieces we made along for just showing them, one of them that had been making very nice bowls from a board, brought that time a bowl he turned from a normall bowl blank, looked good and finished nice, but as soon as I picked it up, it didn’t feel right at all, as it had way to much wood still in the bottom, it felt so unbalanced and clunky, even as it was a good looking bowl, so yes for me it needs to feel right, also if your fingers feel the wall of a bowl, and you notice the uneven thickness, it becomes a mediocre bowl, yes I’m picky :D
     
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  18. odie

    odie

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    There have been times when I've been able to increase the effectiveness of the OBS, by using several wraps of Renfrew hockey tape on the surface in prep for using the OBS. This is possible, because the hockey tape is similar to medical bandage tape, in that it's a thick cloth tape. The sticky portion of the hockey tape tends to transfer to the pores of the bowl itself, so in preparation for the hockey tape, the surface is first wrapped with blue painter's delicate surface masking tape.
    IMG_2567.JPG IMG_2568.JPG
    The delicate surface masking tape is laid down first:
    IMG_2569.JPG
    Then two complete wraps of the Renfrew hockey tape is laid down:
    IMG_2570.JPG
    I then use the spring pressure on the wheels against the tape and let it run for a minute. The result of this, is a little furrow is left in the tape where the wheels track. It tends to improve on an out-of-round condition by compressing more on the high spots, and less on the low spots.......get what is happening here?
    IMG_2571.JPG
    This procedure can sometimes improve the effectiveness of the OBS in reducing harmonic vibrations caused by the cutting action of lathe tool to wood. Anything that can help increase the fineness of the tooled surface prior to sanding is well worth the time to do it.

    Like any improvised techniques for the purpose, it sometimes works out beneficially, and sometimes it doesn't........but always well worth the effort when it does! :D

    ko
     
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  19. Bill Boehme

    Bill Boehme Administrator Staff Member

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    How were you able to determine that there were harmonics in addition to the fundamental vibration frequency?
     
  20. odie

    odie

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    I may have used words that have resulted in some confusion here, Bill.......Any felt vibration I'm assuming to be harmonic in nature, because it is resulting from interaction between tool and wood geometry. For the purposes of understanding what I meant, I'm not making distinctions between the origins, or types of vibrations.....only that it exists, and can be dampened.:D

    ko
     
    Last edited: Feb 2, 2017

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