3D printing on a rotary surface: RepRap Mendel

Does anybody know an open source printer design that is able to print on a rotating tube using a rotary axis?

I am interested in a printer with either a 4th rotary axis or a printer that uses the Y-axis to spin a tube.

In the best case it would be a modded mendel using Marlin firmware.

Here are two links that show it is done:
This one uses a mendel: [www.3ders.org]
This one uses a Hyrel printer: [www.youtube.com]

Any idea if there is an open source project?
I can imagine designing and building the mechanical hardware and wire the motor for a rotary axis. Does anyone has an idea how to mod Marlin Firmware using the y axis as rotary axis?

Edited 2 time(s). Last edit at 05/31/2018 02:31PM by Dahah.

its not all that difficult to make one. I made this towards the end of last year to laser etch some acrylic tumblers. It is primitive but worked fine.
no modifications to Marlin needed. You just need to adjust the Y travel to the circumference of the tube. I considered briefly about removing the
laser and trying to print on a tube but couldn't come up with any ideas on what to make.

rotary y adapter

Edited 1 time(s). Last edit at 05/31/2018 06:29PM by Shank man.

... this is OK for "single-sheet" tubes - for real 3D geometries you'll need a "rotary" slicer or you have to distort the 3D geometry ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

If i would have a rotary slicer software (e.g. modified slicr). Could i use the normal marlin to extrude several layers on the rotating surface? Could it be possible to extrude continious spirals in several layers?

Edited 1 time(s). Last edit at 06/01/2018 06:18AM by Dahah.

... depends on the slicer - the firmwares can move in 3D (e.g. "G1 Xxxx Yyyy Zzzz Eeee F2000"), so a 3D-spiral in short XYZE-segments will print continuous "through the layers"

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

How can you print endless in Y-direction?

For endless Y direction, I would think that if you change the G code to do everything by relative moves instead of absolute, then it should be able to manage. I'm pretty sure that this is the way that some CNC machines work to handle a rotation axis.

The slicer is where I'd see the worst of the problems.

I would assume that the base spindle would probably stay in the printed part, i have some difficulty imagining how one would remove it from the printed part, particularly since the plastic will contract as it cools, which would actually tighten it.

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MBot3D Printer
MakerBot clone Kit from Amazon
Added heated bed.

Leadscrew self-built printer (in progress)
Duet Wifi, Precision Piezo parts

@ VDX Cool! Sounds promising. But how do i segment my model?

@SupraGuy If you print with partly soluble filament you can remove it. This project uses a partly soluble filament: [www.3ders.org]
How would you change the g-code?

Even with relative moves, Marlin asks for bed dimensions/max. travel.
Maybe RRF would ignore infinite Y-axis, when you define M208 accordingly?

Edited 1 time(s). Last edit at 06/02/2018 02:42AM by o_lampe.

You could define the circumference as the max travel, it just means you need to take the long way around once you reach the end of your travel and you'd have a seam (potentially useful for removing the part).

I don't see using a soluble filament being helpful in removing the part. The "inside" of your part would be stuck to your spindle, and your filament would start dissolving from the outside surface, not the inside surface (the one actually stuck to the spindle).

@o_lampe So marlin need to be modded to?

@ trakyan For some parts it is ok if the tube stays inside. For other parts the soluble method is described here [www.3ders.org] and it seems to work.

Quote
o_lampe
Even with relative moves, Marlin asks for bed dimensions/max. travel.
Maybe RRF would ignore infinite Y-axis, when you define M208 accordingly?

Currently, the only continuous rotation axes that RRF handles are the prox and distal arms of a serial SCARA printer, and the bed of a polar printer. But the logic is present to allow any axis to be turned into a continuous rotation angular axis, so support for continuous rotation on other axes would be possible.

However, I can see a logical problem. Suppose the A axis is at -10 degrees and the firmware receives a G1 move with extrusion that ends with the A axis at +10 degrees. How would the firmware know whether it is supposed to turn the A axis 20 degrees the short way during the move, or 340 degrees the long way?

It may be that you can get away with just setting very high axis limits. The maximum axis length that RRF can handle on a Cartesian printer is +/-2^31 mirosteps. Even at 1000 microsteps/mm, that works out at +/- 2km. I think most firmwares use 32-bit step counters, so this may work in other firmwares too.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I posted to early.....thinking

Edited 1 time(s). Last edit at 06/03/2018 05:31AM by Dahah.