Why split the X/Y movement on the table?

Hello everyone,

I have been thinking and I can't seem to come up with a good reason that the prusa models split the X and Y movement between the print head and table.

It seems to me that moving the Z axis along the X adds to the vibrational issues, and binding issues for the filament.

What is the advantage? Is it just a design choice that has worked out to be cheaper and advantageous so its stuck?

Thanks for the help and time,

It evens up the mass to be moved and splits it between two motors. At the size of a Prusa axis there isn't much difference between moving head and moving table in terms of the space used. For larger build areas moving head is better and for smaller ones moving table. 200mm is around the crossover point so you can pick either.

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[www.hydraraptor.blogspot.com]

Nophead is of course correct.
This wasn't obvious to me until I started trying to design a printer, coming from CNC mills my first though was what was needed was rigidity, but it's not the case.
3D Printers are mostly about attaining speed with accuracy, with sufficient rigidity.
The focus on speed and the large number of small moves mean that you need to reduce the mass being moved to reduce the inertia.
moving the table is less or similar mass to moving a pair of steppers and the extruder up and down the Y-Axis.

With Bowden extruders IMO this changes and gantries make more sense. Some of the newer design (Ultimaker etc) have stationary steppers for all axis.

There is a secondary issue IMO which is it's hard to assemble a square cuboid out of things like threaded rod, so most of the gantry designs use either lasercut parts to make the box or Al extrusions. I'm not really sure how those align with the original rep-rap vision.

Polygonhell Wrote:
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> There is a secondary issue IMO which is it's hard
> to assemble a square cuboid out of things like
> threaded rod, so most of the gantry designs use
> either lasercut parts to make the box or Al
> extrusions. I'm not really sure how those align
> with the original rep-rap vision.


Fairly well, it seems; have you checked out the Tantilus?

Yeah I like Tantilus. I might try ripping off the housing idea if I can ever get my prototype working.

That makes sense. Thank you.

Ps what is Tantilus? I can't find it anywhere?

Its Tantillus with two L's [reprap.org]

I will be releasing more info hopefully this weekend.

For those of you that want an entirely printed bot the case is available [github.com] and the rest will be available a little later.

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FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
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That thing is awesome.
Hopefully it will be my second reprap.

Thanks for the great work.

I plan on starting my Tantillus case print tonight. This is awsome. Great work Sublime! Is the bowden set up for 3mm or 1.75?

Entropy Wrote:
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> I plan on starting my Tantillus case print
> tonight. This is awsome. Great work Sublime! Is
> the bowden set up for 3mm or 1.75?

3mm but it should not be hard to convert it to 1.75 as it uses standard nuts threaded onto the tubing to hold it in place.

Also be aware that NO one has printed it successfully in ABS.

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FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
Tantillus.org	Mini Printable Lathe	How NOT to install a Pololu driver

I'll try a section in ABS, if it's a no go, then PLA it is. Are the motors NEMA 17's or 14's? I can't really tell by the pictures.

They are Nema 17's and need to be less than 40mm long or you will have clearance issues (which could be over come).

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FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
Tantillus.org	Mini Printable Lathe	How NOT to install a Pololu driver