Stock on Base Alignment features

[[Je...]]

Hello all, I have a problem I have been trying to find a reliable solution to for quite some time. If I have stock on my part in the areas of base Alignment and origin, how do I satisfy the alignment and calculate for stock without throwing all nominals on the entire part out. IE. My spatial rotation and Z origin feature (a plane) has .025" stock as well as all Z axis planes so I have no alternative. How can I pick up the part and "tell" the model that there is .025" of stock on those features. I have found a method that tricks the program but if the base alignment window is ever opened then it recalculates and the "trick" is cancelled.

Is the best method measuring all features under a sub alignment with a .025" offset from base alignment or is there an easier way than bulk sub alignments?

[[Br...]]

You could click the "special" button in the base alignment window and offset the base alignment accordingly. But then I think you will need to shift the model too. So you would go to CAD>Modification>CAD model Transformation, and move the nominal CAD appropriately into the Base Alignment. Then program from there. Maybe someone with a lot of experience with stock material will have an easier idea of how to tackle this.

[[Ma...]]

😱 Hast du ein Skizze, Bild oder Zeichnung wie das aussehen soll ❓

[[Je...]]

Sorry but no drawing. I am posting from mobile and I am unable to upload a drawing.

Imagine a 4" cube. On each X and Y side of the cube there are several holes than run parallel to the Z+ plane (which is spatial rotation and Z origin). Let's call Z+ datum -A-. Let's say each hole has a basic dimension of 1", 2" or 3" from -A-. If I check the cube in it's finished form then all dimensions are easy to satisfy. The problem comes in when I am checking the cube before it is complete, say, before a final skin cut of -A- after heat treat. If there is stock on -A- of .025 and I check the part then the program still looks for the basics of 1" 2" and 3" but they will measure at 1.025, 2.025 and 3.025. and any positional tolerance will report out. My need is a way to make an offset to -A- as a theoretical plane relative to the stock on -A- without having to shift the model each time.

This is also a huge factor when roughing out a large solid from billet to be heat treated and trying to use space points to validate against a model when the part has .100-300" stock all over.

[[Ro...]]

Well first of all i wuoldnt use those unfinished surfaces for a base alignment.
base alignment does not have to be your datum surfaces, you can probe them later and add them to a secondary alignment or just add to your feature control frame.
You will probably need to use miniplans, where you have a selection for "rough" or "finish" with in this case an offset plane for your Z only used with the rough dims.

[[Je...]]

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As I said, sometimes I am validating a roughed blank prior to heat treat and final machining against a model. In that scenario there are no finished surfaces whatsoever. Like validating a casting. Looking for a way that doesn't involve shifting the model.

[[Me...]]

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This is the easiest way to do this. I often have the same issue when qualifying first op parts. You cannot go wrong using Brett's instructions.

[[Me...]]

1) Create a off-set plane for the plane that you have stock material
2) Then create a secondary alignment use the off-set plane for spatial and z original, make sure this secondary alignment is in the same place as the current base alignment you have (if not, adjust the amount of off-set),
3) Now you are safe to change your base alignment to the secondary alignment

[[Je...]]

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Thanks Yaowen Mei, this is essentially what I did before reading your reply.

I created a secondary alignment that used an offset plane as the origin. The offset plane recalled the origin plane from the base alignment. After creating the secondary alignment I went to my first feature after base alignment group and checked "keep position" then applied the secondary alignment. Nominals do not change. In order to apply the alignment to all features I used the paint brush. A global change from measure plan editor didn't allow "keep position"

After changing the alignments I created a "result element" as a text input for amount of stock on the origin feature. I then gave the offset plane a formula to recall that value and multiply by (-1) before continuing the program.

The amount of stock is a prompt to be input by the operator and is now dynamic for each run. Now all nominals are correct and the program can still be edited without fear of not calculating the right amount of stock. Also we are not hamstringed by the machinist leaving incorrect stock amounts as they often do.

Thanks for everyone's help