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Why so down on lantern toolposts?

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  • ptauser
    replied
    Originally posted by tdmidget View Post
    What? You have a T slot less than .080" wide?
    No, tmidget . It is 6mm wide at narrowest, 10mm at widest. The important measurement in this context is the button size at the base. It is 2mm thick x 10mm diam.

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  • tdmidget
    replied
    Originally posted by ptauser View Post
    Gary,
    My Lorch KD50 has a 2mm T slot. I don't think this leaves enough room for a washer and a shoulder bolt.
    Dave.
    What? You have a T slot less than .080" wide?

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  • ptauser
    replied
    Gary,
    My Lorch KD50 has a 2mm T slot. I don't think this leaves enough room for a washer and a shoulder bolt.
    Dave.
    Last edited by ptauser; 03-23-2013, 11:16 AM.

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  • Gary Paine
    replied
    Originally posted by ptauser View Post
    If a T is threaded to the top part, every time you rotate it the tool height changes (not a lot with a fine thread , but it matters in watchmaking)
    Dave.
    Dave, If the T is essentially a shaped washer and a shoulder bolt from the bottom engages the lantern post, this is not the case. The tool height does not change with rotation. Instead of a shoulder bolt, I have also used a blind hole and fine tuned the engagement to a slip fit with the T-slot by putting just the right amount of lead shot pellets into the hole and tightening it up.

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  • tdmidget
    replied
    Originally posted by macona View Post
    'Cause they suck.
    +1 on that. And those of you who love them so, don't even know the proper name. It's a "ring and rocker" toolpost. If lanterns had been as bad as these POS, the light bulb would have come much sooner.

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  • macona
    replied
    Originally posted by Sun God View Post
    Why does everyone get so down on lantern toolposts?
    'Cause they suck.

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  • ptauser
    replied
    Why so down on lantern tooposts?

    Hi folks, I use small and large watchmakers lathes and will not use lantern tool posts for fear of ripping out T slots. This is real expensive. The suggested cures are not acceptable. If you replace the button on the bottom with a T, it is integral with the top part, and cannot allow the tool post to rotate. If a T is threaded to the top part, every time you rotate it the tool height changes (not a lot with a fine thread , but it matters in watchmaking)
    Dave.
    Last edited by ptauser; 03-22-2013, 08:03 PM. Reason: Did not sign it.

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  • Jim2
    replied
    Originally posted by philbur View Post
    I assume under the adjusting nut is nothing but free air. The adjusting thread is only seated as well as the clamp bolt is tightened, apply some more load when cutting and the thread may adjust its seating.

    A four way tool post is sitting block of iron on block of iron, with no overhang in the toolpost and absolute minimum overhang of the cutting tool. Apart from a relatively thin adjusting nut the tool in the picture is basically unsupported all the way back to the tool post diameter , and then is only sitting on a thread.

    Phil
    Hey, you think that threaded ring has problems--you oughta see the lathe underneath it and the operator turning the handles! The new VMC won't be here 'til next month though, so we just gotta get by 'til then, LOL. . . .

    Jim

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  • Arthur.Marks
    replied
    Originally posted by philbur View Post
    It would be interesting to see a photo of the air gap underneath the height adjusting nut when mounted on the slide.
    That is true. The design essentially creates a bridge with either end as supports and the holding pressure bearing down directly in the middle. Usually it doesn't matter, but you can deform a 3/8" square shank if you aren't aware. I still use it on occasion with a disproportionately taller shank toolholder:


    Schaublin later updated the design to eliminate that problem with two hold-down bolts. They then aligned directly above the knurled height-adjustment nut:


    And parts assembly:




    FWIW
    Last edited by Arthur.Marks; 03-22-2013, 12:34 PM.

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  • MrFluffy
    replied
    Also interesting to note that the 102 in the later photo's on that page has had its lantern replaced by a tripan 111 qtcp

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  • MrFluffy
    replied
    Originally posted by philbur View Post
    Also notice that it is from a watchmakers lathe, used for processes where hand held tools are often rigid enough.

    It would be interesting to see a photo of the air gap underneath the height adjusting nut when mounted on the slide.

    Remember the question was "Why does everyone get so down on lantern toolposts?" Not "does a lantern toolholder have a place in the home workshop?" I think the answer to the question is that they provide insufficient rigidity for use as a general purpose holder.

    Phil
    No its not, its from a 102 which schaublin denoted a toolmakers lathe, lathes.co.uk has some shots of the range showing the arrangement they had :-
    http://www.lathes.co.uk/schaublin/page2.html


    I draw you to my above comment that I dont use this toolholder anymore as I use my multifix b to do everything it can do and more.

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  • Edwin Dirnbeck
    replied
    When I was a youngster ,I used a rocker, lantern toolpost for about 10 years full time in a high pressure job shop setting.I swore that some day I would hunt down the guy that invented this abomination and destroy his decendants .These things are an abomination to use and should be thrown in the trash.However I am better and over it. laugh laugh rant over.

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  • metalmagpie
    replied
    To anyone frustrated with height adjustment on 4-sided tool posts: buy cheap sets of feeler gages and take them apart. Now you have a whole bunch of nicely made shims.

    metalmagpie

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  • philbur
    replied
    Also notice that it is from a watchmakers lathe, used for processes where hand held tools are often rigid enough.

    It would be interesting to see a photo of the air gap underneath the height adjusting nut when mounted on the slide.

    Remember the question was "Why does everyone get so down on lantern toolposts?" Not "does a lantern toolholder have a place in the home workshop?" I think the answer to the question is that they provide insufficient rigidity for use as a general purpose holder.

    Phil

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  • 1-800miner
    replied
    Also notice that they used buttress threads to bear the pressure.

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