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If ever break a tap here a low cost machine. https://www.aliexpress.us/item/3256807236835449.html?ug_edm_item_id=3256807236835449&pdp_npi=4%40dis%21USD%21%24668.44%21%24244.66%21%21%21%21%21%4021410e8e17409930996665071d56b8%21%21edm%21%21%21&edm_click_module=alg_product_3_5731715720&creative_img_ind=4&edm_log_data=gmod-edm-item-list-three-columns.track-edm-item-list-three-columns-log-link&tracelog=rowan&rowan_id1=aeug_edm_92102_1_en_US_2025-03-03&rowan_msg_id=gunsCOWS_92102_%2443728ba50a6446c5920855ae62c76158&ck=in_edm_other&gatewayAdapt=glo2usa

?? Sextant vs GPS ?? Part 1 of 2 GPS is the most accurate around 40 inch or 1 meter. The drawback list. Satellite ? and other countries take out Satellite and space debre Sun spots Thunder ? Power aka battery dead About anything effecting electronics. ?????? The Sextant While the theoretical maximum accuracy of a celestial fix is 0.1 miles, in reality you will probably never achieve closer than 1 mile. How Accurate is a Celestial Position Fix? The theoretical accuracy of a celestial position fix is based on the accuracy of a sextant. Most sextants let you measure angles to within 0.1 minutes of a degree. 0.1 minutes {6 seconds 0.12 miles 600 feet at equator } on the altitude of a celestial body translates to 0.1 nautical miles on the surface of the earth. In reality, however, it is almost impossible to actually achieve an accuracy of 0.1 minutes with a sextant. You are taking your measurements from a moving boat, which is floating on a moving ocean. The horizon needs to be clear, and the celestial body needs to be a perfect, bright speck. It is far more realistic to get an accuracy of 1 minute with a sextant in day-to-day conditions. An accuracy of 1 minute with the sextant implies a final position fix accuracy of 1 mile. With some reading in WW2 the Navey found it 1? with a good operator most was under 5 miles . Of course, getting that sort of accuracy relies on minimising every other source of error. Unfortunately, in celestial navigation, there are plenty of potential sources of error: . Errors reading the measurement from the sextant Errors identifying a celestial body Potential inaccuracies in your chronometer Errors in identifying prevailing atmospheric conditions Errors in your calculations Rounding errors Errors plotting the final fix operator holding the sextant On plus side is no power need No satellites Works with Sun spots Works when electronics does not No power need or batteries Fortunately though, practise and precision can be used to reduce or eliminate most of these errors. We can therefore say that an experienced navigator can realistically expect an accuracy of around 1 mile when completing a celestial position fix. Beginners, on the other hand, will be lucky to achieve an accuracy of 10 miles the majority of the time. Dave [img]https://th.bing.com/th/id/OIP._r0SgDl4wmCPBVt4pQVWSAHaFj?w=166&h=124&c=7&r=0&o=5&dpr=2&pid=1.7&PC=EMMX01[/img]

Most production machine Shop will have this for both quoting and doing. This also used in design and engineering so can receive the finished whan on part. This finished can change the cost of making the parts. This where I used is beside the drafting board. First start with black plastic and later purchase the chrome one for better view. So if see this on drawing you know more about why. Dave

Here little data on magnetic north vs true north.

Designing a small BUBBLE SEXTANT & build . Here my first drawing of a Pocket Bubble Sextant. Please comment Dave Note PDF file is a clearer drawing

Photos of machine shop in 24" kitchen cabinet plan to be in a Armoire as remember Dave

The following items have been added to the Files area of the [email protected] group. /5)Charts_&_Tables/HARDNESSTESTER Hardness (3) (1).pdf By: davesmith1800 <davesmith1@...> Description: A simple hardness test using a paint stick and 3/8" hardened ball from a ball bearing

Here photos of my cross feed exstension. I polished by using the threading die chuck die in the lathe chuck. Then screw thread in the tailstock. Put the on slow and ran the die over the thread over the threads about 5 or 6 times. The last photos of the nut on cross slide is from the internet I did not to disable my lathe. Dave

Sextant tap and see how works . Note hos mirror moves then plumb to the horizon

Building ideas & History The history of navigation dates back to ancient times, with significant developments in various civilizations. The first part Celestial navigation, use of landmarks, and early navigational instruments Celestial Navigation: Ancient navigators used the positions of celestial bodies, such as stars, the sun, and the moon, to determine their position and direction during travel. The North Star (Polaris) was particularly significant in the Northern Hemisphere Use of Landmarks: Sailors relied on visible landmarks such as mountains, cliffs, and coastlines to orient themselves. When landmarks were absent, they used dead reckoning, calculating their position based on speed, direction, and elapsed time Early Navigational Instruments: Tools like the astrolabe, a device for measuring the altitude of celestial bodies, and the compass, which provided a way to determine the direction of travel, were crucial for ancient navigation These techniques and tools enabled ancient sailors to navigate vast oceans and uncharted territories, expanding trade and communication across vast distances Indo-Pacific Navigation: Began with the Austronesians from Taiwan, who spread southwards into Island Southeast Asia and Island Melanesia around 3000-1000 BC. They used tools like star navigation and wave detection to navigate the Pacific Greek Navigation: By the third century BC, the Greeks began using the Little Bear (Ursa Minor) to navigate. They also used circumpolar stars to determine latitude Chinese Compass: In China between 1040 and 1117, the magnetic compass was developed and applied to navigation, allowing sailors to continue their course even when visibility was limited Portuguese Exploration: In the 16th century, Portuguese explorers took the lead in long-distance oceanic navigation, opening a network of ocean routes covering the Atlantic, Indian, and western Pacific oceans. Modern Navigation: The invention of the sextant in 1757 and the chronometer in the late 18th century revolutionized navigation, allowing for accurate determination of longitude and latitude. Open to public after 1983. The Global Positioning System (GPS) was developed in the 20th century, transforming navigation into a modern technological marvel . Flight 007 from Alaska to Japan open up GPS. THE EVENT (Korean Air Lines Flight 007 (KE007/KAL007)was a scheduled Korean Air Lines flight from New York City to Seoul via Anchorage, Alaska. On September 1, 1983, the flight was shot down by a Soviet Sukhoi Su-15 interceptor aircraft. The Boeing 747 airliner was en route from Anchorage to Seoui.) This even that open up GPS TO World