RBMO minutes for June 12, 2010

Attendance was good, with many attendees bringing robots and projects.

Dale demonstrated the beacon finder and obstacle avoidance/beacon finder contests.

Denise brought a robot chassis made from Meccano parts. Meccano makes Erector-set-like construction kits.

An informal discussion of circuit prototyping broke out. The merits of solderless breadboards vs. soldered protoboards were discussed. Dale and Kirk discussed using wire-wrap wire in soldered prototypes to good effect. Kirk uses thru-hole protoboards from Sure Electronics.

AHRC Regular Meeting minutes June 26, 2010

The upcoming Robot Rally, to be held October 23rd, 2010, was discussed. Build your robots now.
A possible outdoor competition was discussed, perhaps for 2011, also the use of GPS in relation to it.

Show and tell:
A small RC robot spider was shown.

The latest iteration of a Lego-based line follower was demonstrated.

Mold making for brass was discussed, and examples shown. Molds for plastics were also discussed. Freeman Supply was mentioned as a good source of related materials:

Related to the main presentation, there was a demo of plastic sheet bending by heating with a bender that holds a heated nicrome wire held near the sheet at the desired bend.

Main presentation

Kirk Charles presented a hands-on demo of mechanical construction using plastics. He demonstrated cutting plastic tubing to size for making standoffs of any length. For sources of plastic tubing he mentioned the usual sources of industrial produicts, Mcmaster Carr and MSC:

He discussed different plastic types such as HIPS (High Impact Polystyrene), ABS (Acrylonitrile Butadiene Styrene), and SKP (Some Kinda Plastic). Notable tools used are dial calipers and automatic centerpunch as available from Harbor Freight, and a heat gun (as used for paint stripping), available at Home Depot and Lowe's.

Basic chassis material used is Plastruct styrene available as 7" x 12" sheets with thicknesses of 0.08" 0.06" and 0.04", and Plastruct Bondene styrene cement. Kirk used 0.08" thickness for a chassis.
While not found on Hobby Town's website, these specific products are available at Hobby Town's Duluth location:

For more advanced designs done with CAD, the design can be printed full-scale and glued to the plastic sheet with
3m Super 77 adhesive:

Kirk mentioned Tangent Tutorials as an excellent tutorial for Eagle circuit board CAD software:

Kirk began building "The Fifteen Minute Robot Chassis" about 15 minutes before the end of the meeting. It actually took about 30 minutes to design and make, still a remarkably short time. Due to Kirk going overtime, the Beacon Killer contest is delayed until next month. All are encouraged to build and bring their beacon killer robots to the next regular meeting. Rules for the Beacon Killer contest are under the Polyathlon rules here:

As the demo was winding down dangerous substances were discussed, including DHMO (dihydrogen monoxide). This website has a large amount of pertinent info on this widely used chemical, including an MSDS (Material Safety Data Sheet):

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