----- Original Message ----- From: "tony moss" <[EMAIL PROTECTED]> To: "Sundial Mail List" <[email protected]> Sent: Saturday, October 15, 2005 5:42 AM Subject: The kindest cut...
> Fellow Shadow Watchers, > The following may not be new or of interest to long time SML members but there are always new recruits who may find it useful. > > This is not always a quick process and my gnomon took about 30 minutes but only because I had specified a smooth finish requiring a slow 'travel'. The profile for a 'Rotary' gearwheel sundial plate 48" diameter and 10mm thick in stainless steel took five costly hours. As a design tip for anyone using WJC for the first time I would advise against any sharp 90° internal corners. These should always have a small radius of about 3mm. For some reason when the jet turns through 90° it cuts an unwanted notch in such corners. It also pays to indicate which side of the line you wish to cut when a combination of outer profile and inner piercings are involved. Guess how I learned that the hard way!! > Hi Tony: Here is a tip for subsequent Water Jet jobs, when cutting sharp angles, continue the cut past the corner, cut back at a 45 deg angle, position the cutter for the next cut in the angle, and continue on. Imagine the number 4, with the material being cut, in the lower right quadrant of the crossing. The two 'pointy' ends of the 4, (top and left) get the notch, not the work. Most modern CAM systems have a mode to do this for you if the corners have enough angle. If you can live with tiny radii at the corners this will work too. Truly amazing machines, they are also used to cut everyting from ice cream to plutonium! Dave G. http://atensundials.com -
