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Finishing cuts/scrapes

Discussion in 'Getting Started' started by Kyle Waugh, Apr 21, 2020.

  1. Kyle Waugh

    Kyle Waugh

    Joined:
    Feb 15, 2020
    Messages:
    2
    Location (City & State):
    Greeley, CO
    I have been turning for about 1 year. I am just now deciding I have been sanding too much and need to improve my finishing cuts and scrapes.
    Yesterday I turned a dry piece of elm into a hollow form shape on the outside. It was chucked with a woodworm screw and tail stock support. I had a lot of end grain torn grain and tried to improve this before I ever turned the piece around to work on the inside. The chuck was never moved/changed.
    Using fine cuts with a 3/8 inch gouge, scrapes with the same gouge and with a negative rake scraper I still could not get rid of the torn grain. I seem to have a very fine vibration on the piece of wood- almost like it is out of round. The tools get a very slight bounce off of the wood. Why would this happen?
    I just cut the wood so it is round. The wood is dry so I do not think it is moving. The piece is not even close too being to big for the lathe. I do not feel a vibration off of the lathe itself. Again, I did not rechuck.

    Kyle
     
  2. Robert D Evans

    Robert D Evans

    Joined:
    Jan 31, 2020
    Messages:
    122
    Location (City & State):
    Hoschton, GA
    You may think the wood is dry but in reality, when you removed the center, stresses were relieved and it started moving. There are also several other things that could be in play. The wood could have different moisture content (weight) from one side to the other.

    Also, a woodworm screw is not my choice for holding a piece for finish turning. I only use a woodworm screw to hold a smaller rough bowl blank long enough to get a tenon on it and then mount the wood in a chuck. Bigger bowl blanks get a faceplate.

    Lathe speed and tool sharpness could also be a factor.

    Some wood is just punky and hard to get a good finish cut on. Especially end grain. Get it close and then put several coats of sanding sealer on it. Let it dry and then do your finish cuts. The sanding sealer will stiffen up the grain and allow for a better finish cut.

    And some wood is just possessed and destined for the wood stove.
     
  3. robo hippy

    robo hippy

    Joined:
    Aug 14, 2007
    Messages:
    2,853
    Location (City & State):
    Eugene, OR
    My first suspect would be the wood worm screw. End grain pieces, like most hollow forms, are generally mounted on a face plate or in a chuck. These methods are far more secure than the worm screw. For the screw to work best, the surface needs to be dead flat, otherwise, the piece will rock and wobble. One side note here, screws and nails into end grain want to split the wood more than they want to grip the wood. If using a face plate, angle the screws, which in framing is called toe nailing.

    Other than that, the surface for less sanding usually requires lots of practice to learn proper technique, and sharp tools. Find a club. Clubs have mentors, and you can't beat a hands on session.

    robo hippy
     
  4. Kyle Waugh

    Kyle Waugh

    Joined:
    Feb 15, 2020
    Messages:
    2
    Location (City & State):
    Greeley, CO
    It is a face grain piece/bowl blank. I call it a hollow form but it is somewhere between that and a bowl. I have not hollowed it yet. I was trying to finish the outside as best I could before hollowing. So, sounds like I will go ahead and turn it around, put the tenon in a chuck and try again to smooth the outside. I suspect it will be a little out of round then and I will have to cut some more. Sanding sealer is an interesting idea.
    Robo- I am a big fan. Your videos have been very educational and inspiring.

    Kyle
     
  5. Arkriver

    Arkriver

    Joined:
    Jan 18, 2006
    Messages:
    92
    Location (City & State):
    Pueblo West, CO
    We are lacking a lot of info to really help you. What size is it. You are using a 3/8 gouge. I hope it is bowl gouge. That size bowl gouge will give you more vibration the a 5/8 gouge. If you can slip a piece of paper between the chuck jaws and the wood at just one point you will introduce vibration and of course if you have a 12in bowl and are using 2 jaws you need bigger jaws if not a bigger chuck. Lot of things to think about. I have not found elm to be very difficult to turn. Allyn
     
  6. hockenbery

    hockenbery AAW Advisor Staff Member

    Joined:
    Apr 27, 2004
    Messages:
    6,478
    Location (City & State):
    Lakeland, Florida
    Home Page:
    It is not possible to see what you are doing wrong.

    Could be problems with the directions in which you must cut the shape.
    Try doing a hemisphere shaped bowl so that the proper cut is from foot to rim in the direction of the rim. With a Hollow form shapes cuts need to be made along the curves from small diameter to large diameter. Something to tackle after you succeed on the hemispheric bowl.

    Float the bevel, cut toward the headstock not perpendicular to the ways.

    In demos I do a slow motion of the proper cut. The 3 rpm cut showing the cut while I rotate the bowl by hand.
    Fast forward to 10:00 it the video below to see this. Note the direction of cut.

    View: https://www.youtube.com/watch?v=Lo0bGSafZq4
     
    Last edited: Apr 21, 2020
    Mark Hepburn and Bill Boehme like this.
  7. Bill Boehme

    Bill Boehme Administrator Staff Member

    Joined:
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    Pictures would be a tremendous help, especially a detailed close up shot that focuses on how the piece of wood is mounted on the chuck. Rotate the piece around to get at least three views showing the chuck jaws mating against the wood. The reason that I would like to see this is that I am speculating that there might not be solid contact between jaws and wood all the way around which would allow wobble or vibration.

    Another wild guess is that the problem could be related to tool control and/or sharpness. We can't feel the sharpness of your tool (bowl gouge or spindle gouge?) or see if you've been using the gouge with the bevel rubbing to get shavings (as opposed to scraping with it and getting dust and chips). but when things get back to normal it would be beneficial to connect with a mentor. Here is a list of mentors in the Rocky Mountain Woodturners that meets in Loveland.
     
    Mark Hepburn likes this.

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