Inspect operation 2

00:00

Inspect OP two.

00:02

After completing this video, you will be able to

00:05

visually inspect a part,

00:07

use common hand tools for inspection.

00:10

Better understand how clamping can affect a parts dimension. Our

00:15

part looks fantastic, looks great, nice surface finishes

00:20

and looking at the Cher,

00:22

there are no rolled edges, no birds.

00:24

So we know that our champer tool is nice and sharp.

00:28

The only features we cut in this second operation are the face

00:32

which establish our overall height.

00:34

And

00:35

our Cher

00:36

our overall height is supposed to be 0.63 inches.

00:40

Now there is no tolerance on this dimension.

00:43

So we look to our block tolerance

00:45

two digits past the decimal place. So our tolerance

00:49

is plus or minus 0.02 inches. Now,

00:53

this is well within the accuracy range of a good set of calipers.

00:56

So that is what we will be using to measure these parts.

01:01

I'll wipe the jaws on the calipers,

01:03

close them all the way no light can be seen between the caliper jaws.

01:07

So we know that they are fully closed and flush.

01:10

We will rezero our calipers by pressing and holding the zero button

01:14

and can then measure our part 0.628 inches.

01:18

Now, this falls well within our measured tolerance of plus or minus 20 thou,

01:24

we will write this down on our inspection sheet.

01:32

This part measured good. We're gonna pass it.

01:35

But what if it measured out of tolerance out of spec?

01:38

Well, at that point, we would go to our control

01:41

and make a change to our tool or our work offset,

01:45

we will go ahead and make an offset correction.

01:47

So our next part is even closer to our 0.63 inch nominal value.

01:53

Again, to be clear,

01:55

the height of this part measures 0.6 to eight inches. It's good.

01:60

We don't have to make an adjustment.

02:02

Uh We're doing this because we need to show you how to adjust tool and work offsets.

02:07

And it's always a good idea to stay right in the middle of our tolerance range,

02:11

right on nominal.

02:13

Our part is two thou two short

02:19

Now, this face

02:20

was machined with tool seven,

02:23

our half inch and mill. Now, we need to bring this face up

02:27

by two thou

02:29

and we have a couple ways to accomplish this

02:31

one. We could bring up our T seven

02:35

adjusting our T seven length wear by plus 2007 inch. That's on the tool offset page.

02:41

The next time we run this part, it should measure 0.63 inches tall

02:46

instead

02:47

of 0.628.

02:49

Another method to adjust this face. The overall height of our part

02:54

is to change our G 54 work offset instead of our tool offset.

02:59

Why would we do that?

03:01

Well, if we adjust our G 54 and we bring that up, it brings all of our tools,

03:07

both of our tools in this case

03:09

up together. If we bring our G 54 work offset down,

03:13

it brings both of our tools down. So everything is moving up or down together

03:18

with our G 54 work offset.

03:20

This might sound like a small distinction, but there are big ramifications to this

03:25

changing a tool offset versus a work offset

03:28

later on in the future.

03:29

When we've got two vices on a table each with its own work offset,

03:34

adjusting a tool offset will affect

03:37

every work offset, every operation that that tool touches.

03:41

So if we brought up our, our tool seven,

03:44

it would bring that tool up on both

03:46

G 54 and G 55.

03:49

That could be a problem

03:50

making a change to a tool affects everything that tool touches.

03:55

Making a change to a work offset

03:58

will only affect the operation that that work offset affects G 54.

04:03

Change only affects

04:04

one. A G 55 change will only affect

04:07

two. But again, we'll talk more about this in upcoming videos.

04:11

Lots to think about.

04:12

There is no one method that can be applied to every part in every situation

04:18

we got to put on our thinking caps and, and decide are we gonna adjust a tool

04:23

or a work offset?

04:25

Ok.

04:26

Onto our champ

04:33

So technically, her part is good

04:36

if we are somewhere between zero

04:38

and 40 thou wide,

04:40

using a loop in our calipers, we can see that our Cher

04:43

is just about 20 thou wide. Now, this is not a terribly accurate method,

04:48

but I can absolutely guarantee that the champ

04:50

is between zero and 40/1000 of an inch.

04:53

So I am writing down 20 thou and passing this feature.

04:57

If it were a tighter tolerance,

04:59

we could have used an optical comparator.

05:01

The comparator can also be used to verify our champ for angle of 45 degrees.

05:05

We inspected our champ for tool upon installation.

05:08

We found it to be a 45 degree, 90 degree included tool.

05:13

Well, that's it. It's the last dimension on our op two

05:17

in process inspection report. So we can just ship the part to the customer, right?

05:21

Well, not so fast.

05:22

We need to give the part a final inspection. We can call that

05:26

uh a final inspection report or a first article inspection report.

05:31

And the reason we want to go ahead and measure all these features again

05:36

is because we might have affected op one dimensions

05:40

during

05:41

two. And here's what I mean

05:43

when we held this part in our vice

05:45

and machined out the OD and the ID. During

05:48

one, we inspected it, everything was perfect,

05:51

but

05:51

we held it on those features

05:54

in the jaw

05:55

during our second operation.

05:57

And it is possible that we could have crushed that part, put too much

06:02

elbow grease on to it and deformed it.

06:04

Where if we were to take our calipers and measure the outside, rotate 90 degrees,

06:08

measure it again, we might get different numbers.

06:10

We might have turned our circle

06:12

into an oval.

06:14

And the only way that we would find this out is during a final inspection.

06:19

So check everything again, in this case, see if we've done everything properly.

06:24

And if we really do have a good part,

06:27

this is where a good machinist can shine over time.

06:31

We will gain knowledge,

06:32

letting us know how metal moves and we'll

06:35

use that knowledge to make more perfect parts.

Video transcript

00:00

Inspect OP two.

00:02

After completing this video, you will be able to

00:05

visually inspect a part,

00:07

use common hand tools for inspection.

00:10

Better understand how clamping can affect a parts dimension. Our

00:15

part looks fantastic, looks great, nice surface finishes

00:20

and looking at the Cher,

00:22

there are no rolled edges, no birds.

00:24

So we know that our champer tool is nice and sharp.

00:28

The only features we cut in this second operation are the face

00:32

which establish our overall height.

00:34

And

00:35

our Cher

00:36

our overall height is supposed to be 0.63 inches.

00:40

Now there is no tolerance on this dimension.

00:43

So we look to our block tolerance

00:45

two digits past the decimal place. So our tolerance

00:49

is plus or minus 0.02 inches. Now,

00:53

this is well within the accuracy range of a good set of calipers.

00:56

So that is what we will be using to measure these parts.

01:01

I'll wipe the jaws on the calipers,

01:03

close them all the way no light can be seen between the caliper jaws.

01:07

So we know that they are fully closed and flush.

01:10

We will rezero our calipers by pressing and holding the zero button

01:14

and can then measure our part 0.628 inches.

01:18

Now, this falls well within our measured tolerance of plus or minus 20 thou,

01:24

we will write this down on our inspection sheet.

01:32

This part measured good. We're gonna pass it.

01:35

But what if it measured out of tolerance out of spec?

01:38

Well, at that point, we would go to our control

01:41

and make a change to our tool or our work offset,

01:45

we will go ahead and make an offset correction.

01:47

So our next part is even closer to our 0.63 inch nominal value.

01:53

Again, to be clear,

01:55

the height of this part measures 0.6 to eight inches. It's good.

01:60

We don't have to make an adjustment.

02:02

Uh We're doing this because we need to show you how to adjust tool and work offsets.

02:07

And it's always a good idea to stay right in the middle of our tolerance range,

02:11

right on nominal.

02:13

Our part is two thou two short

02:19

Now, this face

02:20

was machined with tool seven,

02:23

our half inch and mill. Now, we need to bring this face up

02:27

by two thou

02:29

and we have a couple ways to accomplish this

02:31

one. We could bring up our T seven

02:35

adjusting our T seven length wear by plus 2007 inch. That's on the tool offset page.

02:41

The next time we run this part, it should measure 0.63 inches tall

02:46

instead

02:47

of 0.628.

02:49

Another method to adjust this face. The overall height of our part

02:54

is to change our G 54 work offset instead of our tool offset.

02:59

Why would we do that?

03:01

Well, if we adjust our G 54 and we bring that up, it brings all of our tools,

03:07

both of our tools in this case

03:09

up together. If we bring our G 54 work offset down,

03:13

it brings both of our tools down. So everything is moving up or down together

03:18

with our G 54 work offset.

03:20

This might sound like a small distinction, but there are big ramifications to this

03:25

changing a tool offset versus a work offset

03:28

later on in the future.

03:29

When we've got two vices on a table each with its own work offset,

03:34

adjusting a tool offset will affect

03:37

every work offset, every operation that that tool touches.

03:41

So if we brought up our, our tool seven,

03:44

it would bring that tool up on both

03:46

G 54 and G 55.

03:49

That could be a problem

03:50

making a change to a tool affects everything that tool touches.

03:55

Making a change to a work offset

03:58

will only affect the operation that that work offset affects G 54.

04:03

Change only affects

04:04

one. A G 55 change will only affect

04:07

two. But again, we'll talk more about this in upcoming videos.

04:11

Lots to think about.

04:12

There is no one method that can be applied to every part in every situation

04:18

we got to put on our thinking caps and, and decide are we gonna adjust a tool

04:23

or a work offset?

04:25

Ok.

04:26

Onto our champ

04:33

So technically, her part is good

04:36

if we are somewhere between zero

04:38

and 40 thou wide,

04:40

using a loop in our calipers, we can see that our Cher

04:43

is just about 20 thou wide. Now, this is not a terribly accurate method,

04:48

but I can absolutely guarantee that the champ

04:50

is between zero and 40/1000 of an inch.

04:53

So I am writing down 20 thou and passing this feature.

04:57

If it were a tighter tolerance,

04:59

we could have used an optical comparator.

05:01

The comparator can also be used to verify our champ for angle of 45 degrees.

05:05

We inspected our champ for tool upon installation.

05:08

We found it to be a 45 degree, 90 degree included tool.

05:13

Well, that's it. It's the last dimension on our op two

05:17

in process inspection report. So we can just ship the part to the customer, right?

05:21

Well, not so fast.

05:22

We need to give the part a final inspection. We can call that

05:26

uh a final inspection report or a first article inspection report.

05:31

And the reason we want to go ahead and measure all these features again

05:36

is because we might have affected op one dimensions

05:40

during

05:41

two. And here's what I mean

05:43

when we held this part in our vice

05:45

and machined out the OD and the ID. During

05:48

one, we inspected it, everything was perfect,

05:51

but

05:51

we held it on those features

05:54

in the jaw

05:55

during our second operation.

05:57

And it is possible that we could have crushed that part, put too much

06:02

elbow grease on to it and deformed it.

06:04

Where if we were to take our calipers and measure the outside, rotate 90 degrees,

06:08

measure it again, we might get different numbers.

06:10

We might have turned our circle

06:12

into an oval.

06:14

And the only way that we would find this out is during a final inspection.

06:19

So check everything again, in this case, see if we've done everything properly.

06:24

And if we really do have a good part,

06:27

this is where a good machinist can shine over time.

06:31

We will gain knowledge,

06:32

letting us know how metal moves and we'll

06:35

use that knowledge to make more perfect parts.

After completing this video, you'll be able to: 

  • Visually inspect a part after machining.
  • Use hand tools to inspect a part.
  • Better understand how clamping can affect a part.

Video quiz

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