Bill WW

Great, Troy. I'll make some for the grandkids - and their parents for Christmas. From one mechanical engineer to another: if you have had your fluid dynamics courses, you know Newton had little to do with this. The puzzle is best explained by Bernoulli's equations, and demonstrated by an airplane wing - the moving air over the curved top of the inner part creates a lower pressure and lifts it out of the shell.

About leaving the vacuum pump running:I made a vacuum chuck for my lathe, same principle, vacuum holds the workpiece. I found that if you make the jig out of wood, air will leak through the pores in the wood and will loose vacuum. You can try to seal the wood with sealant, but likely the pump will need to continue running.

Great work, Charlie. First step in any shop project should be a solid way to hold the workpiece. You found a good one.

Thank you David, will definitely try your method!Forgot I did this Instructable. Wow, look at my finger and the Exacto knife in step#1! Someone should have yelled at me about that!Bill

Yes, I assumed a drill press, but maybe others may not.

Very nice jig. It is important that users clamp the jig into position before using it, as you show in the photos.

Of course it wasn't your intention to sound "supersmart", the author requested that we help him calculate the outward force: "...any have the moment of inertia calc for the outward force?"

Jeff, re: your question on outward force. At your rotational speed of 2.4 rev/s (40 mph and 4' radius) centrifugal force from an iphone 7 (138 grams) is 8.6 pounds. That is an acceleration of 28 g.

In my case it was an expensive lesson. Compounding the corrosive nature of salt water, here on Puget Sound we have a pretty extensive tidal range, which causes a pumping effect on the submerged phone.

Thanks for the tips. However, I found that salt water (sea water) is a much different problem compared to fresh water. I dropped mt iphone 7 overboard in 20' or so into Puget Sound. A diver got it back the next day, but it was quite dead, even a repair service could not help revive it.

Phil, I saw that slide rule also! I have mine (55 years) and my dad's (about 100 years old).The K-cups also make a nice container for mixing epoxy glue.

The "sharpened tube way of finishing it to round"? Where can we find out more about this, have not heard of it. Thanks.

I just set it there. You could glue it down, but it's not necessary. Let me know if you have any more questions. Good luck.Bill

Thank you for viewing my Instructable.I assume you mean the force when the solenoid is activated and touching the iron bar.Some manufacturers provide this information on their website. You may want to check.Otherwise, you will just have to find a hand held scale such as is often available for weighing luggage, such as this one: https://www.walmart.com/ip/TraverGo-Analog-Luggage-Scale-Black-TR1300BK/55187870You will have to tie the scale to the solenoid with the solenoid on the bar, then lift the scale until the solenoid breaks contact. The scale reading will indicate the magnetic force.Hope this helps.

Thanks for the comment! I apologize for the hype in the title: "...Supersonic Speed". No chance of hitting mach 1. Maybe with pressure on one side vacuum on the other? I looked at your chart and guessed that you got over 250 m/s. I had trouble with the end seals also, then made that holder thing.with the thin basket wrap plastic. My cannon still just sits in the corner of my shop gathering dust. But I inherited a couple of grand kids and I'll probably show it to them sometime soon. Good luck with the scout project.Bill

Nice work; I can always use another work holder! I use the same method of using weights when gluing items. Most of the exercise I get from the weight lifting weights is lifting them to the work bench.

Wow, thank you, Zig! Somehow I missed that article, I will print it out and study it in detail - with my physics book open. I have seen that reference to specific heat of air. Looks like you are new to Instructables? Welcome, you will find it entertaining. I've been pretty inactive for a few years. Appreciate the comment. Bill

This Instuctble Is as good as it gets. Great detail and clarity. It is 100% right-on (I do segmented woodturning a lot). I believe you can buy the segments from Jerry Bennet at Segeasy.com. Or if you are cheap like me, use a large 30 degree drafting triangle and make perfect 12 segment rings. Looks like we have the same lathe.

Ah yes, my good friend. It could have gone either way ;-)Since the border between these countries has changed over the centuries, both could have claimed ownership of the one-way valve. However, I suggest you petition the International Valve Agency and ask for a re-naming. Should the diode also be considered.So good to hear from you again.

A valid concern. But glueing a magnet on my drill has worked well for me for several years, no problems.

Mike, another great one, thanks.

I do this also, I use the magnet to hold the screwdriver bit. Perfect.

Nice work Linn, you do keep busy!All the best to you and family.Bill

Be nice, Markl. Arbodude has shared a good project.You are correct that the latent heat of vaporization is about 7000 BTU/gallon. But we do not know the air flow rate of 68 degree air. If his swamp cooler evaporates two gallons per hour (a lot of water) that is 14000 BTU/hr. He needs to source a lot of water, but that is part of the the game. Experiment and learn.

Excellent project Arbodude, thanks for sharing. Let us know how it worked for you.

OK, I'll try. Bill

I'm trying to stay retired, but projects pop up and I can't say no. I had a Popular Mechanics magazine from the late 40's that announced what became the ball point pen. But all they said was that a new writing device had been invented that could write under water.

Dumpster diving can be a gold mine at many companies. A friend of mine worked in R&D at a manufacturing company. He collected a lot of equipment and stainless fasteners from projects that did not work out.

Glad one of my Instructables could help you. Your son could climb a big hill with a 24 volt drive!Bill

It isn't a project. I entered a contest several years ago and they needed a video from me. I would have deleted it, but due to a glitch was not able to. If you want to see the solar powered Stirling engine running, there is a short video on YouTube. Just enter my name and "solar powered Stirling engine".Thanks for your interestBill Wells

First, where are you located? I hope I included enough metric units.Part of my problem is that I made the cannon four years ago and forgot much.1. The office tape may be a problem. For covers, I used a very thin plastic film, the green material you see in step 5 (and other steps). It needs to "pop" when punctured. The covers are held in place by vacuum; turn on vacuum pump, then hold one cover at suction end, have someone hold cover on discharge end while pump is running.2. Make sure the ball is all the way at the suction end of the tube before firing. Good luck and let me know how it goes.Bill

Thank you for your comment.Using US standard pipe sizes based upon ASTM D1785 specifications, following are PVC pipe dimensions:1 1/2" PVC pipe, schedule 40 1.610" 40.9mm1 1/2" PVC pipe, schedule 80 1.500" 38.1mm And the standard ping pong ball diameter is 1.57" 40 mmSo, using schedule 40 pipe there should be about 1mm clearance for the ball to fit into the pipe. You may be using schedule 80 pipe, which indeed will be too small. Good luck and best wishes.

Thanks kndclark.Yes, I believe you are correct. Close to speed of sound but not quite. But the title does get attention. I hope somewhere In small print I said "close" or "maybe".I believe supersonic speed could be reached with compressed air on one side and vacuum on the other. I have not tried tat yet! Bill

Good thoughts , Carpenter. Someone in my woodturning club had the design details, but of course now I have lost my copy. Darn, now that I need it. (1) There are a lot of carbide tipped turning tools out there now, like the Easy Wood tools. And I occasionally abuse some of my saw blades without damaging the carbide tip. Have knocked the saw tooth tip off, however - another story.(2) Good point about the tooth profile. (3) Yes, we would need to consider the rake angle, good point (no pun intended). Maybe I will finally find the plans.

I have also seen a design for making a woodturning parting tool from a saw blade, but incorporating the carbide tipped tooth. Thanks for this Instructable, I need a marking knife.

"Awsome"? "Awesome"? I didn't notice. What I liked, other than the design, was learning a new word: TUBIFY.

Your cookies look much better than the woodworking and electronics projects I usually look at on Instructables. And you do not have to think about blocking these "cookies" from your computer!

Fantastic! But now my car will be forever banished from the garage.

Great, and your design raises the cooling fan inlet so air can get in. On my Dell the fan inlet is pretty much blocked right there at the back.

Very nice, and drilling the hole in the corner is a valuable feature. For those nice tight glue joints you made, you do not need much clamping force so "spreading the angle" should not be a problem, and you have the metal square behind to check. Good work, thank you.

Be sure to use original JB Weld, not the "quick" variety.

Really good shop storage option; I like the lip at the top which keeps the boxes stacked.

HA! good joke.

Oh, I wondered... my misinterpretation. Maybe we should go metric and say your motor is between 2kw and 6kw. I think you need a major scale-up here, that is like 10 times the power I tested. I doubt the brake blocks I used would work in your case. It would be best if you did not just clamp down on the motor shaft only, you should have something like a brake drum. Remember the key equation: Power = torque x RPM.

My workbench is much more messy now compared with four years ago.

​Maybe not too much, in my tests, the AC motor tested 0.15 HP, the DC motor 0.35 HP. Your engine I assume is 3/8 HP, or 0.375 HP. Pretty close. The main thing to be aware of (and be careful of) is that when you clamp down on the Prony brake it will heat up fast; and even faster for higher HP engines. You may want to make modest changes to the design, just use the equations I listed. Good luck with it.

Your bearing press jig is the key; I'm going to have to rig up something for tapping straight. I'm using the same cutter as yours. I made a decent threaded box with my prototype #1 jig, but it only has a 1" x 6" long lead screw. I would like to use a long section of 1" 8tpi all thread as you did, but can not find it locally - it needs to be perfectly straight, as yours seems to be. Where did you get that all thread rod? ThanksBill

Thanks for your comments and valuable suggestions. Yes, I am now rotating the LCD more often, which does help. My "new" problem with the S9900 is that Nikon packed so many buttons and dials that my fat fingers often hit the wrong keys. But I'm learning...Bill

Thanks Daniel - Patching only goes so far, as you know. This year I broke down and had a new roof put on! I live in Olympia. Bill

Thanks BtheBike. Yes, should help in both Winter and Summer. The only downside, of course, is that it will block your view out those sliding doors!

Nice work, including your guitar music.So you cut 8 tpi threads with your jig; have you tried other lead screws for cutting other tpi? And did you post photos of your tapping press addition? I'm ordering the 60 degree cutter tonight, so I'm on my way to a threading jig for my lathe.Thanks much.

Nice project, thanks. Your method is better (in some ways) than using a machinist's V head square, which is small for large items.But I initially stopped at the first method, with carpenter's square and speed square. I think I understand the method, do you just measure out 1/2 way, draw a line, and repeat?

Thanks - I should have figured that out, obviously did not.