Slots and features of size with true positioning

[dhycorp]

I am looking for some examples of for coding that automatically adjusts the tolerence of a line to line distance to reflect the MMC deviation. What I am doing is measuring slots using 2 lines to obtain the size and a mid-line to obtain the location in the axis. The reason that I do not wish to use the autoslot is due to the fact that it does not measeure the side walls and only measures the radii on the ends of the slot. There is often time mismatch between the radii and the walls so I would like to keep measuring the walls for the most accurate representation of the location of the slot. Any examples would be appreciated. Thanks in advance.

[Perry Fisher]

You can create a generic circle from your lines representing the slot walls then apply MMC to the circle.

[kmcmm]

Creating a generic circle front the lines is probably the best solution your problem, but you can also use variables to figure the MMC tolerance and input that into your dimension in the edit window.

[DaddyBluto]

Change your round slot to a square slot and tick the width measure box. The instructor that used to be in Nashville taught me this and it works great. Just make sure you have a large enough radius that you are on the long walls. If you have 3.7 you can see where the points will end up. HTH

[rangerboat72]

Who was your instructor in Nashville?

Change your round slot to a square slot and tick the width measure box. The instructor that used to be in Nashville taught me this and it works great. Just make sure you have a large enough radius that you are on the long walls. If you have 3.7 you can see where the points will end up. HTH

Who was your instructor in Nashville? Sounds like the same guy that got me started about 2 1/2 years ago...

[tking]

Change your round slot to a square slot and tick the width measure box. The instructor that used to be in Nashville taught me this and it works great. Just make sure you have a large enough radius that you are on the long walls. If you have 3.7 you can see where the points will end up. HTH

Thanks, I'm gonna try this as soon as I get a chance!

TK

[craiger_ny]

If you would like to continue your current practice of measuring it but would like a way of coding the rest to get what you want then post your code for measuring the slot and we can work out some examples by picking up from there.

Craig

[T Miller]

^^^^^^ Has no auto slot feature *sniff *sniff

[DaddyBluto]

Ray Wilson. He has gone out on his own now. Good guy and very smart.

[rangerboat72]

Ray Wilson. He has gone out on his own now. Good guy and very smart.

That's who I thought it was...

He seemed like an awesome guy. He's gone out on his own now? Programming or what?

[CMMPGMR]

Maybe someday the software engineers will make the autoslot measuring feature so that a slot can actually be measured correctly in regards to GD&T.
Most slots are TP referenced to a datum plane or perpendicular to that plane
not just in a 2D location. If dimensioned this way then there is a zonal perpendicularity requirement to that datum. Round slots are actually 2 cylinders & 2 planes intersecting tangently. Shorter round slots would have some difficulty measuring the 2 planar surfaces but the 2 cylindrical surfaces could always be measured. One might consider constructing a feature set including 2 cylinders & 2 points one on each side of the width to correctly report the 3D TP utilizing the cylindrical axes & the distance between the 2 side points. Also, machining is so high speed now days that machine programmers do not give tooling time to actually cut the radial ends at a decreased feedrate so tools push off slightly resulting in the radius ends to be considerably smaller than the actual slot width. It would also greatly depend on the slot tolerance to determine if a slot would actually need to be measured this closely or not. Most of the slots I measure do & it would be nice to have the software do most of the work for me by measuring the feature as stated above incorporating cylinders & points combined.

[dhycorp]

Tolerence changing

Creating a generic circle front the lines is probably the best solution your problem, but you can also use variables to figure the MMC tolerance and input that into your dimension in the edit window.

Do you have any examples of the variable input/read for tolerence changing?

[CMMPGMR]

Maybe someday the software engineers will make the autoslot measuring feature so that a slot can actually be measured correctly in regards to GD&T.
Most slots are TP referenced to a datum plane or perpendicular to that plane
not just in a 2D location. If dimensioned this way then there is a zonal perpendicularity requirement to that datum. Round slots are actually 2 cylinders & 2 planes intersecting tangently. Shorter round slots would have some difficulty measuring the 2 planar surfaces but the 2 cylindrical surfaces could always be measured. One might consider constructing a feature set including 2 cylinders & 2 points one on each side of the width to correctly report the 3D TP utilizing the cylindrical axes & the distance between the 2 side points. Also, machining is so high speed now days that machine programmers do not give tooling time to actually cut the radial ends at a decreased feedrate so tools push off slightly resulting in the radius ends to be considerably smaller than the actual slot width. It would also greatly depend on the slot tolerance to determine if a slot would actually need to be measured this closely or not. Most of the slots I measure do & it would be nice to have the software do most of the work for me by measuring the feature as stated above incorporating cylinders & points combined.

[dhycorp]

PC-DMIS limitations

In all actuality, I would perfectly happy if PC-DMIS would give an option to measure the walls and include those measurements in the overall construction of the autoslot. This would be ideal for the calculation of the MMC and the application of best fit true positioning to the datum structure without loosing any accuracy to the true form of the slot.

[CMMPGMR]

Maybe someday the software engineers will make the autoslot measuring feature so that a slot can actually be measured correctly in regards to GD&T.
Most slots are TP referenced to a datum plane or perpendicular to that plane
not just in a 2D location. If dimensioned this way then there is a zonal perpendicularity requirement to that datum. Round slots are actually 2 cylinders & 2 planes intersecting tangently. Shorter round slots would have some difficulty measuring the 2 planar surfaces but the 2 cylindrical surfaces could always be measured. One might consider constructing a feature set including 2 cylinders & 2 points one on each side of the width to correctly report the 3D TP utilizing the cylindrical axes & the distance between the 2 side points. Also, machining is so high speed now days that machine programmers do not give tooling time to actually cut the radial ends at a decreased feedrate so tools push off slightly resulting in the radius ends to be considerably smaller than the actual slot width. It would also greatly depend on the slot tolerance to determine if a slot would actually need to be measured this closely or not. Most of the slots I measure do & it would be nice to have the software do most of the work for me by measuring the feature as stated above incorporating cylinders & points combined.