bend up or down?

How does solidworks detemine bend up or bend down on the flat patterns
in the drawings. A lot of times I notice that I think it should be a
bend down a solidworks will say bend up, does anyone know what is
driving this in solidworks?

 

There is really no room for intepretation here - it is based on the
sheetmetal feature from the 3D part before it was unfolded. If you use
the unfold with bend line annotations, it absolutely explicited. I
think it's also based on the view that you laid out. Of course if you
flip the view around 180, the bend lines will be down verse up. Are
you using the automatic bend line annotations?

Mark

 

You do realize, don't you, that you ca flip the flat pattern, as far as bend
up/down.

WT

 

Thanks, I realized shortly after posting that I could flip the view
and it would change the bend up or down. In your experience has the
solidworks annotations ever steered you wrong as far as bending up or
down. I just tend to get worried with some of these complex sheetmetal
parts, and I am probably over analizing them at times. I try to use
base flange as much as I can instead of sketched bends. thanks for the
feedback.

 

I have never seen it be wrong. When you think about things in SW, that's
probably one of the most stable in that it knows which way a flange goes.

WT

 

Stew and Wayne, the only time I've seen this to be wrong was once, in
SW07, on a mirror part that had the sheet metal feature added. After
discovering the error in the shop, I reopened the print to correct it
and did a Ctrl-Q rebuild, and then the pattern notes corrected
themselves. For some reason that view didn't rebuild before we
printed. The view property references and everything else were
correct, and as a rule I rebuild before printing.

I generally put the part side up with the first flange that will be
bent in the up direction. The operator then is looking at the part in
his hand, ready for the first bend. This helps eliminate forming parts
backward. This also forces me to review the flat view before finishing
the print.

regards, Diego

 

Interesting reasoning - I like it. This, of course, may get trumped by
coated material, etc.

WT

 

We bend a lot of large parts and we dont really have a rule of thumb
when designing them. I am trying to make it easier on our guys in the
shop, we tend to have an issue with things getting bent backwards. I
show an Iso view to clarify but it only sometimes further confuses.
Dont even talk about some of the prints we delt woth that had 1st
angle projection, that thru us for a loop. Any suggestions on what
views you like to show on the drawings?

Regards,
Stew

 

Adding a pictorial view has helped our shop understand prints, and
having the flat pattern with the bend direction and dimensions to the
bendlines has cut down on parts being bent backward. This year we will
be moving toward only sending our own prints, not our customer prints,
to the shop. We are currently primarily a job shop fabricator and our
customer prints are so varied we think using only our own prints in
the shop will help to reduce errors - people won't have to interpret
each customers' prints. I plan to implement some level of reduced
dimension or critical dimension prints for the shop, with the emphasis
on manufacturing information.

Two other things we've done this past year have helped. We are now a
paperless shop. Job routings are viewed on computers and the prints
are linked to the routings. If I want to update a print for clarity or
change a routing it's done immediately without having to find and
replace paper print copies. I can use either a tif image of the print
or an edrawing; most of the shop likes the edrawings because of the
added viewing options. The other thing we did was hold several print
reading classes. We had people from the shop and the office attend and
this has helped; we emphasized the importance of reading the entire
print, rather than just looking for the information for just the
operation being worked on. That approach helps catch errors before
more time and money is spent on an incorrect part, and people are
getting better at inspecting their own setups.

regards, Diego

 

There should be a symbol in the title block for that.

You might want a coordinate system symbol of some sort
added to the model too for all I know.
Right, top, down ...

 

An iso view is alway nice & with 3D CAD or CAD/CAM
systems they should be almost free (if space allows).
No need for full scale ...