Time to make a model

[artdutra04]

Originally Posted by lemiant

Hi Everyone,

Here is a question for teams that fully CAD out their robot before building it: How many hours does the model take (it would be helpful to include the number of people and distribution of hours)? Can this time be decreased with more CADers?

Thanks for your time,

- Lemiant

If you know your CAD software really well and already have a design with zero issues memorized, you can probably model it in a day or two. However this is rarely the case in reality, as the reason to use CAD is to find problems and fix them before spending money making physical prototypes. So the time it takes to model the robot is proportional to exactly how much you design everything ahead of time and fix problems.

On 228, we only model what we need to build the robot, which is primarily everything mechanical (and large control system components for mounting locations and weight/volume considerations). Adding screws, wiring, pneumatics tubing, etc. doesn't necessarily help us, is very time consuming, and in an assembly already with several hundred parts, adding these really start to bog down your computer.

Instead, what we do is assign a part number (such as 11-DRV-012) to every custom or modified part on our robot, draw up a 2D machine drawing for said part, and either send that (along with the CAD model) to our machine shop sponsors or print it out tobe machined on the manual mill or lathe in our shop. We then put all of these part drawings into a binder, which theoretically could be used to build an exact clone of our robot.

Here's the CAD model of our 2011 robot. This was probably about 80-120 man-hours of work, with the average probably around 4-6 man-hours of work a day for the first three or four weeks.

Adding more people can help or can hinder (it all depends on communication and organization); you will need a robust revision control scheme to keep all changes to the CAD models updated and propagated to other group members. Things being designed in parallel also need careful attention paid to interfaces between the subsystems, and making sure they do not try to occupy the same space, and that the still work as a system.