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trouble hollowing

Discussion in 'Getting Started' started by Jake Truxal, Nov 28, 2009.

  1. Jake Truxal

    Jake Truxal

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    I'm working in a walnut bowl that is 9" in diameter and 9" tall, the bottom 5" are more of a pedastool so I only need to holllow about 4". I'm about an 1 1/2" deep now and the tailstock is preventing me from getting a good angle to cut with. If I remove the tailstock support the bowl is still too heavy for the jaws and if flies off the lathe. Good thing I have rubber matting on the floor in front of the lathe to stand on, it saved the bowl from shattering. The wood is green so alot of water weight too. Any suggestions?
     
  2. Jake Truxal

    Jake Truxal

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    p.s. the bowl currently weighs 9 lbs.
     
  3. odie

    odie

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    Panning for Montana gold, with Betsy, the mule!
  4. Owen Lowe

    Owen Lowe

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    I wonder about the method you're using to hold it in the chuck - and if your tools are truly sharp (so that you don't have to exert undue pressure to cut).

    Can you elaborate on the holding method?
     
  5. Jake Truxal

    Jake Truxal

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    it is in a Grizzly chuck (vicmarc knockoff) #3 Jaws. I should have mentioned, this is end grain, not face grain. Problem as a newbie I keep catching my spindle gouge and knocking it off the jaws. Gouge seems pretty sharp, just having trouble getting the angle with the tailstock in the way. I went to my flat scraper and making good progress cutting with the tip.
     
  6. Joe Greiner

    Joe Greiner

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    Are you using both hex sockets to tighten the chuck? There's enough frictional drag in scroll chucks to benefit by using both, until neither one tightens any further. Ditto with Jacobs chucks, a subject of perpetual debate.
     
  7. MichaelMouse

    MichaelMouse

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    End grain is normally done with scrapers for plunging, but can be done with cutting tools by turning the gouge edge 90 degrees to the handle as well. That's the principle behind hook and ring tools - or the ones that use metal-cutting inserts.

    Since your tailstock is superior in every way as a support compared to any steady, you want to try and keep it. Don't know if you have scrapers in your tool kit, but they'd do the job at some cost to your elbow. High sharpness angles require a lot of force.

    I have the luxury of many tools on hand, so I use a pointy grind gouge. The point doesn't skate when plunging, and the sides peel very well once the instability of the cylinder is over come by the support of the bevel.

    Here he is. http://i35.photobucket.com/albums/d160/GoodOnesGone/a63b77ab.jpg

    How he's used is to push in to bottom and pull out, with the edge peeling the face grain, just as if it were a spindle. Only difference is the edge is 90 degrees to the handle. Shaves with little pressure after some practice. http://i35.photobucket.com/albums/d160/GoodOnesGone/725a28f2.jpg

    He's quick, and you can see, even hogs fairly cleanly. The final smoothing passes will be less aggressive. http://i35.photobucket.com/albums/d160/GoodOnesGone/5fa71f2e.jpg He doesn't care if he's cutting on the right or the left side, so you can keep your pillar trimmed up square by pulling on his right side. I don't bother boring a hole in endgrain as many do, because the pointy shaves so well.

    Here's a hook tool in use. A ring is a closed hook, my pointy is a broad hook. http://www.aroundthewoods.com/hookuse.shtml
     
  8. john lucas

    john lucas AAW Forum Expert

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    I've turned bowls up to 19 " with my Vicmarc's and Grizzly knockoff. Do you have a shoulder on your tenon for the top of the chuck jaws to ride on. If you are only gripping a tenon the vibrations from hollowing will rock the piece back and forth which compresses the fibers and it will rock itself out of the chuck.
    The shoulders prevent the rocking. On green turnings it's also a good idea to stop every so often and tighten the chuck. Because it does compress the fibers of the wood it will get loose even with the shoulders on the tenon.
    Did you make a dovetail tenon? Ideally for the Vicmarc chuck you should have a dovetail tenon shorter than the jaws. This will allow the shoulder (which should be good and square) to ride on the top of the jaws.
    Hope this helps. I love my Vicmarc's. I've thought about getting the 5" Vicmarc but since I've been able to turn anything I've needed with the 3" model 100 It's just hard to justify.
     
  9. Jake Truxal

    Jake Truxal

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    Thanks to all for your input and suggestions. Sone additional detail in response to your questions below. Amazing how you pros are so willing to take the time to help us newbies. I long for the day when I get to anywhere near your level. THANKS!

    John,
    Yes, I have a shoulder on the tenon and a dovetail. It is green wood so stopping to tighten now and then is someting I'll try. (Joe, yes tightening with both hex sockets, at least I am now, not sure If I was when I started :confused:) I was figuring I just still had too much weight 8" away from the jaws to support without the tailstock?

    Odie,
    Yea, I was looking at the steady rest thread. Good Tip. I'll make one when I get a chance. (As soon as I finish the longworth chuck that has been laying around for 2 weeks waiting to have the grooves routed...)

    Mike, Not sure what you mean by:
    " Only difference is the edge is 90 degrees to the handle."
    The tool edge is obscured by all teh great shavings you are getting in the pic :) I think what you mean is what I ended up doing with my flat scraper, I found instead of using straight on and holding on a horizontal angle and cutting with the edge
    | |
    ==> |____|

    I can take off obout 1/32 - 1/16 at a time, slow and exhausting but the most consistent and catch free aproach so far. Can you use your "plunger gouge' with the tailstock still in place, I note a steady rest in your pics.
     
  10. MichaelMouse

    MichaelMouse

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    What you're doing is cutting with a high sharpness angle. Called scraping. The edge of the pointy gouge is ground so that it is facing straight up like a U, with the cutting happening at a lower sharpness angle. Takes some of the load off of you because of it, and with a bit of nose up it skews pulling out for a lower effective angle. A regular gouge features the edge at 90 degrees to the way we're cutting.

    If you've got a large pillar, and from what your dimensions were, it shouldn't require but an inch, you'll want to cut alongside and bottom it at what's called a negative sharpness angle. The turners call them negative rake scrapers.

    Sounds like you're turning today rather than framing and gluing up panels for Christmas bookcases. Wish I was turning, but promises are promises, and the recipient is my granddaughter.

    Grilled cheese and tea on board, back to the basement.
     
  11. Joe Greiner

    Joe Greiner

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    Pillar for tailstock

    To get maximum real estate, and keep the pillar, unlock the tailstock clamp and wind it forward; back off a couple turns and nudge the whole tailstock into the work. Then clamp and re-wind forward. Or, start that way at first.

    The pillar can taper down to the bottom of the bowl and still provide substantial support. By the time it doesn't, the bowl should be fairly well balanced.
     
  12. Jake Truxal

    Jake Truxal

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    I managed to finish hollowing the bowl with my scrapers. Then I went to retrue the outside (I left this for last since I kept knocking it off the chuck), and of course as I do on every project I did something stupid and thought "hey why dont I use this 1" skew that I have never used before to smooth the outside. long story short, the bowl is now 1 1/2" shorther than it started out...:(
     

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