3D Printer for Printing Fixtures

[David Atkinson]

So work has asked me to make up a proposal for a 3D Printer to make inspection fixtures, especially gang fixtures. Lead time and cost on machined aluminum fixtures too too high.

Of course, I know nothing about 3d printers. I need a few different options in different budgets - everything from 1k-20k. I am thinking a 12x12" print area would be a good starting point.

Does anyone make fixtures this way? Any thoughts, advice, or other comments?

[Norbert Bendl]

We use an Ultimaker 3 Extended two-nozzle filament printer (around 4k), but I don't print fixtures with it yet. I don't know how exact your fixtures need to be and what your timeframe is, but those two aspects (and the lack of an easy to use CAD software that I'm allowed to use) have kept me from trying to print fixtures with it. For me, filament printers are more a toy than a professional tool. The dimensions of the prints are not exact enough (nozzle diameter is usually 0.4 mm, resulting in a +/-0,2 mm tolerance for most of the printed geometry) and it needs way too much time (many hours for a rather simple print). If something goes wrong - and there's a lot that can go wrong, the ever-present warping being only one of many potential problems - the waiting time doubles or triples.Apart from that, the standard PLA material is the easiest to print with, but not very durable. We need fixtures for serial production, but PLA simply isn't made for that. All the other materials available are more or less problematic to print with.

My conclusion: Compared to the output of our professional SLS printer (about 100k) used for prototypes in another plant, a filament printer is kid's stuff. So my recommendation is, go for a decent SLS device

[Richard Gallo]

I have been doing quite a bit of research into this as my department simply doesn't have the budget to fixture the parts I have to inspect. As you've found, quality fixturing is prohibitively expensive.

If your handlers wont/can't spring for fixturing, you're most certainly not going to get $100k for a metal sintering printer.
This is my scenario, so I've had to seek out a "creative", "low cost" solution.
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There is a fundamental issue with conventional DLP and lower end laser SLA printers where there's distortion across the entirety of the work volume. This problem appears to be prevalent with all but the most high end printers.($10-100k)
Others have tried to to adjust for this distortion manually by printing/inspecting grids and then editing the g-code manually. But when dealing with a 3 dimensional part this problem only becomes manifold.

distortion.JPG (121.4 KiB) Viewed 12294 times

UV LED DLP projectors seems to eliminate this problem. There's no barrel distortion from laser galvos, and no lens distortion from low end optics.

These are basically a cell phone screen with UV pixels and an LCD masking layer above it that hardens a photoreactive polymer, one slice at a time. This gives you per pixel accuracy where your only issue is minor blooming.

I've been looking at Moonray (small work volume, but stable dimensional accuracy across the work volume. Used for dental prosthetics. roughly 5000$usd) and on the lower end of the price spectrum, the Phrozen Shuffle XL (large work volume, but poor to nonexistent manufacturer support 1300$).

No printer is ever going to be perfect, but at these prices there's certainly a much better chance of getting funding from management. And once you've proven that 3d printing has value, then you can push for the 100k printer.

[Thomas Gorman]

For what it's worth, the Form 3 has a parabolic mirror that is supposed to correct for SLA's typical outer-edge accuracy issues. Small-ish build volume, but certainly well under the $10k price mark.

[Richard Gallo]

For what it's worth, the Form 3 has a parabolic mirror that is supposed to correct for SLA's typical outer-edge accuracy issues. Small-ish build volume, but certainly well under the $10k price mark.

I've heard similar.
But I can't find a single example of anyone using the full work volume of their Formlabs printer. I would really like to see someone print a cubic, full work volume grid and then throw it up on the CMM for analysis and post their results.

Even if the distortion issue has been completely resolved, even the most cursory search online reveals endless tales of poor customer support and extremely long delays in trying to get replacement parts and consumables. All this resulting in significant downtime (expense!) imposed on customer. I take everything I read online with a grain of salt, but the sheer number of complaints that come up, compounded by some of Formlabs own apologies on those same posts make it evident that there is indeed a dire supply chain issue.

We are all trying to solve problems and reduce costs by going to 3D printing, but no one wants to be responsible for buying into a brand that creates new ones. It's such a new segment, there's just very little in the way of concrete fact to grasp onto in order to make a genuinely informed decision.

[fabrizio funassi]

We have been replacing aluminum fixtures with 3D printed ones years ago. This technology is perfect for our needs and the cost of the printer pays off in just a few months.
We have a markforge mark 1 (± 15000 $) and we have the possibility to make the outer layers in carbon fiber in order to reinforce the points of contact with the pieces, it's also possible to vary the hardness of the fixturing according to the material it will have to support

[fabrizio funassi]

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