Optimum Lock angle for an escapement pallet

Discussion in 'Clock Construction' started by dandydude, Jun 12, 2016.

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  1. dandydude

    dandydude Registered User

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    Hello,

    I would like to know what is the optimum lock angle for an escapement. If the lock is too less the problem i see is that very precise setting is required for setting it in beat. If the lock is too much would the swing increase?

    Thanks
    Dandy
     
  2. shutterbug

    shutterbug Moderator
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    #2 shutterbug, Jun 12, 2016
    Last edited by a moderator: Dec 31, 2017
    Re: Optimum Lock angle for an escapement palet

    Do you mean the angle of the impulse face? For a general reference, 2° is good. That changes as the pendulum weight increases, but that's a good starting point.
    Otherwise, I'm not fully understanding the question :)
     
  3. dandydude

    dandydude Registered User

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    #3 dandydude, Jun 12, 2016
    Last edited by a moderator: Dec 31, 2017
    Re: Optimum Lock angle for an escapement palet

    Hello Shutterbug,

    I meant the lock angle. Beyond the 2 degrees, the small angle you leave where the scape wheel tooth can come to rest.

    Thanks
    Dandy
     
  4. KurtinSA

    KurtinSA Registered User
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    Re: Optimum Lock angle for an escapement palet

    Do you mean lock depth?? That sounds like more what you're asking about. :confused:

    Kurt
     
  5. dandydude

    dandydude Registered User

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    Re: Optimum Lock angle for an escapement palet

    Dear Kurt,

    I just downloaded an a reference image and have sketched what i mean by lock angle.
    Any inputs appreciated.

    Thanks
    Dandy

    IMG20160613204253.jpg
     
  6. shutterbug

    shutterbug Moderator
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    Re: Optimum Lock angle for an escapement palet

    I don't think it's something most of us worry about, with the exception of the clock maker. Probably not something you can alter easily, or would want to. If you have a solid lock and an adequate impulse, the clock should run.
     
  7. dandydude

    dandydude Registered User

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    Re: Optimum Lock angle for an escapement palet

    Dear Shutterbug,
    Iam making a clock. I need a little bit more lock. Just wondering if i increase the lock angle, does it automatically translate into more swing? More swing is obviously require to clear the teeth. Or do i also have to proportionately increase the impulse angle?
    Thanks
    Dandy
     
  8. etmb61

    etmb61 Registered User
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    Re: Optimum Lock angle for an escapement palet

    Is this in reference to a torsion clock?
     
  9. shimmystep

    shimmystep Registered User

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    Re: Optimum Lock angle for an escapement palet

    Given your pic is of a deadbeat, the lock angle should be 1deg.
    If you want increased lock you need to be able lower the anchor deeper into the escapement wheel teeth.
    The lock angle itself, in situ, will vary depending upon the depth of the anchor in the EW teeth (when adjusting a completed anchor) given that this is measured from the edge of the locking face/impulse face, to the drop point on the locking face. So if you lower the anchor into the teeth then you will increase the distance between the lock/impulse edge and the drop point....so increasing the angle.

    If you want more swing you will need to increase the impulse angle, as no power is gained whilst the escapement wheel tooth is on the locking face, unless of course the curve of that face is incorrect, in which case it may give some unwanted recoil.

    The locking angle is something that is drawn in when designing the escapement as a whole where you are drawing the ideal.

    Please correct me if I'm wrong
     
  10. dandydude

    dandydude Registered User

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    Re: Optimum Lock angle for an escapement palet

    Dear etmb61,

    The image is just somehting i downloaded from the internet for me to sketch on. It had an angle for lock already marked, which made it easier for me to explain what i was really looking for.

    Thanks
    Dandy
     
  11. dandydude

    dandydude Registered User

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    Re: Optimum Lock angle for an escapement palet

    Dear Shimmy,

    Thanks a lot for the info you provided. What happens when you only provide a 0.25 degree lock angle?
    I am using a dead beat graham style escapement.?

    Thanks
    Dandy
     
  12. shimmystep

    shimmystep Registered User

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    Re: Optimum Lock angle for an escapement palet

    A 0.25deg lock angle would be pretty hard to factor I would think, and I'm not sure is necessary:???:
    If made by design then I would say it would reduce your capacity for tolerances in manufacture.
    Yes, you are using a Graham dead beat design there.
     
  13. etmb61

    etmb61 Registered User
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    Re: Optimum Lock angle for an escapement palet


    Not counting over-swing, the anchor pin ideally pivots through 8 degrees. Of that the first 2 degrees are for the 2 degree lock angle, and the last 6 degrees are for the impulse. During the impulse, the torsion spring gets a little twist. When the escape tooth drops, the spring will twist a bit back. The large lock angle of allows the escapement remain stable at the end of the impulse while the pendulum "catches up".

    The larger lock angle would also minimize the slight variations in length and wear of the escape wheel teeth and pallets.

    If you don't have sufficient lock angle the escapement will probably flutter.

    Eric
     
  14. Tinker Dwight

    Tinker Dwight Registered User

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    Re: Optimum Lock angle for an escapement palet

    It is not a critical measurement. It needs to account for bushing
    slop and eccentricity of the escapement wheel. Excess angle will
    require added power to make up for the additional time spent
    in lock.
    It will also cause additional imbalance of the impulse across the
    center of the swing. This has a slight effect on the power dependent
    timing keeping of the clock, similar to circular error. Some have even
    used the error to compensate some for circular error. It is not something
    that on can easily calculate as factors like frictional loss of the teeth
    on the pallets play a part.
    I personally believe it best to keep constant power and have a minimum
    safe angle for best results.
    Tinker Dwight
     
  15. dandydude

    dandydude Registered User

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    Re: Optimum Lock angle for an escapement palet

    Dear Shimmy,

    I have been working with a 0.25 degree and it work well. The problem is if someone else were to try and set my clock in beat, they would find it difficult. I want to design something more user friendly. I wouldnt mind a little extra lock and swing for this reason.

    Thanks a lot for the input

    Dandy
     
  16. Tinker Dwight

    Tinker Dwight Registered User

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    Re: Optimum Lock angle for an escapement palet

    It has nothing to do with setting the beat.
    Tinker Dwight
     
  17. shimmystep

    shimmystep Registered User

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    Re: Optimum Lock angle for an escapement palet

    "swing" ?? What type of clock are you making dandy? Posted in 400day/torsion clocks currently.
     
  18. dandydude

    dandydude Registered User

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    Re: Optimum Lock angle for an escapement palet

    Dear Shimmy,

    I have only posted an image that i randomly chose from the internet to explain what i mean by 'lock angle'. One of the members wanted to know what i mean by 'lock angle'.
    Iam building a regulator clock with a graham style dead beat escapement.

    Thanks
    Dandy

    - - - Updated - - -

    Dear Tinker,

    I just found it easier to set the beat when the swing was a little bit more. Easier for someone not familiar with the whole exercise of setting it in beat.

    Thanks
    Dandy
     
  19. shutterbug

    shutterbug Moderator
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    Re: Optimum Lock angle for an escapement palet

    That being the case, I'll move this thread to a more beneficial location....clock construction forum.

    - - - Updated - - -
     
  20. shimmystep

    shimmystep Registered User

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    Re: Optimum Lock angle for an escapement palet

    Sounds like a plan. Confusing while its in the Torsion/400day forum.

    Good luck Dandy, let us know how you get on :)
     
  21. John MacArthur

    John MacArthur Registered User
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    Re: Optimum Lock angle for an escapement palet

    Typical Graham escapements have 1 degree of lock and 2 degrees of impulse. Higher grade jeweled ones can have less of each: 1/2 degree of lock and 1-1/2 degree of impulse.

    good luck
    Johnny
     

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