Harrison 140 . metric screw cutting gearbox

  1. foxbat452

    foxbat452 Forum Supporter

    Messages:
    13
    Location:
    Wiltshire UK
    Am new to forum .
    so my 140 harrison has a problem . in the gear selector is a little 22 tooth gear wheel as of last night it has 2 teeth missing . while cutting a screw something happend came out of gear bounced back and hit the gears . . questions 1 has anyone got a gearbox . 3 knobs across the top and selector at the bottom . metric .
    2 anyone happen to have one .. a gear that is .
    3 does anyone have part number or the spec of that gear .
    help much appreciated

    20200523_124143_copy_784x1613.jpg

    20200523_124243_copy_784x1613.jpg

    poor lathe needs help please .
     
  2. Seadog

    Seadog Forum Supporter

    Messages:
    5,659
    Location:
    NE London - UK
    Ouch. There's no way that it should be able to drop out of gear unless the tumbler lever wasn't properly engaged.
     
  3. foxbat452

    foxbat452 Forum Supporter

    Messages:
    13
    Location:
    Wiltshire UK
    i found the problem broken spring in the latch . thats fixed . tirned out a previous own thought it was a good idea to use grease in the screw cutting gearbox where is days use oil .
     
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  4. Tinbasherdan

    Tinbasherdan Bodger in chief

    Messages:
    5,061
    Location:
    Bolton, England
    Think I would carefully build up with weld and file it back
     
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  5. Pete.

    Pete. Member

    Messages:
    9,024
    Location:
    Kent, UK
    Give me the OD and tooth count. If it's less than 12DP I can probably make one.

    EDIT: just seen the 22 teeth. What's the OD?
     
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  6. Hopefuldave Intergalactic pot-mender

    Messages:
    1,426
    Location:
    The Shed of Danger, surrey, England
    I've done that a couple of times, braze is probably a better idea as that gear's likely to be cast iron - or there's always HPC Gears, they're surprisingly reasonable for smaller gears and you can bore/bush to fit, won't need power feeds / threading while making it.
    You'll need to measure it for DP and pressure angle, DP take the outside diameter (over the teeth), add 2 to the number of teeth and divide that by te diameter, should come out as a whole number, pitch angle roll it over a piece of plasticene and inspect the angle from "vertical" that the rack you rolled out makes, will be either 20 or 14.5 degrees

    Dave H. (the other one)
     
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  7. foxbat452

    foxbat452 Forum Supporter

    Messages:
    13
    Location:
    Wiltshire UK
    so the gear has 22 teeth . OD is 38mm gear teeth width is 10mm tooth depth is 2.66 mm .then 7.2 mm shoulder. 12.6mm bore .
     
  8. Pete.

    Pete. Member

    Messages:
    9,024
    Location:
    Kent, UK
    38mm = 1.5" diameter. Teeth+2/diameter =24/1.5= 16DP gear.

    Give me the tooth thickness, total thickness, shoulder diameter, press the bush out and give me the hole diameter, in inches please.
     
  9. Hopefuldave Intergalactic pot-mender

    Messages:
    1,426
    Location:
    The Shed of Danger, surrey, England
    Put that in Inches! 22 teeth, 1.5" so add 2 - 24 / 1.5 so a 16 DP gear, 3/8" wide, 1/2" bore
    :)

    *looks like* 20 PA, but best to measure it

    Dave H. (the other one)
     
  10. foxbat452

    foxbat452 Forum Supporter

    Messages:
    13
    Location:
    Wiltshire UK
    bore is 15.8mm . shoulder 25.4 mm. tooth thickness ??? right down in the rad at the bottom 3.5mm to 3.7 mm they are so worn .
     
  11. Pete.

    Pete. Member

    Messages:
    9,024
    Location:
    Kent, UK
    So, 1" shoulder and 5/8" bore.

    Tooth width and overall width please. Does your caliper not measure in inches>
     
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  12. foxbat452

    foxbat452 Forum Supporter

    Messages:
    13
    Location:
    Wiltshire UK
    width of the the tooth is 10 mm . it does but stupid little button dont work
    very strange the rest of this gearbox is mint
    20200523_200157_copy_784x1613.jpg
     
  13. Pete.

    Pete. Member

    Messages:
    9,024
    Location:
    Kent, UK
    Overall width?
     
  14. foxbat452

    foxbat452 Forum Supporter

    Messages:
    13
    Location:
    Wiltshire UK
    17.20 mm sorry not having a good day
     
  15. Pete.

    Pete. Member

    Messages:
    9,024
    Location:
    Kent, UK
    11/16" wide are you sure the teeth are 10mm wide not 9.53mm?
     
  16. foxbat452

    foxbat452 Forum Supporter

    Messages:
    13
    Location:
    Wiltshire UK
    20200523_203541_copy_784x1613.jpg
    i would say originally was 10 mm
     
  17. Pete.

    Pete. Member

    Messages:
    9,024
    Location:
    Kent, UK
    29/64" exactly Unusual size but there you go.
     
  18. foxbat452

    foxbat452 Forum Supporter

    Messages:
    13
    Location:
    Wiltshire UK
    all the other gears in the box are 11mm . suppose gives clearance on shift . so mr pete whats a gear going to cost good sir .
     
  19. Tinbasherdan

    Tinbasherdan Bodger in chief

    Messages:
    5,061
    Location:
    Bolton, England
    I might have a norton box off a Kerry, wonder if the selector gears are the same?
     
  20. Pete.

    Pete. Member

    Messages:
    9,024
    Location:
    Kent, UK
    *sucks through teeth*

    Well, you know there's a lot of work involved in making a gear. You have to make all the teeth exactly the same and then try to fix them all on spaced out evenly. Plus it's the weekend, and a bank holiday so that pushes the rate up.

    Not really, I think you've had a bad enough day. Pay the postage and a small donation to the forum and we'll call it quits :)

    Here's your gear, try not to break this one :D :D :D

    M300 tumbler gear.jpg

    P.S. I made it quicker than you measured it :D
     
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