65065785 GD T Self Evaluation Test Level 5 5a1994 T0L5 T01A RevA

GD&T SELF EVALUATION TEST - DIFFICULTY LEVEL - 5 (of 10) Reference – ASME Y14.5M - 1994

by David Hebert (GD&T Senior Level Certified but not associated with ASME)

Test # - 1994-TL5-T01A-RevA

To use these test you simply “run” the slide show and use the down arrow key to navigate. If you find any mistakes please let me know and I will fix them and post the updated file to the www.mygdtsite.com. The part number above reflects the current rev. Hope this helps, let me know! Dave Hebert (Senior Level GD&T Professional) Note: these tests are not associated with ASME

A

B C D 8/9/2014

If errors are found, or if you have any questions, please let me know…..http://www.mygdtsite.com

1




While inspecting the part on a surface plate the inspector found that the hole is off: X _Axis by 0.4 Y_ Axis by 0.4

Does this part meet the Positional Tolerance specification? A

Yes

B

No

The cylindrical tolerance size required for the dimensions shown above is a 1.13 tolerance zone . See below for the formula.

C D 8/9/2014


2




I’ve just finished grinding this gauge and found it is .00005” below the minimum spec. What’s my best option?

A

B C D 8/9/2014

Look to see if the drawing size has a Straightness spec at MMC attached to the surface of the part. This might buy some bonus tolerance. Look to see if the drawing size has a Straightness spec at MMC associated with a size dimension. This might buy some bonus tolerance. Look to see if there is a Straightness Spec at RFS and determine the Bonus Tolerance to see if the part still meets spec. The part is small enough, keep it held tightly in your hands on the way down to inspection and the heat from your body should bring it into spec (coefficient of thermal expansion). If errors are found, or if you have any questions, please let me know…..http://www.mygdtsite.com

3




This shop is always so cold on Monday mornings and to top things off I’ve just finished grinding this gauge and found it is .00005” below the minimum spec. What’s my best option? ref. 1.4(k) A

B C D 8/9/2014

Since it’s cold in the shop there is a chance that the part may expand enough to get within spec when it is inspected. Y14.5M 1994 states the temperature to be at 70F . Since it’s cold in the shop there is a chance that the part may expand enough to get within spec when it is inspected. Y14.5M 1994 states the temperature to be at 68F. Since it’s cold in the shop there is a chance that the part may expand enough to get within spec when it is inspected. Y14.5M 1994 states the temperature to be at 65F. Since it’s cold in the shop there is a chance that the part may expand enough to get within spec when it is inspected. Y14.5M 1994 states the temperature to be at 72F . If errors are found, or if you have any questions, please let me know…..http://www.mygdtsite.com

4




This shop is always so cold on Monday mornings and to top things off I’ve just finished grinding this gauge and found it is .00005” below the diametrical minimum size spec. What’s my best option? A

B C D 8/9/2014

Look to see if the diametrical surface has a Straightness spec at LMC and associated with a size dimension. This might buy some bonus tolerance. Look to see if the drawing size has a Straightness spec at LMC and associated with a size dimension. This might buy some bonus tolerance. Since it’s cold in the shop there is a chance that the part may expand enough to get within spec when it is inspected. Standard states the temperature to be at 68F or 20C. Since B and C are true you may wish for the part to warm up before deciding. If errors are found, or if you have any questions, please let me know…..http://www.mygdtsite.com

5




I’m setting this part up on the surface plate trying to get the primary Datum feature to stop rocking but can’t do it. What should I do? Choose the best answer.

A

Take a file to it and flatten it out until it comes to rest flat so that no rocking is allowed.

B

Shim it up on both sides so that it becomes stable somewhere in the middle.

C

Use all the allowable motion available so that you can bring the part in spec as you measure it.

D 8/9/2014

If the part rock’s on the Primary datum, return it to be reworked, its out of spec. If errors are found, or if you have any questions, please let me know…..http://www.mygdtsite.com

6




Hey chief you got to help me out. I have this drawing with a very tight positional tolerance and a circle with an M inside of it right next to the tolerance. I just can’t quite meet that position spec. shown, and the funniest thing is this Engineer gave me a mile for the hole tolerance, go figure…... What should I do now? A

Make the holes towards the lower limit so you can use the extra tolerance for location.

B

This might be a feed and speed thing, carbide should get things tight enough.

C

Call the Engineer to see if he can balance out the tolerance on the spec so the “positional tolerance” is equal to the “hole size tolerance.”

D

Make the holes towards the high limit so you can use the extra tolerance for location.

8/9/2014


7




Hey Joe, I’ve got these parts coming in that flex all over the place, their impossible to inspect. Once their installed in the machine (the ones they build) all is fine. What should I do, I can’t get them by incoming Inspection.

A

Your going to have to make the parts thicker, I know the weight is a concern but there is no choice, they have to be inspected before we can use them.

B

Just have inspection force them flat so they can get the measurements they need.

C

Maybe you can specify something on the drawing that can tell them how much force to apply on See 6.8.2 in 1994 Y14.5M the part . It doesn’t matter, if it works in the machine its all academic at this point, their stamping process is in production so things won’t change now.

D 8/9/2014


8




I just got another call from manufacturing telling me that some of the pinned assemblies won’t go together. They believe the dowel pins and clearance holes don’t always line up. What do you think I should do?

A

B C D 8/9/2014

It would be best to determine the Resultant condition of each hole (dowel pin hole and the clearance hole) to see how the alignment is works out and fix it if needed. It would be best to determine to determine the Virtual condition of each of the hole (dowel pin hole and the clearance hole) to see how the alignment is works out and fix it if needed. Sounds like a projected tolerance zone is in order and it won’t hurt to double check your positional specifications. I know they make oversized dowel pins. You might want to check to see if that is the problem. If errors are found, or if you have any questions, please let me know…..http://www.mygdtsite.com

9




Hey Joe you are not going to believe this one!!! That part time high school kid they just hired had the head of the milling machine set to 1 degree and milled the entire surface of this plate that way (profile shown below) . The spec is .005 and there is a T inside of a circle after it. The deepest part of each pass is .010” . What the heck do we do with this?

A

The T dictates the entire surface must fit within in that window, it goes back to rework.

B

The T stands for Thickness. Just make sure that all of the surface area is within the thickness spec.

C

Just set the part on the surface plate, set a parallel across the ridges and run and indicator across it to see if it passes inspection. It doesn’t matter what that surface looks like.

D

You are going to have to measure the highest and lowest points on each wave and divide that number by 2 to see if you are in spec.

8/9/2014


10




Someone just told me that Rule #1 in the standard says that (and I am paraphrasing here) a part at it largest allowable size tolerance has to have perfect form? Which of the following is true?

A

Bar stock applies to this rule.

B

Straightness spec applied to the surface of the part does not follow this rule.

C D 8/9/2014

Straightness spec associated with a size dimension of the part does not follow this rule. Flatness spec applied to the surface of the part specified at MMC does not follow this rule. If errors are found, or if you have any questions, please let me know…..http://www.mygdtsite.com

11




What happened to the good old days when all we needed was tolerances in title blocks. Is there a cost associated with GD&T? Which of the following is the best answer?

A

GD&T is costly and should only be used for Production parts because of the additional cost.

B C

Anyone you talk to says that as soon as they see GD&T they think of higher cost. GD&T should only be used on parts that require tighter control for that specific reason. GD&T does constrain dimensions compared to Title Block tolerances. GD&T defines exactly what you want for design intent. With title block tolerances you cross your fingers and hope?

D

All of the above is true.

8/9/2014


12

65065785 GD T Self Evaluation Test Level 5 5a1994 T0L5 T01A RevA

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