Long bowden tubes suck! This was even more apparent after installing a volcano clone heater block on my printer. You need precise control of the filament to keep blobbing in check.
Try this experiment- print out one of the many manual extruder knobs here on Thingiverse and install it on your extruder. Make sure the filament is fully inserted in your nozzle, and cool down your hot end. Once it is cool and the filament is fully fused into your hot end, turn the extruder knob back and forth and see how much the filament can move at the extruder with no movement at the hot end. The longer your bowden tube, the worse this is.
After looking through Thingiverse for a decent direct drive conversion for my CR-10 and not finding anything I liked, I decided to model my own. This fits on a stock CR-10 using the original style hot end (I am using the Micro Swiss all metal hot end).
My design goals were-
Cost as near to ZERO dollars as possible
Easy and clean installation
A strong and solid mount
Clear view of the hot end during printing
To those with concerns about adding mass to the X axis carriage- I say this: On an i3 style printer, It is irrelevant! Even with the big full size Nema 17 motor on the X carriage, it still weighs less than the y-axis- especially on a big printer like a CR-10. For comparison, my complete x-axis carriage assembly is 559g, a CR-10 glass plate alone is 1kg. Once you add in the heat bed, y carriage, etc, it's easily 2kg. And to make matters worse, the bigger your print, the more mass your y axis gets. Last I checked Cura 4.0 doesn't offer separate X and Y speed/acceleration/jerk setting, and definitely doesn't scale settings as the print increases in mass. If you are a speed junky, get a core-xy or delta printer.
Amazon Basics PETG
I printed it using a 0.6mm nozzle, 3 perimeters, 1mm thick top and bottom surfaces. I used a 0.2mm support Z distance in Cura. It prints best in the orientation shown, and a brim may be needed depending on how well your bed adhesion is. I used Cura's support blocker feature to limit the supports to where it is needed (see pictures). With these settings it used about 56g of filament and took about 3.5hrs to print.
I tried a version using Maker's Muse sacrificial bridging method with no supports. It saves time and filament but I think the surface quality is better with supports.
Remove supports, clean up any stringing and file/sand off any remnants of the brim as needed.
Gently file/sand the mating surfaces to make sure they are flat and will mate up flush to their respective components.
Depending on your printer's calibration you may need to run a 5/16" drill bit (which is about 0.05mm smaller than 8mm) to achieve a good press fit of the spacer sleeves. If the fit is too loose, you could epoxy the spacers into the bracket. Take care to make sure they are perfectly flush with the mounting surface.
Remove your X carriage and the two v-slot rollers, hot end assembly, extruder and extruder motor.
Press and/or epoxy the spacers into your direct drive extruder bracket.
Reinstall the v-slot rollers and the direct drive extruder bracket onto the x-axis carriage. The bracket locks into place on the x-axis carriage kind of tightly. It may take a little force to make it snap into place.
Install the extruder and extruder motor onto the bracket, but leave the screws loose enough for the motor/extruder to slide freely in the slotted holes.
Cut a piece of bowden tube about 35mm long (this measurement may vary depending on your hot end/extruder setup) and insert between the hot end fitting and the extruder.
Test the fit of the hot end, and trim the bowden tube a little at a time until everything fits properly.
Reinstall and tighten everything that goes on your x-carriage- extruder, hot end, fans, auto leveling sensors, etc...
Reinstall the x-axis carriage onto the z gantry and adjust the v-slot eccentric. Install and tighten your belt.
It is necessary to extend your extruder motor wires and re-route them through the hot end braided sheath to retain your full print volume. I had some leftover 4 conductor rgb-led extension cables that I spliced/soldered in.
The wires and filament need to be routed IN FRONT of the frame uprights, or you will loose Z height as there will be interference with the top cross bar. If you drill out the mounting holes on the stock CR-10 spool holder bracket to 4mm, you can use any M4 screws and t-slot nuts to mount the spool on the top cross bar, Ender 3 style.