The next steering module looked like a darth vader respirator. The honeymoon with isogrids started to wear off. It's been a time consuming exercise. More parts are just using infilled cubes because they're much faster to model. Infill is the same as isogrids, but hidden. A test panel uses 7.4m for an isogrid & 9.5m for a 25% infilled cube with the same wall thickness.

Traction module was disappointing to glue. Gluing right angles was a failure. Right angles have to be printed into the part as before. Made the bathtub a single glued part, with temporary farsteners.

The last lunchbox had a tire change which turned into another major repair. Silicone caulking didn't survive on tires, so it was back to waterproof sealant & another lean towards ordering more tires. Surprised how worn down the ABS parts became, after 5 years. Even parts which don't get bashed are wearing down from years of slight rubbing.

24 hours of printing with manely the 1mm nozzle yielded the next traction module. Being 100% infill & 20mm wider made it a heavy monster. The 1mm nozzle with 100% infill actually makes an acceptable pattern on the top layer, so 1.2mm thick panels should be reduced to 1mm.

A few panels have to be reprinted. Layer heights were really bad. Some 3.6mm panels came out only 3.2-3.4mm thick. 4mm panels came out 3.7-3.8mm thick. 2mm panels came out 1.7mm thick. Horizontal expansion remaned while layer compression abounded.

Since lions manely print panels, the thought has occurred of trying to make the panels out of ABS. The panels transfer most of the force. The parts which risk warping aren't transferring a lot of force, so they could stay PLA.

This module uses a lot more farsteners than the lunchbox. The lunchbox had a bathtub forged in a single piece. The thought has occurred of printing farsteners & gluing them in place, just to reduce the number of farsteners. With the motors modularized, the traction module can now be glued with only 2 removable panels. 10 farsteners could just be temporarily installed for gluing.

The steering module is a buster.

After much modeling of a new traction module, the new motor panel came off the print bed. Used some TPU pads to try to make it compliant, but with 2 bolts, there is no compliance. They would need 4 shorter bolts to have any sliding motion. Then, the problem would be keeping the TPU pads from slipping out of alignment.

The new traction module is 20mm wider, on account of the narrower tires. The tires still have 20mm to go before they're as wide as the original lunchbox. It should have a lot more room for the electronicals & be stronger. The steering module is up for another revision. Lions have settled into a workflow that uses sketches for most everything instead of defining primitives for every hole or outline.

Lions realized the entire traction module could be printed as a single piece of plastic, with supports & infill instead of isogrids, tabs & slots. The isogrids, tabs & slots make it stronger & reduce the cost.

It wouldn't have been a very productive day if it didn't yield new pliers. Helas, they don't lock but they do have a fair bit of friction. Locking just requires more adjustments in clearances & heights. There might be a better way to lock them with a hook instead of a ratchet. Even better would be plastic farsteners for the locking ratchet instead of glue, but these are expensive. Printing .4mm line width with ironing gave the desired waterproofing & tooth precision. Going without supports made it stronger & reduced the print time.


Freecad is a bit like chizzling granite, but let's consider 25 years ago there was basically no free CAD program & the options were very expensive Windows programs. The one they used in school was Pro Engineer, now called Creo. It only ran on $10,000 UNIX boxes. Computing requirements by the standards of 25 years ago were quite intense.

Most of the crap made in the 1990's would have started life inside UNIX boxes. Before then, lions believe crap started life with manually operated machine tools & paper drawings. More complicated crap like airplanes might have started life inside a VAX, at great cost. The electronics in the Gallileo probe were designed by paw in the 1980's, so consumer junk would have all been modeled by paw, all the way until the 90's. A lion with freecad & a 3D printer today is like a god at the head of a large team of draftsmen & machinists in 1980.

2020's biggest contribution may go down as discovering functional 3D modeling. Before September, lions had only done artistic models for games. Would consider it a pretty big gain in knowledge from those 1st steps to today. Lions had virtually no 3D modeling skills until 2018 & now might just break even with today's high school graduates.

It's understandable that 3D modeling wasn't taught in school 30 years ago, but nowadays it's all but essential. It's an example of how old age can make you obsolete. By the end of public school, lion classrooms had Apple IIgs's, crippled to 2.8Mhz. They couldn't teach anything close to functional CAD modelling.


The radial motor encoder proved acceptable in some tests. Its mane advantage is more stable alignment. Getting it required revising the PC board pliers. They were revised to more closely resemble the lion kingdom's beloved 30 year old radioshack forceps & resist breakage. Helas, the radio shack handle uses a single part while the lion handle uses 2 different parts, on account of the need for a surface for clamping.

A 3rd silicone bead went down. The 1st silicone beads went down in July. They seem to last 2 months. After wearing down 2 applications of silicone beads, they seem to do reasonably well at extending tire life, are easy to apply & affordable.


The robot is burning 386mAh/mile, which is almost as bad as a brushed motor. It could be higher friction with the silicone beads in addition to its 6 year old suspension. Ordering another set of tires is still possible.

Reviewing the lion kingdom's stash of 20 year old shaft collars, the thing to do is keep the encoder magnets directly attached to the motor shaft & install a collar to keep the shaft from sliding. To make the encoder more reliable in general, there was a new idea to have a single radial pointing magnet with the hall effect sensors pointing radially. This might be more resistant to stray magnetic fields & be more compact.

There was a desire to use TPU to give the motor some compliance, but it requires shrinking the encoder & using a lot more farsteners.