"One Perfect Part at a Time"


CNC 4th Axis Update

The Taig CNC mill is closer to having its 4th axis operational. All that is really needed is to get the wiring completed. The tail post is not mounted where seen in the pictures. I was making adjustments to the height. You can see it is easily adjustable.

I will bolt down the tail post once I have an application where I need to use it. I now have the shims I need so a couple of bolts in the base and I’m in business.

When I have it running I’ll post a SHORT video to prove it works, Ha!  There is nothing more boring than watching 10 to 20 seconds of a CNC axis moving around doing nothing.

Small Ideas

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… Continue reading

4th Axis on My Taig

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… Continue reading

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

I had the chance to use the GWizard tool this weekend. I have been working on a wax mold project and thought it would be a great opportunity to optimize my speeds for milling 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

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