Small Ideas
January 5, 2012 | Author Dan'l
I see I keep writing about one topic over and over again in my forums and blogs. It has to do with the size of the machines I enjoy using in my hobby. I keep repeating myself because it just feels so good to me in the choices I have made. Of course I am pushing my personal preference and that certainly doesn’t mean nor do I intend it to mean that my personal preferences are anything but personal.
If the reader doesn’t like my preference, I am not here to make a convert to my way of thinking. I assume the only reason you are reading this is you have a similar interest in machining or you are trying to decide just where your interest (in machining) lies. I too always dig into the unfamiliar when I have the chance.
I have always enjoyed model making. That means making small things that resemble or are realistic versions of larger things. But that doesn’t mean I only build models. That preference has also spread to building full size items that are also small.
For instance, my latest interest is in the kind of CNC machining that is done in jewelry making. It is very small and very detailed and can be held in the palm of one hand. I am not going to buy gold and diamonds and make “bling” jewelry, but I would like to make parts with that kind of detail. A study of jewelry making can go a long way in learning how to do detail machining.
The small CNC milling machines that can do this are not the cheap ones. High precision is absolutely necessary when working in the realm of the very small. I believe my Taig mill can take me onto the edge of the playground at the lowest cost, but with everything required including software, it is at the $5000 range of investment minimum and can get well into the tens and twenty’s of thousands.
This is one place where machine run out measured in tenths (>0.0001) and poor tolerance machines do not make the cut. It’s a whole ‘nother world of machining. I plan to creep up on it and see how far (small) I can go.
If I have the “knack”, the patience and the skills, and can make things I can sell; then I may go farther. That is not my goal at the moment. I would like to test my limits of course, but what I want to do is make the best use of what I have.
Today I would like to make the molds and models for casting. As detailed elsewhere in this blog I have already proved to myself I can do this. I feel good about that and it is a lot of fun. I don’t need a big honking 3 phase behemoth VMC machine to play with the big boys. There are big boys in the micro machine world too. Ha!
4th Axis on My Taig
December 31, 2011 | Author Dan'l
I did a lot of research on how to implement a forth axis on my Taig CNC mill. I had some wild ideas not to be discussed here <grin> but that is the enjoyment of thinking outside the box. In this case the box is a pretty good one so I finally dropped back into the conventional world.
The screw drive of the standard rotary table has a lot of benefits in this 4th axis application. There are a few limitations in the area of backlash (controllable) and rapid speed (not really necessary.)
With small mills like the Taig and the Sherline, weight (mass) is a required parameter to consider. Most rotary tables are designed to have a lot of weight as part of their design. It adds stability for normal machining. However for miniature CNC machining, it is undesirable to abuse your drive system with a lot inertial mass to start, stop and reverse perhaps up to a hundred times a minute.
The winner in my selection is the Sherline 3700-CNC rotary table with motor mount. At $320 it is not the least expensive of my 4th axis schemes but I think it is the best in this case.
First point is the weight. At 8 pounds it is heavy enough and when you look at it, you see it carries no extra weight in a heavy case or mounting system flanges.
Second point is it is specifically designed for CNC operation internally (Sherline says in the worm housing) as well as the included #23 motor mount and coupling.
Third big point with me is the drive is 72/1 turns. Some rotary tables are 40/1 (yuk!). At 72 turns and 1/4 stepping, each step is 0.00625 degree. (Sherline uses 1/2 stepping.) A 90/1 would have been nice but I didn’t find small tables with that ratio. There probably wouldn’t be much “meat” in the gear mesh on 4” tables.
Forth point is it is a 4 inch table which fits well with the intended use in mills of the micro variety.
I intend to make my own mounting plates and accessories. Of course this adds weight as does the stepper motor. I am considering using the Taig tailstock (when needed) I as see more options using it.
Of course I will be posting everything here as my 4th axis project progresses. Right now the table and a 130 oz/in stepper motor are on order. I have the material on hand to make the base. 2012 looks like a good year!
Thinking Small for 2012
December 30, 2011 | Author Dan'l
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 be into all kinds of machining wax and aluminum. I plan on casting in pewter and also resin (plastic).
Am I psyched? Yes, and it feels good…
There will be more in 2012 in this blog on the subject.