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

[Dyne]

I know that I said I wanted to finish the release before making the major changes I have planned.  However, I have now entered crunch mode for Dragon Con, so if I'm going to do these changes, I need to do them soon.  I have already exported the various parts as they currently exist, I just need to finish going through and writing the instructions.  Unfortunately, I probably won't have time to do that before the con.  I don't think it's a big deal, because I don't think anyone is in a rush to build this, and releasing after these changes just means that a few parts will have two versions to choose from instead of one.

Here are the two major changes I presently want to make to the CAD:

1. Make the neck static
   
2. Improve the belt tensioning system
   

Since I'm actively working on the first one right now, I can talk about those modifications in more detail.  As a refresher, here are the parts we are concerned with:


In Black is the electronics cover.  There are two screw holes on each side that attach it to the rest of the droid.

In Green is the starboard side lower neck stalk (there is a mirror on the port side that isn't shown here).  It is split down the middle vertically, and on the end nearest the red part, the outer hub with the short diagonal slot is a separate cover held on by magnets.

In Red is the current upper neck stalk, which is split vertically as well, and has two embedded threaded rods for increased stiffness.  The rear rod extends into the head while the forward rod extends only just past the top of the neck.

I have three requirements for the changes to these parts:

1. The green part(s) will be truncated aft of the black part.  Instead of a functioning portion of the mechanism, they will be cosmetic parts held on with magnets.  (They need to be easily removable to provide access to the screws attaching the black part to the droid.)
   
2. The red part will be (to some extent) unified with the black part, rendering the neck static.
   
3. The threaded rod in the rear section must be preserved, because it serves as the pivot for the head's rotation.
   

Now, the issue with that second requirement is that it would normally make finding an acceptable print orientation challenging.  The black part is printed as shown, while the red part (being split down the middle) is printed with each half lying flat on the bed.  If these are merged, either the black part would be split down the middle as well (which would weaken it substantially) or else I would need a lot of support material to print the red part standing up.  Luckily one of my friends made a suggestion that will simplify printing: replace the central parts of the stalks with metal (or whatever).

You may recall that I called out the thinner portion of the rear stalk in my previous post as having a diameter of 12 mm.  That is near enough to the same outer diameter (13.05 mm) as the aluminum tubing that I have looked at for the head rotation of my Treadwell build and used as the mounting post for my 99-99 build.  The tubing's inner diameter (9.25 mm) is also large enough for the threaded rod (7.73 mm), which fulfills my third requirement (with some necessary attachment points at the top and bottom.  The thinnest sections of the front stalk (23.812 mm) are just a bit bigger than the outer diameter of 1/2" schedule 40 PVC pipe (21.4 mm), so that works too.  

I can adjust the rest of the neck greebles to match easily enough and the differences in size would be hard to see. With that done, then they can be printed in halves or upright and then epoxied around the inner pipe or tube.  This is similar to how James is doing his Treadwell neck.

Both the tubing and the pipe are easily stiff enough (at the short lengths necessary) to provide support for the head of this droid, assuming that the part that they slip into is strong enough to hold them.  (I have more concerns about whether the M3 screws holding the black part on will pull out the brass inserts that these screws thread into.)

Shown below is how the red and black parts have been merged with the black part.  I am pondering exactly where to make the splits to remove the greebles and leave space for the new cores.



The next image shows how I plan to truncate the green part(s).  As previously mentioned, the leftover parts will be held on with magnets, but I still need to add some supports underneath so they rest on the black part.


If you prefer to look at the physical droid's chassis, the truncation would happen near the small gap visible in the far wall of the droid's chassis, just to the right of the far motor.


As you may be able to tell here, it's not easy for someone to see far enough into this area to tell how far those arms go without getting pretty close, especially since the arms and the interior parts are all actually black.


As these changes get made, I will also be rewiring the droid to remove the existing fuse panel and make the battery easier to connect.


The picture of LD-F1's chassis above also has a clear view of the location where I am likely adding the new belt tensioner (if I work out the details in time).  

Specifically, just above the upper run of the secondary belt (the one not shown that runs between the silver intermediate pulley and the large drive sprocket on the left.   I'll go into this later if and when I get further along with it, but it basically involves a hidden rotating disc hidden inside the front chassis walls, attached to an idler on the outside pressing against the belt.  I'm also removing the slot in the intermediate pulley's mount while I'm at it, and the pulley's axle will be threaded into brass inserts instead of a just hidden (read: inaccessible) locknut that likes to loosen.  A better solution that I think I've mentioned before would be a hex head (not hex SOCKET head) M3x60 screw, but those are not common.


Edit: I have now adjusted for the new structure and split up the parts.  In the following images, the thicker white cylinder is the PVC pipe, and the thinner silver cylinder is the aluminum tubing.  The various colors represent which parts are printed as a unit (or as two halves, as convenient).  I may split up the red part further for easier printing.


The second image above is the cross section showing how the PVC and Aluminum tubes are situated internally, as well as the upper and lower holes for the threaded rod and the lower lock nut recess.  The upper end will be held on with the lock nut that sits above the rotation gear/neck.


As a side note: Probably to the great surprise of nobody that has read my build threads in the past, I have been unable to resist the urge to distract myself by starting another project for Dragon Con.  At the beginning of this month I began work on a mouse droid.  I really want to get the Mouse ready for Dragon Con because that's where most of my builds debut, but I have my doubts I can get much more than the chassis (from Michael Baddeley's printable chassis) up and running in time because I also have to do some coding to get my sound board and control type working for Penumbra.  The body shell is still TBD at this point.  The build thread for the Mouse project is on the Mouse club forum.