Thoughts on extending the Da Vinci Jr (Page 3 of 3)

Other than the prusa I3 MK 2 4 color upgrade kit  you are the first I have seen  doing 4 colors . The first in the wild if you will . I have thought of doing the whole rbg bend thing and it would likely work but one would likely factor in a a bit of Hysteresis.(The phenomenon in which the value of a physical property lags behind changes in the effect causing it, as for instance when magnetic induction lags behind the magnetizing force.)
Tin

OK, so I have a version 1 of my "purge bucket" for the left nozzle. I created it in Onshape because doing something this detailed in OpenSCAD would be insane and take forever.

https://cad.onshape.com/documents/f2aa3 … 7e53c899a4

Once I get it all printed out and fully tested I'll post it on Thingiverse. For now I'll post the bracket and blade STLs here.

The neatest thing about this is I'm using a clip-on attachment for the left side Z carriage. I wasn't sure at first how best to attach this to the Z axis, but this clip actually works quite well, and it would be easy to modify to add other attachments/tools that need to follow Z.

The blade itself I print in TPU. It can be a little tricky to wedge it into the slot, but it fits snugly, and just barely grazes the nozzle which is exactly what I wanted. The really tricky part is that there's hardly any clearance between the center of my nozzle and my Y axis bed levelers, so the tip of the blade is just a mm or two away from the nozzle center, and my levelers just barely clear the end of the bracket when Y moves. Very tight spaces

The bracket has to be printed with the brace flat against the bed, and you have to use supports for the clip parts since they're then floating. S3D's supports are pretty nice and pop out very easily and cleanly. However, because of the length and thinness of the bracket parts, you almost have to have a heated bed to print this properly. Fortunately I just picked up an MP Select Mini last week, which is still both large enough and hot enough to print this bracket perfectly. Printing it on my Not-so-Junior did not work well. No heated bed there, and it's currently living in a chilly basement The bracket lifted off the bed by a good 3mm at the far end, making it not fit properly. You could probably manage it with a very wide brim.

Pics to come soon.

That's why, for lack of a better name, I'm calling it my Not-so Junior But yes, you're basically right. The frame, Z and X movements are stock, but practically nothing else remains of the original.

So, I hit a few snags with the purge idea. I still think it's the best solution, but unfortunately the physical construction of my monster makes the intallation of a purge blade not work so well. There's just not enough clearance between the parked hotends and my bed mounts to allow for a blade that can wipe the nozzle.

I did get one designed for the left side, and it printed perfectly and fit well -- sort of. But I made the cup too tall by accident, and there just isn't enough room to get that blade past the hotend without it hitting the bed mounts. The cup idea is pretty silly anyway, since the amount of purged material I'm dealing with far exceeds what a cup this size could hold.

Anyway, I think it was a neat attempt, and the clip-on part for the Z carriage could be useful elsewhere. If I ever redesign my bed mounts I might revisit this idea.

In other news, I attempted to print a 4-color frog based on the fun 2-color frog on thingiverse: https://www.thingiverse.com/thing:329436

I printed this at 0.2mm layer height by just purging into thin air and adding an ooze wall to keep the strings off the print. It's a messy process, and there are still some bugs to work out, but the results weren't completely disastrous. I had a lot of trouble removing the supports and ooze wall -- lessons learned below -- so it didn't come out that well, but you can still see basically what's possible here.

Things I learned with this print:

• Purging into thin air is fine, but it's good to clear out the mess once in a while so it doesn't build up too bad. It wasn't an issue for me, but in theory you could end up with the purge strings interfering with your bed, gumming up the works, or just getting dragged into your print

• I used S3D's "waterfall" ooze shield at a 2mm offset. With the messiness of the purge, the supports and ooze shield at this distance just ended up fusing with the print, and it was very, very hard to remove. I had to chip away at it gradually with wire cutters and needle nose pliers.

• All those tool changes, especially for a piece this small where the actual time spent per color per layer is short, dramatically increases the print time. This small ~3x3cm piece (I reduced its size 50%) took 9 hours to print. It's definitely not a very scalable process.
  

• Simplify3D, despite its $150 price tag, is really about $150 worth of bugs. If you don't set its ooze shield and supports to use All Extruders, it will happily attempt to cold-extrude from the inactive nozzles without using your toolchange gcode routines. I figured this out the hard way when I tried to set all the supports and ooze shield to print in white, which probably would have made removing those additions much easier.
  

You can see the interesting-looking ooze shield in this shot:

I'm attempting a new print of the same piece, this time with a larger offset for the ooze shield, and I'm trying out using a consistent temperature for both filaments in each hotend without cooling the inactive nozzle. Since I'm retracting the inactive filaments a whole 110mm, there's really not much chance for ooze anyway, so I'm trying to reduce the print time by keeping the empty nozzles hot. I'm also keeping the left nozzle at 190 and the right at 205 so that I don't need to perform any M109s during the toolchanges. That alone seems to be reducing the print time to about 6 hours from the original 9.