Free 186 More Best Homemade Tools eBook:  
Get 2,000+ tool plans, full site access, and more.

User Tag List

Page 1 of 3 1 2 3 LastLast
Results 1 to 10 of 21

Thread: Metric threading with inch based leadscrew

  1. #1
    Supporting Member olderdan's Avatar
    Join Date
    Jun 2016
    Posts
    781
    Thanks
    1,456
    Thanked 1,531 Times in 463 Posts

    olderdan's Tools

    Metric threading with inch based leadscrew

    Noticing recent posts mentioning 127 tooth conversion gears I thought it may be useful to show a different method using standard gears, namely a
    54T pegged with a 44T giving a very close conversion for most thread lengths.
    This is not my idea but taken from a site called Workshop Protects which seems to no longer exist, fortunately I took screenshots of it.
    Metric threading with inch based leadscrew-screen-shot-01-22-17-11.48-am.png
    Metric threading with inch based leadscrew-screen-shot-01-22-17-11.54-am.jpg

    Hope someone finds this useful.

    186 More Best Homemade Tools eBook

  2. The Following User Says Thank You to olderdan For This Useful Post:

    Seedtick (Sep 28, 2017)

  3. #2
    Supporting Member ncollar's Avatar
    Join Date
    Oct 2012
    Posts
    354
    Thanks
    23
    Thanked 180 Times in 126 Posts
    Olderdan
    Do you have any idea what the foot notes are for the three astrichs? ***

    2000 Tool Plans

  4. The Following User Says Thank You to ncollar For This Useful Post:

    olderdan (Sep 29, 2017)

  5. #3
    Supporting Member hemmjo's Avatar
    Join Date
    Feb 2017
    Posts
    2,542
    Thanks
    224
    Thanked 1,446 Times in 820 Posts

    hemmjo's Tools
    Looks like the *** line got cut off on the screen shot.

    I have this link tucked away for when I need to cut a metric thread on my old Logan lathe.

    Metric Threading

  6. The Following 2 Users Say Thank You to hemmjo For This Useful Post:

    DIYSwede (Dec 17, 2019), olderdan (Sep 29, 2017)

  7. #4
    Supporting Member olderdan's Avatar
    Join Date
    Jun 2016
    Posts
    781
    Thanks
    1,456
    Thanked 1,531 Times in 463 Posts

    olderdan's Tools
    Quote Originally Posted by hemmjo View Post
    Looks like the *** line got cut off on the screen shot.

    I have this link tucked away for when I need to cut a metric thread on my old Logan lathe.

    Metric Threading
    Thanks Hemmjo, that is a very comprehensive article, thanks for the link.

  8. #5
    Supporting Member olderdan's Avatar
    Join Date
    Jun 2016
    Posts
    781
    Thanks
    1,456
    Thanked 1,531 Times in 463 Posts

    olderdan's Tools
    I think the three asterisks indicate a slightly increased error for those pitches but I have not done the maths.

  9. #6
    Supporting Member ncollar's Avatar
    Join Date
    Oct 2012
    Posts
    354
    Thanks
    23
    Thanked 180 Times in 126 Posts
    No, three *** mean there is more info for it.

  10. #7
    Supporting Member
    Join Date
    Feb 2016
    Posts
    55
    Thanks
    130
    Thanked 32 Times in 21 Posts
    I would second Nelson's recommendation: the 37/44 tooth combination shown there yields a 1.2703:1 ratio: very close to the ideal 1.2700:1 ratio. according to Logan's web site, it's only 2/100s of 1% error. the 54/44 combo yields 1:2273:1.

    Kudos to OlderDan for bringing this to the surface: an easy way for inch-based lathes to cut metric threads!

  11. #8
    Supporting Member mklotz's Avatar
    Join Date
    Aug 2015
    Location
    LA, CA, USA
    Posts
    3,433
    Thanks
    357
    Thanked 6,378 Times in 2,116 Posts

    mklotz's Tools
    Quote Originally Posted by olderdan View Post
    Noticing recent posts mentioning 127 tooth conversion gears I thought it may be useful to show a different method using standard gears, namely a
    54T pegged with a 44T giving a very close conversion for most thread lengths.
    This is not my idea but taken from a site called Workshop Protects which seems to no longer exist, fortunately I took screenshots of it.
    Click image for larger version. 

Name:	Screen Shot 01-22-17 at 11.48 AM.PNG 
Views:	445 
Size:	23.1 KB 
ID:	19915
    Your text in your writeup says 54:44 gear pair

    54/44 = 1.2273

    but the text in the picture you included seems to indicate 56/44

    56/44 = 1.2727

    which is, indeed, closer to the desired 1.2700000....

    Was the "54" a typo or am I missing something here?

    Of course, 47:37 is still a lot closer...

    47/37 = 1.27027027
    ---
    Regards, Marv

    Home Shop Freeware
    https://www.myvirtualnetwork.com/mklotz

  12. The Following 2 Users Say Thank You to mklotz For This Useful Post:

    DIYSwede (Dec 17, 2019), olderdan (Sep 29, 2017)

  13. #9
    Supporting Member olderdan's Avatar
    Join Date
    Jun 2016
    Posts
    781
    Thanks
    1,456
    Thanked 1,531 Times in 463 Posts

    olderdan's Tools
    It was indeed a typo, thanks for pointing it out, probably would have been better to let the chart speak for itself.
    I am sure there are better combinations but the chart is for standard SB change gears which are all of an even number.

  14. #10
    Supporting Member mklotz's Avatar
    Join Date
    Aug 2015
    Location
    LA, CA, USA
    Posts
    3,433
    Thanks
    357
    Thanked 6,378 Times in 2,116 Posts

    mklotz's Tools
    Quote Originally Posted by rebuilder1954 View Post
    I would second Nelson's recommendation: the 37/44 tooth combination shown there yields a 1.2703:1 ratio: very close to the ideal 1.2700:1 ratio. according to Logan's web site, it's only 2/100s of 1% error. the 54/44 combo yields 1:2273:1.

    Kudos to OlderDan for bringing this to the surface: an easy way for inch-based lathes to cut metric threads!
    Another typo I think...

    44/37 = 1.11892

    The correct form is...

    47/37 = 1.27027027...
    ---
    Regards, Marv

    Home Shop Freeware
    https://www.myvirtualnetwork.com/mklotz

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

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
  •