Results 1 to 8 of 8
  1. #1
    Perk is offline Cast Iron
    Join Date
    May 2004
    Location
    Nebraska
    Posts
    405

    Post

    Can someone post the calculation for thread helix angles? I need to make a thread dial for a Stanley Engine, the Major Dia. on the screw is 2.25 with 2 TPI. If my figures are right the pitch Dia. is 2Ē. I didnít get any manuals with this machine so if someone could help me out here, that too would be appreciated. Stanley 1704 made in Halifax England.

  2. #2
    dsergison is offline Diamond
    Join Date
    Oct 2003
    Location
    East Peoria, IL, USA
    Posts
    4,333

    Post

    being a zero load appication it doesn't really matter.

    and far easier to tell you that than to figure it out. [img]smile.gif[/img]

  3. #3
    johnoder's Avatar
    johnoder is offline Diamond
    Join Date
    Jul 2004
    Location
    Houston, TX USA
    Posts
    21,572

    Post

    If 2" P.D.:

    (2.000 X 3.14159) divided into .500" = 0.07958 = tan of 4.55 degrees.

    John

  4. #4
    lathefan's Avatar
    lathefan is offline Titanium
    Join Date
    Nov 2003
    Location
    Colorado
    Posts
    2,120

    Post

    If you don't mind having a canted threading dial, make a mount for it that allows you to tilt it to line the teeth up with the leadscrew.

  5. #5
    Perk is offline Cast Iron
    Join Date
    May 2004
    Location
    Nebraska
    Posts
    405

    Post

    I donít have a problem with a canted or tilted thread dial but I didnít think it would be a problem to apply the helix angle to the teeth on the spur gear either. My experience with gears is fairly limited, machined a few straight tooth spur gears on horizontals but thatís about it. What am I over looking?

  6. #6
    carlquib's Avatar
    carlquib is offline Aluminum
    Join Date
    Apr 2004
    Location
    Hazelton, Idaho, U.S.A.
    Posts
    83

    Post

    I have made several of these threading dials. All I did was to fixture the blank at the appropriate angle, I measured mine to get a good enough approximation, then ground a single point tool that matched the thread profile. Then it was just a matter of turning the crank on the dividing head and gashing out the teeth. Not very pretty but very functional and takes less time than making a hob.

    -brian

  7. #7
    EPAIII is offline Stainless
    Join Date
    Nov 2003
    Location
    Beaumont, TX, USA
    Posts
    1,737

    Post

    Acme thread is very symetrical. Measure the OD or Major Diameter. Measure the Minor Diameter. Add them together and divide by two for the pitch diameter. Multiply pitch diameter by pi (3.141) to get the circumference at the pitch diameter. Divide the lead (1/TPI if Engilish) by the pitch circumference and take the arc tangent of that value to find the helix angle.

    Overall formula:

    HA = arctan(L/((OD+MD)*3.141/2))

    HA is Helix Angle
    L is Lead
    OD is Outside Diameter
    MD is Minor Diameter

    Be sure all measurements are in the same units.

    Paul A.

  8. #8
    Lumpsmith is offline Aluminum
    Join Date
    Apr 2005
    Location
    Vallejo,Ca USA
    Posts
    207

    Post

    The gear on my Emco Maier V-13 is thin, about 1/16" thick so helix angle does'nt matter.If your lathe lead screw does'nt have a slot in it for power feed you can make your gear the same.

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
  •