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1. ### The North Pole

Make yourself a solenoid. Then, use the right hand rule on the (conventional) current to identify the North pole. Then use that to identify the polarity of the compass needle. More here... https://physics.stackexchange.com/questions/337822/direction-of-magnetic-field-in-a-solenoid
2. ### Everything is Becoming Magnetized! Help!

The on axis hole between the magnets in your device is ok but really isn't needed. The technique I use is to hold the tweezers (or whatever) perpendicular to the spinning tool and a short distance in front of it; you'll need to resist the attraction of the magnets, the tweezers shouldn't touch...
3. ### Everything is Becoming Magnetized! Help!

If you don't have a soldering gun or a bulk tape eraser, make one of these... https://www.homemadetools.net/forum/diy-demagnetising-tool-works-72881#post203385
4. ### Mathematical question

What you suggest is exactly what I used in my earlier post (post number 29 in this thread). However, one must do the math to understand why the number of rotations has that '1' added to the ratio of the radii of the two circles. Go back and read #29. The math is trivial, involving nothing...
5. ### Trying to get flame licker to run

Clean the valve and the surface it sits on thoroughly. But, more importantly, preheat the cylinder; hold it in the alcohol flame for a minute or so prior to trying to start the engine. If the cylinder is too cold it will quench the flame (i.e. suck the heat from it) before the valve can close...
6. ### Mathematical question

Easy to say after reading what I posted last Sunday to your other thread (Reading, understanding and following instructions)... A coin of diameter 2R is held stationary while a smaller coin of diameter 2r is rolled around its circumference until it returns to its starting position. How many...
7. ### Reading, understanding and following instructions

A coin of diameter 2R is held stationary while a smaller coin of diameter 2r is rolled around its circumference until it returns to its starting position. How many revolutions does the smaller coin make ? The number of revolutions (N) can be found by dividing the distance the center of the...
8. ### Demagnetize

A soldering gun (not iron) will work for small items. Stick item in loop that forms the tip (not touching the tip), turn on gun, withdraw item slowly to a distance of three feet or so before turning gun off. A larger loop tip can be made from heavy gauge copper wire. Look at yard sales...
9. ### Brian builds Atkinson Engine

If you can tolerate slightly elliptic sections instead of perfect circular arcs, then tilting the mill head (if that's possible) and traversing the table will do it. See my RADIUS program for the necessary computation.
10. ### Accurate cross holes - without a jig.

Or, if your geometry permits, mount the work in the vise such that a small portion of the jaws aren't grasping anything. Use your indicator/edge finder to find the middle of this gap. In effect you're using your vise jaws as improvised caliper jaws.
11. ### PM Research No. 1 Build

Your argument makes sense. Modern commercial nuts are often chamfered on both sides. If the chamfer is there for your purpose, as opposed to just making them burr-free, then it would be logical to chamfer both sides so the operator can't get it wrong.
12. ### PM Research No. 1 Build

For model nuts, I use... D = major bolt diameter 1.5*D = across flats nut size 0.9*D = nut thickness I've always mounted nuts with the chamfer/rounded side up. I'll be interested to hear an argument for inverting that choice.
13. ### Yet another Quick Change Tool Post

Another use for the Al holders is to hold a wiggler to aid in centering in the fourjaw. I prefer to use a pump center but some folks like wigglers. Like Bogs, I can't imagine that the grade of steel for toolholders is a major concern. The loading at which toolholder strength becomes an issue...
14. ### Yet another Quick Change Tool Post

Ian, If you set up in production mode to make tool holders, consider making four or so solid ones in aluminum to use as holders for stuff other than cutting tools. I use one for a DI to center stock in the fourjaw and another to hold a Dremel as a poor man's toolpost grinder. The more you use...
15. ### gripping the inside of a small hole

How about getting a pair of those snap-ring pliers that have jaws that open when the handles are squeezed. Grind the points down to the point where they will fit into the banana jack, It wouldn't provide a wonderful grip but it might be good enough for your purposes.
16. ### I can't quite place my finger on it...

Indeed, although a rollicking good performance of the lumberjack song... http://www.youtube.com/watch?v=5zey8567bcg will still have me laughing until I hiccup. Anybody remember John Cleese as the minister of silly walking? http://www.youtube.com/watch?v=IqhlQfXUk7w I think of this sketch...
17. ### I can't quite place my finger on it...

Steamer, I don't want to talk to you no more, you empty headed animal food trough wiper. I fart in your general direction. Your mother was a hamster and your father smelt of elderberries. ;D
18. ### I can't quite place my finger on it...

I know you lot are weird, Bogs, but it's still a bit of a push. Imagine getting up in the morning and saying to yourself (I'm pretty sure this guy talks to himself), "Today I'm gonna don my kilt and my Darth Vader helmet, grab my bagpipes and unicycle around the parking lot in full view of...
19. ### I can't quite place my finger on it...

There's not "something" wrong. EVERYTHING is wrong!
20. ### Cheap and quick solution to a problem

No, Ron, this is what I use to mix the martinis...