Stock Size Discrepancy

[pjjackley]

So my stock size comes out pretty rough due to poor bandsawing (e.g. a pretty slopey rectangular prism, and also more than an 1/8" undersized from the stock size I specified in the initial setup).

Let's say that the dims are roughly 1/16-1/8" undersized (smaller stock than expected).

Do I NEED to go fix this in the stock sizing for every part I do?

Say I left the setup stock size in 360 as what it was originally planned to be. When I then go to set my true z-zero on the actual machine at the true stock top, does it take this value into account and machine off less? Or will my part essentially end up 1/8-1/4" undersized if I did facing operations on both opposite sides.

Another way to say it is... Does the machine Z-origin that I set while actually machining override the 'stocktop' value and then the distance between 'model top' and 'stock top' float/calculate? I don't want to face both sides and have it be 1/4" smaller than it should be if this stock top value is rigid from the initial setup.

I'm failing to understand where my machine z-origin value fits in. In most of my operations I set the origin to be at the stock-top. I reckon I'd be able to change it to model top and then definitely play with my height/feed height clearances to make it work out.

[weber_dominic]

Yes. If you set your WCS at stock top, your part will be too small since Fusion or every other CAM has no idea how high your actual stock material is. It only calculates a difference between stock top and model top.

Play around with your heights to make it accurate.

[seth.madore · Accepted solution]

For this reason alone, I prefer to have my WCS set to model top. When I set my WCS at the machine, I'll set zero to the top of stock and then offset that amount .005-.01" until the top surface is cleaned.

Fusion (or any other CAM software) has no knowledge of your part being sawcut too small.

[programming2C78B]

it's better to be too small, all that will happen is a few whisper/air cuts around your outside profiles. WCS should be on center though, not one saw cut edge. 

WCS is best set to model top and doing as Seth said.