Total runout 4

[machine78]

We have a part that has two shafts opposite each other. (.187 dias.x .375 long each) Each shaft has individual datum callouts (A & B) with a total runout callout of .0005 to A-B. We have a few interpretations here on how this should correctly be inspected. At the moment we are simply placing one shaft in a "V" block and rotating it with an indicator on the opposite shaft. Use of a C.M.M. is out of the question because each part needs to be inspected, once it comes off the machine in production quantity's. Any insight would be appreciated.

 

[ringman]

The callout requires that the related surfaces be verified with respect to the Axis A-B. It is not clear from your statement what surface is related to A-B. However the setup that you indicate verifies the relationship of one end to the other. This is not consistent.

Clarification required!

 

[kbro151]

Seems like the indicator would vary with both the profile of the shaft it is resting on and any misalignment between the axes of the two shafts. Do you care if the shafts are cylinders?

 

[Heckler]

What is this part used for? I am curious because total runout of .0005 is a costly callout.

Best Regards,

Heckler
Sr. Mechanical Engineer
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[dingy2]

Please let us know what diameters are datum A & B. Are they countersunk ends?? Once I have the datums, I can tell you how to measure these on a divider head or chuck.

Dave D

 

[ctopher]

It would be more clear what datums A & B are. I agree with Heckler about .0005 being a costly callout.

Chris
SolidWorks 06 4.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 10-27-06)

 

[israelkk]

See C:\My Web Sites\GD&T\

http://www.tec-ease.com\tips\march-98.html

 

[israelkk]

Here is the correct address

http://www.tec-ease.com/tips/march-98.htm

 

[ringman]

Israelkk,

The examples in tec-ease are not compatable with the problem stated. It requires an axis A-B.

Try Figs 6-49 and 6-51 of the Y14.5 Std.

 

[machine78]

Thanks for all the replys!!! Sorry for the confusion.
Datum A is one of the .1870 dias which is a male feature. The opposite dia. of .1871 is the B datum, which is also a male feature, they are separated by a rectangular section. At each diameter callout the total runout of .0005 A B is attached. The width of the rectangular feature that separates the two shafts is .750

The part is for a military application...the whole part is critical, and very expensive for its size.

Hope this clears things up!!

 

[israelkk]

I assume this is a gimbal part.

I do not understand why there are A and B. Why not use just A and then give the other shaft with total run-out of 0.0005" with respect to A. Usually such a part is turned on a lathe using centering holes. This way you can get the 0.0005" run-out quite easily.

Anyway, if this is a given drawing I think you need to place both shafts on two very accurately aligned V blocks and then while you rotate the part measure the run-out on both shafts while they are supported on the two V blocks. If the part has two centering holes (one on each shaft edge) then you can use the centring holes as A-B and measure the run-out on both shafts.

I assume this is a gimbal part.

 

[Heckler]

We are a contract manufacture and design house for lubrication pumps and systems for both military and civilian airborne applications. I have never used total runout and I'm not sure our QA department has the means to inspect .0005 total runout. I realize you said this part is critical but unless this thing spins at 90K rpm I think total runout is an overkill.

Best Regards,

Heckler
Sr. Mechanical Engineer
SW2005 SP 5.0 & Pro/E 2001
Dell Precision 370
P4 3.6 GHz, 1GB RAM
XP Pro SP2.0
NVIDIA Quadro FX 1400
o
_`\(,_
(_)/ (_)

Never argue with an idiot. They'll bring you down to their level and beat you with experience every time.

 

[dingy2]

Ok, now that I know where the datums are here is what I would do. Since there appears to be a feature control frame with total runout on each diameter, we will have to check each one separately.

Place the datum A in a inspection grade chuck but just at the end of the diamter and not much length of the material in the chuck.

Get is digital indicator in at least .0001 or better and true up the other end. This is done by contacting the top or highest point of the diameter B which will be its C?l, then rotate the part. One will see the readings move up and down. Tap it down at the highest point and re-tighten the chuck at the other end. Continue this until you have the datum B running true (little FIM or TIR). You are now set up to datums A - B.

Take your indicator to the feature and contact it at its C/L or highest point. Rotate the part and note the extreme readings. You are taking a circular runout right now.

Move the indicator to another segment on the feature and perform the circular runout again without re-zeroing the indicator.

Move the indicator again so that you have both ends of the feature and centre measured, again, without re-zeroing.

Total runout is the combined readings from the 3 segments. If in 1 segment, the lowest reading was -.0003 and the highest reading was at the other end and it was +.0004, the total runout is .0007.

Hope this helps.

Dave D.

 

[ringman]

Dingy2,

Are yu making reference to inspection IAW Y14.5? If so, my version of Y14.5 does not seem to support your combining of the readings to establish the total runout. It is assessed on each segment as applicable by the Feature control frame on that particular segment.

 

[GDTcoach]

You will want to establish the datum axis using both diameters. You might be able to do this by using 2 V-blocks and aligning the two diameters with an indicator. Once they are aligned, you can check the total runout of each diameter. If the part has centers, you could do the same thing using the centers. The centers or V-blocks are not really the datum simulators. They are just a way to hold the part to align the common axis to the travel of the indicator. I found a Tip that explains this at:

http://www.tec-ease.com/tips/march-03.htm

 

[dingy2]

Using centres would mean countersunk holes in the ends and that would change everything. Each countersunk hole be a datum and the total runout would be to the end holes rather than the features noted.

Using V-blocks would be really tough. One block would have to be higher by 1/2 the diameter difference than the other one if the diameters are different. This is rather difficult.

Having a two point contact on a datum surface is not a good as a 3 point - 120 degrees apart and better yet, a 4 point.


Dave D.

http://www.qmsi.ca

 

[GDTcoach]

The centers are merely to hold the part. They would be moveable (at least one is) to align the two features using an indicator. They are not establishing the axis. The same with the V-blocks. This is a very common practice on large shafts to establish a common axis between the journals. Once the axis is established, the total runout of each journal relative to the established axis may be checked.