Advice needed from Clockmakers, or maybe 3D modellers
Michael Gilligan | 15/11/2015 19:38:37 |
![]() 23121 forum posts 1360 photos | I am planning to build a Verge Escapement for a Seconds Pendulum. ... Yes, I know there are much better timekeepers [this one is for 'research']. I am having some difficulty understanding how a rotating cutter can produce the required surfaces. [maybe I'm just being thick]. The process is demonstrated in this YouTube video: But I cannot see how the radial surface of each tooth is maintained when the next tooth is cut. My wheel will have 15 teeth, and should be very similar to the one in this video. For 3D drawing, I only have Sketchup [v8 Pro], which is driving me to distraction, trying to 'model' this apparently simple piece. ... If someone with proper 3D software could model the cutting of two adjacent teeth, I would be most grateful. MichaelG. Edited By Michael Gilligan on 15/11/2015 19:42:16 |
JasonB | 15/11/2015 19:54:46 |
![]() 25215 forum posts 3105 photos 1 articles | Something like this, the cutter only cuts the tooth at the bottom on each pass |
jason udall | 15/11/2015 19:55:16 |
2032 forum posts 41 photos | Being less than well versed in clockwork. ...what is to be made is a thing looking like a hole saw? My first guess.. Working on end of (hollow ) bar..cutter machines one tooth at a time ..axis of cutter such that non cutting bit in air..and of suitable profile. .include a radial wipe to cutter move..to leave tooth as flat as needed |
jason udall | 15/11/2015 19:55:56 |
2032 forum posts 41 photos | Or a bit like the diag above ![]() |
JasonB | 15/11/2015 20:02:26 |
![]() 25215 forum posts 3105 photos 1 articles | Or if the slope is curved just make the cutter to profile Don't know why you can't file it by hand and eye Edited By JasonB on 15/11/2015 20:04:08 |
Michael Gilligan | 15/11/2015 20:06:51 |
![]() 23121 forum posts 1360 photos | Jasons both Yes it looks fine in those diagrams ... and is exactly what I thought should happen. Maybe it's just my clumsy attempt at drafting, but it appeared that the curved face of the cutter would upset the geometry of the previous surface when the blank is indexed for the next cut. I may now crawl away and hide in the corner for a while MichaelG. . Updated to reflect Jason's second diagram Edited By Michael Gilligan on 15/11/2015 20:35:06 |
Michael Gilligan | 15/11/2015 20:10:18 |
![]() 23121 forum posts 1360 photos | Posted by JasonB on 15/11/2015 20:02:26:
Don't know why you can't file it by hand and eye Edited By JasonB on 15/11/2015 20:04:08 . I could ... it was the geometry of the mechanised process that I was struggling with. MichaelG. . P.S. ... the slope is curved; it's there to clear the Verge 'Flags' as per the second video.
Edited By Michael Gilligan on 15/11/2015 20:23:27 |
Neil Wyatt | 15/11/2015 20:55:00 |
![]() 19226 forum posts 749 photos 86 articles | Verging on the ridiculous, Michael. N. |
roy entwistle | 15/11/2015 21:02:59 |
1716 forum posts | Michael You could have problems geting a one second pendulum to swing far enough for the verge flags to clear the escape wheel Just a thought Please let us know how you get on Roy Edited By roy entwistle on 15/11/2015 21:07:06 |
Michael Gilligan | 15/11/2015 21:03:28 |
![]() 23121 forum posts 1360 photos | Posted by Neil Wyatt on 15/11/2015 20:55:00:
Verging on the ridiculous, Michael. N. . Ha ###### Ha GOTO your own thread and update the title. |
Michael Gilligan | 15/11/2015 21:06:59 |
![]() 23121 forum posts 1360 photos | Posted by roy entwistle on 15/11/2015 21:02:59:
Michael You could have problems geting a one second pendulum to swing far enough for the verge flags to clear the escape wheel Just a thought Roy . Roy, Many thanks for the thought, but; as I mentioned, this is 'research' and I'm basing it on Huygens' original. MichaelG. |
Mark C | 15/11/2015 21:47:19 |
707 forum posts 1 photos | Michael, If you let me know the dimensions of your wheel and the size of the "flags" i will try and sketch it up for you and check the geometry so you will know it will work before you cut anything. Mark |
Michael Gilligan | 15/11/2015 22:17:23 |
![]() 23121 forum posts 1360 photos | Posted by Mark C on 15/11/2015 21:47:19:
Michael, If you let me know the dimensions of your wheel and the size of the "flags" i will try and sketch it up for you and check the geometry so you will know it will work before you cut anything. Mark . Thanks, Mark Hopefully, I can send that tomorrow ... I'm scaling some details from a woodcut !! MichaelG. |
Michael Gilligan | 15/11/2015 23:32:15 |
![]() 23121 forum posts 1360 photos | Mark C, I have sent you a PM MichaelG. |
Mark C | 16/11/2015 01:20:58 |
707 forum posts 1 photos | just uploading it now!
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Michael Gilligan | 16/11/2015 07:41:22 |
![]() 23121 forum posts 1360 photos | Mark, That is a thing of beauty THANK YOU MichaelG. |
NJH | 16/11/2015 11:29:42 |
![]() 2314 forum posts 139 photos | Michael For my ( only! ) attempt at cutting an escape wheel I ground up a cutter ( from a broken centre drill - always plenty of those to hand!) and fly cut it. OK your "teeth" are at right angles to the one I made but it should still be possible I feel. Do let us see your progress! Regards Norman |
Ian S C | 16/11/2015 12:53:28 |
![]() 7468 forum posts 230 photos | NJH, you beat me to it, I use that method for gear cutting, and see no reason not to use it in this case. Ian S C |
John Haine | 16/11/2015 14:23:10 |
5563 forum posts 322 photos | Roy, surely the pendulum period doesn't matter? Yes, you need quite a big pendulum amplitude for a verge escapement, which affects accuracy as circular deviation is large. That's why the anchor and deadbeat escapements were invented, to operate with small deflections. |
Michael Gilligan | 16/11/2015 15:20:02 |
![]() 23121 forum posts 1360 photos | Norman, and Ian Thank you for the comments regarding single-point cutters Although I do need to collect & configure some equipment or this job; I am pleased to say that I am happy with the general wheelcutting process [I even went on a short tutorial course at BHI Upton Hall a while ago] ... But I have, to date, only cut flat wheels; and it was specifically the geometry of the cutting process for Contrate & Crown Wheels that concerned me. It appears that my concerns were ill-founded, and it was simply that [using SketchUp] I couldn't correctly draw a cutter going through a tubular workpiece. Thanks again ... and I am quite content for this thread to morph into a general discussion of wheelcutting if anyone so-wishes. MichaelG.
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