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32bit controllers for 3D printing. The next BIG thing.

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Joules:
This is an early post for the start of an up and coming printer rebuild.  The plan is to use a Duet 32bit controller.   Some of you may remember me getting a couple of Mini Kossel printers a few years back.  Both of them had Duet controllers, however the mechanics and extruders had other issues.  The sample shell prints I did proved very accurate, but managing solid prints caused layer slip.  My bad I think as I struggled with the setup and kinematics of a delta printer, hope to revisit it at a later date.

The current machine is an older Printrbot Metal Plus (they shut shop last month).  It features Hiwin linear rails for XY operation and over sized recirculating bearings on the Z bars.  The thing is a Prusa style machine with moving table.  I am not a fan of moving table for tall delicate prints like the boat hulls, but let’s see how far we can get. It has problems with its controller and the supplied power supply was a joke, but at the time I had no idea it was dipping as the steppers all moved at once and suffered unfathomable under extrusion and layer slip.   Well I know now and it’s new power supply arrived the other day, more parts inbound.  I did do a mod for the hot end swapping out the oozy supplied dribbler for an E3D V6, the tests of this new hot end are looking good with direct drive extrusion.

JHovel:
Have you considered changing the design to a moving gantry instead of the table moving? I would think that would be relatively easy to do with linear rails... I like your thinking and approach.

Joules:
Joe, the conversion is needed to make use of this printer, at some time my Mini printers will reach a point where they need more than just service and they will be retired.  I agree about moving gantry, I have a Core XY design using linear rails being developed in CAD, but it is a long way off reaching actual physical build.  I had been looking at the coming Anycubic Chiron, but it has the moving table and still uses an 8bit Marlin controller.  I should gain valuable knowledge on the controller that I can then apply to the Core XY design.  I have tried to avoid building printers as I use them as a tool and hoped other engineers would have developed them further than they are now.  My time is better spent in other areas, but with a limited budget I am running out of options.

PekkaNF:
I dabble in precision. May explain why I'm having hard time even imagining to buy a 3D printer.

What sort of options are there for stable vertical axis table and extruder on X/Y stage?

Pekka

Joules:
Forget the printer being desktop, use a ballscrew directly under the table like a knee mill and spin the nut, use a large single Hiwin rail and block for the table guide.  The printer has to have an enclosed metal chassis for rigidity.  Look at aircraft spars or carbon cycle tube for the gantry design, you are looking for light very low flex.  The more weight in the XY, the more inertia you have to deal with.  Servos are a step too far on cost, but if cheap hybrid ones become available...  The nozzle is lightly loaded, but direct drive for the filament is a must, a weight penalty on the gantry.  Bowden drives have too much hysteresis for accurate metering of extrusion.  The 3D printer has to be looked at as a high speed motion device, not a cnc milling machine, but still requires high prescision.  My downfall is not having access to CNC machining for parts.  Printed parts are OK for testing but not the finished item.  My build volume aim, 300mm x 300mm, with a 400mm Z. That would make the printer about a metre tall, so mostly storage in the base.

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