a mandrel

Total noob question…

I have a friend (and neighbor) who makes jewelry. She uses these forms called ‘mandrels’–sort of conical shapes that might be circular or elliptical or, say, octagonal in cross-section. She has some ideas for some more exotic shapes, and she wants me to 3D print them.

I’ve gotten the shape she wants into an svg, and pulled it into Blender. That much was easy. I can extrude it and make an odd tube. I’m now trying to make my tube into a cone, and getting stuck. I’ve been following the directions on Youtube entitled ‘Introduction to using curves in Blender - part 3 - Aparima Blender Club.’ (this being my first post I can’t add a link.)

They work till I add the second Bezier curve. It sort of makes a duplicate tube instead of just adding a curve so I can taper, and I can’t seem to grab and move the Bezier handles separately. I seem to be stuck just moving the whole object.

I recently installed blender, so it should be pretty up to date.

Could you give us some more information, specifically this mandrel shape. Also do you have any previous experience with blender? I have a hard time judging your knowledge and skill level since this is your first post.

The issue of moving the entire object could be as easy as entering edit mode (as opposed to object mode). But then again you might already know this so some more information would be helpful :wink:

I have basically no experience with Blender. I’m a software developer, so I can generally figure things out, but I was messing with this kind of a while, so I came here. This is the first thing I’ve done with it.

So, ok, got it in edit mode, but now I can seem to edit the bezier handles, but not the line endpoints. I can make the curve bend but I can’t move the endpoints. And it seems to have associated itself with its own copy of the other curve, so instead of tapering my original tube I have two tubes. I need to associate both beziers with one curve, one to make a tube, another to taper it. I think.

If that’s the wrong way to go about this, let me know.

this site won’t let me upload an svg for some reason, but this is the png I derived it from:

I read the post and even did a bit of mandrel googling and I’m pretty much more confused than when I started. Your post is a bit ambiguous and could be interpreted a few ways. If you have a photograph or a even a sketch of the shape you’re trying to achieve, post it. Combining your, presumably cross sectional shape, with my new mandrel knowledge I took a guess at what you might be looking for. Is it something close to this? If so there are about 15 ways to go about it, bezier curves just one – and not a bad one at that.

Yeah, it’s a hard thing for me to describe. I’m sorry if I haven’t done it well. I think your version is close to what I’m thinking. Maybe I’d go a bit smaller at the tip, but I think you have the right idea.

I’m not surprised that there are a lot of ways to do it… Blender is impressively full featured.

And I appreciate you googling around to get an idea of what I’m trying to do.

So where are you at with this? Did you create the curves in blender using a reference image or import them from Illustrator(or other). Is your goal to print this in 3-d? If so that will dictate a few other things. For one, every material you print with (steel, silver, ceramic) has different minimum wall thicknesses and you need to make sure the mandrel bit is large enough (thick enough) for the material you want. Also, and this isn’t such a big deal, you need to keep an eye or your scale. I printed one necklace in 3-d and it was great, now the way the company I used worked was basically one blender unit could be imported as either 1 millimeter, or 1 inch, you choose when uploading the model. So I guess pick a unit and stick with it, or check the 3-d printer’s specs.
As for the modeling, if you have the cross sectional shape as bezier, you could do a bevel object and taper. Or you could convert the curve to a mesh and extrude it a few times, scaling it along the way.

I took the image from my friend and messed with it in Gimp and Inkscape to make an svg, and then imported that into Blender. I’m not exactly sure what material I’ll use to print it, but I’m thinking probably solid PLA or maybe nylon. At least thick walls. I have access to two printers at my local hackerspace, but I don’t have printing in metal easily available.

I think my friend uses a hammer to work the metals into the forms, to make bands in the right shapes. I might use the hot acetone-vapor trick to smooth it out when it’s printed.

‘if you have the cross sectional shape as bezier, you could do a bevel object and taper.’ That’s what I’m trying to do. I’ve made some progress. The problem I’m having now is that I don’t see how to make my conical form center on the center of my imported svg.

so now when I move the endpoints of my taper line, it moves the center line of my shape, not just its edges. When I select my tube and tab into edit mode, the line it’s bezeling appears above the tube, not inside it. Thus:

I dunno if that has anything to do with it or not.

OK, fixed that with Origin to Center of Mass on my c urve. now I need to make it watertight, that is, close the ends.

ah, the Fill Caps checkbox! Quite handy.

I think you are complicating yourself. I would do this:

Import the svg. Convert it to mesh. Select all and extrude. Select all the vertices in one extreme and scale down to the size you want.
To fill the extremes: select all the vertices in one extreme and extrude and right click, now scale down and collapse all the vertices in just one.

Yeah, gotta agree with bao, mesh extrusion probably simpler here. My internets been diwn two days, i am going thru serious withdrawals. And what exactly do u mean by having access to a printer at your local hackerspace? That sounds interesting.

a 3D printer. Two, actually. A Lulzbot A0-100 and a Makerbot, at Pumping Station: One, here in Chicago. And there are volunteers with expertise, it’s super awesome. And we have a million other toys too.

As for mesh vs curve, the shape is done and manipulable in the way I need it to be. I see Blender has Python hooks, and I know Python, so I may try scripting the process and doing other mandrels for my friend if she needs. We’ll see how it works out. Or scripting it with a mesh, just for education’s sake.

Thanks to all so much for your help!