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/diy/ - Do It Yourself

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704450 No.704450 [Reply] [Original]

Hi /diy/, so I have a small plastic gear from an Instax camera that's missing a couple teeth. There is no source for replacement parts for these cameras. However I was thinking I could get it duplicated by a 3D printing service. So I made a quick 1200dpi backlit scan of the gear and I'm going to photoshop the missing teeth in, but how do I go about turning that into a 3D model?

>> No.704451
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704451

>>704450
Here's the repaired version

The gear is 0.061'' thick

>> No.704453

>>704450
Trace the outline and then extrude.
Chamfer edges.

>> No.704457

>>704453
using what software?

>> No.704473

>>704457
autocad

>> No.704485

>>704450
Wouldn't it be easier, faster and better to mold/cast a new one? You can very easily make a mold out of it.

>> No.704498

>>704485
I don't have much experience with mold making and this is a fairly high level of precision.

>> No.704501

Measure the bore diameter and nominal diameter, and search industrial supply companies and gear manufacturing companies for 24 tooth plastic gears with the matching specs. Just because Instax doesn't sell replacement parts doesn't mean that every part is proprietary. Thickness isn't quite as important - if it's slightly too thick you can sand it down with sandpaper taped to a table.

>> No.704502

I'm not particularly convinced this part is printable.

Most of the processes with this kind of resolution are very brittle or wear fast.

Obviously FDM is out, any so is any form of powder based printing as they have horrible mechanical properties (and a surface finish like sandpaper).

The best you are going to get is probably a photoresin/stereolitheography print but I hear those resins are pretty brittle as well.

>> No.704507

>>704501
what's a good starting point? Googling gear manufacturing/supply companies isn't really helping. But it seems like there must be a website somewhere that supplies very small plastic gears in a wide range of sizes. Like the mechanical equivalent of digikey.

I'm also experimenting with making a mold out of paraffin wax and filling it with cyanoacrylate glue, but i'm not sure how well it will work.

>> No.704511

>>704457
Solidworks would be better than autocad for this.

>> No.704514

>>704502
Fdm is a lot stronger than most diynosaurs like to admit. A well dialed in printbot jr could make this.

Op, Google for the openscad gear library. Easy, programmatic way of recreating your gear.

>> No.704515

Oh man, so damn close, the bore is just 0.4mm too large... I'm gonna order a couple anyway and see if I can't somehow reduce the bore size.
http://www.surplusshed.com/pages/item/m4167.htm

>> No.704521

>>704507
>Like the mechanical equivalent of digikey.
It's called "McMaster-Carr"
http://www.mcmaster.com/#nylon-gears

There was a company called "Small Parts Inc" that had a great catalog of this stuff. Amazon ate them, but you can still find PDFs of the catalog online and use them to order from amazon.

>> No.704534

>>704515
going back to mold idea, if you're willing to experiment(and maybe learn a new trick), you can make a mold of that replacement gear, flatten where the indent will be for the bore so you can make a copy with no bore, then use different drill bits from small to large til you get the perfect size.

>> No.704617

>>704515
You'd ideally get one with slightly too large and bore it out.

>> No.704621

>>704617
You mean slightly too small?

>> No.704624

>>704514
FDM is out because of the size of the part. The minimum extrusion width is probably larger than one of those gear teeth.

>> No.704628

>>704621
Yea sure did.