SpiderBot Delta 3D Printer

Hi all. I have been pushing the envelope lately, trying to print using the stock 0.35mm hot end and stock filament extruder at .05mm layer height. Neither appears to be up to the task- consistent filament slipping of the extruder causing uneven extrusion, and print head jams- especially using PLA, caused me to seek alternatives. Don't get me wrong- there is nothing really wrong with stock Spiderbot- especially using the 0.5mm hot end and printing at .15 to .2mm layer heights, but I wanted something more precise, capable of truly flawless high resolution prints like the Ultimaker 2 touts. I wanted to prove Spiderbot can print as well as- or better- than an Ultimaker.

In pursuit of .05mm, I began with a swapout of the hot end. Bingo. No more jams, but still uneven extrusion (and sometimes 'skipped' extrusion. I then swapped the filament extruder to a rather expensive, all aluminum CNC machined model with a geared stepper motor- it was a thing of beauty and my Christmas present to myself. Bingo. No more uneven extrusion, and so much grip I could grind the filament to pieces if not calibrated correctly. Armed with those two upgrades, I then pursued better accuracy- moving from 1/16 microstep to 1/32 microstep stepper motor drivers- doubling resolution of the z,y, and z axes.

So, after about $250 in upgrades, which includes:

new extruder (and custom designed and printed bowden adaptor)
new 0.3mm j-head all aluminum hot end (and custom designed and printed mount)
new hot end cooler (and thingiverse designed and printed duct)
four new stepper motor drivers using DRV8825 drivers configured for 1/32 microstep x, y, z axes, and 1/8 microstep e axis
reconfigured / recalibrated repetier firmware


I am now successfully printing at 40mm/s, with 2mm/s x/y/x jerk, with 33% infill at .05mm layer height. Prints are so fine, you cannot see lines between layers- print comes out smooth all over, with sharp corners, and no 'patterns' visible on vertical walls. It does take time to print, but if you want quality, the Spiderbot design (with a few mods.) is definitely up to the task.

I will post pictures of the first prints, and begin documenting the upgrades this weekend on my blog for those interested in hacking.

I am struggling with taking a close up picture that shows the detail of the print properly- soon as I get my macro lens on my digital camera to focus properly, I'll attach a picture here and more on my blog.

edit: picture now attached, but not of great quality. Print is deprime test object from thingiverse- great for calibration of extruder.

Cheers.
djs.
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    • Accepted Answer

      Joules
      Joules
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      Wednesday, April 16 2014, 10:18 AM - #permalink
      DJS,
      when you take some macro photo's can you back illuminate the model, i.e shine a bright torch into or through the 3D plastic model. This will really show up the structure on thin walled items.

      Your developments are very interesting to me. I have been watching the developments in micro stepping, and just recently borrowed a Rostock Max to play with. Unfortunately I am still sat on the fence over which delta bot to go with.

      Joules
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    • Accepted Answer

      Blake
      Blake
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      Tuesday, November 18 2014, 06:09 PM - #permalink
      Hi DJS,

      I've been running my V1.5 Spiderbot for a few months now and have come to the realization that the bowden extruder is it's Achilles heel. Overall I'm extremely happy with the printing results but managing high precision prints with the extruder 0.5meters away inherently causes a loss of control at the hot end. I searched the forum (and google groups) for relief and found that you had experimented with a direct mounted light weight J style extruder at the hot end.
      Was it the below image(MICRON 3DP "ALL METAL" 1.75 MM J HEAD EXTRUDER COMBO)
      What mods did you make to pull this off, and was the magnetic 3 sphere system able to support the load?

      Thanks,
      Blake
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    • Accepted Answer

      Wednesday, November 19 2014, 03:16 PM - #permalink
      I am a proud owner of Spiderbot v1.0, which has since been upgraded to v1.3. There may be slight modifications needed to make the same setup work on V1.5+

      PLA jams: The first issue was PLA jamming in the barrel of the stock Spiderbot extruder. An all metal hotend like that on Spiderbot is not optimal for printing PLA (ok, but not optimal), but works fine for ABS. If you can forgo printing in ABS, or restrict extrusion to 240 degrees C or less, a partial metal hotend such as the Aluhotend v6 is a much better choice. Link is here. This has a PTFE liner all the way to the tip of the hotend, reducing friction for PLA prints. This type of hotend MUST be fan-cooled from the side to eliminate heat creep up the barrel, but since the change I have not had any jams, and am able to print cleanly with a PLA extrusion temperature of 215 degrees C and a bed temperature of 50 degrees C.

      Retract/Stringing Issues: I noticed that the stock pneumatic push-fit connectors used for the bowden tube slip, causing a couple of millimeters of random play, which made it impossible to get a clean retract without stringing. Using a cable tie the same width as the collar around the push-fit connector helps secure the push-fit, and reduces this play somewhat, but it is better to purchase new push-fit connectors with same ID and OD from another manufacturer. That cleans up that issue.

      Skipping Steps: Since I moved to a 0.3mm nozzle when I bought the Aluhotend, the extrude pressure went up quite a bit from 0.5mm stock Spiderbot, so I still had skipping issues with the stock bowden extruder. The only way to solve that is to look at a new extruder design. Since I had retract/stringing issues, caused by play in the bowden setup (the longer the bowden tube, the more play there is, the higher the retract speed and retract distance you need to eliminate stringing) I decided to convert to non-bowden direct filament drive right at the hotend, or a close to it as I could get. My first stab at a direct drive extruder was the one you have pictured, but without the Micron hotend (I already had the Aluhotend). It turned out this was still to heavy and bulky to mount at the hotend, but is an excellent extruder as a bowden replacement for the stock Spiderbot. The smallest and lightest direct drive extruder is the PG35L micro extruder. I ordered one from Ultibots here with all hardware as a kit: Link is here for $75 USD. Turns out this was the best purchase I have ever made. After some placement/design work, I ended up mounting the extruder below the effector instead of on top- the PG35L motor extends out to the side, and MUST have its own cooling fan to keep the PG35L cool. I will publish wiring, mount parts, Repetier config changes for those interested. Downside is that you give up quite a bit of vertical height with the extruder mounted where it is, but at least it does not knock off any of the effector arms. With this setup, I am able to extrude cleanly with zero stringing using a retract speed of 15mm/s and a retract distance of 2mm, down to a layer height of 0.05mm..... Takes a while to print anything that fine, and I do not see appreciable print quality improvement below 0.1mm. My standard layer height is 0.18 mm.

      Here is a picture of the extruder printing on glass with PLA at 0.3mm width, 0.18mm layer height: Picture Here

      I'm going to take a second stab at moving the extruder above the effector instead of below it, and design a new mount if I can validate I have enough clearance.

      If you're interested, I'll post more details on my blog, but I hope this is enough to get you started.

      BTW: I have been trying to print full 3d printed quadcopter on Spiderbot, but continually run into the issue of bed size- 190mm diameter is simply not large enough to print out a lot of parts. I have embarked on building a second printer- dubbed "Wolfstock 360", as it has a 360mm diameter bed. It is heavily based on the Wolfstock design of makerslide large format Rostock Delta printers, with some of my own mods. Here's a sneak peek at the build as it stands today. Controller is an Arduino Due with RADDS driver shield and DRV8825 drivers instead of the Megatronics to achieve higher step rates without stutter.

      Picture Here
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    • Accepted Answer

      Blake
      Blake
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      Wednesday, November 19 2014, 04:18 PM - #permalink
      Thanks for the thorough feedback David-This is really helpful.
      Micron just sent me the CAD for their all in one solution but at 480g I was concerned it would be to heavy, your feedback informs me not to bother...

      What is the weight of the PG35L micro extruder with your J hotend?

      -Blake
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    • Accepted Answer

      Wednesday, November 19 2014, 05:41 PM - #permalink
      Weight of the entire effector assembly, including the three-sphere aluminum ring with magnets, extruder, PG35L stepper motor, hotend, two fans, and wiring is 270g. I print normally at 150mm/s travel, 40mm/s extrude, and 7mm/s jerk, but can go up to 20 mm/s jerk without issue. Keep in mind the magnets on Spiderbot v1.3 have about 1/2 the holding power of Spiderbot 1.5, so you might be able to push these settings/speeds. :D
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    • Accepted Answer

      Blake
      Blake
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      Wednesday, November 19 2014, 06:52 PM - #permalink
      Fantastic, Thanks for the data!
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