Featherweight Schnauzer Part 18

Quite a lot of time has past since the last update about the status of my featherweight combat robot Schnauzer but finally there is some progress to report. Building a combat robot one can clearly observe Pareto's Law in action. Parato's Law simply states, that 80 % of the result can be achieved with 20 % of the effort. However, the flip side of this rule implies that finalising a project (doing the last 20 % of the work) will consume 80 % of the effort. And with a combat robot, you do want to go for the 100 % solution because everything else might leave you with a pile of rubbish in the arena. That being said I'd like to switch to the main purpose of this post which is to describe the latest updates on Schnauzer.

In the new version of Schnauzer only its rear wheels are directly powered by electric motors. The front wheels are powered by toothed belt which transmits the power from the rear wheels via an cogged-belt pulley(s) and tooth belt to the front wheels. This can clearly be seen in the next picture which displays the drivetrain of the left side of the robot.


In the picture above the considerate reader might have observed some shiny things at 1/3 and 2/3 of the lower tooth belt. Those are DIY deflection sheaves built from ball bearings. Their purpose is to lift the tooth belt up and over an angle bracket which is connecting the base plate with the hardox (side and front) armour.


Unfortunately the purchased tooth belt was a bit too long and therefore is not sitting tense enough on the two cogged-belt pulleys. Loss of traction in the heat of combat might be result. In order to circumvent this the design of a tooth belt tightener was necessary. The tightener was designed utilzing Autodesk Fusion 360 which is a very powerful tool and also has a startup license 🙂 Here is the finished design:


Upon completion of the design process I called up my reliable supporter of 3D prints and sent the design files to him. On the next picture you can see the printed belt tightener (well the part that is printable at least).


The next step was to insert the belt guide (which will later on press against the tooth belt) which consists of two ball bearings plus three washers. The tooth belt tightener is supposed to be mounted on the top plate of the robot facing downwards. When the top plate is closed and firmly connected with the rest of the robot the belt tightener should press against the tooth belt and  eliminate any belt play.


Next up: Integration with Schnauzer and finalizing the top plate (need holes for screws, removable link, ...).

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