Flatten a sticker
It’s interesting sometimes the lengths you have to go to solve a little problem. I frequently get emails or calls from folks who maybe I’ve met once upon a time, and maybe not. A lot of them ask me to solve some sort of a problem they’ve got. Sometimes the problems are interesting. The other day I got one that should have been easy to solve, but wasn’t. Or maybe I was just looking for the complex solution. Anyway, here it is. Maybe you can learn something, and maybe you can teach me something. I’m sure there were other ways to solve this, but this is the way I did it.
This particular problem boiled down to the fact that this fellow had a curved face, and he wanted to know what the shape of it would be if it were flattened. He wanted to put a sticker on the face, and needed the shape of the cutting die. It took me a couple of emails to understand just what he was talking about. The blue face above was the one the sticker needed to go on.
We know from the exercise with the bottles earlier that stickers have to be limited to curvature in one direction, because they don’t stretch, and you don’t want them to pucker when applied.
This one’s simple, right? The curvature of the face is just an arc. PPppphhhbbt! that’s simple. Right? You can just use sheet metal to flatten it. Wrong. The curvature is just an arc, but in order to get a SolidWorks part to flatten, you have to have a straight edge, and this part is all curves. You might have been able to fake it with a tiny straight edge, but I thought this could be done without cheating.
Well, you could take measurements and just remodel it flattened and call it done. Yeah, well, this is a different age. We would have done that 10 years ago, but these days, we have to get an answer from the computer, whether the computer is right or not, and whether it saves time or not. Keep looking.
Maybe you could put a split line down it and use Deform to deform the split to a straight line. Yeah, but Deform is awfully… approximate.
Um, Rhino? Rhino could do it, but giving up and using tools that are meant to do that sort of thing seems terribly… defeatist. Doesn’t it?
Ok, so all the obvious stuff doesn’t work. Let’s try combining a few things.
First, Lets make something we know we can flatten. So I took the profile of the sticker and used it to make a sheet metal base flange. But you have to play some tricks because SolidWorks Sheet Metal and multibody functionality don’t mix well together. (I played some trix to get them to show up here together for display purposes).
Then cut it to get the oval shape. But what with? Ah! a Ruled surface. Check. That’s always perpendicular to the surface, at least you can make one that way. I just made the outline of the sticker a spline shape just to give it a random shape that didn’t look too much like a simple oval.
But… if I cut away the outside, I don’t have any straight edges left to flatten the part. Drat.
So cut away the inside instead, leaving the outside. This better reflects the cutting die anyway.
And that’s something you can flatten…
Anybody want to take a crack at showing a different method?
So did that answer the question, or is that cheating? I just modeled the part of the material that the cutting die will discard, not the part to keep. But with a little boolean work, it’s not hard to get the negative of that part.
I just thought this was interesting because the original part started out as a shelled plastic part, and we went through surfacing, multibodies and sheet metal to get to the shape of a cutting die for a sticker.
Matt, I needed a decal like this one and I didn’t know just how to do it. I created a sketch on a tangent plane and used the face as the starting point and offset that face by .06″. This gave me a flatten face in which I used the “flex” feature (because I knew the radius) to make the decal. So, I guesed I went backwards but in the end I came up with a flat decal in which we could make and a decal which I could show in the assembly.
Steve
I would have done it the crappy way. Extrude rectangular surface to match curvature, then sketch the profile. Use the Wrap feature to Scribe it onto the surface, and keep tweaking until it matched up with the original shape. Lame-o, I know, and it probably wouldn’t have given as accurate of results.
the sheetmetal functionality in SW is very handy for flattening unusual things however preserving the bend edge is a gotcha.
what would be cool is if they could allow you to insert a phantom edge/face say like a zero offset surface for it that would be the phantom basis for the bend instead.
This bend marker would remain even if the edge went missing.
Another idea I suppose is sort of an overbuild like you have done and then some sort of boolean capability like multi bodies where you can choose and suppress the unwanted bit.
I am sure this type of thing could be done.
hmmm hope that hairbrained vision made sense
I would have done it like that, but with a split line instead of a ruled surface (I wouldn’t have thought of the ruled surface).
A while back I needed to solve a similar problem with a label that was applied to a drafted surface (prescription bottle) and wanted a simple way to model it such that the draft was accounted for, but the vertical ends of the label were parallel to one another. I finally figured out the trick to the geometry and got the label just perfect (used Wrap if I remember correctly) after a bit of tweaking and understanding the conical shape of the label. I then applied a decal to the label and rendered the whole scene. Definitely made the scene “real” with the extra work (and made a happy client).
Oh–and I don’t see modeling the outer cut-away portion of the label as “cheating”. After all, you’ll likely want to create a placement fixture for this label (if doing this for a production environment) and modeling the cut-away portion is exactly what you’ll need to create such a fixture.
This is interesting. It was only last week one of my customers came to me and asked if I could put decals on the helmets I had drawn up for them. The tricky part wasn’t to project the decal drawings onto the helmet, but to “unwrap” them afterwards. I had to pass on the project after researching it because I found no cost effective way to actually do that without a lot of hand finishing. I talked to a Maya and Studio Max reseller and they assured me their programs could do this sort of thing. Problem with that, I have no clue how to run their programs. With a month lead time on 8 helmets, that didn’t leave much time for learning/fumbling through a new program. Now I guess they will go back to Korea to get it done.
Using 2010 now, but still not getting the results I need.
Slightly different SM problem.
I design boats. Take the side of a simple boat as a sheet metal part that runs straight at the back and curves in to a point at the bow. My boat is structurally suported by transverse frames reuflarly spaced. I can generate the SM part flattened OK, but I want to scribe onto the part the vertical lines where the frames will go. Clearly when you flatten the part I need these frame lines to be visible, and they won;t be evenly spaced ofcourse on the expanded part. I have spent the afternoon searching for a solution without success. Can you help? it seems such an obvious thing to be able to do – creating refernce lines on SM parts for later assembly…
David Gray
What I want to be able to do is project a reference grid onto
Sometime I have to flatten packaging labels from a curved surface. I usually take an offset of the label panel, thicken it, and use the sheet metal tool – add bend feature too flatten it.