continuous feature

[[Lo...]]

Our programmer is having some difficulties with calypso and (2) continuous features. This is basically a sheet metal stamping that has 2 flanges about 12" apart. There are holes pierces thru the datum A plane with CF listed. I have never seen any print with the CF called out. I think i understand the meaning, but does it change how they are actually evaluated. Then how do yo you get calypso to do this? I provided a "well drawn" print of what is being asked from our customer.

I dont believe the feature control frames are correct, but we we will discuss with the customer?

[[Cl...]]

Wouldn't that mean the 4 circles should be measured/evaluated as two cylinders?

[[An...]]

CF prevents exactly one cylinder measurement.
By [CF] it is then agreed that the geometry element for forming the reference should not be the cylinder, but linear supports in a prism. (Contacting feature), DIN EN ISO 5459

[[Lo...]]

This has brought up all kinds of questions. Does the CF change how we should align the part? Will Calypso accept the call outs as drawn or will we have to do some additional work to get what is intended.

We typically avoid 3d feature in the base alignment with stampings.

[[Ma...]]

I would say that first callout "Perpendicularity" is wrong - can not make | A | B(M) | while defining base B

[[Er...]]

IN the ASME Y14.5, (refer to 2009, 3.3.23) CF stands for continuous feature and means both holes should be evaluated as a 1 continuous cylinder. Double check what standards your print is referring to before evaluating what's required.

[[Lo...]]

We are going to have to play with this one since we typically try to keep cylinders out of the BA (origin/planer) due to past issues with skewing caused by form error.
In calypso I believe there is a way to to do TP of a cylinder and have it tell you what end the deviation being reported to from? If done as one feature we need to know what direction to move the holes.

[[Lo...]]

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We get a lot of prints that need to "altered"or done differently. Remember, Engineers don't make mistakes, they make deviations! LOL.

[[Ro...]]

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Hi Lonnie,
No need to put the cylinders in the Base Alignment. Your BA just finds the part for you. You can create a circle on each side, and then recall those into a cylinder. That way you can get the data for the individual holes if you need to move them independently, as well as the cylinder for the callout on the print.

If you want to see each side of the cylinder then turn on axis endpoints and it will report each end.

[[Lo...]]

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We typically align the program per the datum scheme. This is due to people that dont know how the CMM works implementing rules or as a rule of thumb. With the CF being applied to B and C, i didn't know if alignment trickery would have to come in to play. We live in a 2d world and do very little 3d evaluations. We have tried in the past and ultimately end up changing cylinders, etc. to 2d features.

Would I use a cylinder as datum B and datum C in the feature control from for the TP?

[[Ro...]]

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Hi Lonnie,
Yes.
A couple things on the drawing. The callout for B is incorrect. -B- can't have perpendicularity to itself. Also, if they want material condition on -B- they need to put it with the tolerance, not as a secondary datum callout.

The callout for-C- is pretty straightforward. Rotation around -B- isn't constrained so you can best fit the rotation when reporting the TP of -C-.