Bridgeport for Beginners!

Thanks Matt! And it was just what, 9months ago and I could barely spell bridgeport and now I am one?
It is a great adventure! My mechanic tonight was showing me a bunch of locally made tools that are priceless for working on jet engines and aircraft. 5 mins surfing fleabay got me thinking....
There is a TON of stuff guys need at AFFORDABLE prices to help them do their jobs on aircraft. Who knows, might be a fun way to help some people out, learn a thing or two and make a couple bucks in the process??? I know, my mechanic is happier than a pig in shit! Today I got yet ANOTHER new challenge.

Ya see, we have a need to very carefully pressurize aircraft fuel tanks. I'm talking like 1psi, NOT 2! With this tiny amount of air pressure and defueled tanks, you can run around with a spray bottle with soapy water and find where the problems are.

This should be a real no brainer. We already have the acrylic. It installs where a fuel cap goes. I think it needs a safety regulator... And NOT harbor freight either!
Any thoughts from the peanut gallery, I'd like to hear 'em.

 

I've been using a homemade H20 manometer that I originally designed for my wood dust collection system. It works a lot like a Peto tube, measuring air speed or vacuum.

I use it every time in my furnace to measure the PSI in water column now, for combustion air. I have found air is just as important as fuel with a pretty good mix. I haven't gone into this with trials as I would like to demonstrate it at least five or six times with constant outcomes.

Edit; I tested my own natural gas, with the same set up, at 8 inches of water column.

 

It be hard for me to send a board with a hose on it filled with water and food coloring out for calibration. One thing about us, if it's got a gauge on it, it better have a current calibration sticker on it when the man with the black hat rolls in!

 

True, but water column gauge that are certified are still out there. As well, mercury gauges are out there.

Water is a constant, mercury is a constant and gravity is a constant.

Edit; our geological reference to our oceans are also a reference.

 

You need a one pound weight on a pivot acting on a diaphragm disc valve with one square inch surface area: no regulator to jam and blow up a fuel tank like a balloon. Easy to calibrate with a digital balance too

 

but, what if you had 28 inches of water column? What would that equal in psi?

 

That's easy!: https://www.efunda.com/formulae/fluids/manometer.cfm gives a result of 1PSI

 

At the tallest mountain in the world, would this be the same? Or would there be any mixture between? Would there change in the balloon pressure?

 

Well as it varies with altitude, it can be used to test altimeters, I used to help my Dad do that as kid in light aircraft with a water manometer sealed at one end and a look up table.

 

I am doing this same thing with my flight instructor with density of air. I'm questioning 10,000 feet versus 20,000 feet and I feel it like I'm stepping on toes.

I've never cruised over 7000 feet in a personal craft.

 

It may come down to how knowledgeable to instructor is about basic physics, there are people skills needed to please the person and get your qualifications. The local state system of training colleges here believes that there is no need for instructors to have subject specific knowledge about classes they teach, so long as you have their certificate in workplace instruction qualification you can teach any topic at all. I had a friend storm out of a marine engineers course as the textbook had a cut-away diagram of a diesel fuel injector with labels like "Pintle" "Nozzle" and "Fuel line" that was labelled as "Boat winch" and the instructor insisted the textbook was correct. There have also been mass walk outs by prison guards doing a firearms refresher course as the instructor could not get a magazine into a pistol and another walk-out from a shot firer's course to handle explosives. Just been waiting to see if they offer brain surgery the same way too .

 

That's not entirely accurate, what you and your Dad did worked because of the way the manometer was sealed so the water column would be supported by air pressure and atmospheric air pressure varies with altitude and weather conditions.

The pressure exerted by a simple straight water column open at the top is a function of, the height of the water, the density of that water and gravity. So 28" tall water column will exert a pressure of approximately 1 psi at its base, anywhere on the surface of the earth. I underlined approximately because water's density changes with temperature and gravity changes with location, https://en.wikipedia.org/wiki/Gravity_of_Earth. The effects of temperature and location are rather small so for most practical purposes can be ignored.

 

That makes sense, my O2 system has a blowout disc if the pressure gets too high. I wanna look closer at what the fuel guys are using. Seems this thing just holds 1psi differential pressure. I cant tell from the photo how they are accomplishing this.

 

While cruising my favorite scrap yard, I find this!



OMG, could it be another KURT? Who cares, it was 50bucks and had the swivel on it! I couldnt get the cash outta my pocket fast enough. It had a customs and border patrol sticker on it. After I took it off the swivel, it's not a kurt. No worries. The pin on the swivel didnt fit my kurt. That's easy to solve.



Used the press, shoved it out, turned it down on the lathe and pressed it back in. Here is the trial fit. Works like a champ. Now for some cleanup and more obnoxious blue paint and I can get rid of my tired old bridgeport vise. Any one want it? Just pick up shipping and it's yours!

 

YAHTZEE!!

 

Very well done! Color matched and everything. Surprised you were able to restore the numbers on the measurement part. Those don't usually shine up well in my experience.

 

I know Oxtoolco pooh poohs swivels, but I like having it.

I cleaned up the numbers with a brass wire wheel on the buffer, then 400grit followed by 600grit, then a buffing wheel. Good enough for me. That's the same blue I painted the vise with. If ya go too aggressive, ya lose the numbers.

 

I too do not like using a swivel. There's just too many variables introduced and things to go out of whack. Most of the time you can flip the block in the vice to do angles. For doing compound angles (which is rare), I will put a grinding vice in the mill vice using angle slip gauges or sin bar. For more accurate angles I'll put up my tilting rotary table.