Heli Rotorhead is a professional CNC machine programmer, maintainer, and parts loader who has been passionate about airplanes and engine motors since he was young. As a CNC machine programmer, Steven is the ideal person to tell us where some beginners make mistakes.Below is his interview. let's start.
1. can you tell us about how you became a model engineer?
Officially I’m not an engineer but I clearly have an engineering brain. I seem to have an affinity for analyzing devices and then understand the what-why-how of what I study. Small details of operation and construction reveal themselves to me with relative ease.
2. Last time you told me that your engine collection is probably exceeding 1000 units and has designs of all types. It seems that you've collected all the different engines of the maket. Which one is your favorite one? Have you ever machined any engines yourself?
No official count has been made. I did attempt to generate a computer database of all my engines but wasn’t disciplined enough to follow through with the listings. My last tagged engine was number 47 I think. Have gone WAY passed that now! Favorite engine? Hmm… That’s a difficult answer. You aren’t going to believe it considering how‘mundane’ this model engine sounds but it’s the early 1970’s Micromeccanica Super Tigre G60 ‘Bluehead’ R/C nitro. I’d consider that my favorite flying engine. A favorite display (model) engine would have to be my UMS (Evolution) nine cylinder, 99cc radial. I’ve yet to make from raw materials an internal combustion engine but at 16 years old I built two air/steam engines out of telescoping brass tubing, cut using a motorized hand grinder and then soldered together. One is a single cylinder with a square cylinder and piston (yes, square!) and the other is a flat-four cylinder also soldered together. The flat-four is an original design and no precision machine tools were used in its construction.
(SuperTigre G60 Bluehead)
(UMS 99cc 9 cylinder radial)
3. I find you have owned your own machine shop. Could you share how build your workshop?
I guess you could call it a “machine shop” but it’s nothing more than some nice tools squashed into a small furnace room in my basement. My current operable tools are: Late 1950’s Craftsman/Atlas 6X18” metal lathe, bench top drill press, 20-ton hydraulic press, homemade toolpost grinder for the lathe that doubles as a milling and drilling attachment and lots of cutting tools/attachments. There’s a metal-cutting bandsaw in an adjoining room that receives quite a workout. Soon to be added to the working tools (but not in the basement) will be a mill-drill with CNC conversion and a 12” Atlas screw-cutting lathe. Those two will live in the outdoor shop building along with the 5HP air compressor, media blast cabinet, belt sander, 8” wheel grinder, standup buffer and powder coating tools. Building a shop is a constantly evolving environment.
The 6” Atlas metal lathe
4. You have been a professional CNC machine programmer, maintainer, and parts loader. Which one is your favorite job? What is your favorite part of working as a CNC machine programmer?
I’ll give programming the big thumbs up from that list. The ability to create precise, highly complex shapes and parts with relative ease is so satisfying. Just loading parts can put me to sleep, but someone’s got to do it…
5. What is your favorite creation from your time in your machine shop?
That’s an easy question. I had an idea for a custom helicopter rotorhead to fit one of a number of large RC helicopters I owned. There were some parts to this head that could have been made easily if I had access to a working milling machine. There is a milling attachment for my 6in lathe but what can be done with it is extremely limited. Some engineering creativity was required to figure out a design that satisfied my needs and could be manufactured on my existing tools. I did start out basing the rotorhead design on a large pair of purchased blade grips that I won off of eBay and all other components that matched the grips were ones I made. The outcome was exactly what I needed and had excellent flying qualities when paired with a flybarless stabilization system. But the first test flights were without any flight stabilizers and was very easy to handle as long as there was minimum wind. The helicopter seen on my Facebook “About Me” page is flying with that rotorhead and I took the photo while doing the flying. One (left) hand on the camera, one (right) hand on the cyclic controls. Was so easy to fly.
And as a helicopter hobyyist, I had an idea for a custom helicopter rotorhead to fit one of a number of large RC helicopters I owned too. There were some parts to this head that could have been made easily if I had access to a working milling machine. There is a milling attachment for my 6in lathe but what can be done with it is extremely limited. Some engineering creativity was required to figure out a design that satisfied my needs and could be manufactured on my existing tools. I did start out basing the rotorhead design on a large pair of purchased blade grips that I won off of eBay and all other components that matched the grips were ones I made. The outcome was exactly what I needed and had excellent flying qualities when paired with a flybarless stabilization system. But the first test flights were without any flight stabilizers and was very easy to handle as long as there was minimum wind.
Large RC helicopter rotor head
6. What is your favorite part of working as a CNC machine programmer?
I think I already gave an appropriate answer to this question in question #4. No need to repeat the reply.
7. In your experience, what is the hardest part of learning to CNC machining?
If I didn’t already have a little basic machining background I would have not been able to learn the CNC part well at all. At the time (1984) the code our shop wrote was by hand with no CAD-CAM assist. This meant the person writing the code had to know the characteristics of the materials being cut and how to efficiently and safely cut them. The difference between cutting Teflon and cutting 17-4ph stainless steel is enormous, for example. The machines were dumb in that regard and couldn’t help you. You had to have some feel for how fast the cutting tool can spin without melting, how fast the tool can advance through the chosen material and what is needed to get a consistent surface finish and consistent or accurate dimensions. So understanding how to‘talk’ to the materials is without a doubt the hardest. Today the CAM (Computer Aided Manufacturing) portion of the system can suggest the type of cutting tool considered best for the type of work as well as the feedrate and speed (RPM) of the tool. It’s usually a safe but not optimized set of parameters that will allow parts to be cut. The machine operator then has the option to override the suggested feeds and speeds to get the parts made faster, as long as the tool’s abilities aren’t exceeded.
8. what advice would you have for beginners looking to improve their CNC machine skills?
If it was still the old days before the sophisticated CAD programs commonly used today, I’d suggest finding the time to get access to a machining center that’s between jobs and let the shop forman or manager show the person some good techniques and good habits that will improve productivity. Today the CAD programs will spit out code that will get the machine 85% there. The programmer, if motivated to make minor changes to speed up production or improve part quality/appearance, will have to carefully edit the existing code and remove wasted tool motion or speed up feedrates or slightly modify a tool path if there’s a need to optimize the way the part is being made. This is a leaned skill that takes time to develop and build confidence.
9. Which one is your favorite scale engine?
Of the engines I currently own it’s a tie between that 99cc, nine cylinder Evolution radial and the CISON V2 twin cylinder Pan-Head engine. Both are very impressive and ‘realistic’-sounding. The Pan-Head is particularly liked for its realistic look and impossible-to-miss exhaust sound. What’s there not to love?