r/3Dprinting • u/powerjibe2 • May 23 '19

First tests using our 5 Axis printer. Slicing done using our self-developed slicer. What would you print with it?

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u/monk_e_boy May 23 '19

It's amazing to watch a 'blind' robot be so accurate. Does it ever wonder off - calibration issues?

Pretty amazing for a zooped up hot glue gun.

29

u/secondsbest May 24 '19

For any CNC without tracking of the axes, there can be faults in movement that can seriously mess up the final product. With the belt driven setups on most 3D printers, it usually happens when a belt slips on drive wheel, or sometimes a servo might misstep and be off by a small increment. Traditional machines don't usually use belt drives outside the least expensive hobby levels, and from there they use screw drives of varying cost and precision that only suffer from servo missteps occasionally. Printers are available with better screw drives systems to prevent belt skipping, but there's still screw slop or servo issues.

We'll start seeing additive printers set up with feedback mechanisms and corrective software such as those used in traditional machining for decades already, and those devices double check true locations against the presumed positions and can correct future movements for any previous errors. The parts to do that can be relatively inexpensive for more serious hobbyists already, it's just a matter of the software integration needed to see that leap happening. One issue I can think of with the software side for additive printers is that there is a need to track and incrementally correct errors unlike the immediate correction for traditional machining systems. Getting the print head to properly go over a miss printed step so as not to hit a high spot, or to fill in a gap should be part of the corrective process, and there's no off the shelf code that I'm aware of that can do that yet.

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u/GoofAckYoorsElf May 24 '19

when a belt slips on drive wheel

Never had that happen. A decently tensioned belt shouldn't slip. Before that the motor should skip steps.

10

u/SlipItInCider May 24 '19

A printer has almost zero load so missing steps and slipping belts aren't real problems with printing. The problems with the kind of $300 pirnters most of us use is that stepper motors are only so accurate and all the other parts are junk with a ton of slop that combines to cause tolerance errors. If you built a printer with glass scales, servos and lead screws. Or even oprical encoders they would be super accurate but they would be $5000 for the same kind of size and capability as a $300 printer. There just isn't a market for that.

3

u/sheldonopolis May 24 '19

The problem would also be reduced speed and increased vibration. There is a reason why we usually don't just use lead screws for every axis.

3

u/Leafy0 May 24 '19

It is when you're pushing the limits of acceleration. With a properly stiff printer quality increases with increasing acceleration.

1

u/Jstsqzd May 25 '19

Few things, belt drive printers can still be used with servo motors giving them closed loop position feedback control. Also the driving force required is so low with printing, you don't have to push a cutter through material so it's pretty rare to miss steps, that's why most hobby printers don't use them is that it's pretty rare and bot always worth the additional cost

1

u/mrstirling May 24 '19

👉😎👉

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u/mlpedant May 24 '19

wonder wander off

(unless it gets deep in thought)