Shaft Alignment

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Do you mean that a portion of the shaft has been flattened ?

technically no problem since the flat surface also will rotate about the same axis, but the readings will be a bit difficult to take since the points on the flat are at different radial distance from the axis. However if you do the laser alignment, then this will not create any problem.

Here if the dial is on the blue dotted line on 0^o position and then you move to 90^o and the dial does not remain at this point (not possible either when you are moving two de-coupled shafts) then there will be errors. One way is to take the high point , but that too becomes a bit difficult, especially if the shafts are large.

dear sir

if we are rotating both shafts in coupled position and one machine is higher 20 thu then other and there is some horizontal offset is also reading what will be readings on 90 and 270 degree in presance of flat surface under the dial plunger

arshad bbc You may end-up with wrong answer or no answer if you don't phrase your question properly.

What are you trying to do?

Why 20Thou offset is is there?

how shafts are coupled?

where are you holding?

What are you trying to check with dial ?

Are you testing it or doing production setting?

many more questions.

Before getting an answer you need to figure out question, I would suggest you just sit down with your boss or with your job-mates and write down question with complete details, A Drawing presentation will help a lot.

In a coupled conditions the readings are a bit constrained by the couplings, especially if it is a rigid one.

As mentioned in the above post, the presence of the flat surface will not effect if sufficient precaution is taken (ie the dial is maintained on the same point on the flat).

The vertical offset is understood but why do you maintain the horizontal offset ? (never came across this feature)

(The vertical offset is maintained between the drive and the driven especially in high speed machines to account for the unequal journal floats in operation.)

Why don't you get hold of some alignment service persons (there are laser alignment services, and they bring their equipment and do it at your works) Important if it is a high speed machine.

Else just make a sketch of the shafts and try to rtoate this and see what happens to the axes as they do. It is a simple geometrical exercise really. We used to do this in our olden times.

Why the flat surface? Never camd across this, it is likely to create unbalance .

I don't quite understand what the flat spot under the dial plunger has to do with anything. Move the setup so you don't have this problem. It's obvious that you guy's have not been instructed on the proper method of machine alignment. When doing shaft alignment, dial positions are usually referred to as the positions of the clock, facing the non-movable machine. The 90-270 degree position would be referred to 3 or 9 o clock position. Up and down, would be 12 and 6 o clock. The trick to a good alignment is to have the dials reading the same number in all positions (12,3,6,& 9). Use a felt marker to mark the position of the shaft, on the machine, of your readings. After your shim moves, you can check your dials exactly by the marks. A perfect alignment would be to calculate your machine growths and add or subtract shims for the off sets.

Say What ?????????

Exactly.....