Old criterion vs new precision import boring heads - Page 2
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  1. #21
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    Quote Originally Posted by CarbideBob View Post
    I think many miss the fact that the tool tip does not need to inline with the slide and just use a standard setup on boring heads.
    Doing so ruins the calibration on the screw but you make very small diameter moves with ease.
    Way off and you can get 10:1 but your bar has to be close to right size as you have little room to move.
    That's an interesting idea that I wish I had thought of in one instance.

    Needing to hold a couple tenths isn't usually something I need to do but I can think of one case where I wish I had that thought. I probably could have used it.

  2. #22
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    Quote Originally Posted by ripperj View Post
    Are there just a couple different size holes in that range ? Are reamers an option?
    On the initial part I have in mind, there's a couple holes in the .75-1" range that will receive an OD ground hydraulic piston without any seal, so the surface finish and bore size need to be better than what a reamer will do. I'm basically replicating a part that was made back in the 1950's, so if they did it then, there's absolutely no reason I can't duplicate them now with a cnc.

    For anyone familiar with Jake brakes on semi engines, I'm basically making new Jake bodies and pistons (a grind shop will make the pistons) for an obsolete application that's still popular in the enthusiast world.


    I like the trick of turning the boring bar in the head, that's definitely one of those tricks that so simple you never think of it haha. I suppose I can try that wihh the old critter head on some test holes and see if I can get any kind of repeat tolerances in the short term.


    That's for the feedback eveyone! Lots more good info here than I expected. After about all the internet and eBay hunting I can stand, the maritool precision boring set is looking better and better. Once I buy a used bare precision head for $400-600, then buy an assortment of bars/arms, etc, I'll be over $1k real easy and have a buch of hodgepodge parts. I suppose I'll try to see what I can hold with the current tools, make as many parts without boring as possible, save up some profits, and then buy the maritool set!

  3. #23
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    The tolerances of +/- .0005" with a generic (new) criterion will worry you a bit, but it’s done, & going from 3/4” to 1.5” (you’ll always want more) is likely the best choice.

    I quit locking these & those like these sometime in the early 70’s (except for the big Flynn 6”+ 2 hole heads). I just set gibs for slight drag and try to keep tool balance within reason (little criterions I REMOVE the micrometer screw to set gib & re-assemble). They pretty much give you what you set all things equal.

    I agree with C’Bob about DeVlieg microbores needing 3 hands (1 tensions the cutter one way, 1 wrenches the micrometer adjust collar & the last tightens the locking capscrew underneath…) BTDT.

    Erickson tenth-sets are pretty cool but have pretty short size ranges & high price tags... Wally-bangers have lots'a range, facing & grooving plus big price tag.

    Good luck,
    Matt

  4. #24
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    Have you looked into indexable tooling, drill, facemill, endmill. You might be able to find something in a reasonable price range that can be used as the proper boring bar size if just one cutter is left installed and use the tool as a single point tool with speeds & feeds adjusted for the use case? The sizes you need might be too pricey if a solution exists, but I thought it worth mentioning.


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