Spruce300

SPRUCE300 : An Open Source Mashup : Prusa MK4 Parts for the Sovol SV06 Plus

WHY?

My toolhead carrier broke after only a couple months of use.  My Y motor mount wasn't straight.  The screws that hold belt idlers got pulled off-axis under tension, causing rubbing and artifacts.  Swapping Z bearings requires a hammer and there is no way to pre-tension them.  

I wanted a complete set of printable replacements for all injection molded plastic parts found on the SV06 Plus.  

A BIG THANKS TO PRUSA RESEARCH AND SOVOL! 

They released their CAD files under an Open Source license, making this possible.    This mod is unofficial and unauthorized.  Neither Sovol nor Prusa should be bothered for support.

THIS IS A PRELIMINARY RELEASE.  

All parts are installed and working on my printer, but I currently recommend it only for those who have a second printer.

I NEED YOUR FEEDBACK.  

Give Spruce300 a like on Printables, and feel free to ask questions.  The more interest there is, the more time I will put into documentation.  

THIS MOD COMES IN 5 SECTIONS

1. Spruce X and Z Gantries (here)
2. Spruce Y Belt System (optional) (here)
3. Mk4-Style Toolhead Block A
4. Simple Toolhead Block B
5. Spruce Nautilus Part Cooling Duct
    

The X and Z gantry mod is all-or-nothing.  Rods and lead screws are in different positions.  

The Y Belt System can be installed alone on an otherwise stock SV06 Plus.  Y rod holders will be released in a future update.  

NON-PRINTED PARTS FOR XZ

M3 socket-head screws of various lengths up to 35mm.
M3 and M4 nuts.
1x 4mm steel dowel-pin, 20mm long.
A new belt

4x 20mm x 12mm x 1mm rubber pads (for Z bearings)
The rubber pads can be printed in TPU or cut from inexpensive rubber strips from AliExpress like https://www.aliexpress.com/item/1005005900732831.html (1mm thick, 30mm wide).  They ended up being 1.1mm thick but seem to work ok.  

A square m3 nut for the X belt tensioner is optional but highly recommended.

NON-PRINTED PARTS FOR Y

M4 socket-head screws
M4 nuts
1x 40mm M3 socket-head screw
1x M3 nut (lock nut recommended)
1x 1mm thermal pad (maybe from m.2 SSD heat sink)
1x 4mm steel dowel-pin, 20mm long

PRINTING AND PREPARING PARTS

The supplied STL files are pre-oriented for printing.

Parts are intended to be printed in PETG.  Supports are not required.  I recommend 4 perimeters, 4 bottom layers, 6 top layers, and 30% grid infill.  When slicing, ensure that no seam will touch a bearing, rod, or extrusion.

ASSEMBLY

Prusa Research's document for the Mk4 is currently your best guide.  It doesn't all apply, but follow the assembly order as best you can.

The stock Gates Y belt should fit.  You will need a new length of belt for X.  

I have made the Y motor and idler mounts so that they are easy to straighten with some light sanding where they meet the metal frame.  

BEARING COVER

I have included 3 different variants of the “end cover” bearing holder, labeled 8, 10 and 12.  Variant 10 should work with 1.0mm pads.  Variant 8 is 0.2 mm tighter.  Variant 12 is 0.2 mm looser.  If your bearings are stuttering or binding, try the "12" covers.  If you find that a carriage makes a loose buzzing noise when you tap on it, try the "8" covers.

2020 TOP BAR

The “2020” parts can be used with a 450mm 2020 extrusion to replace the plastic top bar.  You will need to drill 4x 5mm holes, 18.5mm and 38.5mm from each end of the extrusion.  Mount the rod holder parts using 4x 5mm screws and T-slot nuts.   

TLDR STUFF:

MECHANICAL CHANGES (compared to the stock SV06 Plus)

The X linear rod spacing has been increased to 40mm center-to-center.  The Z lead screws have been moved to be in-line with the Z linear rods.  The Z rods have been moved outward.  Both the screws and Z rods have been moved closer to the vertical frame extrusions.

Mounting holes for Prusa style lead screw nuts have been preserved.  I have not tested them, but if you can find 25mm diameter Tr8x4nuts, they should work.

The motor bracket is now plastic, and a thermal pad is necessary to help cool the motor.

Z CARRIAGE BLOCKS

The MK4 uses a single LM10LUU bearing in its Z carriage blocks.  The SV06 Plus uses 2 LM10UU bearings.  The Spruce Z blocks are designed to use the original LM10UU bearings, but I am concerned that the rubber pads may actually force the 2 bearings out of alignment.

I tried some LM10LUU bearings but they were really loose on the Sovol rods.  If I can find some bearings that work, I will release some LM10LUU  Spruce Z blocks in the future.

OTHER DIFFERENCES FROM THE PRUSA MK4 PARTS

Belt idlers have been changed so they are compatible with the Sovol idlers.

The rubber pads for the Z motors have been removed.  Prusa's Z motors have an integrated lead screw instead of using a coupler.  

The Mk4 uses 8mm rods on the X axis in a slightly-offset configuration.  I have adopted the 40mm spacing of the MK4 but having them offset offers no benefit to the Sovol toolhead.

Other small changes include (mostly) hexagonal instead of square nuts, mounting holes for rectangular lead-screw nuts and access to Z motor coupler screws.

Z LEAD SCREW TOP BEARINGS

Using bearings to constrain lead screws without also using oldham couplers is considered bad design, but that's what Sovol did.  In any case, they are great to have during assembly to get everything lined up.

My Z top parts allow you to drop the bearings (and the lead screws themselves) in from above.  The F688Z bearings are held in carriers that can be printed in TPU or TPE for vibration damping.  I have included a small tool to allow you to remove the carriers without any other disassembly.

608ZZ bearings should also fit.

A NOTE ON LICENSING

Prusa Research has released all printable part for the MK4 under the GNU General Public Licences V2.0.  In keeping with this, I am releasing all of my modified designs under the same license.  I am also releasing my from-scratch toolhead carriage design under this license except for the part-cooling fan duct, which is based on Leander Perez Blanco's "Nautilus" design and posted separately under the Creative Commons License.

ISSUES AND PROBLEMS

The toolhead carrier comes very close to the injection moulded Sovol top bar when at maximum Z.  I recommend changing the maximum Z height to 320mm if you do not install the 2020 extrusion.

Converted for use on the Sovol SV06 Plus.