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nc5a
12-13-2017, 06:12 PM
I discovered sometime ago that my Starrett 199's don't indicate the same even though both are calibrated correctly when swapped end for end on a surface plate with locating stops.

One reads level and the other reads one mark off level. Granted one mark is 0.0005" in 12" so not terribly off but these are precision levels and should read the same, or should they? Is one line off level acceptable as long as the calibration is correct and how do I figure out which level is correct. I leveled my surface plate with the one that currently shows level but maybe the one that shows one mark off level is correct.

I haven't spotted either one yet but my initial gut feel is they are pretty flat as finger pressure on the corners and centers shows no movement of the bubble.

So is there a trick to determine which is correct? I don't have any other precision levels or metrology instruments at my disposal.

Ron

J Tiers
12-13-2017, 06:43 PM
A level can be (must be) adjusted to read right. If one repeats the same reading when reversed, it is correct. Set the other one to match it.

If they both repeat correctly when reversed, then I am not sure what the question is..... Are you saying they repeat when reversed, but then they also do not indicate on the same line? That they both repeat, but not at the same place?

CCWKen
12-13-2017, 07:07 PM
Levels are self testing--You don't need any other equipment. But you do need clean surfaces. You're into the dust spec and oil film error range.

nc5a
12-13-2017, 07:49 PM
A level can be (must be) adjusted to read right. If one repeats the same reading when reversed, it is correct. Set the other one to match it.

If they both repeat correctly when reversed, then I am not sure what the question is..... Are you saying they repeat when reversed, but then they also do not indicate on the same line? That they both repeat, but not at the same place?

Jerry,

They both repeat when swapped end for end but do not read the same. One reads level and the other reads one mark off level. They both are placed in the same spot with the help of stops and the base of each level and surface plate is clean.

nc5a
12-13-2017, 08:00 PM
Levels are self testing--You don't need any other equipment. But you do need clean surfaces. You're into the dust spec and oil film error range.

Ken,

I thought the same thing but after several cleaning sessions with no change it must be something else. I bought these off Ebay so it could be that one or both have been refurbished at some point. But the real question is how can I tell which one is correct. My wife tells me I have a bit of OCD and she may be right because the fact that two precision levels reading differently yet calibrated correctly, just doesn't set well with me.

Dave C
12-13-2017, 08:01 PM
Sounds to me like both levels are off by a smidge and your surface plate is too since it was leveled with one of them. Use both levels to re level the plate. The correct reading will be the split between both levels. Once the plate is true, use it to set both instruments to zero.

RichR
12-13-2017, 10:14 PM
I think what you are suggesting is impossible. Identical levels calibrated in the same spot must provide identical readings. Here's my theory, your
levels are not identical. One of them is more sensitive. Both are correct, but one is not sensitive enough to register the tiny amount of tilt of
your surface plate.

J Tiers
12-13-2017, 10:23 PM
Either what RichR said about being different, or they are actually irregular, or another possibility.....

See if you can rig up an arrangement to deliberately TILT the levels enough to move by one division. A screw adjustment, or a longer smooth piece tilted with shim stock.

Set with one of them to be off one more line. then check with the second. Do this for each line on the first level. record and report the results.

Either they will move different amounts, OR one will not move a consistent amount, more at one setting and less at another (vial not ground right).

Also possible is that the high spot on the level is not in the middle on one.... not where the lines show.

.LMS.
12-13-2017, 10:38 PM
Clearly this is stressing you, so you should send me one of them, and your problem will be solved. :cool:

CCWKen
12-13-2017, 10:57 PM
Jerry,

They both repeat when swapped end for end but do not read the same. One reads level and the other reads one mark off level. They both are placed in the same spot with the help of stops and the base of each level and surface plate is clean.
If one reads one mark off when swapped end for end, it is not adjusted correctly. I'm still not clear by your description though. Mark the high side of the level with a piece of tape. rotate it 180 degrees. Does the bubble follow the tape or move to the opposite side?

J Tiers
12-13-2017, 11:10 PM
I took it that reads at the SAME MARK when turned around.

JRouche
12-13-2017, 11:56 PM
am I overlooking something. Set both sights to level a or b level and they are both set. You just have one sight off.The bubble will always be level. Hence the name.

Then check your table and level it accordingly. JR

Forrest Addy
12-14-2017, 05:50 AM
I wonder if a bruise or some easily over looked raised metal is affecting interchangeable readings. Have you glided a stone over the reference surface while being acutely aware of sensations in your fingers signalling catches on microscopic burrs and other proud metal defects?

Have you blued your levels to your surface plate (note: most master precision grade levels are deliberately scraped or ground with a 0.0005 concave to ensure end bearing when placed on a flat surface.)

Fasttrack
12-14-2017, 07:35 AM
A level is only as good as it's vial. That seems to be a key piece of information missing in many of the responses. Imperfections on the inside the vial, improper shape of the vial or improper marking can all make the bubble appear to be level when it is not or vice-versa.

A vial from a cheaper level will not make a suitable replacement for a 199. I see guys make this mistake more often than not - I've even seen guys who insist on using cheap plastic levels with acrylic vials for leveling machines. They've heard that levels are self-calibrating and have checked their cheap plastic level and believe that means it has the same sensitivity as a master grade level.

Let me reiterate: a master precision level provides accuracy and precision because of two reasons - the precision housing AND the precision ground vial. A bad vial makes for a bad level.

boslab
12-14-2017, 08:37 AM
Suppose the whitworth principle applies, you need a third, then you can compare them all like straightness etc
Mark

akajun
12-14-2017, 08:39 AM
I have two, both lived a hard life in the Avondale shipyard in New Orleans and were no longer flat on the bottom. I surface ground them flat and both have been re scraped by a professional scrapper with the proper relieved base. They both bucked in nicely and are identical and repeatable to themselves. Something with one of yours, is not flat, or its not bucked in properly.
I will say that bucking in a 199, is a lot more troublesome than a 98. Small tiny adjustments are the order of the day.

BTW if anyone is looking for a 199 PM me.

Moxiedad2001
12-14-2017, 08:58 AM
I agree with others that what you are describing is not possible unless there is some extraneous factor involved. Two thoughts: Are you placing each level in exactly the same position (not side-by-side), replacing one with the other in turn? As Forrest suggested, some irregularity in the reference surface may be interfering. A second possibility is that some irregularity in the vial of one level is causing the bubble to be less sensitive. Someone suggested that the markings may be off, but if that were the case then you wouldn't be able to get the same reading when flipped end to end.

lynnl
12-14-2017, 11:31 AM
......

Also possible is that the high spot on the level is not in the middle on one.... not where the lines show.

Everyone is addressing a different problem than the OP stated. (except JT, see above.)
The OP said the reading is consistent when swapped end for end. Dust and surface irregularities have nothing to do with it.
The issue is that the lines on the vial are not positioned properly with respect to the arch of the vial; or another way of looking at it, the vial was not mounted properly in the body of the level.

JRouche
12-14-2017, 12:41 PM
I have two,....

BTW if anyone is looking for a 199 PM me.

Oh cool. Giving them away are you, cause nothing is for sale here. Ill take one.. JR

Paul Alciatore
12-14-2017, 01:03 PM
Yup. And what about some burr or raised area on the object you are trying to level with them. After all, that is where the discrepancy seems to occur.




I wonder if a bruise or some easily over looked raised metal is affecting interchangeable readings. Have you glided a stone over the reference surface while being acutely aware of sensations in your fingers signalling catches on microscopic burrs and other proud metal defects?

Have you blued your levels to your surface plate (note: most master precision grade levels are deliberately scraped or ground with a 0.0005 concave to ensure end bearing when placed on a flat surface.)

J Tiers
12-14-2017, 01:18 PM
The vial is really all there US to a level, the rest of it is just a holder.

The vial can be good or not so good for a given sensitivity.

If it is good, then it will have the bubble move one division for every 0.0005" in 12 " (or whatever the sensitivity is), AT EVERY LINE. That means the vial is ground correctly. With that, you can find perfect level AND you can measure how much off level it is, until you run ut of bubble range.

If the vial is ground poorly, it may not read one line change for each increment..... BUT it can still have the bubble between the lines for the perfectly level condition. So you can find perfectly level, BUT, you CANNOT measure how far off level it is. That may not be a big deal.

The bubble will always go to the top (the highest place) of the vial. It does not matter to the bubble where the lines are. The top is the top.

So if the surface the level sits on is perfectly level, and you set the level on it, the bubble will be at the top. Suppose you mark the ends of the bubble with a sharpie on the vial. Then if you turn the level around, the top is still the top, and the bubble should still be in the same place, right between the lines you marked.

IT MIGHT NOT BE BETWEEN THE LINES THE MAKER MARKED ON THE VIAL. But you can just adjust the vial screw, and move the bubble to where it is between the lines. All that does is move the "top" to another place on the vial.

The repeating in the same place when turned around on a perfectly levl surface is just the bubble finding the top.

If the surface is not level, then the top will be in one place when the level is set in one position, and it will be in a DIFFERENT place if the level is turned 180 degrees and put back.

NOW.. for the OP.

I am still not clear on the problem he is having. It sounds like the one level is repeating in the same place on the vial when turned around, but that place is not between the calibration lines. If he marked the bubble position with a sharpie, it would be the same place turned either way, but is one line away from the correct place.

If so, then he can adjust the screw to move the bubble between the lines, and it will then be between the lines for either direction on a level surface.

Remember, the key is that when the surface is level, the bubble will be in the same position in the vial even of the level is turned around. It will always be at the "top" of the vial.

JRouche
12-14-2017, 01:51 PM
Its a very straight forward procedure. Instructions. JR

http://bbs.homeshopmachinist.net/attachment.php?attachmentid=2026&d=1513277388

http://bbs.homeshopmachinist.net/attachment.php?attachmentid=2025&d=1513277388

J Tiers
12-14-2017, 02:24 PM
Note that the instructions are assuming a non-level surface, so the "absolute position" will vary, but the number of divisions off-center should remain the same. On a perfect level surface, the bubble should be in the middle for either position.

3 Phase Lightbulb
12-14-2017, 02:31 PM
Make sure both levels are the exact same temperature. Keep them together for an extended period of time before comparing the readings with each-other in any orientation.

danlb
12-14-2017, 02:34 PM
If one reads one mark off when swapped end for end, it is not adjusted correctly. I'm still not clear by your description though. Mark the high side of the level with a piece of tape. rotate it 180 degrees. Does the bubble follow the tape or move to the opposite side?

This is the key. If one has the bubble in the center even when the level is rotated end for end, then that's the one that is perfect AND the surface plate is level. If the surface was tilted, the bubble would move when you changed the orientation.


I think this is right, but feeling fuzzy headed this morning. For the other one that has the bubble off 1 mark.... If it moves an equal amount to the opposite side, then the surface it is on is slanted. If it moves an equal amount to the same side, the surface is level and the vial should be adjusted.

nc5a
12-14-2017, 03:33 PM
I've read my OP several times and it seems clear to me but some have said it wasn't clear what the problem is. So let me take another stab at it from another direction.

Lets first assume that the surface is level and because of locating blocks each level is in the same position each time it is placed on the surface. Let me also assure you that the surface is clean and the bottom of each 199 has been very lightly stoned.

I place the first 199 level on the surface that is level based on a carpenters level and let it settle for a couple minutes making a mental note of bubble position. Then I flip the level 180 degrees and again let it settle for a couple minutes and again noting where the bubble is. I find that the bubble is not in the same position when flipped 180 degrees. So I adjust the screw and recheck bubble position. After doing this 3 times the bubbles settles into the same position each time the level is flipped 180 degrees. In this case the bubble shows the surface level.

I place the second 199 level on the surface and go through the same routine. The second level is off a little more than the first one but after 4 adjustment cycles the bubble settles in to the same position each time the level is flipped 180 degrees. The only difference is the second level shows one mark (0.0005") out of level.

Both are Starrett 199's with the same sensitivity and both appear to be in excellent condition. I have put finger pressure on the corners and centers to see if the bubble deflects and neither of the 199 bubbles move viewing with the naked eye. I have not spotted the bases yet to see how they print, that will be the next test and I will provide photos of the results. I suspect the problem is related to the vials in some way. The bases could have issues as far as contact points or lack there of but for some reason I'm having a hard time seeing that.

The bottom line is, if both levels calibrate/adjust properly per Starretts instructions then both should read the same bubble position when placed in the same spot on a surface, level or not.

Ron

J Tiers
12-14-2017, 05:13 PM
The question is specifically about "the same position".

Which of the following is the true case?:

Case 1: You set it one way, and mark the ends of the bubble with a sharpie. One mark is one line to the right of the center. You flip it, and the bubble is again one mark to the right, but no longer in-line with the original sharpie marks

Case 2: You set it and mark it as before, and the bubble is one mark to the right of center. You flip it, and now the bubble is STILL ALIGNED TO THE ORIGINAL MARKS, and is now one line to the LEFT of center.

JoeLee
12-14-2017, 06:03 PM
I calibrated both my 98 4 and 98 8 inch levels off my surface plate. It can be a touchy operation, with the 199 even more so.
Two things I learned, one........ rotate the level on the surface plate, don't pick it up and set it down. two....... when you rotate the level don't grab it around the vial because the heat from your fingers and change the reading and also create some static charge that will pull the bubble. Even exposure to sun light or having a lamp over the top of it will cause changes.

Some of these vials tend to loose fluid over several years. That will affect the reading. Starrett once told me that these are calibrated at 72 degrees.
Are the bubbles the same length in both levels???

These levels are also slightly concave on the bottom side, meaning they only sit on the ends. You should be able to verify this slipping a .001 or less shim under the center of it.

JL................

larry_g
12-14-2017, 06:20 PM
Op

One way that these level checking conversations get out of wack is that the references and nomenclature gets confusing. I find it easier to refer to the orientation of the level as east and west and the reference is the table being measured. What I would like you to say is that one level is saying the surface is level, and the other level is saying that the surface is rising at a rate of .0005"'foot to the east. Now if your reverse the level is it still running out of level at a rate of .0005"/ft to the east? If it shows that your now running out of level at .0005"/ft to the west, then you have a vial that needs adjusting. If it shows still running high to the east then you have two vials that are not of the same sensitivity relative to the markings.

I'd suggest that you do your tests on an inclined surface that you can read the inclination with the two levels. Do they agree in the amplitude of change if you change the inclination?

lg
no neat sig line

lynnl
12-14-2017, 06:43 PM
I've read my OP several times and it seems clear to me but some have said it wasn't clear what the problem is. So let me take another stab at it from another direction.
......
......

I place the second 199 level on the surface and go through the same routine. The second level is off a little more than the first one but after 4 adjustment cycles the bubble settles in to the same position each time the level is flipped 180 degrees. The only difference is the second level shows one mark (0.0005") out of level.

.....
.....
Ron

Well I thought your original description made sense, and left me pretty sure of what you were saying. However I could see some potential for misunderstanding.

Your statement: "The only difference is the second level shows one mark (0.0005") out of level." doesn't specify whether that one mark shift is always to the same end of the level, or if it's toward the other end when you flip the level.

e.g. lets assume this troublesome level has a "1" on one end and a "2" on the other end; I'm understanding you to mean that the shift or offset is always toward end # 1 (or 2 if you prefer) regardless of which way you orient the level on the surface plate.

nc5a
12-15-2017, 03:26 AM
Here are the spotting results of the two levels. They aren't real bad by Starrett standards but both could use point scraping to breakup the wide areas and hopefully move contact toward the perimeter at each end.

The 1st and 2nd photos are the base of the level that showed the surface to be level. The 3rd and 4th photos are of the level that showed one mark off level.

I think when the dust settles I will scrape them flat on the bottom as they don't get used daily so wear would be minimal.

https://i.imgur.com/f4ck3AHl.jpg
This was the first print, I decided to give contrast on the others
https://i.imgur.com/xojaNril.jpg

https://i.imgur.com/9cjeM7Ml.jpg

https://i.imgur.com/auoUEnQl.jpg

Magicniner
12-15-2017, 04:06 AM
Since you can post photos how about some of the readings for clarity? ;-)

bob_s
12-15-2017, 10:25 AM
Nice surface plate.
24"x36"? Grade A or AA? Recently calibrated/inspected?

3 Phase Lightbulb
12-15-2017, 10:29 AM
Just toss them in the garbage.. BTW, where are you located? What day is trash pickup over there? :)

nc5a
12-15-2017, 01:19 PM
Nice surface plate.
24"x36"? Grade A or AA? Recently calibrated/inspected?

Bob

I bought the plate new a year or so ago and built the stand. It's 30" X 48" X 6" grade B.

https://i.imgur.com/Eph7k27.jpg
https://i.imgur.com/KkhqyZs.jpg

nc5a
12-15-2017, 01:24 PM
Since you can post photos how about some of the readings for clarity? ;-)

What readings are you referring to? If it's the position of the bubble you're looking for I'm sure you can picture a centered bubble and one that is one line off center. In short, I have no photos of the bubbles.

J Tiers
12-15-2017, 02:00 PM
What readings are you referring to? If it's the position of the bubble you're looking for I'm sure you can picture a centered bubble and one that is one line off center. In short, I have no photos of the bubbles.

Yes, of course.

But, I don;t think you have answered the one most important question. The only one that really needs to be answered in a way that leaves no doubt. The sharpie is optional, used in the question for clarity. We really need to know if the "one line off" follows the level, or stayss in the same relative position to the granite flat.

Which of the following is the true case?:

Case 1: You set it one way, and mark the ends of the bubble with a sharpie. One mark is one line to the right of the center. You flip it, and the bubble is again one mark to the right, but no longer in-line with the original sharpie marks

Case 2: You set it and mark it as before, and the bubble is one mark to the right of center. You flip it, and now the bubble is STILL ALIGNED TO THE ORIGINAL MARKS, and is now one line to the LEFT of center.

nc5a
12-15-2017, 03:32 PM
Jerry,

I was certain I answered your question but after looking back at my replies it's clear I did not address it.

Case 1 in your example is correct which indicated the level is adjusted/calibrated properly. So that leaves two possible causes. The base of one or both need to be tuned up or one or both have vial issues. And I suppose it could also be a combination of both. But if you look at the spotting on the bases they don't look too bad.

I contacted Starrett tech support and they responded very fast with the following.

Hi Ron,



I believe the difference in readings are the result of the point of contact on the base of the level with the surface plate. Check the base for any wear, damage and where the contact is being made (should show small shinny areas where the base has been rubbing on the surface plate. These contact points should be near the ends, ( within 1 “) not towards the middle. If the contact areas are not at the ends, then the level will not give a good reading, and the base needs to be re-scraped.

First, I would stone lightly the entire base and edges, of both levels, to remove any dings or burrs. Then retest using the 180 degree method. If the contacts are still towards the center and not the ends, the base is worn and needs to be re-scraped.

Second, If both bases have contact points on the ends, then the vial could be adjusted.



Bill Gates

Quality Manager

L. S. Starrett Co.

978-249-3551 x255

wgates@starrett.com

J Tiers
12-15-2017, 05:44 PM
OK. That clarifies what is going on. Thank you.

Mr Gates could be right. The one that showed one off is also the one that is scraped with the slight center hollow, which is typically how you want it to be. That hollow is only a tenth or two, basically one scraping pass over the middle area.

And, I notice that the one that is indicating level by being in the middle, is also contacting in the middle and NOT at the ends. With this one, try something..... Clean the level base and the flat. Put the level on the flat (you may want to try a couple places with this), and then with your finger, push the side of the level at one end. Try again pushing the OTHER end

If the level seems to spin at a point in the middle of the level, then there is a high spot in the scraping, and it will not be reliable until that is corrected.

If the level turns around a point that is closer to the opposite end, possibly 15% to 30% from the end opposite where you pushed, then it is OK.

Try pushing at BOTH ends, and at several places on the flat. If it seems always to spin in the middle, or close to it, then it is failing the "hinge test", and needs rescraped to have a slight hollow in the middle like the other one.

JoeLee
12-15-2017, 06:08 PM
The last two pictures show that the ends of the level are not making contact on the edges. My guess is there would be some slight rocking.
The first two pics show full surface contact right to the edges of each end of the level.
I wold be careful scraping because if you remove too much from each end you may be hitting in the center of the level. Remember these are slightly hollow in the center..

JL...............

Magicniner
12-15-2017, 07:04 PM
What readings are you referring to? If it's the position of the bubble you're looking for I'm sure you can picture a centered bubble and one that is one line off center. In short, I have no photos of the bubbles.

Yes, but you had signally failed until now to explain the situation in a way that would be clear to anyone not standing next to you and watching what you were doing, like many writers of technical manuals you assumed others know what you know and thus failed to explain adequately for anyone who didn't :D

bob_s
12-15-2017, 07:16 PM
Bob

I bought the plate new a year or so ago and built the stand. It's 30" X 48" X 6" grade B.


There's your problem, assuming bigger is better!

Grade B 30"x48" has a flatness tolerance of 0.0007 inches.

nc5a
12-15-2017, 09:09 PM
OK. That clarifies what is going on. Thank you.

Mr Gates could be right. The one that showed one off is also the one that is scraped with the slight center hollow, which is typically how you want it to be. That hollow is only a tenth or two, basically one scraping pass over the middle area.

And, I notice that the one that is indicating level by being in the middle, is also contacting in the middle and NOT at the ends. With this one, try something..... Clean the level base and the flat. Put the level on the flat (you may want to try a couple places with this), and then with your finger, push the side of the level at one end. Try again pushing the OTHER end

If the level seems to spin at a point in the middle of the level, then there is a high spot in the scraping, and it will not be reliable until that is corrected.

If the level turns around a point that is closer to the opposite end, possibly 15% to 30% from the end opposite where you pushed, then it is OK.

Try pushing at BOTH ends, and at several places on the flat. If it seems always to spin in the middle, or close to it, then it is failing the "hinge test", and needs rescraped to have a slight hollow in the middle like the other one.

Jerry,

Neither level is touching in the center, both are making contact on the ends. The first picture shows blue spotting at the ends on top of yellow on the base. I did this because the first spotting (2nd photo) with blue was very light and didn't show up well in the photo.

J Tiers
12-16-2017, 01:23 AM
Jerry,

Neither level is touching in the center, both are making contact on the ends. The first picture shows blue spotting at the ends on top of yellow on the base. I did this because the first spotting (2nd photo) with blue was very light and didn't show up well in the photo.

Do both pass the "hinge test" then? In that case they are OK for contact.

CCWKen
12-16-2017, 03:56 PM
Forget it Lynnl, I tried to get a simplified answer back at post 10. The dance continues so I dropped out.

3 Phase Lightbulb
12-16-2017, 04:16 PM
Jerry,

I was certain I answered your question but after looking back at my replies it's clear I did not address it.

Case 1 in your example is correct which indicated the level is adjusted/calibrated properly. So that leaves two possible causes. The base of one or both need to be tuned up or one or both have vial issues. And I suppose it could also be a combination of both. But if you look at the spotting on the bases they don't look too bad.

I contacted Starrett tech support and they responded very fast with the following.

Hi Ron,



I believe the difference in readings are the result of the point of contact on the base of the level with the surface plate. Check the base for any wear, damage and where the contact is being made (should show small shinny areas where the base has been rubbing on the surface plate. These contact points should be near the ends, ( within 1 “) not towards the middle. If the contact areas are not at the ends, then the level will not give a good reading, and the base needs to be re-scraped.

First, I would stone lightly the entire base and edges, of both levels, to remove any dings or burrs. Then retest using the 180 degree method. If the contacts are still towards the center and not the ends, the base is worn and needs to be re-scraped.

Second, If both bases have contact points on the ends, then the vial could be adjusted.



Bill Gates

Quality Manager

L. S. Starrett Co.

978-249-3551 x255

wgates@starrett.com

I just called him to see if I could schedule a conf call about the problems and the future of windows and he refused to acknowledge any problems with their windows. Unbelievable. I guess he really did distance himself completely.