Thinking Small for 2012
I am investigating very intently the world of very small CNC machining. I am looking at small items such as mold machining for model parts and jewelry sized items using very small milling bits and high speed spindles. Actually I should call it CAD/CAM/CNC. It is far more than running the CNC mill.
I also looked at micro machining but that is a very high tech world that is still outside the needs and abilities (and machinery) of the personal machinist. It is truly amazing what can be done in the very tiny micro machining. I am not going there.
What I can do using my Taig CNC Micro Mill and a +10,000 rpm spindle is overwhelming. My recent Christmas ornament project is what has driven me into this investigation. The fantastic finish in wax that I was able to obtain actually surprised me. The Taig is a truly capable machine in this precise machining task.
I have now found web information of other, higher speed spindles added to the basic XYZ Taig movement. The Taig non-linear bearings and ways actually are up to the task for precision machining. I have many hundreds of hours of operation on my machine and it is still holding the performance line.
For now I consider myself “good” as far as machinery needs. I also have the appropriate software for CAD/CAM. That may change but not for quite some time. I will be adding a forth axis very soon, but other than that, I am comfortable.
I have the HB2 for larger projects and I will use the Taig for my miniature machining. I hesitate to use the word “micro-machining” but I am thinking it within my own definition.
I will also continue in my mold making and casting of components. I will definitely… Continue reading
G-Wiz(ard) Wax
There is no wax material guide in the tool but there is two kinds of plastic listed, both hard and soft. At first I thought soft would be good but as I thought about how wax actually mills, it acts like a hard plastic with the type of chips it makes. Soft plastics kind of gum up and take special consideration in my limited experience with them.
So I picked the hard plastic and started plugging in the numbers for the Taig mill and the cutting tools I am using. I used a 1/8 ball mill for roughing and a 1/16 ball mill for finish.
I was pleased to see there would be no problem running the rough at full speed (for me that’s 50 IPM) at 20% step. I am sure it could go faster. The spindle RPM on the Taig was 10,600. BTW it will run all day at that speed.
The chips were wonderful and very clean. I use a continuous air blast to keep the chips clear and the tool and wax cool.
My next goal was to get an excellent finish with as little bench work as possible. The GWizard figured out a 0.002” step over which is about 3.2% and a 20 IPM feed again at 10,600 RPM. It took me (the machine) two hours to run the finish pass in the picture.
With the air blast I never saw the chips in the finish pass. Just a very clean smooth area growing slowly as it worked 90 degrees to the roughing pass. I had left 0.020” for the… Continue reading
Milling Wax Adventure
The year is running out fast. I will soon have to say good-bye to 2011. This is the year (last Saturday actually) that I became 65 years old. Time enough for pondering that event, now to keep moving. Ha!
I did some machining of wax on the Taig CNC mill Saturday. I love machining wax (the hard blue kind). The wax is not good for creating real finished useful items but it makes excellent models for making molds and doing casting.
I spent the morning doing the design work in VECTRIC Aspire software. I was creating a Christmas ornament as a negative. I learned how to mirror and reverse the lettering and other “thinking inside out” processes in 3D design.
The afternoon was spent machining the design into the wax, using the Taig CNC mill. That was an adventure.
I haven’t run that machine for some time. The milling started out OK, but I got a couple of stalls and lost steps in the Z axis. The mill has never done that before so it was a surprise. I wasn’t pushing rapid travel or cutting speeds that hard either. Lifting the spindle and motor is fairly hard work.
The rapids are only set at 65 IPM and I was running about a third of that. So I ran through the software set-up and MACH3 warned me I was pushing the limit on pulses for the pulse generation frequency for which I had MACH 3 set. The Taig has twenty TPI screws so it takes a lot of very short pulses with 1/8th stepping (32,000 per inch) to get any speed from the drives.
That’s 32,000 per inch so at 60 IPM travel (keeping the math simple) that’s 1 inch per second requiring 32,000 Hz (32 kHz)… Continue reading
Looking Ahead 2012
I offer a little machine shop rambling today. It’s getting close to the end of another year so I have been taking stock of what I have accomplished this year and what I need to be thinking about for the next year.
One big item is my operation of the “The Hobbyist Machine Store” website store. I already have written that I dropped one of the “me too” product lines. The store is too small to be a good income producing venture. I would have to say it financially compares to being slightly better than leaving my money investment in a low producing CD or savings account. However, the investment of time is nowhere near justified by that financial return. It certainly does not produce what I term a living income.
I began the THMS business because I wanted to establish a reputation for the store and myself. The next big driver for starting this small business was and still is my access to the mini-mill and lathe steel replacement gears. That product will definitely continue for the foreseeable future as long as the supply is available.
Future products will be single source or self manufactured. I will move away from only hobbyist machine tools. I am working on some saleable product ideas I can personally produce with small machine tools. I.E, products manufactured within a small machine shop. The store will be the outlet for those products rather than offering the machine tools themselves.
One consideration rejected was to bring back the model locomotive wheels I produced by CNC machining. Unfortunately rejected because it is an extremely narrow market niche. I have decided I am not going to invest effort (mass produce) extremely specialized, speculative products. I made the wheels for myself so it was not… Continue reading
GWizard – First Looks
A visitor to this blog named Bob Warfield left a comment about a post he made in his blog HERE. Bob is also the creator or progenitor of machine shop “Speeds and Feeds” software called GWizard. It probably isn’t fair to call it just a Feeds & Speeds as it does so much more.
Bob told me he was known for The CNC Cookbook Blog as well as anything. So naturally I had to dive in and take a look. Sure enough there was Bob standing there grinning and holding plate with pumpkin pie. You’ll probably have to scroll way down to find him now (and the pie). This CNC Cookbook is a great place to read and study about the “science” of rotary machining.
I like a guy that doesn’t hide his face from his peers and customers.
I perused carefully everything I could find on that web site. Where was this when I needed it!? Of course always the skeptic, I had to figure out what was the “deal” going on here. The biggest question for any CNC machinist (well at least for me) is how hard can I push feeds and speeds and what are the reasons. It would seem obvious that this sort of program would have been offered long ago. But… it is a very complex subject. Tool manufactures are of course going to shade any such tool program toward their own products.
Bob admits it could be done with a spread sheet and in fact that is how he started. When I first started CNC machining I eventually found the safe speeds for the kind of work I usually do, but it had taken a lot of effort. I could have built a spread sheet myself but the effort would have kept… Continue reading