I have recently obtained a friend’s old Formlabs Form 2 SLA printer. I I am an absolute beginner to printing, but I am pretty excited to get into it....
laser -> “special” resin required. Formlabs recently moved on to LCDs meaning in the years to come the last third-party manufacturers will stop producing those resins as demand further declines. Leaving the first-party FormLabs as the only option ($100+/kg).
Difficult to maintain resin tank. Requires a vacuum oven and an upfront investment of roughly $150 for chemicals. There are conversion kits/prints for FEP film to resolve this limitation.
I’ve made a large number of custom prints, and all of them were created using TinkerCad. It’s an amazing toolkit, stupid easy to use but versatile. That is … until something needs a tiny adjustment somewhere. That’s when I feel it would’ve been neat to use parametric CAD instead....
I finally got a filament drying box and I’m using it prior to and during prints. It seems to be helping. I’m a bit of a color queen, so I keep a pretty big backlog of different filaments. I’ve been storing them in vacuum bags but the vacuum bags often seem to lose some of their vacuum after a few months; the whole process...
Instead of those bags with a valve take a look a the kitchen department. They have vacuum seal machines used for sous vid cooking.
This is practically identical to the original packaging and can hold the vacuum for years to come. Leave the bag longer than required to allow it to be resealed multiple times (roughly 3cm are cut with each opening & resealing).
For the frequently used filaments place them in a drying box.
That’s exactly why it is a partial model/design to rapidly iterate on it: 1g, 10-minute print time. The full version with all the print-in-place parts takes 16 minutes.
Another aspect is collecting designs for a library. From now on I can copy past this subassembly into bigger designs and know it will just work. If I need to modify it I know how and where to change it to get the desired outcome.
If you consider sharing mechanical design concepts as not in line with the spirit it’s fine but others are likely interested in seeing how things work and takes it as inspiration for their designs.
Go and recreate it. Nobody stops you. Could provide the STL but wouldn’t be worth a lot as this is so dialed (tolerances) that it comes down to the specific printer/extrusion system. There are older revisions with huge tolerances (0.4mm) that work but wear down rapidly. To print this exact version it needs to be capable of printing with 0.23mm gap/tolerance between parts.
v10 should still be 0.4mm tolerances (easy to print) on all sides and working. Otherwise not a great design but enough for you to understand that there are dozens of parameters to tune in such a “simple” mechanism and it is (nearly) impossible to nail it on the first try. Have we started talking about optimizing the force required to break it loose? That’s one more thing that needs to be accounted for.
I think you still somehow assume this is some kind of ad to sell this design for money or I am a jerk for not just publishing it with source files.
Also not everybody spends their time designing and publishing whatever is popular at the moment on Makerworld to collect points/store credit. There is a different world that doesn’t run on Fusion360 source file most people could edit and can design parts with a particular material & print(farm)/process in mind to get the most out of the FFF 3D-printing process.
The teeth is indeed a critical aspect. It has to be symmetrical as this assembly is mirrored to block the rotation in the other direction.
An alternative to this would be printing the spring with the contact surface separately and inserting it into this print (pause at layer height, insert part, continue print) allowing other geometries (that would overlap with the teeth if printed in place) and pretension. The downside is it’s a manual task and one more separate part to keep track of.
This is small and the tolerances of the center hub cause the teeths/“gear” to move approx. 0.3-0.5mm of centre. This means what you see in the CAD/slicer isn’t how it will look once printed. I had to narrow the gap down as much as I could to get the largest contact area. If you make it a sled on one side there is less material/surface area.
A further consequence is that the tip of it doesn’t touch anything as such you could remove the very tip to adjust the sound signature. The feeling is slightly changed but primarily this replaced the high-pitched plastic sound with a deep tone.
The nice aspect is that in the blocking position, it is a solid connection meaning it can take as much load as the teeth (tip) can support (hence the trying to maximize the contact area there). The spring element is only there to return this blocking “bolt” into position after a teeth passes through.
here you go: www.thingiverse.com/thing:6595547Likely a old version with 0.4mm clearance that does work. If not message me and I could send you a later revision with 0.23mm that definitly works.
How does it work?
one direction: pretty obvious the spring bends out, the teeth pass through the other direction: the spring gets slightly pulled/stretched (the leading tip of the teeth pushes it) which causes the tip to be pushed against the block (left in the picture) and blocking the mechanism.
In other words, this mechanism works by having a physical path for the compression of the spring but in the opposite direction when would need to stretch to move pass the teeth it is stopped by a wall/block.
For motors, the limit is the wire insulation so might get away with 100°C ambient. If you can’t move them out there are also water-cooled extruders: www.dold-mechatronik.de/mebs-Hemera-WaCo-Mod-EN
Printing fast/without cooling can also go the other way:
By printing very fast the last layer may still be “hot” when the new layer is added. As the temperature differential is smaller there is less stress within the part once it is cooled down.
Regardless of the scanner use matting spray. Either a commercial that evaporates or baby powder + IPA or baking powder.
OpenScan was already meantioned by somebody else.
The CR scan otter won’t work for small parts and the CR-scan software isn’t great for example there isn’t an undo button to remove the last x seconds of bad scan data.
second failure: Prusaslicer overlapped support and the part. At least my hotend survived that failure.
Called it a day and moved on to a different printer for this print. Also, did I mention that I managed to kill another z-endstop on that printer today? Forgot to remove a finished print before running G28.
The end stop is located on the carriage (toolmount/receiver). Moved sideways into the print and the bed adhesion was stronger than the pin of the switch.
Quick and dirty 5 minutes craft: Draw a rough shape, define the contact surfaces & load, click run, and get the optimized shape. The last step is converting the output to a printable shape and running one more simulation to double-check it is strong enough....
Is there any software that does take toolpaths into account?
Not as far as I know. The next best option is to define anisotropic properties in the z-direction but this doesn’t close the gap between simulation and slicer output.
How good is it? Good enough. Work with safety margins and temper the print if it is close. An important aspect to make Ansys, Nastram, … work with FDM is experience/rule of thumb. Knowing how to read the result and how to set up a simulation/model to get close enough results.
Most valuable is where and how it will fail as this is pretty accurate. For the exact load capacity it is the simulation result decreased by some rule of thumb based on experience.
Inventor has a GUI for it. There are more options.
A slightly higher wall count for prints and the weight of the unoptimized solid is pointless in this instance as it starts with a larger slab and tell it to remove x% of weight. With the simulation result you either increase or decrease the x% removed setting and run it again till the load part strength is correct. Very basic in this regard but this was a quick design. How the spool is relative to the mounting points isn’t optimized. It was just me drawing something.
This particular part is 70g each with the filament being approx. 100mm moved forward (leaver length) and were simulated to withstand roughly 12kg and tested with 5.5kg+spool weights.
In a broader picture: See it as a demonstration of what all those nice tools in the CAD package can do. In this application with a little bit of thought could come up with a similar or better solution but for an I don’t care design approach the output is already good. A proper design approach would be putting thought in in where to place the contact surfaces relative to the spool and then run this software or go a step further and allow a different software to also change that parameter. Keep in mind those simulations are computationally expensive. Complex/advanced questions might take days to solve while a simple question like this is less than 1 minute.
The load was in the circle/groove facing down.
The other constrain was the faces contacting the 3030 extrusion being fixed and a keep-out zone was defined around those to ensure no material there was removed.
Otherwise, it was just a flat slab as shape.
What at first surprised me was how this part works: There is a point defined by the lowest/left triangle (tension & compression) on which all the weight rests. The remaining structure is is a cross beam (top mounting point to spool) to support it (tension) and the structure on which the spool rests (compression).
Resin Printing: Good for a Beginner with Limited Space?
I have recently obtained a friend’s old Formlabs Form 2 SLA printer. I I am an absolute beginner to printing, but I am pretty excited to get into it....
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I’ve made a large number of custom prints, and all of them were created using TinkerCad. It’s an amazing toolkit, stupid easy to use but versatile. That is … until something needs a tiny adjustment somewhere. That’s when I feel it would’ve been neat to use parametric CAD instead....
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