Shorten lathe chuck jaws...

Discussion in 'Advanced Gunsmithing & Engineering' started by eww1350, May 6, 2017.

  1. paperpuncher

    paperpuncher

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    I found the picture that I was trying to describe. I think this will accomplish your goal without doing irreparable damage to your chuck jaws
    jaw.jpg
     
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  2. Alex Wheeler

    Alex Wheeler Gold $$ Contributor

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    Great way to bend a barrel. That set up wont let you hold a barrel without it wanting to center, thus making you force the muzzle end over and hold it there with the spider. This is really a problem if to time the curve of the bore, because you have just created your own curve in the bore and when you take it out f the lathe it will spring back to its original shape and now your "timed barrel" is not. If you loosen the spider on the muzzle end and the barrel moves then you are using the spider to force the muzzle into position, bending the barrel and causing a bind. You can bend a barrel very easy. The spider on the muzzle end should only be used for support, not as a jacking screw IMO.
     
  3. carlsbad

    carlsbad Details matter. Silver $$ Contributor

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    Alex,
    I think the setup he is showing provides a point contact with the brass rod so it can move when you adjust the spider. Picture is hard to decipher. --Jerry
     
  4. Alex Wheeler

    Alex Wheeler Gold $$ Contributor

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    I know, I see the rods. That setup with want to force the barrel to center.
     
  5. jkohler

    jkohler

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    Alex's Mimi vblocks with the bearing works sweet. It's really a nice stress free and sold set up. I really like it anyway. Thanks for sharing it Alex.
     
  6. paperpuncher

    paperpuncher

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    I dont see how the clamping force this setup imparts would be different than a spider with radius ed contact points or a pc of copper wire wrapped around the bbl shank and held in a 4 jaw or a 4 jaw with tabs between the jaws and bbl. It is still a small radiused contact area I would think it would allow the barrel to gimble. Are these other set ups equally problematic in terms of binding? Just curious.This is not my chuck BTW I just saw it and thought it to be a rather clever design. I have a longish headstock so I use a spider to shorten things up as much as possible.
     
    Last edited: May 8, 2017
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  7. Bamban

    Bamban

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    l
    Here is what I did with the Grizzly spider for my Jet 1024, just bolted, centered and indicated it true to the face plate. Using the aluminum finger clamps, the barrel gimbals on the 1/4 inch ball hearings. Simple cup point 3/8 x 24 set screws have enough cup and to bear on the ball bearings.

    The nuts behind the faceplate for the clamp down grade 8 bolts are the plain unistrut bolts, they have enough width in them that they don't rotate when torqued down.


    20170502_234912.jpg
     
    Last edited: May 8, 2017
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  8. Ggmac

    Ggmac

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    I think the OP want to shorten the distance thru the headstock !
     
  9. X Ring Accuracy

    X Ring Accuracy Site $$ Sponsor

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    Or buy a set of aluminum jaws, cuts easy and save your old ones.
     
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  10. Alex Wheeler

    Alex Wheeler Gold $$ Contributor

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    Just think about it in one plane. 2 set screws 180 apart clamped to a barrel, if you move the barrel at all in that plane theres a bind. When using spiders or copper rings you have to hold the barrel very light so your not bending it. Then the thing wants to move on you during chambering. Once its all dialed in and the bend in the barrel starts to deform the copper and straighten at some point during the work. I would see this happening because I would check the throat with an indicator after every step of the chambering process, and have to make small adjustments to keep it perfectly dialed in. The more solid your setup the better, and lightly holding a barrel with a bend in it with copper is less than ideal IMO. At least a copper ring can pivot a little with a barrel rather than stationary copper rods in the jaws.
     
  11. Alex Wheeler

    Alex Wheeler Gold $$ Contributor

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    You wont get it much shorter than this.
     
  12. eww1350

    eww1350

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    That is an interesting idea.. Just finished sawing off the 2 steps on the front of my chuck jaws, and milled them to clean up the saw marks... Just shortened my length by 1-1/8"...:):)

    Thanks for all the great ideas, keep them coming others will want an alternative to what I did..


    Eddie in Texas
     
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  13. Cloudrepair

    Cloudrepair

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    [​IMG][/IMG] [​IMG] [​IMG] what I used to make mine.
    I'm using brass pads now.
     
  14. Cloudrepair

    Cloudrepair

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    I had been thinking about cutting down the jaws on a 6' 4jaw also but for other uses. Now that I found a nice 8' 4 jaw buck chuck. I may still do that with the 6'.
    I would use the cutoff tool on my angle grinder method, I use that tool All the time.
     
  15. Alex Wheeler

    Alex Wheeler Gold $$ Contributor

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    Why not steel? No more need for a sacrificial metal in the setup as you not bind anything up now.
     
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  16. Cloudrepair

    Cloudrepair

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    that would work good with less compression.
    You always have good ideas.
     
    Last edited: May 10, 2017
  17. Cloudrepair

    Cloudrepair

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    I wasn't being sarcastic i do like that idea.
    Maybe I need to rearrange my methods, right now I haven't wanted to throw the barrel back in the lathe for polishing after chambering and crowning/threading the muzzle
     
  18. Alex Wheeler

    Alex Wheeler Gold $$ Contributor

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    I knew you weren't. I have inverted cones I made for my barrel spinner. I polish after the works all done and the cones let me not touch the bore.
    I did a test this am. I have a barrel in the lathe and had the throat dialed in. Went to back of the barrel and to move it .0001" I had to push the muzzle end .004". But the barrel spung back. I had to push it .035" to over come the grip I had on it with the chuck so that it stayed that .0001" when I backed off the spider. So this type of chuck will hold a barrel in position without an out board spider but with a ring you need the help of a spider. So how much bend are we putting in a barrel to get it indicated in? That .035 I pushed the muzzle only showed about .0018" on the breech end. If I had to move and hold the breech end .002" I would have put a .035" bend in the barrel. Now, you could loosen the chuck and chase it back and forth and probably get a decent setup, but it would take a long time. Holding the barrel only at the breech the weight of my finger deflects the muzzle .001"
     
  19. Cloudrepair

    Cloudrepair

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    I need to do some more testing.

    Alex do you use a little grease on the ball bearing tip screws?
     
  20. Alex Wheeler

    Alex Wheeler Gold $$ Contributor

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    Not purposely, but they do get plenty of oil....
     

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