[Idea?] Can a Scara bot print 2 or more identical parts at the same time?

Just a quick 1am thought,

If you were to add another set of arms, to the same controlled central rotating pipes but 180deg out of phase on a morgan, you could then have another bed, hotend etc. The extra set of arms would then move identically to the opposite set, allowing you to print 2 of the same object at the same time. You just need to add temp control for the hotend.

This might be useful in fast scale replication situation. It may be possible to have 3x arm sets at 120deg and print 3-up.

I've probably just overlooked some glaring issue with this idea, but thought I should post it anyway and see what people think.

Sanjay

That is a great idea! The Morgan would need the rails moved appart to each side of the pulleys so you can use the two for both sides. The frame would need to be reworked but it can be done.

I was hoping that 4 could be done at the same time with the elbow joints shared but some mental math shot that idea down. 3 without shared elbows would probably be the coolest machine on earth. I might mock that up for grins.

You can also use standard electronics for this because all the extruders could be slaved together mechanically. Three printers for the price of one.

Keep up the crazy ideas!

yes, its very good idea.

i like polar bots a lot, but from engeneering pow it would be much easier to set up relular cartesian machine with wider X axis and 3-4-5 extruders on it.

you can try put additional extruder on mednel 100 mm x offset and 2 additional y offset 100 mm for try, then you have 4 prints with 100 x 100 mm base.


about 3 set of arms...yes, but not in same Z height., because when arms are in near of tower they are very wide, depends how close is heatbed to tower...

Edited 1 time(s). Last edit at 07/06/2013 01:05AM by woo.

There is no theoretical limit to how many you can have with the same z. In reality, I think 3 is about all you want to do. The secret is to make the secondary arms short enough so they will almost make a straight line when the primary arms are spread as far as they can go.

YOUTUBE CANDY!



Edited 1 time(s). Last edit at 07/06/2013 01:37AM by nicholas.seward.

naaajs!

I can't leave this alone.

I did this as a joke but I think it has value. I am officially crazy.

YOUTUBE CANDY!



Edited 1 time(s). Last edit at 07/06/2013 11:25AM by nicholas.seward.

I think the difficulty will come from sharing the same Z axis. There will be differences in the hot end heights and arm variations in the Z heights over the bed area. With just one Arm, the bed and arm Z differences can be auto calibrated out. When they are all common, that can't happen. All the mechanics have to be perfect and manually aligned, or there has to be some sort of Z micro actuator that can make small compensations individually.

Each bed on 4 springs would make for quick calibration.

have a homing feature similar to a kossel but move each bed's z axis independently until hitting a homing switch attached to each extruder head.

I am actively developing this. I am going with a single motor for the z and a single motor for the filament drives. Here is the plan.

The z will pull all up at one. Each side will have a spring loaded platform for independent adjustments.

The filament drive will have a long shaft that has been hobbed 4 times.

If a quadrant messes up you can keep running by releasing the idler for that quadrant and then turning that hot end and heated bed off. I think I will keep all the temp control separate from the controller board. I will have 8 knobs connected to some simple pwm circuitry.

Homing is going to be manual. You push the hot end all the way in or pull it all the way out and then rotate the arms to be centered on a platform. You also push the beds to the bottom position. You only have to do this once while it is being continuously powered. That could be months between homings. I will build in a larger than normal factor of safety so the chance of skipping steps will be relegated to the occasional cosmic ray instead of the occasional bump. With 4 heads that only need to go 60mm/s that should not be a problem.

Why so complecated? You can print out a dozen parts at the same time if you use a plate with a dozen extruders all in one head.with the appropriate distance to each other. You find those multi heads in milling amchines f.i. that mill PCB boards. they often have 6 or more tools in one head. It all depends on the size of the parts. Just look for multi spindle.

Ah, but you need expensive linear rails for that.

Ok, crazy idea time - what if the multi-Morgan had one station with a fixed platform (not attached to the Z mechanism like the rest), and an optical mouse sensor instead of a hot end? With a printed grid taped to the fixed platform, it could accurately determine its X/Y position via the sensor, independent of motor steps. It wouldn't even need stepper motors at all for X/Y, you could use much cheaper/easier to drive DC motors, with a servo loop in software.

The idea could be applied to a single-station printer, too - mouse sensor would be mounted directly above the hot end, facing upwards, with the "mouse pad" being a ceiling on the printer. The arms could be made a lot thinner than a Morgan normally needs, if the head was spring-loaded upwards so that the sensor rides on the ceiling (which just needs to be made perfectly parallel with the print bed).

I am sure that can be done. I am sure you can feel the however coming. There are a lot of things that you would have to pioneer. For me, I just slap two steppers on the XY and get perfect placement after I tweak the mechanical advantage value in software. You also lose one side. For my application, I want to squeeze in as many printers as possible.

jasonharper Wrote:
-------------------------------------------------------
> Ok, crazy idea time - what if the multi-Morgan had
> one station with a fixed platform (not attached to
> the Z mechanism like the rest), and an optical
> mouse sensor instead of a hot end? With a printed
> grid taped to the fixed platform, it could
> accurately determine its X/Y position via the
> sensor, independent of motor steps. It wouldn't
> even need stepper motors at all for X/Y, you could
> use much cheaper/easier to drive DC motors, with a
> servo loop in software.
>
> The idea could be applied to a single-station
> printer, too - mouse sensor would be mounted
> directly above the hot end, facing upwards, with
> the "mouse pad" being a ceiling on the printer.
> The arms could be made a lot thinner than a Morgan
> normally needs, if the head was spring-loaded
> upwards so that the sensor rides on the ceiling
> (which just needs to be made perfectly parallel
> with the print bed).

Mouse sensors would not be enough, they have a hard wired rudimentary DSP and the native video resolution is poor at 16x16 to perhaps 64x64 pixels. They might work on the Bamboo Printer [reprap.org] because it still maintains rectilinear motion (even though each actuator swings it through an arc). It could be done with a dedicated camera (USB web cam perhaps) and a bit more processing power to calculate the exact position from the 'map' image. The double hinge tool pivot that was originally considered on the Wally would have maintained the head in rectilinear motion.

The filament feed would have to come from the side if the sensor was above an only arm as well.

Also there are limits to how much one needs to economise on a production printer. If you have enough work for it to print 4 identical parts then it is often faster to clone the printer a few times and pool them. Maintaining a tricky fussy 4 head machine for production does not sound appealing to me, any failure mode will only involve one printer while repairs are taking place.

The thought of having a second set of opposite arms on the Morgan just for cantilever balancing does appeal to me though I would just put a weight there so there are no tipping forces on the framework rather than trying to calibrate multiple heads and beds together. It is not really required as the Z-axis is used to dynamically zero the bed at all points.

---

Kalle
--
Lahti, Finland
The only stable form of government is Open Source Government. - Kalle Pihlajasaari 2013

One QuadMorgan will exist. I suspect that it won't be that bad to operate based on my previous experience. I am building a bot farm but I am not so crazy to think that this will be the best solution. I will do some science and see how it works out. Simpson and Wally are both great examples of bad ideas that ended up working out.

BTW, My plan is to have manual adjustment for leveling each bed since I can't do it virtually with the multiple heads. If one quadrant fails, I can pull the power for the hot things and the filament drive to keep from wasting plastic.

Worse case scenario, it is hard to operate but I get some of the coolest 3D printing footage known to man.

nicholas.seward Wrote:
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> Worse case scenario, it is hard to operate but I get some of the coolest 3D printing footage known to man.

Going to the moon was very hard, but the video of the Earthrise was to die for.

Quote
maboo
Why so complicated? You can print out a dozen parts at the same time if you use a plate with a dozen extruders all in one head.with the appropriate distance to each other. they often have 6 or more tools in one head .

I'd argue that a significant problem with that approach is that it is not generalizable. What happens if you need to print 6 15x100mm objects one day, and five 18x100mm objects the next day? The three-bed or solution will get you 3x the productivity, (number of prints produced per unit time,) regardless of whether the prints are small dice or large skulls. Those PCB drilling rigs are set up to manage the same-size master-board day in and day out.

Starting from Morgan as it exists today, one could get by with only THREE modified parts - the Psi and Theta A arms, (becoming three-pointed stars,) and a similar part to lift 3 Z-bed mounting brackets. And I think you'd want a different shape of supporting structure - the thought of TWELVE of the angled pvc legs in one structure makes my head swim.

The independent moving beds seems like an over complication of a simple problem. In essence you want to increase the distance from extruder to bed, but by placing the motors closer to the top of the tubes, gearing the insides of the gear wheels keeping the same cog ratio, you should be able to reduce the overall footprint of the vertical members and mount the head gantry on the Z axis. Using three rails and one z axis threaded rod you can keep the number of parts down while keeping the simplicity of the original design in a multi-bed printer.

I don't have time to model any of this, but by replacing the inner rod with another tube and mounting the arms, tubes and motos on a "riser" that has a threaded hole in the center, the Z-Axis motor could be mounted above the assembly with the threaded rod going down the center of the tubes. Using a larger threaded sleeve on the riser would add stability as it moves, and in an ideal configuration a Teflon sleeve could extend all the way up the inner tube providing the greatest support. Of course, that might just be overkill.

I feel like it's almost Mad Science time.