Chinese "precision" levels

[rhb]

I just received a pair of Chinese 0.0002"/10" levels, a 6" and a 6" x 6" which I thought might be of interest here.

https://www.amazon.com/Nakkaa-Precision-Straightness-Parallelism-Equipment/dp/B0B2R3SQB2

https://www.amazon.com/ALL-CARB-Precision-Frame-Spirit-Level/dp/B0971ZDJL5

I put some Canode on a grade B surface plate and spread it with a soft rubber printer's brayer. You can see the results in the photos. It was immediately obvious that the vertical side of the square was very flat from the resistance when I slid it across the surface plate.

I don't have a proper reference to test the squareness, so I'll leave the horizontal face alone until I do.

I've not checked either by reversal yet, but adjusting a level is not a big deal. The square came with an adjusting wrench.

I should note that I was given some 0.0002"/10" bare vials. While I was setting one up to sense electronically I bumped the teet on the end. After the fluid evaporated I could see that the vial was not uniformly ground over the entire length. It's very difficult to see and impossible to photograph. You get what you pay for. However, as I typically place the level on the carriage when I'm leveling a lathe the lack of flatness really doesn't matter. When I checked my Clausing 4902 yesterday with my 8" 0.0005"/10" level it became apparent that the floor of my shop had tilted a few thou in the last 3-4 years. That side of the shop is on about 5-6' of fill, so that's not at all surprising. I did observe a 0.0005" twist between the extremes of travel which I'll correct later today. To center the bubble I'll just put a feeler gauge blade under one end.

Have Fun!
Reg

 

[jccaclimber]

Frankly that doesn't look worse than the brand new "hand scraped" Starrett I got a few years ago:
https://www.practicalmachinist.com/...starrett-box-label-before.404748/post-3959901

 

[rhb]

OMG! I'd seen the start of that thread, but didn't read far enough to see your post. What an embarrassment! I use a brayer to ensure that I have a very thin layer. I have wracked my brains trying to figure out an affordable way to measure the thickness, but so far no success. Easy to do with a few $100K of stuff. Much harder without it.

However, I just got some LVDTs including a B&S/Tesa 599-988 lever unit. One of those might work with a pair of ground disks, one pressed onto the spotting medium and the other on the plate.

The only thing I can compare to that Starrett level was when the support guy for an $80K a year annual maintenance fee program said, "If you find a solution, would you send it to me so I can give it to the other customers?" They had to scrape me off the ceiling with a putty knife at work.

20+ years ago I started buying Chinese calipers, mikes, etc for personal hobby use from Enco. I also bought a B grade gauge block set and tested them. They all passed. It was insanely time consuming, so I've never retested them, but have been thinking I should despite the limited usage.

I've debated sending the levels back, but in truth if the vials are good I can fix the rest without a lot of trouble. As I now know what to look for I'll be taking the levels apart for more detailed inspection of the vials. Chinese 0.0002"/10" vials are around $10. An equivalent spec UK made vial is $75. At tier 1 prices the two levels would go back in a heartbeat. Accompanied by a scathing commentary. At what I paid I don't mind providing a bit of sweat equity.

I wonder if they are not deliberately ground to be low in the center so they don't rock. Rocking would be *very* conspicuous on a 0.0002"/10" level. I suspect that the number of buyers who would spot them on receipt is tiny.

 

[rhb]

I put both under an LCD microscope and the vials are fully ground. Whether they are correctly ground is yet to be determined. I think I need to cobble together a differential screw adjustable table that lets me tilt them known amounts.

It makes sense that reject vials would show up on Alibaba for cheap. Certainly lots of reject RF connectors show up on ebay. Most of the name brand connectors from Amphenol et al are made in China. Hard to imagine a Chinese manufacturer melting down the rejects. Just sell them off cheap to whoever will buy them. I've gotten M-F SMA connectors which could not mate to each other.

 

[jccaclimber]

Measure the volume of your blue. Measure the surface area you spread it across. Calculate thickness. Imperfect, but better than nothing.

 

[Tyrone Shoelaces]

0.0002” levels aren’t really for general shop use. My “ go to level “ for 30 years was a “ Wyler “ 0.001” in 10” level. When the customer/job got fussy I had a bigger “ Hilger & Watts “ that worked out at 0.0005” in 10”.
I once bought a very nice “ Hilger & Watts “ box level that was 0.0001” in 10” but I soon got rid of it. It took too long to settle. You could place it down, go and get a coffee, and it would still be moving when you got back. Long jobs were taking an age.

Regards Tyrone.

 

[rhb]

jccaclimber: Good point. I really simply need to calibrate my eyeballs. Metering some canode out of a small syringe would do the trick. Thanks.

Tyrone: Quite agree. I mostly bought them out of curiousity and low cost. Bushwacked by an Amazon ad while looking for something else. Likely the sole benefit of the 6" level will be the knowledge gained from making a setup to measure the accuracy.
I spent 2 hours yesterday checking my lathe bed ways with my 8" 0.0005"/10" level. Objective was to measure way wear. Keeping that in range was difficult and took trying several combinations of feeler gauges to find a combination that didn't overrun the range of the level. The 0.0002"/10" would have been completely useless.

I took readings every inch with the level on the carriage wings. Those are 11" wide so converting the readings to an accurate profile will take careful thought. I still haven't quite figured out that and the geometry of the tenth indicator on the tailstock way will be even worse.

Have Fun!
Reg

 

[Tyrone Shoelaces]

Best level I ever had was an “Hilger & Watts “ electronic level. I borrowed it to level a long planer bed. The readings were instant and you could switch the scale from 0.001” in 10” to 0.0001” in 10”. You could also switch it off and the pointer would return to “ 0 “. I used to joke with guys with it switched off. “ Look at that, bang on all the way down ! “

Regards, Tyrone.

 

[rhb]

I've put quite a bit of thought into electronic level design. There are some short range optical distance sensors with phenomenal specs that are very cheap.

I tested one with a very crude lashup and a mike. I need to revisit that. I'm easily distracted but I keep coming back so lots of things do get finished eventually. My biggest problem is lack of organization and the resulting clutter. Plus 5000 sq ft of stuff Dad left me to deal with :-(

Another option I've considered is a pendulum in a plastic tube with 4 electrodes forming a capacitance bridge.

However, with a new $50 LVDT from ebay, a Talyvel clone is a strong competitor to the other sensor options. Especially with all the photos of one that were posted here.

 

[J_R_Thiele]

Regarding calculating the thickness of bluing by how much is applied and the area covered. Calculate the density of the blue using as large a volume as you can (or ask the manufacturer). If you know the density you can weight a small amount and calculate the volume. You can get sensitive electronic scales for reloading at a reasonable price, making it easy to measure small weights. I do not know of any commonly available device for small volume dispensing. Of course, you could always make your own with some tubing and a micrometer...

If you really want to know the thickness--- examine a scraped surface that has been blued up and rubbed on the plate to polish the highspots. Find a polished highspot with an adjacent area where the blue just touched. Take a good picture of it so you can find them again. Wash off the blue- then use an optical flat and measure the lines between the polished high point the location the blue just touched. Better yet- find 10 or 20 pairs and measure them so you can see if the results are consistent.

 

[rhb]

Troublemaker! I just ordered an 80 mm flat from Ukraine for $59. It's all your fault ;-)

Of course now I have to make the box to hold the mercury vapor lamp, first surface mirror and Fresnel lens I've had stashed for several years for building a monochromatic light source.

I am going to get the smallest volume syringe to measure the volume. As a SWAG I'm putting down a layer which is much less than a tenth.

 

[jccaclimber]

If you can get a dark room for your flat, you can use a cell phone with an app to hold the screen at a single color. A brighter monochromatic source would be better. I’ve been very happy with my former USSR flats sourced from Ukraine.

 

[rhb]

I bumped my order to 2 and the markings are CCCP. I use a flip phone, so apps are a non-starter.

My accumulation of the parts for a proper monochromatic light source should say something about my level of interest ;-) I scanned trash heaps for years to find the parts. If I'm lucky I might even make a flat.

Before I quit my job with big oil to look after Mom and Dad I wanted to get a job as an instrument maker at a university in a town of 30-50K. But academia has become so corrupt I wouldn't touch that with a ten foot pole now. When I was in grad school I got to know some of the staff doing that and thought it would be huge fun.