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Redesigning Davinci 1.0 extruder
#1
So we know the davinci stock extruder is top heavy and shakes a lot. Has anyone thought about redesigning it already using the stock hot end? Before I upgrade my hotend I think it would be fun to see if I can make an extruder that is a better design of the stock extruder.

With that idea out of the way, comes with questions.

1.) Do I need to modify anything software wise with the new design?
2.) As far as cooling goes, the heatsync just needs cooling correct?
3.) Has anyone debunked this idea already?
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#2
To reduce the shaking, you have a simple solution, and a more complicated one...

Simple solution - reduce jerk setting if using Repetier firmware. I think it comes set at 20. Drop it to 15 (my setting) or lower. Watch for blobs on corners if you go lower. You might also see a small improvement if you reduce acceleration settings.

The more complicated solution is to go with a bowden setup which greatly reduces the moving mass since the extruder stepper is moved off the carriage. Many people prefer bowden setups, some do not. Bowden can handle higher accelerations, but it also has disadvantages. It is harder to accurately control extruder dribble. You have to get your retract settings just right, and even then those settings can change when you switch to a different filament type. This is much less of an issue with a direct extruder setup. Pick your poison, both have advantages and drawbacks. Personally, I prefer to sacrifice speed (acceleration) to get better extrusion control with a direct setup. But that's just me...

As for the rest of the parts, you can definitely improve the stock extruder by doing some or all of the following:

Put ball bearings in the idler

Install a better drive wheel.

Install an secondary heatsink to the heatsink bar.

Apply heatsink compound to all heatsink surfaces - including the bore of the heatsink bar itself.

Install a good extruder heatsink fan duct (one that cools the cold end without blowing air around hotend nozzle)

Installing a dedicated layer cooling fan if you are printing PLA (and leave it OFF when printing ABS)

Going further - Replace the stock filament tube with an Mk7 or Mk8 part. Choose an all metal or PTFE lined depending whether you plan on printing exotic filaments that require heat above 240C. Look for a longer one with a necked down section heat-break to get a sharper thermal transition. In order to install a different filament tube, you'll probably need to tap the heatsink bar and install a helicoil. (or fabricate an entirely new bar)

If you do the above, then replace the nozzle with a good mk7/mk8 type part. Choose the style that best suits your printing preferences. More pointy tip design for better bridge & overhang performance, or a blunter tip for smoother upper surfaces. You will loose autolevel capability with a new nozzle. (no big loss)

You can of course go with an E3D (or clone that sells for 1/4 the price, and arguably works just as well), but that will require more extensive modifications or a totally new carriage.

There are a lot of choices and I think you'll find that everyone wants to do things their way and that many will insist that their way is the "best" way.

Do your research, pick a path, and start hacking Smile

P.S. A common non-extruder related problem that can really kill print quality is those damn loose bushings on the right side of the Z-axis table. It seems that XYZ never glues them it they way the do with the X and Y axes. Steal the wife's nail polish and glue those suckers in so the table isn't wobbling around so much.
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#3
Thanks a ton for this good info. I decided to mod my new printer with an mk8 full assembly and fix my broken printer with a new extruder mount to replace the stock mount. It will take a lot of work but will be fun to do. When printing a new carriage for the new mk8 extruder is an infill of 50% efficient enough?
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