Pole Bubble Replacement

I used to have a shelf bracket attached to my wall at about 8' high. Had a hole in it to hang a plumb bob from and was indented so that the pole tip would stay centered. Drop plumb bob, mark the location on the floor. Align the pole top to bottom and extend with some force so that it stays put. Adjust the screws at the bottom of the bubble bubble so that is centered. you can buy setups that do this

I do have a an adjusting jig, the problem lies with getting the new bubble initially
close enough to do the fine tuning.

> I do have a an adjusting jig, the problem lies with getting the new bubble initially
> close enough to do the fine tuning.

If the pole is nominally plumb in the jig, why wouldn't you just center the bubble with the adjusting screws on the vial and then test the adjustment by rotating the pole 180deg, taking out half of the bubble error, if necessary?

When the bubble is good, it should remain in the same position as the pole is rotated, even if somewhat off center if the jig is slightly off.

The easiest method I've found is to use a door frame. Screw a small eye screw into the top of the frame. Drop a plumb bob from the screw to the floor and make a mark on the floor. Screw a spare point onto the top of the pole. Then just take the eye screw out, put the tip of the pole on the mark on the floor and raise the pole to the hole the eye screw was in. Now the pole is plumb (assuming it's not bent). Adjust the bubble accordingly. Basically the same as Sir Veysalot's method, but you don't need a bracket.

Always works for me.

> I do have a an adjusting jig, the problem lies with getting the new bubble initially
> close enough to do the fine tuning.

Bigger hammer? 😉

I went down my basement and drilled a dimple in the concrete floor and immediately above it drilled a 5/8" hole in the door frame. I can set a prism pole in this "jig" and check it at any time.

Mine happens to be plumb, but as Kent points out even if it is a hair off doesn't really matter because by rotating it around the bubble should stay in the same position if the bubble is properly adjusted.

As a further check, I also have an electronic carpenter's level insert that reads to 0.1°. I have found this to be a very accurate double check as well.

Hi Scott,
Where did you get the 8 minute bubbles? Hope all is well I sunny Oregon! You're not missing much here... its already (9:00am) up to minus 11°F!!

Dave

:good:

>When the bubble is good, it should remain in the same position as the pole is rotated, even if somewhat off center if the jig is slightly off.

At best, that statement is unclear, and easy to interpret wrongly, if not outright incorrect.

If the bubble stays in the same position relative to the markings on the level when the pole is rotated, then the pole is vertical.

If you take a perfectly adjusted rod and bubble, and tilt the rod, then as you rotate the rod the bubble moves with respect to its markings as the bubble stays positioned the same relative to the world.

Or am I still not awake?

Scott, think I would only insert two leveling screws and let the bubble case pivot over the center bump in the holder, if your rod has that pivot point. Would chase the bubble with those two screws until you were able to shift the bubble from side to side, then instal the third screw and finish up.
jud.

Easiest I have found is to use a three legged bipod.

Plumb rod and leave screw loose enough so rod spins easily.

Adjust rod, replumb setup do over, repeat.

It is not evn neccessary to set up on a mag nail or any other ponch marked control, but if one is nearby, use it.

Paul in PA

Those 8' vials are pretty sensitive compared with the standard 40' jobs (like 5X as sensitive:-) . The best way to adjust them is using the SECO adjusting jig and using the adjust-rotate 180°, adjust halfway back to center, re-center, rotate 180°, &tc., &tc. method.

To get started, place a pole with a known-good vial in the jig, then adjust the jig to center that bubble, so the jig is plumb, or nearly so.

https://surveying.com/Video/Tech-Tip-Videos/TT19.aspx

> >When the bubble is good, it should remain in the same position as the pole is rotated, even if somewhat off center if the jig is slightly off.
>
> At best, that statement is unclear, and easy to interpret wrongly, if not outright incorrect.
>
> If the bubble stays in the same position relative to the markings on the level when the pole is rotated, then the pole is vertical.
>
> If you take a perfectly adjusted rod and bubble, and tilt the rod, then as you rotate the rod the bubble moves with respect to its markings as the bubble stays positioned the same relative to the world.
>
> Or am I still not awake?

No, you were awake. Thanks for the correction. I replied too quickly and mixed the procedure that I'd use for refining the plumbness of the pole before finally centering the vial bubble.

:good: Wow, I like this and so simple, but never would have thought of it.
Thanks for posting and Thanks for SurveyorConnect.com.

Thanks Sarge - I am using a SECO jig and I did start by setting it up with a pole already in adjustment. I will try Judson's suggestion .

For Dave T. - the 8 min. vials were purchased from Baseline Equipment who is an
advertiser here and also hails from Eugene, Oregon. James Flack is the owner - very committed to first class customer service.

That's how I do it except I fine tune with the total station vertical cross hair.

Center the bubble, lock the third leg, look up and down the side of the pole with the total station. If necessary plumb the pole up to the vertical cross hair and adjust the bubble perpendicular to the line of sight only.

Then rotate the pole 90 degrees and repeat the procedure.

I use two instruments setup at 90° from each other about 20ft from a point the pole in a three legged pod is setup on and line up the pole.

Then I adjust the bubble vial.

0.02

Drilled a hole in garage door header
dropped a plumbob drilled a hole in conc floor
(dimple really) checked with gun
use 2 points on pole one on top and one on bottom
extend pole to lock in place and adjust
big problem seems that it is difficult
to get bubble just right

I set up in bipod with bubble in centre of run and then use Total Station cross hairs to check pole vertical in the sighting direction then rotate pole right angles (for distance). After that check bubble is still in centre. Have to say my Leica pole bubble has never required adjustment !

RADU