The presentation that senior Lego designer Jamie Berard held at Brickcon 2006 and that spawned the entire legal vs illegal discussion can be found here:
The particular case you ask for is discussed in slides 9 and 10:
I actually managed to find the exact set while refining the question. It's set 744, released in 1980.
Here are the reasons why the research I did prior to writing the question didn't lead anywhere:
The yellow motor does not show up when searching parts on BrickLink. It's probably because on the list of set 744 parts, it has a note saying "Part colour ...
It sounds like you're trying to implement a fairly simple bell mechanism such as this one:
You can certainly do this using some string and the pulley element that you mentioned.
I'd recommend tying the string to one of the holes in the pulley. Something like this worked reasonably well for me:
Here it is in action:
You'll likely want to do something to ...
The easiest way to do this would be to use a motor with a high speed (or gear up a lower speed motor) and then attach one of the larger propeller elements to it. You can probably build a custom prop, but it might be challenging to build something with the proper blade angle while keeping it light and strong enough to not break apart when rotating quickly.
There are more than one set with such characteristics. While first four are from 20th century, I've included them anyway, since they are well-known and include characteristics you are interested in.
Let's begin with 8860 - Car Chassis from 1980. This model has steering, 4-cylinder engine, 3 speed transmission, adjustable seats, rear suspension, ...
According to LEGO, this type of connection is illegal, since the pin is stressed when connected to an anti-stud and eventually deforms.
People's MOCs do not follow same policy as TLG does. So you may encounter illegal connections from time to time. Pins are also cheap and usually owned in high numbers, so nobody's really bothered if one gets deformed.
The answer is studs. Note that there are more pieces with the same ability.
Orientation of the bushing does matter when you run a rotating axle through a technic plate. Have the round side of the bushing pointing towards the studs. Otherwise the axle might lock up.
Here's an example from set 852 where this technique is used to attach the helicopter's ...
If you're interested in comparing motors regarding to torque and what they can deliver, I would recommend reading Philo's excellent motor comparison page which has a lot of detailed information, very much useful for tinkerers.
Of course not all of these motors are readily available nowadays and depending on your project some may be less suitable; but there'...
You might want to look at Flex System tubing. It comes in a variety of lengths (including 6L and 7L) and doesn't have a stopper.
For what its worth, this is the technique that Jamie Berard used to create the downspout on the apartment in the Pet Shop:
The sellers on bricklink/brickowl doesn't have ways to get elements before they become generally available.
As 42099 is brand new, pieces that are (currently) unique to that set probably hasn't made it to those sites yet. Have some patience, they will likely be there shortly.
Those sites rely on users submitting inventories so until somebody submits one, ...
While you could indeed manage the project with a tool like GitHub (using the Issues feature), you might be better off initially managing the tasks through a tool like Trello which allows you to create tasks and move them through various status (i.e. Planned, In Progress, Review, Complete) in a fairly simple, intuitive user interface.
An issue with managing ...
I would suggest looking at a speed build of this model and comparing the placement of pieces with that of your own.
So, let's try...this guy's video => The Austrian Lego Fan seems to have banged out a step by step build of this model, which shows a many angles of the area you're have issues with.
To get those butt-dragging results, you may have got your ...
There is an alternative app called BrickController 2. It is available for both Android as well as iOS. This application is actively developed and its maintainer can be reached on Eurobricks forums. You can also report and discuss any issues there.
The application is universal compared with solution offered by LEGO since one device allows you to control ...
Everything's going according to plan. Check out Youtuber Sariel's review on your set HERE.
At about 26mins in, he addresses your concern. He notes the looseness of the feet when fully deployed, and says there are 4 pads stored in a compartment over the front axle. Just build on.
You may want to try Hose, Rigid 3mm D. 6L / 4.8cm or 7-stud long
Hose, Rigid 3mm D. 7L / 5.6cm
Rigid hoses are the same diameter as bars you've mentioned. However they are hollow. But they are hard so they stay where they should when attached to clips.
You can also look at other lengths available on Bricklink.
The motor you have linked is indeed quite old and as far as I know, not compatible with anything newer. Seeing that it works with simple DC current, it wouldn't be hard to construct a converter cable, but it is still some work (especially reducing the voltage from 9V to the 4.5V required by this motor).
The next generation (9V system: large motor, ...
I'll address some points from Zhaph - Ben Duguid's answer:
While you could indeed manage the project with a tool like GitHub (using the Issues feature), you might be better off initially managing the tasks through a tool like Trello which allows you to create tasks and move them through various status (i.e. Planned, In Progress, Review, Complete) in a ...
The EV3 expansion set 45560 comes to mind: https://education.lego.com/en-us/products/lego-mindstorms-education-ev3-expansion-set-by-lego-education/45560
Although intended as a extension to the educational EV3 set, it's mainly technic elements.
Okay, it seems I indeed made a mistake during building, which I solved afterwards:
When assembling the rear mudguard, I noticed that the rear wheel had quite a bit more variability in its sideways adjustment and was quite a bit off center, specifically too far to the left. This caused the chain belt to either run slightly skewed or have friction on some ...
That might be a bit too obvious a solution so maybe you have already considered that and discarded it for whatever reason. But if you have enough clips (or can increase the number of clips easily), you might not have to connect the 3L and 4L bars explicitly rather than just clipping them in next to each other in their own clips and living with the fact that ...
Rebrickable has an option to compare set's main models and some of the B-models as well. However there is no inventory for second model for 8285 set available on Rebrickable. The best I could find is a LDraw file available on Eurobricks.
I've imported this file as a custom list on Rebrickable that could be used to compare with sets and MOCs. Imported file ...
Parts are compatible, and the underlying system hasn't change, but Technic has transitioned away from using traditional studs, so you may find it a bit clunky to integrate older components.
The biggest difference for motors is electrical compatibility, as noted in another answer. Both the wire connectors and voltages used have changed a few times over the ...
There was a Technic sub-theme called Universal that was available mostly in the 1980's. The sets did come with instructions to build as many as 4 different models, but each model rarely used all the parts. The models were more of a demonstration of how to use the parts in interesting ways.
You can browse the sets in the Technic Universal theme here:
In general, the best strategy would be to look up instructions for a set in which the piece is used.
Also a good strategy: ask here ;)
For the specific parts you mentioned, this picture might be helpful:
The 6641 element switches a driving ring in three positions, either engaging the left clutch gear (18946), the right clutch gear or neutral position in ...