Results 1 to 13 of 13
  1. #1
    rhpope is offline Aluminum
    Join Date
    Dec 2005
    Location
    Durham, NC
    Posts
    237

    Default Lathe/grinder dog name?

    Is there a particular name to call the ones with the two ears other than one of the above names?

    http://cgi.ebay.com/LATHE-DOG-STRAIG...3A1%7C294%3A50

  2. #2
    johnoder's Avatar
    johnoder is offline Diamond
    Join Date
    Jul 2004
    Location
    Houston, TX USA
    Posts
    21,823

    Default

    B&S grinding dogs. Originally came in this cast iron holder with the various sizes of square female recess wrenches for the set screws.



    John Oder

  3. #3
    rhpope is offline Aluminum
    Join Date
    Dec 2005
    Location
    Durham, NC
    Posts
    237

    Default

    John,

    That is what I have with my B&S #13 Universal, except mine only has two wrenchs and less dogs since it only swings about 8 inches. I am missing some of the smaller dogs from the 1" range & down and wanted to know what to call them.

    Roger

  4. #4
    Join Date
    Feb 2004
    Location
    Metuchen, NJ, USA
    Posts
    4,577

    Default

    "Fido" ??? <ducking and running!>

    I got one for ya. Send me a PM.

  5. #5
    rhpope is offline Aluminum
    Join Date
    Dec 2005
    Location
    Durham, NC
    Posts
    237

    Default

    SouthBendModel34,

    Sent you a PM.

    Roger

  6. #6
    Bruce Johnson is offline Stainless
    Join Date
    Jan 2006
    Location
    Burbank, CA USA
    Posts
    1,476

    Default

    Okay, I'll be the dummy who has to ask: Why does a "grinding" dog need the the two straight legs, as opposed to the usual single bent leg on a "lathe" dog? What is used to drive it?

  7. #7
    Jim Shaper's Avatar
    Jim Shaper is offline Stainless
    Join Date
    Nov 2007
    Location
    Minneapolis
    Posts
    1,618

    Default

    My guess would be that's so you can use a regular chuck rather than a faceplate to drive it. The two legs would straddle the jaw. You'd still use a dead center in the chuck.

  8. #8
    Peter S is offline Diamond
    Join Date
    May 2002
    Location
    Auckland, New Zealand
    Posts
    4,020

    Default

    They are also known as carriers.
    -----------------

    As to why they are double ended - I have wondered about this myself in the past. Possibly it is to balance the carrier/dog? They are commonly used when grinding between two dead (stationary) centres on a cylindrical grinder when absolute precision is required, it would remove any possible inbalance in this operation.

    Another possibility I mentioned on the forum a while back didn't get much support - but I'll try again

    Joseph Clement invented the double driver (the Clement driver) for turning between centres. Not sure when, but sometime around 1820-30.

    "When turning work between centres, it is gripped by a carrier, the peg of which is driven by a pin on the catch plate screwed to the lathe mandrel. The effect of having a single point of contact was to bend the work at the point it met the tool tip, a result of the twisting action of the force applied. Clement overcame this by designing a double driver with two pins, which equalised the forces tending to make the lathe cut eccentrically".

    Taken from Henry Maudslay & the Pioneers of the Machine Age (various authors). A diagram of Clement's driver is included in this book. What say ye?

    edit: oops, must be day dreaming - answering an unasked question....ignore the above comments, thought we were looking at the forked but double-ended type commonly found around here for grinding.

  9. #9
    johnoder's Avatar
    johnoder is offline Diamond
    Join Date
    Jul 2004
    Location
    Houston, TX USA
    Posts
    21,823

    Default

    Why does a "grinding" dog need the the two straight legs
    Simple. Forget face plates with slots or formal dog driver plates you put on the spindle nose. If a plain cylindrical there is no taking off and putting on things, there is just the driver plate with a stud to fit in between the two legs of the dog. Usually the stud is positionable radially to accommodate differing size dogs.

    If a Universal grinder, you would have a choice of spindle nose tooling for the workhead - a dog driver capable of revolving around a non rotating center, a grinding chuck capable of being rotated by a revolving work head spindle and possibly a face plate and/or rotary magnetic chuck, both revolving with the work head spindle.

    If you are grinding between centers in the Universal, ordinarily the dog driver assembly is in place and the work head spindle is prevented from turning.

    (at least on this 1947 B&S)

    http://smg.photobucket.com/albums/v3...204%20Grinder/

    John Oder

  10. #10
    Peter S is offline Diamond
    Join Date
    May 2002
    Location
    Auckland, New Zealand
    Posts
    4,020

    Default

    John,

    But that doesn't really explain why these dogs have a forked end does it? A single leg would still do the same thing on a grinder - however I have never seen one so equippped.

    Sometimes when I have a part that needs grinding all in one operation, i.e. no place to put the dog/carrier, I tap the end face of the workpiece before hardening, then screw/lock nut in a piece of threaded rod and bend it into the shape required to pick up the driving pin. No fork required.

  11. #11
    johnoder's Avatar
    johnoder is offline Diamond
    Join Date
    Jul 2004
    Location
    Houston, TX USA
    Posts
    21,823

    Default

    But that doesn't really explain why these dogs have a forked end does it?
    In my mind an explanation would be that "places have been switched"

    Instead of a single tail in a slot, we have a drive stud in a fork.

    Yes, we know other ways work, but these were not part of the machine tool designer's intent for these details before us.

    Single tails were intended to be captured in the dog plate's slot, even though they work fine, or seem to, resting on a chuck jaw.

    Here is one of the fork tails in use. I could have also bent some sheet metal around, attached it to the drive stud, and let it drive the work by fitting between the bevel gear teeth, but I did not.

    http://img.photobucket.com/albums/v3...Dcp_1147sm.jpg

    John Oder

  12. #12
    Bruce Johnson is offline Stainless
    Join Date
    Jan 2006
    Location
    Burbank, CA USA
    Posts
    1,476

    Talking

    So, there's no real profound technical reason......B & S just wanted to be different on their grinders. And sell more dogs! I understand now....

  13. #13
    hendeyman is offline Stainless
    Join Date
    Nov 2005
    Location
    elfrida arizona usa
    Posts
    1,049

    Default

    Roger:

    While grinding dog is the more popular term for these two lug dogs, I have to agree
    with Peter S., I have always called them carriers. I prefer this style of dog instead of
    the straight or bent tail single lug dog. The double lug carrier has one major advantage
    over the single lug type, the ability to remove all backlash between the driving pin and
    the carrier. Even if the pin is smaller than the narrowest space between the lugs, a
    snug fitting bushing fitted to the pin solves the problem. The pin can be nicely slid down
    into the "V", making perfect contact. When properly adjusted, there is no stain on the
    center or any backlash. I use this type of carrier for all of my gear cutting and grinding
    work were any lost motion could cause problems. They are also very handy for turning
    between centers in a lathe.

    Hendeyman

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •