JET JOBS
See also
Rapid Prototyping
(Demo jobs, Jet compressor with housing and rotor sharing the same profile. Turbine wheel milled from 316 stainless. All three jobs done with Compucutter. I do not pretend that these "real" components but offer them as an idea of what can be done.)
Having read K. Shreckling's book or borrowed a rotor from a friend, you have some thoughts on how to improve your version of the gas turbine engine. You might start with the power stage. This can be modelled as; YOUR NUMBER of uniform section blades, of YOUR SHAPE set at YOUR ANGLE OF PITCH. You mark out at say 5 times scale the section of the blade on 1mm alum sheet. This is cut out with tin snips and smoothed with emery. A mounting hole is drilled centrally and the template fixed to the mounting post on the digitising beam at the appropriate pitch angle. The stylus moves around the profile of your blade on a programmable size scanning grid taking co ordinate measurements and logging these to your data file. The digitising beam described is fitted with standard
"Compunut" zero backlash nuts, but the software will allow for backlash if you have any. Your file is saved and the digitising repeated for different pitch angles as necessary.
(Digistising beam)
(Digitising tablets are also a good medium for data entry)
A thermo plastic hub blank is mounted on the Compucutter fixture, the cutter is set to the blade "tail" datum, and the blading program is run. You are prompted for depth per pass, and number of passes around the profile. The cutter then climb mills the blade profile, and "beeps" at the completion of the blade. The hub is angularly incremented to the next blade position and the process repeated until the hub is complete.
Because nimonic blanks are relatively expensive it is worth producing cheap prototypes until the blade shape looks promising, then mount the nimonic blank on the fixture and repeat at the appropriate cutting speed/feed with ample suds as previously. It is worth considering the cheaper stainless 316 as a short duration test running blade material.
(Comucutter milling plastic blank. Shows profile sheet ally used with digitising beam)
When used to produce the multi rotor/stator blading pairs in axial flow compressors, plus centrifugal compressor rotors, as well as the power stages, Compucut can allow the enthusiastic, knowledgeable amateur back into the race with the commercial builders for new developments in model gas turbines.
(Compucutter boring the internal profile of the compressor housing (to suit wheel below))
(Compucutter turning 2D profile of compressor wheel)
(Compucutter following compressor wheel profile with slitting saw)
(Compucutter boring the internal curve of a pulse jet)
(Coumpucutter screwcutting thread of pulsejet)
(Rotor milled from Inconel, compressor housing,, compressor wheel, and pulse jet nose venturi in ally)
