Starting Point for part

[B. Jacobs]

I have question. Here is what I have. I have a long cylinder(12.09") that has inside chamfers on it. I need to check the length and the inside diam. I am also checking the OD as a cylinder.

What I would like to know is:
If the length of the part changes by about .030" can I touch one end of the part to get a starting point so the probe will hit in the same location every time?
I will need to do this on both ends of the part. I am taking vector points on a chamfer on the inside so I can construct a cone and get the angle.
I could set up two different aligments if needed.
I programed with one part and it came out perfect but when I put a new part on it didn't hit some of the vector points to make the cone. I think the part is a bit shorter. It didn't go far enough into the ID cylinder to take some of the hits.
I have about 130 pieces to check and would like to do most all of it on the CMM so I don't spend all my time in front of the compartator.
I do not have any CAD for this one.
Thanks ahead of time.

3.5MR2

[Jeffrey Lovely]

You may be able to use RMEAS
so it will reference to another feature

[Wes Cisco]

I would only touch off one end, (near), of the part for the manual alignment. Then after the DCC alignment, (again using only the near end), I would measure the chamfer on the near end. Next I would take (a) hit(s) on the far end with a large prehit and retract distance to accomodate all possible deviations in length. Then create an alignment for that end, from which I would measure the chamfer on the far end. This second alignment might well be only recalling the first and changing the origin of the one axis from the near end to the far end. HTH

[#2#]

I would take a manual hit on each end at the beginning of the program. Then, you can align on one and take a dcc hit there. Align on the dcc and do your cone.

Later when you want to do the other end align on the other manual hit, do a dcc hit, align on the dcc hit and do your cone.

[Underspec]

Set a depth and use sample init/perm hits in your features, that way it goes down the same depth regardless of the height of your cylinder.

I'm not sure if this is what you were asking about.

[Paul Sarrach]

I would check in on its side, on a VEE block.

I would have it so that it butted to some thing that was screwed to the plate, but only just touched the bottum of the part.

I would write a program with a manual alignment and a DCC alignment. After the first run, I would clear mark, mark all, no to the manual alignment.

I would write my program with planes and circles and cones and maybe some lines depending on the size of the chamfer on each end. And create a cylinder some and points make sure I was in the right views and then dimension from there.

Then I would just replace each cylinder and run my program.

[B. Jacobs]

I would check in on its side, on a VEE block.

I would have it so that it butted to some thing that was screwed to the plate, but only just touched the bottum of the part.

I would write a program with a manual alignment and a DCC alignment. After the first run, I would clear mark, mark all, no to the manual alignment.

Thats what I am doing. I have changed my alignments to align in the Y after I take hits for a plane on each end. I have changed the hits so it will hit in the same place each time.
If my thinking is correct, If I align off the plane and move from there it will not matter how long the part is.
So far is seems to be working.

[Paul Sarrach]

If my thinking is correct, If I align off the plane and move from there it will not matter how long the part is.
.[/quote]

You are scaring me. What is the difference in lenths? You can change you pre-hit and Retract to compenstate for that.

[T Miller]

Once your main alignment is done dcc . all you will be doing is transfering the y origin to the other end. that should make your hits come out right.
If need be after you take your hits you can recall the main alignment and go from there

[B. Jacobs]

Paul,
Here is what I have.
I have parts that are 12.09 +/-.015. I have them setting on Vee Blocks. I am taking manual hits for a Manual Aligment. I then take DCC hits for a DCC Alignment. I am using a 1-2-3 block on the back of the part for a reference point.
I but the part against it then clamp it down. I know the back of the part is in the same place every time.
If the part is shorter than the last by say .010, the hit on my chamfer will be different on the front end.
What I have done is made an alignment for the front of the part so it will my hits on the chamfer will be in the same place.
I have done the same thing for the back of the part.
The problem i was having was that the hits for the chamfers were not hitting due to the probe coming out of the cylinder based on the original alignment.
Hope this helped.

[Paul Sarrach]

Take some points on the surface and use them as Reference points when you check the cylinder. What version are you using?

[Jeffrey Lovely]

rmeas

Take some points on the surface and use them as Reference points when you check the cylinder. What version are you using?

I Agree
I thought this would be the quikest fix (RMEAS)

[B. Jacobs]

3.5MR2

By doing the alignments like I stated before, it seems to be working preety good for me.

[Paul Sarrach]

3.5MR2

By doing the alignments like I stated before, it seems to be working preety good for me.

I understand. But next time take one hit on the other plane, then use that as a Ref Meas, that would elimate the need for a new alignment at that end. If you have time, after your run, try it with a part you already have numbers on, and compare. It is just a way to save machine and programming time.

[B. Jacobs]

I will try that.
Thanks for all the help.