Dyne's LD-F1 (D-O concept) build

[Dyne]

T-Minus 1 week (YIKES)

It's the FINAL COUNTDOWN.  NA NANA NA ... NANANA NA NA...

Good news: Barring any major changes that I might need, I have now completed all of the large scale print jobs that I'm going to get done for this droid before Dragon Con, including the idler assemblies, the traction pads, and the head.  I am not going to bother with the side plates of the tracks right now as I am running low on PETG, time, and energy.  The handful of smaller parts that I still plan to print (mostly various small parts for the head) can be done with the PETG that I have left or with some PLA.

In the course of this build so far, I have used up two full spools of silver PETG (and part of that troublesome spool), a full spool of the "silver" PLA, two full spools of black PETG (and the leftovers of a few more), almost an entire spool of white PETG, and some small amount of grey TPU and white PLA (for the LED lenses).



As mentioned in last Monday's post, I'd started printing the left side idler brackets.  I had to babysit this print because I wasn't sure how much filament I had left on the spool of black PETG that I'd bought for this final push.  The print ended up stopping short of the end of the spool by about half of one layer of windings.



I printed the right side on Tuesday, which involved even more babysitting.  I had to use what remained after the previous night's printing, as well as what remained on a couple of other leftover spools of the same filament.  I ended up having to watch until each one got close to running out, and then feed the start of the next spool in behind it.  Needless to say, I was up very late.

After that, I also printed the remaining idlers (including modeling and printing the smaller ones).  This used up nearly all of the remaining black PETG (I have less than half a layer now).  With those printed, I could start on the idler assemblies.

The top idler's axle is a 5/16 x 3 inch bolt that passes through the outer side plate and both idler brackets.  Below that, the centermost of the three rear M5 inserts in the Electronics Box serves as the second attachment point (it's the place where the chrome colored M5 bolt was, in the photo from last post), so it has a slightly longer 20mm M5 bolt.  

Finally, there is an hole to either side for an M3 socket cap bolt.  Each goes through the rear outer side plate and into an insert that I'd already installed in the rear inner side plate.  These M3 bolts are mostly just there to keep the idler mount from yawing.  

I did make a poor decision when I modeled them.  The issue is that I didn't make the recesses for the heads very deep, so they require 35 mm bolts, which have to be screwed into a tightly toleranced hole through almost the entire thickness of the standoffs that are part of the inner idler mount.  I plan to revise the parts in case I ever print them again, because doing this four times was a bit of a pain.


In any event, the process for each idler assembly was:

0. The top idler's axle should've been placed through the hole in the rear outer side plate (pointing outward) when you assembled the side plates.

1. Install the brass inserts in each idler bracket (four M5 and 2 M3 inserts in the outer bracket, 2 M3 inserts in the inner bracket)

2. Place the inner idler bracket onto  the axle for the top idler.

3. Put the hex bolts that serve as axles for the five lower idlers -- they are 5/16 x 2.5 inch bolts -- through the inner idler bracket, pointing outward, with the heads settled in their recesses.  Most of them can't be added after you attach the bracket because they are too long to angle into the holes.

4. Tape the heads of these bolts in place with some gorilla tape (most can't fall all of the way out, but there are too many to easily hold in place and they can move enough to let the idlers fall off before they are secured).

5. Secure inner idler bracket to the chassis with the other three attachment bolts (one M5 x 20 mm, two M3 x 35 mm).

6. Hold the chassis with the idler axles pointing upward, and for each of the six axles, you want to put on the inner 5/16ths washer, the inner 608 bearing, the printed idler itself, the outer 608 bearing, and finally the outer washer.

7. Once that's done for all six idlers, you place the outer idler bracket on, making sure the six axles go into their holes.  Secure the bracket with a nylon lock nut on each axle, but as you do, make sure the idlers are still free to spin.

Once both assemblies are done, you'll end up with this:


(In the above photo you can also see the switch and voltmeter that are normally hidden under the brain box cover.)


I started the large head print on Friday morning, a bit after midnight.  This print lasted a bit over 17 hours, even with the larger nozzle.  Being under tight time constraints, I kind of got in a hurry and didn't notice two things before I started the print.

First, when I modeled my built-in support for the opening for the droid's eye (near the red LED in the pic below), I constrained it to the thickness of the surfaces that it attached to.  When I checked the gcode before printing, I didn't really think about it.  When that part started printing, I noticed that the "support" was actually only one perimeter thick.  Granted one perimeter on a 0.6 nozzle, but still.  Luckily, it was really only meant to keep the circular opening from drooping, and it worked, but it was rather nerve-wracking for awhile.



This is obviously not my cleanest print ever.  I haven't spent a lot of time dialing in my profile after the nozzle upgrade, so there are a lot of blobs, strings, and a few rough patches)  It's also been extremely rainy here for the last two weeks.  The garage doesn't do much to keep the humidity out.  


Second, I messed up the orientation of the print.  By necessity, it's printed standing on its side.  As a test, I originally sliced the head so it was oriented with the top of the part toward the front of the print bed, so from my perspective, the droid's "face" was looking toward the left side of the printer.  

I recently turned up the part cooling on the printer, which blows from the right side of the printer (I haven't gotten around to modding the printer with a fan that cools from multiple directions like I did on my old printer).  That side tends to look better, so I meant to rotate the part in my final gcode so that the droid's face was looking into the air stream.  

You may have realized from the above photo that I forgot to do that, and it was facing in exactly the wrong direction.  I only realized it after the print had already been running for awhile.  Therefore, the nicest surface on the print was the back of the head... which is also the one surface that is completely featureless.

On the plus side, I DID remember to add built-in supports for the corners of this rectangular opening.



17 hours later, the print finished.  It will do.



With the major printing done, I've now moved onto some perfunctory body work and paint, as well as getting started on the wiring.  With luck, I'll have everything wired up and assembled by next weekend, which gives me a little time to do some troubleshooting and performance testing during my spare rest week and maybe do a little work on Four-Nines before I have to depart for Atlanta.

A little Milliput, a random orbital sander, and some primer later and we have this.  Sorry, it's a bit blurry; you'll have to take my word that it's an improvement:




I've also been polishing the lenses.  The red tint is from the polishing compound.  The curves on the surface are artifacts from printing that I'll need to sand more to remove..




In terms of wiring, I've sketched out a plan.  I'll post something when I have time to create a much better rendition.

In the meantime, I've decided that I will not be using Penumbra for LD-F1's first appearance.  Mostly because there's no good introduction to working with it, and I don't have the time or energy right now to go diving in to integrate a bunch of custom code (for controlling the head servos and running the neopixels).  For now, the droid will be controlled with the R/C transmitter that I mentioned over in my Treadwell thread, and the ESP32 will only be running the droid's head neopixels.  

It does mean having to figure out where to mount the receiver, and more complicated wiring in general.  Since I'm not using Penumbra, I'm not using I2C to drive the servos through the PCA9685 servo board, so the servo signals will have to be passed from the receiver into the head individually.  I'll likely still use the PCA9685 as a power distribution board for the LEDs and Servos.

I already wrote a basic sketch to handle the neopixels.  It's currently a bit glitchy, which I believe is due to the need for a logic level converter on the signal wires.  The ESP32, though 5V tolerant on its inputs, is actually a 3.3V microcontroller and its outputs are apparently driven at that voltage.  This can cause weird behavior for neopixels.