Tool Tuesday Ep. 6: The Fell Precision Level 

Me too ..walhalla❤

That seems to make sense...

I just measure it and get it right.

Not sure if this is correct, but I was told to check levels on a reference surface, by rotating the level exactly 180 degrees in place to check the calibration. If the level is true, the bubble will indicate identically in both directions.

Trying to level a surface plate to this accuracy mounted on a rubber mat on a wood floor is a waste of time.

At some point, this is the perfect example of "leaving good enough alone". Otherwise you may want to read into old greek mythology and find some sympathy for Sisyphos.

HIGH $POT'$...it all start's with high spot's , then it's called an accumulation of tolerance's , and then you are called to the foreman's office.

Potential Biden Ukraine re-armament infrastructure spending, bringing back lots of good paying jobs sorely needed today!

Born and raised there when everything left town (70s & 80's)... Ingersoll Milling Machine, Sunstrand Aerospace, Testor's, Atwood, Rockford Products, National Lock, on and on. I lived within walking distance of Ingersoll's main plant on Main... and went trick or treating at Seth Atwood's house (he gave full-sized candy bars). The Fell Precision Level company is not one I had heard of before. Thank you for showing the tool.

I wonder if gravity might have an influence?..

OCD makes the machinist mind go 'round.

Agreed!

He left it hanging a bit, so others stepped in to fill the void.

yep. Beyond me how he talks about "one is off" instead of just rotating it.

@@FireGodSpeedif they’re both reading different values, then 1 is definitely off. Maybe both. Yes, it is beyond you.

But to self check either level, turn it 180deg. The bubble should end in the same place. No matter how ‘out of level’ the surface is.

​@@DB-thats-me That is a good idea in theory but at that scale of resolution you would never be able to rotate it exactly 180 by hand and there for it would look like it is off but may not be. You would need to have a vary precise jig to keep it in the exact same spot.

Usual way is place a straight edge against one side, turn level and re-lay against straight edge. In this case, your not testing for ‘level’, your testing for repeatability. There is an oblique angle that MUSY be level when transitioning between +slope to -slope, and vice versa.

Cosmic rays will bend it.. maaaan! Seriously, a friend of mine helped develop a trixial connection to wafer chucks and even with the whole thing shielded by metal, after zeroing the leakage current out at night, the long term leakage measurements would go up and down, up and down with the days. The cause? COSMIC RAYS emenated from the Sun.

I'd sooner suspect changes in the rubber pads he mentioned.

I wonder if the Fell Level was used in building the LIGO (Laser Interferometer Gravitational-Wave Observatory)?

At 4:00 or thereabouts he says why he does or does NOT do that with this particular level. TLDW?

@@silasmarner7586 Yes, except this is also how you check a level for accuracy. I know, because I have dropped levels and bent them and that's how you know it is bent.

@@silasmarner7586 He is referring to not having to rotate the level 90 degrees because it's dual axis. Precision levels should ALWAYS be rotated 180 because by their very nature they are self proving. If you rotate 180 and the bubble stays to one end of the level, the level needs adjustment, if the bubble stays to one end of the work the level is calibrated. TLDU?

Yeah - bummer to miss the initial level check. That 180° flip tells a story about everything that happens after.

@@SPDLTD no difference; it should settle in the same quadrant if calibrated. I do not know how to adjust that particular level if it is out of calibration. But based on the check with the 199. it is damned close :). But according to the old proverb; a man with a watch knows what time it is; a man with two watches is never certain.

Why would anyone hand scrape anything with the machinery we have today ? Seems a backwards process ?

@@jafo766 , there are at least two reasons. First, engineering is all about building things at acceptable cost. Scraping is relatively fast and is able to greatly improve the flatness of a surface. Second, a scraped surface is more like rolling countryside where the tops of all the hills are at almost exactly the same height. This reduces friction and provides a reservoir for lubrication if that is desired.

My Gerardi vise in not hand scraped ? I know of no hand that can produce a better flatter finish than a surface grinder ? This reminds me of guy's who think they can sharpen drill bit's by hand ?@@stuartschaffner9744

He did have it backwards--but given how often I make the same mistake, I decided not to say anything. Like me, he figured it out the first time he moved the screw and the bubble moved the wrong way.

Yeh, I even do it with my spirit level, just for fun - and accuracy of course

I want to be one the level here, yes you can...

His table is cushioned by rubber , perhaps the density of rubber mounts is to be considered ?

I used to work for a company that made very high end CNC machines. Micron to sub-micron stuff, everything measured with interferometers. Deep, optical mirror finishes straight off the machine, no polishing. One of our machines was so sensitive that, in spite of it weighing a ton and sitting on a very thick concrete lab floor, building works elsewhere on site, which were not audible to us, showed up in the surface finish. Impeller noise from temperature controlled oil pumps located ~30m away which fed the bearings, showed up in the surface finish. Our temperature controlled lab (+/- 1C IIRC) wasn't stable enough, so a double skinned poly tunnel had to be constructed around the machine. I was told that if anyone went into the inner polytunnel the extra body heat would put the parts out of tolerance and/or be visible in the surface finish. I was so glad to be on the software/electronics department and not have to deal with that madness. I went back a few years later and they had a large (couple of metres on a side) CMM in another lab. It was installed on a huge vibration isolating platform to isolate it from people walking alongside. Interesting place to work but despite best efforts, physics always shows up and kicks ass.

Tom on OxTool refilled one, i think he said it was alcohol if i remember correctly. It had a very distinct smell he said. The video is within the last couple years.

Good call, Ill have to check it out. And where has old Tom been lately? AWOL.

I was just thinking the same thing, that would be super trick.

But what if you also have a naval observatory time beep every hour? Really, levels are so easy to check and calibrate and so reliable there's no reason you couldn't check with 2, 4 or a dozen and get the same reading.

The two levels may be well calibrated and will never coincide due to the surface of the stone (no matter how good it is) has small variations (within the stipulated tolerance) as the levels have bases of different sizes and are in different points of the stone, these variations are reflected in reading. This is a phenomenon that occurs with all high-precision instruments, which is why in any measurement there is always a range of tolerance allowed for both instruments.

Isn't it mineral oil?

Looks like mineral oil to me, not water.

Its methanol i think 😊

Sublimation is when a solid skips phase change to a liquid and goes directly to a gas. Water doesn’t sublimate at atmospheric pressure. Evaporation might be the word you’re looking for but as previously mentioned, this probably isn’t water. (Even if it was, it can’t sublimate and won’t evaporate from a sealed container.)

@@Jay22222 at freezing tempratures it does , thats why and also the lower viscosity , methanol is the fluïd used. Lower viscosity let the bubbel move fast even with the slightest movement or mis alignment. Grtz from the netherlands Johny geerts

keith rucker showed the level moving with him walking around his shop. these levels are crazy sensitive id never seen such a precision instrument.