Managed to get 2nd gantry working.

Had a lot of trouble with Motors - the ones I saved from a WeedoX40 wouldn't work.

Eventually I discovered that they have different pin connections to Sovol motors - with have the coils connected on pins 1+4 and 3+6. My motors were 1+3 and 4+6.

So found some other motors - from my MPCNC - which are more powerful - 1.7a - and they eventually worked.

Then had a lot of trouble withy homing and setting values for TMC drivers - will probably switch to end stops for the final build - but eventually got it working.

Then next problem was prints keep losing position - eventually worked it out that I was moving too fast for the MPCNC motors - F36000 was too fast for them - so slowed down to 18000 (300mm/s). And that sorted out the problem.

Decided to try a print - despite plastic bearing posts, and plastic linear rail carriages - ran the print at half speed - but it worked.

Did an initial print on the from gantry - then swapped over the extruder and stepper connections - and reconfigured Klipper for the different motors.

Demo of print on 2nd gantry here
https://youtu.be/7ar74Ne5ryI

Have learn't quite a lot about configuring steppers which will come in useful once I try the Duet migration - which is probably now the next step.

First successful Duet Dual Gantry IDEX test. - ( Phase 1 part 3)

https://youtu.be/A485TMKhmV4?si=gRNhVj0sPUrHJKw3

First layers not perfect and running a bit slow for some reason - but overall a big step forward.

Next step - multiple motion system...

@T3P3Tony Ah - I see you can select the output voltage as being VIN (I didn't spot that initially) - so I think that way I will be able to get 24v on Out1 and Out2 - so that should solve my fan issue. thanks

All belted up.
Short a few parts before I can do a proper test - most important of which is the linear rail carriages for the 2nd gantry, plus some idler posts.

Some belts quite close to each other - will try both gantries out next - will have to swap the carriages.

Rear left

Rear right

Front left

Front right

Top with rear top halves on

@oliof Appreciate that this is a fairly old topic - and sorry for the long post - just wanted to get a few ideas down together.

I have been investigating some options for a multi headed / multi colour printer for printing large multi coloured models.

I think the RatRig VCore 4 / With Hybrid Motors and IDEX 'Dual Markforge' is something like what you were describing in your post back in May.

What I am thinking along the lines of is something like a RatRig VCore4 IDEX RMMU, with a 2nd IDEX Gantry, which also has the ability for limited Z movement too.

I think it is going to need to be powered by Duet/Reprap firmware though - rather than RatOS/Klipper

My ultimate target is a machine/set of machines with the following capabilities:

1. Large build area - at least 300X x 500Y x 250Z - With at least two independent gantries for parallel printing of large objects - probably using the Reprap 3.5 Multi Motion System parallel printing capability
2. Each gantry being IDEX - to allow for fast colour changes for most commonly used colours, and for some models - mirror mode or duplicate mode parallel printing within the IDEX gantry.
3. Filament Multiplexing - probably using something like the Reprap RMMU or BambuLab AMS - as I need up to around 12 colours in total per object.
4. Parallel background colour feeding and purging etc. - which is hopefully supported by RepRep 3.5 (but not by Klipper/RatOS I believe). - See part 2 video for more details of this.
5. For the multiplexed colour changes - The ability for very efficient 'flush-into object' printing to be done - with the flush-into objects potentially being printed at a different Z heights to the main object.
6. Ideally in cases where fairly simple small prints are already in progress on only one of the gantries - the ability to separately start a simple 2nd print on the spare gantry.

I have created a few videos demonstrating a few ideas - the most relevant to my current thoughts is Part3 of this IDEX series.
IDEX Part 3 - Dual IDEX

'IDEX Part 6 - Motors and Belts'
Youtube link

What I would like to do next is add the ability for the 2nd Gantry to have a small amount of Z axis movement ability - so that it can be completely independent of the first gantry. I will probably add a few of the Reprap 3.5 Multi Motion System Gcode commands to my Blender add-on to drive the fully independent simulations.

Will probably also add some animations along the lines of the diagrams posted by @droftarts in this thread to the simulations too.

The next problem is then splitting up models into sections for Multi Motion printing.

I have done some reading of this forum of posts about Multi Motion printing - mainly by @dc42 and can't find a lot of details of any slicer developments.

So unless work is already underway in this area I am thinking about creating a GCODE post processor that does a basic split of single head multi colour prints (probably sliced for a BambuLab X1C) into up to 3 or 4 separate areas per layer if they are big enough be warrant parallel printing on the two gantries at the same time. The reason for the 4 areas is to avoid head clashes - see this diagram.

Plus probably a 2nd post processor that does some more automated mirror mode splitting - I am currently do this in my simulations by pre-splitting up the mirrored / duplicated and single threaded parts prior to slicing into different 'virtual colours' - am then using the tool change commands generated by the slicer to switch the 'virtual' printer between IDEX modes.

Starting to plan for expansion boards - looks like there is room,

Tool Distribution board and first Mini5+ needed for Dual Gantry, with further Mini 5 probably needed for IDEX - unless I can reduce the stepper requirement - by using less for IDEX and Servo's for Z Hoppers.

@dwuk Going down a bit of a rabbit hole with the tweaking - decided to try accurately calculating the time for extrusions - including acceleration and deceleration etc - not sure if these calculations are correct - but probably doesn't matter too much at this stage.

Then used this to select passes with segments in them which quite a big print time difference and then have simply taken the segment with the longest time and either reduced its size down to the minimum size it can be for head clash avoidance, or halved its size. I have then added this adjustment onto the segment with the shortest time.

It didn't select the layers I expected - probably because the segments in the cab are already at minimum size.

It makes the print look a bit more messy - but at least I can pick out the adjusted layers quite easily,

Will run some prints through my simulations with and without the adjustments to see if the layers that have been adjusted print any more efficiently.

Example 3 gantry print shown - with pass1 heads shown in white and pass2 multi colour.

Homing working -

See short video demo

https://youtube.com/shorts/oHtVsdHTPQc?si=w-lnOgmzNzxqfvRK

Lots of refinements to do - but basic homing and 4 AXIS levelling done

@dwuk Servo wired up and tested. On the 1LC board io_0.out, with an LM2596 DC to DC convertor to bring down the 24V input to 5V for the servo.

Prototype parts printed - just need to install them and test them - might be a few days due to other commitments.

Short Video showing both heads in motion.

I can't get synchronisation working yet - so not ready to print more than one layer - but nice to at least see the print heads moving independently.

https://youtu.be/gQX2zZGmyh8?si=oEQOxusDIuququso

@pouryatorabi i presume you already have the feedrate set at 800 before the extrude move - otherwise if its was previously a different speed I believe it will gradually accelerate up or down to 800 throughout the move.

@o_lampe thanks good idea about doubling up - that slip ring has 6 connections and I only need 4 - so I can double up the heater ones - 20A 230v would be masses more than I need.

I haven't done enough actual printing on the SV08 to find any heat bed issues - but it seems to maintain temps ok - although I did get a failure with the PID tuning,

Point taken about the project approach.

One of the advantages of not having a sponsor is not being restricted to specific goals, dates or budgets.

But you might be right that there is a risk of me losing interest in the project - especially as I've just booked a QM2 cruise - so really want to do a model of that ship before I go - so that I can get some comparison photos.

So far all of my changes are just reordering things that were already in the plan (or when better technology like INDX vs Stealthchanger comes along).

On this subject though I am about to change around my bed slinger approach a fair bit to not have a longer bed - but instead just move about 150mm - and add the ability to link multiple SV08's with this ability together - to get 350x700 or 350x1050 for example - with the build plates slightly overlapping the heated beds.

Will probably do dual gantry - but only single heads on the second SV08.

That will then deliver my original plan (and most popular video so far) - see Prusa Multi Mini.

My immediate plans (which I may change)

1. Get 3 headed build working well - with fully parallel, faster printing
2. Rotating bed
3. Angled extruder on rotating bed
4. 150mm bed slinging
5. 2nd linked or independent SV08 with 150mm bed slinging
6. 4th print head - probably on stealthchanger to allow for offloading.
7. iNDX - which may slot in earlier if previous steps go past December.

@o_lampe the bed is already mains with an SSR - so I was planning on putting the SSR output through the slip ring, plus the temperature sensor.

Are you saying that would be ok - or that I should look at a better quality slip ring?

I suppose continuous rotation would only be a novelty feature - I wouldn't need a slip ring for 90,180,270,180,90,0 rotation - which is the main reason fir me adding it.

So I could drop it if a good quality one is going to be massively expensive,

I could always disconnect the cables and use a bambulab cool plate for continuous rotation demo's.

Think I might need a Roto toolboard for when I add an INDX to my front gantry.
Nb/ my picture of the INDX toolhead is slightly bigger than the real thing according to Bondrech.

Might get one now as it could also help with reducing the width on my rear right extruder too - although I suppose I could just rotate the 1LC upwards so that it doesn't take up so much space.

Quite pleasantly surprised to find that slip rings not as expensive as I was expecting - this one for example looks to me more than enough for my needs

Re -print head alignment / dimensional accuracy- I'm think I might get a second ball probe to have on the same arm - with the camera in the middle.

I could then probe each head 4 times - with the arm in two positions.

Should from this be able to get pretty accurate dimensional accuracy /adjustment info.

All of the probing points will need to be in the central area where all of the heads can reach,

Might even be able to do two lots of probing at the same time if I can make the heads as thin as possible in the X direction.

Will also switch over the servo to a stepper motor.

Youtube response about probing.

there is quite a lot more work required to get really good bed levelling.
At present it does 3 stages all only using inductive probes at the moment.

1. Initial Z homing on the front extruder inductive probe only.
2. 4xZ axis motor adjustment using front inductive probe only.
3. Rear right inductive probe based Micro Z alignment vs front micro Z alignment using the two inductive probes.

What I need to add is

1. Use of the inductive probe on the new 3rd print head
2. Use of the Z height values from the ball probe
3. Bed mesh probing from one or all of the inductive probes.
4. I also have an eddy probe for fast bed meshing which I haven't deployed yet.
5. I can also do 'voron tap' type probing by lowering each head to actually touch the bed and then use the optical sensor on each head. I did this for one of the heads - but it all got a bit too confusing - but ultimately I think that type of probing is going to be more accurate than the inductive probes.

Also all probing is currently one probe at a time - whereas i think there are some opportunities for doing some things in parallel.

@o_lampe I do a lot of my long prints without heat on a Bambulab cool plate - mainly to allow for long overnight or out of the house pauses. Bed adhesion for PLA is actually so good I can't use it for small fragile things.

I'm going to make mine heated though from the outset - and just use the standard SOVOL square build plate - perhaps with the corners chopped off if it won't quite rotate.

I notice now on relooking at the video that he has a very wide brim around the chimney - and some of his other prints look ok - so I wonder if the artifscts you noticed are due to wobble because of the very thing chimney.

When printing the sails of my very tall Sea Cloud model (see youtube) I had to add braces between the sails at a few heights to stop the wobble.

You are right about that filament hiding print quality defects - I was actually thinking of purchasing 3 rolls of it for my printer for when I get on to some big parallel prints - as I thought it might hide the joints a bit.

Re printing in the centre - I think it is possible - but just extremely slow. I got the impression that the non planer solution demonstrated is pretty slow - even for the outer parts.

Some inspiration for adding further features to my printer after looking at this very impressive video

https://youtu.be/M51bMMVWbC8?si=kyLhSQ2Y6XhIFs34

It does look very impressive and I can't imagine how that benchy stayed upright when it was just being held in place by that tiny chimney and filament was be added to the benchy in a horizontal direction,

I'm going to try and simulate his printer with his slicer in blender - should hopefully result in some interesting animations.

What interests me probably more than the non planer aspects - is the concept of printing onto the side rather than top of objects - which I think could bring a lot of efficiencies to multi colour printing.

As you only really need the colours on the outer surface - and so would be able to print most of the structure of an object in a single colour like white - and then colour it in with a few passes of the different colours applied to the top, bottom and sides.

Perhaps using a multiaxis printer like in the video, or maybe with something to rotate the print around in more dimensions instead.

I'm going to be adding rotary movement as the next stage of my multi head SV08.

This video inspired me to maybe allow at least one of the print heads to pivot up to a bit of an angle - rather than always facing downwards - and then use it to print onto the side of objects - rotated to the appropriate angle.

Another issue I have is with the probe moving a bit - I've changed a few things - but it is still not perfect. I have been considering changing from using a servo to a stepper - I think a fairly big Nema17 might hold the probe more steady in the Y direction or I could try a Nema23. The magnet is probably better at holding it in place in the Z direction. I might try also trying so somehow interlock something into the indentation of the magnet when it pulls down - to also prevent Y movement.

Re rotary bed
The next challenge after that is bed coverage by each print head.

My current thinking is once per layer rotate the bed 90, 180 and 270 degrees. - I will be rotating a square rather than round bed.

That should allow all 3 heads to access the whole bed, plus allow parallel printing.

If i only rotate it like that and then rotate it back again then I won't have any wiring issues - but I would also like to try making in continuously rotate capable like yours - so that I can do 3 headed vase mode prints.

I think i will need a 4 way slip ring for this capable of mains power - any thoughts on this.

I suppose I could go 2 way - just for the bed heater - and try using something like an IR temperature sensor for temperature - but not sure whether the PWM or whatever stuff would handle that.

Made a bit of progress on alignment issues - i think its a dimensional accuracy issue - and may actually be a problem with my Dual Markforged kinematics when moving in the X and Y direction at the same time.

Or might be due to the backlash compensation I put on the old V axis - which is now the X axis (W) on my third toolhead - which is the one that seems to be squashing up its dimensions a little bit when compared to the other print heads.

i need to take a break from this printer for a few days - so will address the issue later,

One big discovery I did make though while trying to resolve this - is that what I previously thought were strange hangs on things like M598's, M400's or M596's - which led me to completely stop using M598's were probably more like the fact that echo commands sometimes seem to stop working on forked multiple motion systems.

I put in loads of echo's before and after commands thinking I could see where control on each file was hanging - but worked out today that processing was actually still running in loops and commands quite a long way further into the file - usually on G4 500's in loops.

When this happen's M122 still seems to tell you the G4 or other command each file is currently on - so I have changed every G4 to have a slightly different millisecond delay time value - so that it is then possible from the M122 to work out which delay loop each forked file is currently executing.

Might start using global variables to trace current position - rather than echo's to see if that works more reliably.

Nb/ I am still on 3.5.4 - will test out some of this on 3.6 at some point too.