cad/cam/cnc: competing in skillsUSA

masen, 25 March 2012

As a sophomore in high school, I unwittingly took Stuart Smith's CAM class and learned some CAD, CAM, and CNC milling on ProLight and Haas Mills. In fact, I came to learn that my high school just happened to have one of the best CNC labs in the entire country. I went on to take 2nd Place in the Washington state Automated Manufacturing contest in 2007, 1st Place in 2008 and 2009. And 3rd place in the entire Nation in 2008! Who knew? My specialty on the three person Automated Manufacturing team was the CAD designer. The contest is designed to simulate a job process in industry. Each team is given a set of incomplete and possibly inaccurate "engineering" drawings and required to make an industry standard set of dimensioned CAD prints, as well as rapidly prototype the part using a CNC mill. Below you will find some of the drawings that we've had to make over the years at various contests and some files that seem for some reason to be very hard to track down.

Intelitek ProLight post for MastercamX2

Intelitek ProLight post for MastercamX

Alternate links: [x2-alt] [x-alt]

These posts are basically required to use MasterCam at the national competition. They allow posting clean code to the provided machines. Just a word of caution though, when you load up programs posted by these definitions in CNCBase the new CNC control software, you MUST put a percent-sign (%) as the first line of the program to make the arcs work correctly (CTRL+L to unlock the code). Other than that you're golden.

Most of these files require Rhinoceros 4.0 to open, some are in IGS format.

Nationals 2009:

TDN: (local copy)

Nationals 2008:

The goal of this project (and trust me, I wish I had the original documentation too) was to create a mold that could be utilized to create the part that they gave us a drawing of. In this case it was a mold that could create 4 small motor housings. We created a three piece mold which accomplished this goal. The assembly drawing shows what it would look like all put together

TDN: (local copy)

Tips for Competing at the National Level:

  1. READ READ READ all of the provided material. While you are doing this, take a pen or pencil and underline all important details including the company they say you work for, your customer, any missing dimensions from the drawing, what to turn in, etc. They will use this documentation to try and throw you for a loop, so pay attention, it is purposely tricky, but at the same time very straight forward
  2. Time counts, but so does accuracy. According to a Judge I talked to at the 2009 contest, the first person to turn in a part gets 100 extra points, then each person after that will receive about four less points. For example, 2nd turn in gets ~96, 3rd turn in gets ~92, etc. So don't race to get first, because surface finish and accuracy are worth 150 themselves I believe.
  3. Don't run the machine slow. 50"/min is a pretty good bet. My first year at nationals, we wanted a clean finish and were over confident so we ran at 20ipm the entire time and didn't get done, don't let this happen to you
  4. The contest isn't all about the parts. The first part is worth about 1/3 of the total, the CAD drawings are worth about 1/3, and the Change Order/Revision is worth about 1/3 itself. So my advice here is get to the change order. If your parts aren't perfect, you may be able to make up for it by simply turning them in and getting the change order and allowing yourself enough time to get it done. 
  5. Don't forget you can get extra stock. If you mess up real bad, don't be shy, run up to the judges table and get another piece of stock and start over. One team in 2008 did this probably six times if I recall correctly. Now, they didn't win, but at least they weren't totally SOL.
  6. Don't believe everything you hear. Not all of the "officials" know every contest regulation. If someone answers a question for you and you're still not sure, ask the main guy, or resort to reading the book. I've heard of a team losing a medal due to misinformation provided by a judge, and there's not much you can do about it after all is said and done.
  7. If you've never used a real ProLight mill before, you're at a severe disadvantage. They zero parts completely different than a Haas or Fanuc style mill and they are just a tad quirky. Your best bet is to find someone with one in a shop near by and ask if you can use it. You definitely want some hands on experience before the practice day or you'll be struggling.
  8. Manual Facing vs. Machine facing. It's your choice, but doing it manually is easier
  9. Wear the right stuff. This has happened to me two years in a row now. Wear work boots and the designated contest attire (more information can be found at the SkillsUSA website). On that note, remember to always wear your safety glasses when machines are running as any deemed "safety violation" costs you 50 points
  10. Come prepared with your title block already mostly done and your dimensioning properties and scale already set up in a template. This will save you valuable time during the contest and as far as I know isn't against the rules. Keep in mind the CAD drawings are to be industry standard for technical drawings. You may have to look up what that means if you are unsure. At the debrief in 2009 they mentioned specifically that some default settings in CAD packages produced dimensions that were NOT in the correct style, so check these.
  11. Your pieces will fit together. If they are not dimensioned in the engineering drawings remember, offsetting the line for your holes that fit together .005" is a very good idea. It's not much, in fact, barely even noticeable, but it has cost my school's team the gold medal in 2006.
  12. Prepare your resumes in advance. You will turn in a resume. In 2009 Skills was trying to switch over to an all digital resume collection system which I guess failed. Unfortunately, we didn't bring paper copies like they advised and were forced to print them on the plotter on 11"x17" paper, and they didn't look good. (Printing at the hotel was about $10 0.o)