Michael Gilligan | 18/01/2023 18:27:41 |
![]() 23121 forum posts 1360 photos | A sublimely ambiguous title for a patent ! … But coming from Hilger & Watts we can be reasonably sure that the threads would be both ‘very fine’ and ‘very fine’ Enjoy: **LINK** https://worldwide.espacenet.com/patent/search?q=pn%3DUS2717401A MichaelG. |
old mart | 20/01/2023 20:42:01 |
4655 forum posts 304 photos | Difficult to understand, but it looks to me that differential threads are involved to get the super fine pitches. |
Michael Gilligan | 20/01/2023 20:54:51 |
![]() 23121 forum posts 1360 photos | Posted by old mart on 20/01/2023 20:42:01:
Difficult to understand […] . Yes, I’m sure it all made perfect sense to them … whilst they were dictating to some innocent typist MichaelG. |
old mart | 20/01/2023 21:11:29 |
4655 forum posts 304 photos | To get 100tpi,you only need 20 and 25 tpi threads working against each other. |
Michael Gilligan | 20/01/2023 21:26:58 |
![]() 23121 forum posts 1360 photos | Yes but … did you notice the number in the opening lines MichaelG. |
old mart | 20/01/2023 21:35:17 |
4655 forum posts 304 photos | No, you have lost me there. Perhaps it would have been better to read "a device for cutting very fine pitch screw threads". Edited By old mart on 20/01/2023 21:37:18 |
Michael Gilligan | 20/01/2023 21:39:12 |
![]() 23121 forum posts 1360 photos | [ deleted … wrong image ] Edited By Michael Gilligan on 20/01/2023 21:46:03 |
Michael Gilligan | 20/01/2023 21:45:09 |
![]() 23121 forum posts 1360 photos | Posted by old mart on 20/01/2023 21:35:17:
No, you have lost me there. . |
duncan webster | 20/01/2023 23:20:08 |
5307 forum posts 83 photos | 15000 turns per inch isn't a thread it's a surface finish. My starting point for plain turning is 0.004" per rev feed, historical because that's the slowest I could set up on my first lathe. This is 250 turns per rev. Edited By duncan webster on 20/01/2023 23:20:32 |
Martin Connelly | 21/01/2023 00:35:39 |
![]() 2549 forum posts 235 photos | I have not read the patent beyond what is in the image above but I think the idea is to produce a movement 1/15000" per revolution of a knob or shaft which is equivalent to a very fine pitch screw but is not a physical very fine pitch screw. Easily achieved with differential pitches. Martin C |
Ady1 | 21/01/2023 01:34:14 |
![]() 6137 forum posts 893 photos | So its a gearbox? for slow speed |
Roger Hart | 21/01/2023 08:32:43 |
157 forum posts 31 photos | This reminded me of a Sci Am article - Vol 232 no 4 April 1975 in their Amateur Scientist section. Described a grating ruling engine built by Brian Manning for ruling interferometer gratings. The screw pitch problem was addressed by a fine pitch screw of sane tpi driven by a small motor/gearbox with a feedback system controlled by a small interferometer looking at the exact number of wavelengths moved at each step. Used a photomultiplier and a homebrew discharge lamp. All mounted in a big cast iron box to control temperature etc. This chap even evaporation coated in aluminium his own glass plates and made the diamond cutting tool to make the grooves.
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Michael Gilligan | 21/01/2023 08:50:01 |
![]() 23121 forum posts 1360 photos | Posted by Martin Connelly on 21/01/2023 00:35:39:
I have not read the patent beyond what is in the image above but I think the idea is to produce a movement 1/15000" per revolution of a knob or shaft which is equivalent to a very fine pitch screw but is not a physical very fine pitch screw. Easily achieved with differential pitches. Martin C . Then [assuming you are interested] I suggest you do read the patent. MichaelG. |
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