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Thread: Chucking inside a recess

  1. #1
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    Chucking inside a recess

    I'm having difficulty getting my bowls to chuck true. I'm working on a large diameter walnut bowl and started with the flattest side on a faceplate. I trued that up and cut a recess to chuck it in and turned it around and loaded it in my chuck. Then I cut a recess on that side after beginning the outside form. Then I turned it around and tried to chuck it in that recess and just could not get it to run true. I tried for about half an hour, got discusted and called it a night.

    I learned recently that I was cutting my recesses too deep (thank you whoever posted that) so I made them about .250 or a little less. I was making them too deep where the outside of the jaws would bump against the piece, not realizing you're not supposed to do that.
    Would someone please try helping me figure out what I'm doing wrong? I tried many ways including using the tailstock gently pressing on it while I gradually tightened the chuck, sometimes rotating the piece just as it begins to grab.
    My chuck is a Oneway Stronghold.
    Thanks

  2. #2
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    I do not understand your process. I start all my bowls on a screw (the Nova Chuck screw). I then rough and finish the outside of the bowl (while doing this I have roughed in my tenon). The very last thing I do is take a finish cut on the tenon before turning it around and chucking it up in the chuck. The bowl runs very true but once the inside is done there is a little variation in the thickness of the bowl due to the removal of stock from the inside but not enough that I worry about it. If you have started on a face plate I would do the same but make a recess and the final cut would be the recess cut before tuning it around to chuck. I do use dovetailed jaws.

  3. #3
    I start all my bowls on a faceplate and, as Bill does, turn a tenon on the other, end. I much prefer a tenon over a recess. Since I'm using a faceplate I can attach my chuck (Oneway Talon) to the bowl while it is still on the faceplate and see how true it runs. Sometimes a little fine tuning of the tenon is needed but once it runs true I take off the faceplate and mount the chuck on the headstock and turn the inside.

  4. #4
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    As always, possible ways to proceed depend on several things: size, type of blank (rough chunk or plank?), green or dry wood, tools on hand, how perfect you want it to be.

    FWIW, I work basically the same way as Bill:

    - Mount the block on one end. If starting with a plank with mostly parallel sides I cut round on the bandsaw then most often use a screw chuck (Glaser) or turn a tenon on the lathe, or drill a recess with a Forstner bit. If a irregular chuck of wood I might flatten one side off the lathe for a screw chuck or a faceplate or flatten or cut a tenon between centers on the lathe for a chuck. This will be the top of the bowl.

    Then,
    - Mount the block with screw chuck, scroll chuck, or faceplate.
    - Flatten what will be the foot. Turn the outside of the bowl. Turn a tenon, recess, glue block, etc. to hold by the base.
    - Mount the base on the lathe and hollow the inside.

    Assuming this is dry wood, how perfectly round I want it to be the outside may need to be trued both before and after turning the inside. Before, due to slight irregularities in the wood at the point of mounting, and after due to to the wood moving by the hollowing. Wood almost always has internal stresses - hollowing can allow these stresses to relax and the wood will move. When I make a lidded box or bowl that requires a good lid fit I follow Raffan's advice and let the piece sit overnight after turning close to the final wall thickness. The next day it almost always requires truing. Green wood, of course, requires other methods. Just like from stresses, the wood can also move a little if there is residual moisture in the dry blank or as the newly exposed dry wood acclimates to the conditions in the shop.

    As for a trued blank not running perfectly true when turned around, there are several things I can think of that could be going on. One, every time a chuck is tightened in a recess or on a tenon the steel can press unevenly into the wood as it deforms it slightly. Some wood is worse than others. For example, if the jaws press more into one side than the other due to a softer spot there, the whole blank can be shifted or tilted slightly. Two, if there is any "fuzz" in the bottom of the recess (or a bit of sawdust) it can keep the jaws from contacting perfectly. This can even happen when mounting the chuck on the lathe! When mounting a chuck, Chris Ramsey, in a demo on turning a cowboy hat, made a point of first carefully cleaning any sawdust away from the contact points on the chuck on the lathe spindle. (And never use a fiber or plastic spindle washer! - they are notorious for causing problems)

    I usually don't worry about the outside being very slightly out of true with the inside unless the walls are very thin or I want to turn detail on or below the rim which will require touching the outside. In this case, I might true up just the upper part of the outside and blend the transition. I usually true twice or more: once after first mounting, again after hollowing the inside, and maybe again if the wood moves a bit after it sits on the lathe a while.

    Oh, another thing that can cause it to run out of true when chucked: the chuck jaws themselves may be slightly out of true. You can check this on tightened jaws with a dial indicator (turning the spindle by hand) but it may be different when the jaws are expanded. When machining some chuck jaws recently to make them absolutely true for precision work, I expanded the jaws into a ring I made to take up any play. This worked very well.

    JKJ

  5. #5
    This video by robohippy provides a wealth of information on chucking up bowls.

  6. #6
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    Quote Originally Posted by Bill Jobe View Post
    I'm having difficulty getting my bowls to chuck true. I'm working on a large diameter walnut bowl and started with the flattest side on a faceplate. I trued that up and cut a recess to chuck it in and turned it around and loaded it in my chuck. Then I cut a recess on that side after beginning the outside form. Then I turned it around and tried to chuck it in that recess and just could not get it to run true. I tried for about half an hour, got discusted and called it a night.

    I learned recently that I was cutting my recesses too deep (thank you whoever posted that) so I made them about .250 or a little less. I was making them too deep where the outside of the jaws would bump against the piece, not realizing you're not supposed to do that.
    Would someone please try helping me figure out what I'm doing wrong? I tried many ways including using the tailstock gently pressing on it while I gradually tightened the chuck, sometimes rotating the piece just as it begins to grab.
    My chuck is a Oneway Stronghold.
    Thanks
    Bill I do something similar to you, but don’t true turn the face, I do screw the faceplate to the side that will become the top of the bowl.

    I will then shape the bottom/outside of the bowl and make the recess, making sure it is nice and square and clean, you don’t want any slivers or bumps in the recess where the jaw faces have to sit against.

    If this is rough turning I will not sand and otherwise clean the piece, the next step is mounting on my chuck either Stronghold or Talon, depending the size I’m turning.

    You can hang the piece onto the chuck or set the chuck into the piece, either way don’t fasten real tight, just fasten enough so you can still change the position.

    I will set my toolrest close to the edge of the piece and rotate the piece by hand, watching carefully if the distance changes any, if it does, I mark the spot where it is closest and see if it is also on the opposite side, wood will do that sometimes, anyway you can move the pice now to get it turning true by adjusting, I often use a mallet or rotate the pice slightly, I will get it real close that way, where two sides wil just rub the toolrest with barely any difference for the rest of the rim.

    I have some pictures here to show.

    First mounted and outside turned while on the faceplate, then mounted on the Chuck.
    1 faceplate mounted.jpg 3Chuck mounted.jpg

    This is the recess used and the piece is rotating true as shown.
    Recess as used.jpg spinning true.jpg

    This is the piece rough turned, the recess gets trued if this was a bowl being returned before it is reversed and the inside finish turned.
    rough turned.jpg Trueing warped recess.jpg

    This is how clean you should try to get your recess before remounting from the faceplate to the chuck, also the last picture shows that a recess does not need to be deep, experience does help here though
    recess ready for finish turning.jpg shallow recess.jpg

    Hope this helps you get better results
    Have fun and take care

  7. #7
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    Bill - from my short experience doesn't sound like you are doing anything wrong. I was at a demo once and the demonstrator trued up the face of the chuck jaws with a wood turning tool! The four inserts were not very flat. I (maybe we) would have assumed this was flat from the factory. Could this be your issue?

    Mike

  8. #8
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    I don't think so, Mike.
    The problem I'm struggling is that I can't seem to get the piece true latteraly, not out of round. The piece wobbles but may not have much run-out on the edge.....I'm not getting the jaws set equally deep enough. I sand the recess very smooth but it's like I'm bumping against a surface that isn't true. I'm turning the recess shallow enough that the jaws don't touch the surface of the plane outside the recess.

    I'm a bit Leary of chucking on the outside. I figure if the piece comes out at least the chuck will not allow it to fly out if recessed.
    Perhaps I'll practice chucking on a tennon. Maybe my uneasiness will pass.

    This walnut was kiln dryed and has a moisture of about 8-8.5 but the last bowl I turned with it warped anyway.

    Thank you all for your suggestions.

  9. #9
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    Quote Originally Posted by Bill Jobe View Post
    ... I sand the recess very smooth but it's like I'm bumping against a surface that isn't true. ...

    This walnut was kiln dryed and has a moisture of about 8-8.5 but the last bowl I turned with it warped anyway.
    Yikes, I have never sanded a recess. I'm not sure I would recommend that since sanding notoriously causes unevenness in wood. Unless drilling with a Forstner bit I cut the recess then true up the outer edges and the contact ring on the bottom with a very sharp scraper (sharpened on the end and the side), slightly dovetailing if I feel like it.

    JKJ

  10. #10
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    Quote Originally Posted by John K Jordan View Post
    Yikes, I have never sanded a recess. I'm not sure I would recommend that since sanding notoriously causes unevenness in wood. Unless drilling with a Forstner bit I cut the recess then true up the outer edges and the contact ring on the bottom with a very sharp scraper (sharpened on the end and the side), slightly dovetailing if I feel like it.

    JKJ
    I'll try that. I made it small enough that I can cut it larger in diameter. Thanks, John.

  11. #11
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    Quote Originally Posted by Bill Jobe View Post
    I don't think so, Mike.
    The problem I'm struggling is that I can't seem to get the piece true latteraly, not out of round. The piece wobbles but may not have much run-out on the edge.....I'm not getting the jaws set equally deep enough. I sand the recess very smooth but it's like I'm bumping against a surface that isn't true. I'm turning the recess shallow enough that the jaws don't touch the surface of the plane outside the recess.

    I'm a bit Leary of chucking on the outside. I figure if the piece comes out at least the chuck will not allow it to fly out if recessed.
    Perhaps I'll practice chucking on a tennon. Maybe my uneasiness will pass.

    This walnut was kiln dryed and has a moisture of about 8-8.5 but the last bowl I turned with it warped anyway.

    Thank you all for your suggestions.
    Bill - re-read my post. I'm talking about the "face" of the jaws (part that interfaces the bottom of the recess) not being in the same plane.

    Mike

  12. #12
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    Quote Originally Posted by Bill Jobe View Post
    I don't think so, Mike.
    The problem I'm struggling is that I can't seem to get the piece true latteraly, not out of round. The piece wobbles but may not have much run-out on the edge.....I'm not getting the jaws set equally deep enough. I sand the recess very smooth but it's like I'm bumping against a surface that isn't true. I'm turning the recess shallow enough that the jaws don't touch the surface of the plane outside the recess.

    I'm a bit Leary of chucking on the outside. I figure if the piece comes out at least the chuck will not allow it to fly out if recessed.
    Perhaps I'll practice chucking on a tennon. Maybe my uneasiness will pass.

    This walnut was kiln dryed and has a moisture of about 8-8.5 but the last bowl I turned with it warped anyway.

    Thank you all for your suggestions.
    Bill if the outside runs true, like I show in picture 4, then the bowl is running true on the whole outside surface, If there is a back and forth discrepancy, on the top edge of the rim, I will cut that straight.

    As for sanding a recess, that is not a good idea, as the wood will not sand equally, however if the outside edge is turning true, just cut the front flat.

    You can check of what I say is true, and place the toolrest close to any area on the outside and check the true running of it, you will find that it is all running true, just as the outside edge is.
    Have fun and take care

  13. #13
    Sometimes I use a tenon, sometimes a recess depending mostly on the shape of the project. In either case if the piece chucks up significantly off-axis, then tenon or recess is the problem.
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  14. #14
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    So i want the part of the jaw that grabs the piece to touch bottom but not the part that is against the chuck?

    I did disvover a couple of jaw bolts had loosed up a bit. I have it running pretty true now.

  15. #15
    Quote Originally Posted by Bill Jobe View Post
    So i want the part of the jaw that grabs the piece to touch bottom but not the part that is against the chuck?
    This is correct, also take care when shaping the recess. It needs to match the shape of the outside of your jaws with a sharp clean corner. It does not have to flat all the way across but should be flat bottomed where the jaws touch.
    _______________________________________
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