The Sherline Miniature Machinist's Newsletter

Number 22, October 19, 2009

Sherline Workshop Project of the Month

Miniature CO₂ Race Cars/Scotty Hewitt

Scotty Hewitt built these tiny CO₂ powered race cars from aluminum and carved the bodies from balsa wood. A jaunty driver sets a playful mood sitting in the cockpit of each.

Scotty Hewitt was Sherline company owner Joe Martin’s race car instructor when he got his SCCA racing license to race vintage sports cars and Formula Fords. Scotty wanted to learn how to do miniature machining, and Joe wanted more instruction, so they worked a trade. Joe traded a Sherline lathe for extra driving instruction. It turned out to be a good deal for both. Scotty went on to win several Sherline Machinist’s Challenge contests with his steam engines and race cars, and Joe went on to win a Formula Ford championship in the mid-1990’s in the San Diego Region of the SCCA. Scotty has also built a number of extremely tiny steam engines which are now on display along with the red racer shown above at the Joe Martin Foundation’s Craftsmanship Museum in Vista, CA. The previous link takes you right to Scotty’s page.

These racers use a small CO₂ bottle like the ones used to power paintball guns to charge an even smaller cylinder with the car’s frame. This supplies power to the piston engine that drives the rear wheels. CO₂ engines were once used in small flying model airplanes before reliable light weight gas engines and, more recently, electric powerplants were available.

The detailed “engine” in front is just for looks. The real engine is hidden underneath.

Shop Tip of the month

A Simple Adjustable Depth Rod/John D. Cannon

A depth stop allows a part to be inserted through the chuck only to a certain depth inside the spindle so that each successive part is held at the same point. The depth is easily adjusted by moving the rod. In the photo above (left) you can just see then end of the brass rod inside the chuck. The right-hand photo shows how the depth rod is attached to the lathe spindle. Loosening the outer set screw allows you to adjust the rod for depth.

John Cannon of Alexandria, VA sent in a nicely finished brass sample of this project. It mounts on the outside of the spindle shaft and the depth rod goes through the spindle. It is adjusted for length using set screws and acts as a "stop" for parts held in a chuck. This way a number of pieces can be placed in the chuck at exactly the same depth should your setup require it. John has turned down the final 3/4" of the end of the stop rod on the sample to a smaller diameter to fit through the chuck to hold a piece smaller than the 1/4" rod diameter. Mr. Cannon uses brass because he likes the way it looks and works, but you could also use aluminum or steel. Basic dimensions are shown in the drawing below. The bottom of the longer set screw that tightens against the brass rod should be ground flat to keep from leaving deep marks in the brass. You should also file a slight flat on the end of the lathe spindle to provide a seat for the shorter set screw. A regular cup-point set screw will leave a mark on the spindle and can distort the surface, making the stop body hard to remove. Filing a flat on the spindle will make the body easy to remove and also allow it to be attached in the same place each time.

This and more than 50 other helpful tips for Sherline machinists can be found at www.sherline.com/tips.htm.

Product Spotlight

P/N 8760 4-axis CNC Driver box, $600.00

The 8760 CNC 4-axis driver box comes with cables, power supply and new Ubuntu Linux/EMC2 software. A driver box provides the signals and power to turn G-code instructions into stepper motor rotation on your CNC lathe or mill.

Driver Box—The Sherline 8760 driver box is a stand-alone version of the unit that comes inside the Sherline CNC computer. Purchasing the box separately allows you to use your own computer to control your Sherline CNC lathe or mill and thus save a little money. The only requirements are a computer that has at least an 800 MHz clock speed (Pentium III or higher), a 25-pin parallel (printer) port and a DVD drive. The power supply works with any worldwide voltage, and the Ubuntu Linux/EMC2 operating system and G-code control software is included in the package. If you choose prefer to use a Windows® based control program, Mach3 can be purchased elsewhere and works fine with the driver box. The 4-axis box will plug into Sherline stepper motor cables to run the X, Y, and Z axes plus the A-axis for a rotary table. The Linux OS and EMC2 G-code control software is included on a DVD. A second CD includes instructions and a folder of useful utilities to turn CAD drawings and fonts into G-code.

Optional driver box and motor packages— The driver box can be purchased with the number of stepper motors needed for your application, thereby saving you some money. The combinations are as follows:

• P/N 8765—Driver box and 2 stepper motors for CNC lathe ($730.00)

• P/N 8770—Driver box and 3 stepper motors for CNC mill ($805.00)

• P/N 8775—Driver box and 5 stepper motors for CNC mill/lathe shop package ($935.00)

Did you know?

• DC MOTOR RECALL NOTICE—Some Hill House DC motors sold prior to July 24, 2009 may have a defect that could cause a short. CLICK HERE for details. This does NOT apply to Lesson or Protech DC motors, only those clearly marked Hill House on the label and purchased in the first half of 2009.

• An announcement has been made that after 18 years of hosting the Sherline Machinist’s Challenge contest at the NAMES show that the contest will not be held in 2010. This will provide Sherline representatives at the show more time to answer questions about the tool line and accessories. Sherline will allow projects built on Sherline machine tools to be exhibited at Sherline’s booth should anyone wish to do so.

Upcoming Shows

• The Cabin Fever Expo in York PA each January is the largest show on the east coast. See www.cabinfeverexpo.com for information. This is its 14^th year and the show will be held January 16-17, 2010.

• The North American Model Engineering Society (NAMES) will host its next major exposition in Southgate, MI the weekend of April 24,25, 2010. This is the 21^st annual presentation of this prestigious show. See www.modelengineeringsoc.com for details. Sherline will be a vendor at this show.

Joe Martin Craftsmanship Foundation News

• The newest addition to the on-line Craftsmanship Museum is gunsmith and engraver Damien Connolly from Australia. Damien’s talents span many disciplines including gun and knife making and engraving. Details of how a delicate brass script is inlaid into a display box are included. Also, many photos of his newly completed 5-year project to built a tiny 1/5 scale replica of a Kentucky long rifle are shown.

• The donation of a highly detailed brass Bucyrus-Erie Shovel by Les Cade highlights some new additions to the Vista museum displays. See a new page that details what is on display when you visit the museum.

• The museum in Vista, CA is open daily from 9 AM until 4 PM and the first non-holiday Saturday of each month. Admission is free.

• The Joe Martin Foundation is a 501(c)(3) organization and can offer a tax deduction for the full value of high quality miniature metalworking projects, tools or books donated for display. Contact Director Craig Libuse for details at (760) 727-9492 or craig@craftsmanshipmuseu.com. Don’t let your fine work end up in a swap meet or on eBay if something should happen to you. Make plans for peace of mind.