Hello all,
I recently had a short discussion with a fabricator I chose to use for the first time, always a chance for an education. I mentioned that during modeling I would model to the outside dimensions even though they then use inside dimensions plus their allowance. When they mentioned inside I immediately thought that they meant the tangent point as that is where an allowance would start and be calculated from.
That was not the case and what a surprise! That was also without respect to the actual delivered material thickness. This made me think of the one time I received a model that was done to the tangent points. What HELL that was remodeling that one to outsides as all of our bend radii were different! We did use the exported flat to send to CAM and those would have never worked.
Bernie, I work for a fabrication job shop. Many of our customers use SW and supply us with models. The most common change to the sheet metal models I make is the bend radii and k-factor. This allows me to reuse their work but match our tooling and processes. We use both press brakes with bottom and air bending, and a folding machine. Customer models with edge flanges with edge flanges either inside or outside are easiest to deal with, especially when consistently applied. Those who use bend outside are a pita, because I have to adjust the earlier sketches to hold overall width. Those who dimension features to the tangent lines of bends instead of outside or inside surfaces are just asking for trouble.
I take the time to change these models to match our tooling and the parts come out great and the forming department really appreciates the extra effort I make. A co-worker often just exports the flat pattern as is and expects the shop to compensate. If it's one bend and there is sufficient tolerance this is acceptable in some cases, but for more than one bend with tight tolerances it gets difficult to hold size per print. I am a hands on old school fabricator. I appreciate when the model is easy to work with both at my desk and in the shop.
Regards