The Hobbyist's Machine Shop – Blog

"One Perfect Part at a Time"

No Mistakes – Making My Point

I seldom, almost never make mistakes… HA! But I found one in my tool definitions for Vectric Aspire. Um… maybe I do make a few mistakes.

I use a very fine pointed, down to 0.003 tip tapered ball-end milling bits. Tapered ball-end milling bits are defined by their one side taper angle and the tip radius in the Aspire tool table. That was what got me. The tapered bits are identified by the manufacturer with total (combined) taper angle and the tip diameter.

So, what the maker defines as a 10-degree 0.005 tapered ball-mill is defined in Aspire as 5-degree taper bit with a 0.0025 tip radius.

I got the side angle correct but I was entering the full tip diameter as the radius. I realized the problem when I would define stepover as a percentage rather than specified absolute distance. The percentage calculation was showing twice the correct distance.

Therefore, Aspire was also calculating the tool path to be twice as wide as it actually was. That’s because that is what I specified.

Hmm… wonder how long I have been doing that!*

I am trying to imagine how that would affect the milling operation. Probably some dimensional errors, the program calculating the bit to be twice as wide as it actually was. With the tiny bits, there error would not be noticeable or of any importance. Pocket sidewall distance would be a couple of thou’ too small.

I think the biggest issue would be the stepover. If I wanted 20% it would be cutting… Continue reading

Swarf Blower Added to Taig HS Spindle

Wax swarf blower system

The blower that was added to the Taig spindle on the original WAX milling system has been updated to operate on the new high speed water cooled spindle. A full article with pictures can be found here: https://thehobbyistmachineshop.com/cms/projects/wax-fan-v-2-0

This is not a dimensional, How-To article. It demonstrates how 3D printing can be utilized to add accessories to the Taig mill and a high speed water cooled spindle.

More Than a CAD

CNC Milling

A CAD

S. Whiplash, Typical CAD

It’s been a while since I have run my original CNC Taig Micro-Mill. It’s the one configured for metal work and has the mist cooling installed. There is nothing operationally wrong with it as far as I know. Just haven’t had a project where I needed its services.

I have always used RhinoCAD (Rhinoceros) with RhinoCAM to generate the design and the Gcode necessary to run the mill. I am presently working with FUSION360 CAD with its built-in CAM. FUSION360 has become my go-to CAD for 3D printing because of the very good built-in STL generator. Rhino can do STL too but has some issues (for me) in producing first-time usable STL.

CAM is a whole new layer of complexity after creating the CAD drawing. Of course, the first challenge is the CAD, as what is drawn must be something that can be produced by milling. It is possible to draw parts that can never be machined.

The CAM requires the complete understanding of the milling operation and all the tools that can be deployed on the target milling machine. In the case of the Taig Micro-mill, tool size is limited to the machine’s abilities and speeds. I have no need for things like an automatic tool change. I am a hobbyist, not a manufacturing center.

CNC is certainly not “push the button and go”. The complexity is what I love about the process.

I use two different CNC controller software systems to control the movements of the milling machines. The older mill is using MACH3. The newer WAX cutting mill runs on LinuxCNC controller software. I was very pleased to see what is called a POST processor available in FUSION360 for both controller formats.

The POST processor is a function in CAM that… Continue reading

Taig 24K RPM Spindle Article Available

The full article on the Taig 24,000 RPM water cooled spindle conversion is now available on The Hobbyist Machine Shop website. Follow this URL: 

https://thehobbyistmachineshop.com/cms/projects/high-speed-spindle-for-the-taig-micro-mill

The new spindle performance exceeds all expectations. It is not a low cost option / addition to an already  adequate micro-machine tool system, but it does provide a very good way to achieve more than double the stock Taig spindle speeds.

Some applications using very small diameter tooling are performed much better when running adequate SFM and cut travel speeds. High speed spindles and especially water cooled ones like this example are a joy to use because of their extremely quite operation.

The Taig spindle is known for its quiet operation and the water cooled spindle here is in my opinion just as quite or perhaps more so, even running at full speed. Tool cutting sound is the same but the spindle motor has none of the sound of a high speed router.

Comments on ER11 Collets

ER11 Collets

ER11 Collets

The new 24K RPM spindle has an ER11 style collet holder. Attempting to measure the TIR (Total Indicated Runout) is not possible with the measuring tools available at THMS. It should be well under 0.0004 inch.

With ER collets, TIR of .0006” (.015MM) is considered Class 1, .0004” (.010MM) – Class 2, and .0002” (0.005MM) is Class AA (5 microns). Of course, the cost increases with accuracy. Class 2 and higher is my recommendation. A holder with excessive TIR negates this accuracy.

The internal surface of the holder looks well finished. I am going to depend on the fact that a spindle of this design and cost should certainly be well machined. First operational tests confirm this hypothesis.

Of most concern after assessing spindle TIR, is the quality of the ER11 collet used. The spindle is shipped with a ¼” ER11 collet in place in the holder. It is good practice to always have a lightly oil-protected collet, finger tight in the spindle holder. This helps prevent contamination and corrosion of the mating surface. Wipe out the spindle protective oil before use.

ER style collets are self-ejecting, so a sticky collet is not an issue. I have read negative “user reports” from clueless owners of ER16 and larger collet retainers (the nut — that has a double meaning) telling of the threads being very poorly machined. The off-center ridge inside the nut is an ER design feature. Not a manufacturing fault. Do some study of the ER collet system.

The ER11 collet has the retaining ridge but it is too small to be made off center. I bought a second nut to be sure. Therefore, the ER11 collet is much harder to insert and remove than the ER16 and larger collets because the retainer ring is centered… Continue reading

Categories

NOTE: Log in is for admin and members only, not required to post comments.