Sextupteron

The "normal" problem is when the part has weird overhangs and you need to avoid them...

@uncle_bob: Can you give me an example? In my mind I think I can come up with a generic solution. Just work your way up the surfaces ( do what you want on the interior) and obey the 45 degree rule. (You also have to remember to give clearance for the extruder.)

I don't disagree with you that it would be beneficial to have fine control but I suspect that we could automate a lot.

I'm more familiar with the issues on a CNC than on a printer. You are correct that it's often a "clearance for the extruder" (or tool) sort of thing. On a CNC it's - chop this out ( or rotate the part) to get room to do that. On a printer it would be - don't build this out yet or you won't be able to get in to do that. I'm looking around my desk for a normal something that would have the problem....

... right in front of me ..

How about a normal LCD video monitor sitting on a conventional stand? Stand sits on the table. Arm from stand joins the monitor half way up the back of the monitor. You can indeed print it. It may drive the software a bit nuts. I'll see if I can find someting else that would be a bit crazy on autopilot.

NOTE: The Sextupteron can tilt 58 degrees so you can only do a 13 degree negative overhang if we obey the 45 degree rule. This restriction will keep the the layers fairly well behaved. This restriction will also prohibit printing a monitor stand in its standard orientation.

If the build platform was to rotate independently (in conjunction with the Sextupteron upper) could you eliminate over hang restraints?


(note: I have not read this whole thread and not sure if you already have a controllable platform, so excuse my random jump in)

@ddseeker: There will always be some kind of restraints. With the design as is you can't do more than a 103 degree overhand from vertical. You could do more if you add some additional degrees of freedom but I suspect that with creativity that the relaxed restrictions on overhangs will open a whole new world of possibilities. (By rotate independently, you would need to rotate it about the x or the y axis. Rotating about the z axis would add no additional capabilities.)

Rotating Bed, something like this

Has a 5 axis robotic arm been considered? Belts, string and printable gears come to mind.
A regular mendel 90 with a rotating bed (edit: like ddseeker suggested in the link above) is probably most straight forward.

Edited 1 time(s). Last edit at 12/27/2013 03:32PM by TheTechnicalNoob.

Now that I understand how the sexupteron operates; I'm awestruck nicholas. Truly. An ingenious design. Any news on progress?

I collaborated on a paper with Ilian Bonev (one of the tripteron's creators) that covered what he calls the Hexapteron. (I am still on the fence about going with this name change.) He is having one of his students make an aluminum version. His hope is to get it printing and to get a few more papers out of the deal.

I personally plan to make a laser cut version or an aluminum extrusion version once there is a cheap enough controller that can handle this.

The Sextupteron will exist.

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nicholas.seward
once there is a cheap enough controller that can handle this.

Is the arduino mega 2560 not powerful enough? Arduino Due with RAMPS?

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bobc
I am currently testing a 3 extruder board for Arduino (RAMPS-FD [reprap.org]), and soon a 6 extruder extension board (EXT6 [reprap.org]). So that is 11 axes and 1 extruder, or 3 axes and 9 extruders depending on configuration, or any combination in between.

So if anyone wants to build a sextupteron, I would be happy to provide a beta board and firmware help, in order to help development. You would need to provide a Due and stepper drivers. Alternatively if there was a design and some build instructions I could maybe build one, my mechanical skills are limited.

I do believe bobc offered an electronics solution already

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hephaestus

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bobc
I am currently testing a 3 extruder board for Arduino (RAMPS-FD [reprap.org]), and soon a 6 extruder extension board (EXT6 [reprap.org]). So that is 11 axes and 1 extruder, or 3 axes and 9 extruders depending on configuration, or any combination in between.

So if anyone wants to build a sextupteron, I would be happy to provide a beta board and firmware help, in order to help development. You would need to provide a Due and stepper drivers. Alternatively if there was a design and some build instructions I could maybe build one, my mechanical skills are limited.

I do believe bobc offered an electronics solution already

+1 Hence my question of why not the Arduino Due if processing power is the limit.

Let me rephrase. I know that there are solutions. I am waiting for the total electronics solution to drop under $150 and require no electronics work on my part. I have very good reason to believe that this will happen. ;-). I have plenty of other projects to work on while I wait.

By total electronics do you include PSU, heatbed, steppers, hot end?

Otherwise Due + RAMPS-FD plus pololus is around $150 already.

I'm looking at replacing the Due with a Cortex M4 at ~200MHz with hardware FPU (single precision).

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@bobc: Can you provide sources for this?

Here is my math. I found the prices quickly so there may be cheaper things out there.

$32 for Ramps-FD
$31.5 for 7@$4.50 pololus
$40 Off Brand Due

Well, that is $103.5 using the cheapest possible prices. The only problem is how do we expand it for the 7th driver?

Good question, I knew I should have an answer ready for that

Sources for which exactly?

ATM, the world lacks a plug'n'play expander board. Certainly something could be lashed together with a Sanguinololo or stripboard, but Reprap deserves something better.

I am working on EXT4, I have just sent off gerbers to get some PCBs made. It will be a cheap and simple solution, and compatible with any base board.

RepRapPro also have an expansion board, not sure when it goes on sale. It's designed for their Duet board, but is probably usable with other boards. (The Duet solution is a bit pricey I think, although it has some nice features).

I am thinking that the 6 axis motion would form an interesting challenge on it's own, and tool heads could be considered later. One thing I am keen to evaluate in a prototype is whether a Cortex M3 or M4, is able to handle the real time math, or if something bigger is required.

NXP have an interesting dual core chip, a Cortex M4 plus M0. The M0 could handle stepper driving and acceleration profiles, with the M4 doing the user interface and number crunching. The great thing is all these chips are around the same price as an ATMega256, with much greater capability, and that trend is likely to continue.

Right now, I wouldn't push anyone into buying RAMPS-FD, there is a new revision coming up soon which fixes several issues, but v1 is usable for prototype work.

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I obviously found sources for all that I listed but I just don't have a source for the 7 stepper solution that I need to make this a reality. At least I haven't found a complete solution under $150.

It's a pity that Decapede hasn't made it to production. I'd like to help, but I don't have Altium. I've no idea what sort of price they had in mind...10 steppers surely enough for everyone?

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Oh, I can find legitimate uses for more than 10 steppers. Let's see...a Sextupteron with full color printing (I assume you would want at least 4 colors to get a decent spectrum.) and a gripper for assembly. I am sure I can come up with some other examples that are more practical but the point is that design is similar to a gas. It will fill up the space it is given. If it is super cheap to drive 12 steppers then you will probably see designs that use 12 steppers.

Hmm, there's a challenge

The cost per CPU pin goes down as the package size increases, but the soldering becomes increasing difficult. Splitting the task between multiple CPUs needs a high-speed low latency comms bus. More steppers means more CPU power as well.

I think I can daisy-chain expansion boards, I will have to think about the best way to do that.

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nicholas.seward
$31.5 for 7@$4.50 pololus

Where can you source polulu stepper drivers at $4.50 a piece? I paid around $11 a piece for mine.

Edited 1 time(s). Last edit at 01/16/2014 10:43PM by TheTechnicalNoob.

@TheTechnicalNoob: They aren't exactly pololu's but I just did a quick search and reported the cheapest thing I could find. stepstick

I love this design! Wouldn't something like the Beaglebone Black with an advanced BeBoPr++ or CRAMPS be a better controller for an advanced design like this?

@Dejay: That would be a great setup.

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ConceptFORGE
Wally, GUS Simpson, LISA Simpson, THOR Simpson, Sextupteron, CoreXZ

How about the Smoothie board?
It's open SW and HW, the developers seem very capable, and they are currently working on support for 6DOF, shipping boards now with 5-stepper support. Actually, they say their system is powerful enough to handle many more DOFs, using off-board stepper drivers, which could be useful for multi-color extruders.
[shop.uberclock.com]
They've finished shipping their Kickstarter promises now, so the boards are for sale to the public.
I mentioned the sextupteron to them, and they're interested...
Dave

FYI, Bas today announced the DECAMUX that allows to control 10 stepper motors via two PEPPER penta stepper boards with the Beaglebone Black / BeBoPr. LinuxCNC seems to be limited to 9 stepper motors atm though.

Edited 1 time(s). Last edit at 07/13/2014 10:30AM by Dejay.

I have a Beagle Bone Black with the CRAMPS that is capable of controlling 9 steppers. That could mean a Sextupteron with 2 extruders and 1 gripper.

It is really exciting to see all the solutions start to pop up with real processing power backing them up.

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ConceptFORGE
Wally, GUS Simpson, LISA Simpson, THOR Simpson, Sextupteron, CoreXZ

Nicholas, gret design, I think you need to lead the development of the new reprap, just saying.

hello some software is already exist for this new system ? 6 axis ? amazing concept !