Scanning 2D profile for 3D printer?

[T i m]

3D printerists.

I would like to print a base 'box' for a CCTV dome camera but it's a weird half round / elliptical shape.

Whilst I could probably measure it at various intervals and translate that into Sketchup, I wondered if anyone here had 2D scanned (on a flat bed scanner) an object to get an accurate profile and then imported that into their preferred 3D drawing package?

I'd assume you might still have to scale the resultant image (x, y) but that would be easier than having to draw it from scratch.

The base would simply mimic the base profile of the camera but provide some space / depth for cables and connectors etc.

This is partly need (for a mate) plus an exercise to see if it can be done easily (I have no doubt it can be done etc).

(You can buy the bases but they are ~£10+ and you could probably print

20 for that). ;-)

Cheers, T i m

[Richard]

[Theo]

I do this quite often for things to laser cut (PCBs and similar). The trick is to make sure it's 1:1 - in my case the flow is to scan to PDF on a big office photocopier, which gives me a 1:1 PDF file. Then I import into Inkscape and trace round the image to produce a clean line that the laser cutter will accept (it's very fussy).

You can probably do the same, only to produce a path that you then extrude in your 3D modelling package to make a tube of the appropriate shape.

One thing to be wary of is there's usually a bit of parallax when the item isn't absolutely flush to the glass, so the output often needs a bit of tweaking by the odd half-mm here and there. Expect to throw the first one away.

Theo

[T i m]

Cool.

Ok, I can do that ...

Ok. ;-)

Hmm, so is there no 'lasso tool in Inkscape to make that task easier or would it typically need tweaking in any case?

I have a scanner app on my phone that allows you to do that.

Luckily, in this case I can remove the camera 'ball', clearing the back of the camera housing of any cables etc and then the base should stand flat on the bed of my scanner pretty easily.

I should be happy to make my scan fit the required dimensions in Sketchup, as long as the scan is a reasonable reproduction of the basic shape. Luckily, it doesn't have to exact, as long as the camera sits on there reasonably well and the mounting holes line up etc.

Whilst I'm happy to do that ... as long as I err slightly (.5mm) in whatever direction that makes the fit between the things more likely, I generally find I can even use my first print (even if I sometimes don't).

In fact that is part of the buzz I still get when designing and printing things, it's used more like a tool than a hobby now. ;-)

Thanks for the tips, I'll give em a go!

Cheers, T i m

[Theo]

There is a bitmap tracing thingy, but it's not very useful. Automatically generated lines typically have too many points - that transfers into very complex shapes you're trying to print. It's better to reduce the number of points to make a simpler shape. You can set the tool to smooth the edges by reducing points, but then it rounds off all the corners.

Even 1mm off the glass is enough parallax to make things slightly out. It's still a problem unless it's perfectly flat.

(scanners don't have a large depth of field, so anything more than a few mm away will be out of focus)

Mounting holes are usually the problem, due to parallax. If you're printing in a soft material they can often be stretched a bit (regular screws become self-tapping with enough force :) It's more of a problem in non-soft materials (eg 6mm acrylic).

Theo

[The Natural Philosopher]

Many years of making models from scanned drawings has taught me that you simply measure the relevant dimensions and redraw it.

[T i m]

Ok, thanks.

Ok.

Understood.

In this case it is perfectly flat, it's 'machined' flat in fact and would be the surface that goes up against the mounting surface so no extensions or undulations etc. There are some (3) cable exit 'gaps' around the rim but they wouldn't cause any lifting issues.

Understood. That's why I only suggested flatbed scanning, not scanning from my camera etc. Ironically, I still have access to the 3D scanner we built alongside the printer but I thought a 2D scan would be quicker and more accurate.

Again, these appear on the same face as the overall section so should pickup ok.

(PLA)

Understood.

What I would typically do is either overlay what I had scanned with a geometric reproduction to see how close I was (assuming the original was created from an engineering drawing) and tweak accordingly or create my 'best match, do a test shallow print and adjust from that.

Cheers, T i m

[misterroy]

I recently scanned a flat 5 sided shape which had three holes, alongside a ruler. The three holes were in the correct places, or close enough not to matter. The shape needed tweaking.

[T i m]

<snip>

That's a good idea. ;-)

Thanks for the feedback.

Maybe I'll actually get time to try it. ;-(

Cheers, T i m