Precision Level Problems

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FireLance
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Precision Level Problems

Post by FireLance »

Hi all,
I’m new to machining and just trying to learn as I go. I find a great deal of assistance from YouTube and forums due to the lack of mentors in my immediate friend circle.
I’m having a great time of it, although things take longer than they should and with more attempts.

I have lately run into a problem that I can not solve by reading forums and watching tube.

Last summer, I purchased a lathe and to “level” it a also bought a Findmall 12” Precision level (0.0002/10 inch). It cost about $115 and I know “nice ones” can be much more expensive.
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I have watch the videos and read forums here on proofing and calibration of these levels.
The level was calibrated when I received it and I used it to level my lathe.

Some of you will get a laugh out of the next part.
I took the level out a couple days ago to better understand the calibration process. As I said it was calibrated right out of the box and I didn’t have to touch it to level my lathe. I purposely moved the adjustment screw to throw it out of calibration so I could bring it back in.
Let’s just say that I have learned a valuable lesson on “not fixing things which are not broken”.

I have followed all the procedures that I find on this forum.
1. I’m working on a fairly level flat stable piece of granite.
2. I spun the level 360 degrees until I found an area in which my small bubble read level and marked the outline of my level on a piece of paper which I taped down.
3. I flipped the level 180 degrees and attempted to slowly adjust the bubble in small adjustments at a time.

When I start the bubble is buried at one end.
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I can adjust it to center (I have tried lesser adjustments)
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but when I flip the level 180 the bubble is again buried. The adjustments necessary to move the bubble back even a little are enough to bury the bubble again upon the next 180 flip.
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It a viscous circle that I can not figure out.

The level was never damaged and like I said started this whole adventure calibrated and working normally. Any help would be greatly appreciated.
Rich_Carlstedt
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Re: Precision Level Problems

Post by Rich_Carlstedt »

I worked with a laser level and had the same problem and frustations
So I took it apart and found the "pivot" end was not fastened and was floating
Apparently the manufacturer (in China) set the level and then glued the setting.
Moving the adjustment meant breaking the bond and resulted in no way to set the sensor. ( laser tube)
Taking it apart and fastening the end solved the problem

rich
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Harold_V
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Re: Precision Level Problems

Post by Harold_V »

One thing that comes to mind is that the "surface plate" (the piece of granite) isn't level (or flat) to begin with. If that's the case, you'll never accomplish the task by the method you're pursuing.

Fact is, the surface plate NEED NOT be level. It just makes adjusting easier. You can still accomplish the task you now must perform.

Start with getting the surface plate as close to level as you can with the level in the near proper adjustment. When you turn the level 180° make sure you place it in the same spot so you are comparing against the same surface (sounds like you already have that figured out). You'll do that by trying the suggestion, below.

Instead of trying to get the bubble in the center, try getting it to stop in the same place when the level is rotated. If you can accomplish that, you will know that the surface plate is off by the amount the level indicates by the offset bubble. If that is the case the bubble will favor the same side when the level is rotated. If it follows the rotation the level is not correct and is still in need of adjustment, which is the problem you're having right now.

None of this is relevant if the problem is the one that Rich suggested, although it would be rather unusual for them to share the same problem, but certainly not impossible.

Keep in mind that the surface plate, in order to be reliable, should be level in both directions. Once you have the level functioning within reason, it might be a good idea to try to further level the surface plate. Ultimately, in a perfect world, when you rotate the level in any direction it should read the same, with the bubble dead center. At that point you can safely assume that your level and surface plate are as close as they can be with the equipment at your disposal.

Make your adjustments slowly and give the level time to respond to the changes. Also, keep your hands off the level as much as possible---so you don't introduce heat distortion.

H

Edit:
One more thing. The level of resolution of this type of level is extreme. The slightest error in the base of the level can make adjustments border on the impossible. It would be a good idea to try pressing on each end of the level when it is in contact with the granite. You should see no change. If you do, the level isn't flat, or it's bearing only on the ends. High precision levels are generally hand scraped to ensure that they are flat.
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armscor 1
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Re: Precision Level Problems

Post by armscor 1 »

Hi Harold, for once I have to disagree, my Starrett 98 is purposely manufactured with a bow, that is high on the ends, minuscule amount so it does not rock.
Don't ask me how but no evidence of any scraping marks.
My British Watts precision 12" block level only has pads on each end.
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Harold_V
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Re: Precision Level Problems

Post by Harold_V »

armscor 1 wrote: Sun May 28, 2023 2:14 am Hi Harold, for once I have to disagree, my Starrett 98 is purposely manufactured with a bow, that is high on the ends, minuscule amount so it does not rock.
First, my comments are directed towards precision levels. The Starrett 98 isn't one of them (the Starrett 199 is).
I, too, have one of them. Mine is a 6". I lapped the base to make it flat.
Don't ask me how but no evidence of any scraping marks.
Correct. Mine didn't have them, either, nor did I expect that it would have. As I said, it's not a (high) precision level and should not be compared to one.

H
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FireLance
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Re: Precision Level Problems

Post by FireLance »

Thanks for all the comments.

I will take the level apart as soon as I get a chance and check out the rear attachment point.

The level does not rock when pushed on. It is pretty much brand new with no wear on the base. I only used it once before and it has been stored safely in the original wooden box.

Keep in mind, that the granite surface plate was the same used at the start of this “adventure” when the level was calibrated. It read near level and has not moved. The room is temperature controlled and the surface plate and level are kept out of any sunlight or heat source.

I can not move the bubble in any increment no matter how small that stays. In one orientation, the adjustment is clockwise turning of the screw, once the bubble moves a small amount I flip 180 and the adjustment is counterclockwise. The number of turns it takes to make the bubble move even the smallest amount undos anything on the opposite flip. When turned back 180 the bubble is again buried.
FireLance
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Re: Precision Level Problems

Post by FireLance »

Just in case it helps, I wanted to post my conclusion.

I checked my rear attachment as Rich suggested and it was secure. So good to check but it was not my issue.

I was already doing the process that Harold suggested but his post got me thinking.
Harold stated that the surface plate technically didn’t have to be level.
Mine was level and my precision level was consistent with the side it buried the bubble. So I shimmed under the “low side of the level” very slowly adding shims. I noticed the same problem described above BUT the adjustments needed to move the bubble began to slowly decrease.
So I would add a shim and adjust the level bubble to center and flip, add a shim and repeat. Each time the needed adjustment turns on the screw decreased until I had the level reading exactly the same in each 180 degree flip.

I’m not sure I needed to do the next part or not but I did.

I started slowly (one at a time) removing shims and adjusting the bubble. This time I was not concerned with it being in the center, I just wanted it to read in the same location in both directions. I continued this process until all the shims were removed and I was back on the bare surface plate.
Now I very slowly adjusted the bubble back into the center over the course of multiple flips back and forth.
The level is now back to being calibrated and I will not be messing around with it again unless forced.

Although no one came up with the exact fix, your input did make me think about the problem differently which ended up teaching me something and fixing the problem.
Thanks!!
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Charles T. McCullough
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Re: Precision Level Problems

Post by Charles T. McCullough »

I suppose now you all are gonna tell me the Level App on my cell phone is not accurate enough.
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Steggy
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Re: Precision Level Problems

Post by Steggy »

Charles T. McCullough wrote: Tue May 30, 2023 2:17 pm I suppose now you all are gonna tell me the Level App on my cell phone is not accurate enough.
Dunno. Sometimes I think people who are obsessed with cell phones aren’t on the level. :D
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Charles T. McCullough
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Re: Precision Level Problems

Post by Charles T. McCullough »

Steggy wrote: Tue May 30, 2023 3:12 pm
Charles T. McCullough wrote: Tue May 30, 2023 2:17 pm I suppose now you all are gonna tell me the Level App on my cell phone is not accurate enough.
Dunno. Sometimes I think people who are obsessed with cell phones aren’t on the level. :D
At least it was enough to convince the concrete contractor that my front step was NOT at all level and he would not get paid until it was! (Some people cannot even SEE level. It is tipped forward about half a bubble for water drainage; but not tipped so sideways I could not stand up straight on it!)
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Harold_V
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Re: Precision Level Problems

Post by Harold_V »

FireLance wrote: Tue May 30, 2023 1:23 pm So I would add a shim and adjust the level bubble to center and flip, add a shim and repeat. Each time the needed adjustment turns on the screw decreased until I had the level reading exactly the same in each 180 degree flip.

I’m not sure I needed to do the next part or not but I did.

I started slowly (one at a time) removing shims and adjusting the bubble. This time I was not concerned with it being in the center, I just wanted it to read in the same location in both directions. I continued this process until all the shims were removed and I was back on the bare surface plate.
Now I very slowly adjusted the bubble back into the center over the course of multiple flips back and forth.
Something isn't adding up.
If you managed to get the level reading with the bubble off center, at the same side of the granite (not the level) and then centered the bubble, the granite isn't level. Can't be. Once you have the level reading identically (bubble off-center, but always to either the left or right, doesn't really matter which), that's the true orientation of the vial as opposed to the base of the level. If you then did any adjustments, the level isn't reading correctly. Can't have it both ways.

Now then, if, when you flipped the level 180° the bubble flipped also, then the granite IS level and the further adjustment simply corrected the level until the bubble was centered. Make sense?

Maybe that's what you said and I just didn't understand.

H
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FireLance
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Re: Precision Level Problems

Post by FireLance »

H,
I did a poor job of explaining myself.
You are correct.
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