I came across a very educational post on Practical Machinist.

The topic-starter used over-aggressive speeds and feeds for his tiny BT30-taper machine and the retention knob (a.k.a Pull Stud) snapped causing the holder to drop lower, disengage from drive lugs and mess up the spindle bore in the process.

Just in case you don't know. Retention Knob looks like this and is used to pull the tool holder in to the spindle bore, thus holding it in place:

(Retention knob is the detail on the right)

This whole article is to remind everyone the importance of proper tool holder and retention knob maintenance.

Retention Knob Tips

• Retention knobs (according to HAAS) have service life of about 6000-8000 hours.
  That means that if a tool holder is used 3 hours a day, you should replace the knob after 8 years in service.
  For smaller BT30 knobs, you should probably replace them every 4 years.
• Retention knobs should be lightly oiled or greased (if TSC is used) once a month to lubricate the draw bar.
• There should be no visible damage or rust on the knobs.
  
• Do not exceed the maximum cutting force recommended by your machine manufacturer.
  Some of those high-helix end mills create large down-force that could in certain cases cause the knob to snap!
• Also retention knobs should be torqued to manufacturer specs and the tightness should be regularly checked. Overtightened knobs may lead to taper of the tool deforming and causing uneven contact with the spindle bore.

Tool Holder Maintenance Tips

• Keep Tool Holders clean. Especially the taper part that is matching to the spindle bore.
  Wipe them with a clean cloth. 
• Do not use sand paper to clean tool holders! Soft Scotch-brite is acceptable to clean very dirty ones.
• Repair dings and notches on the taper.
  Even an aluminum chip will cause a ding, that will create a high spot around it.
• Replace worn-out tool holders with new ones.
  Signs of ageing is uneven contact with the spindle bore and fretting (blackening of taper in certain spots)
• It is also a good idea to re-grind the spindle as well when replacing the tool holders - there are lot's of services that do that for very reasonable price.
• Like wise when a new machine is purchased, only new holders and retention knobs should be used. Using old worn out holders on a new spindle bore will lead to its premature wear and even damage.

Those are all the things I could think of at the moment.
Let me know if there is anything missing.

Have a safe and productive week!

3D Prining is about to to take over traditional machining the same way CNC Machining took over manual machining.
Eventually 3D printing will replace casting too.

Since 3D Printing does not require complicated setup and programming, this in turn will lead to massive loss of machining-related jobs.

Read more to see if this is true!

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Before we start milling away our stock we first need to get down to the required depth.

This is not a problem with external features when we can plunge outside.

When machining closed pockets, however, we need to find a way to get down to the machining depth first.

As usual there are several ways to get the job done. The plunging methods listed here are not ordered by their preference.

For various machining operations on different materials some may be more preferable than others.

Straight Plunging into a larger Pre-Drilled hole

This is one the best ones in my opinion.
Very few machining modes can compete in effectiveness with drilling and this method will get you the best combined tool life on most materials and (in case of many deep pockets) the least machining time, even when tool change time is factored in.

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As unhappy I am to learn that something may be wrong with the software I develop and love, negative feedback is essential in learning whether i am doing everything right.

So a couple of days ago I received an email from a somewhat disappointed user. 

He (lets call him Peter) was complaining that HSMAdvisor calculator gave him "excessively high" speeds and feeds for his 3/4" 4 flute 3.0 LOC  end mill in aluminum.

With the data Peter entered he was getting around 10000 RPM(SFPM 2117) and the feed of 270 inches per minute while usual practice in the shop was side-milling aluminum at that (2.8" axial) depth at only 325 SFM

After double-checking the numbers I replied that in fact his numbers seemed very slow and if for some reason he HAD to run that slow (heck, i machine most steels faster than 325 SFM) due to some conditions, perhaps, he was ought to change the conditions themselves.

This is what I am getting for Peter's end mill setup:

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Have you ever wondered how much tool life can deteriorate when using coolant with High-Speed Machining (HSM)?
Or maybe you never really saw the boost in tool life when using HSM techniques because you had to use coolant?

Well, here is a test result I just got from running the same tool at the same Speed and Feed with and without coolant.

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We all know what the CNC Milling Machine spindle is used for - to hold the tool. But it is old and boring. Everybody does that.

Here are the 6 interesting and maybe less common ways to utilize machine spindle, increase productivity and solve some problems you never thought you had.

Use your Spindle as a fan to blow chips and coolant off of your work-piece, table and fixturing.

I saw this little gadget at a local IMTS show and it was quite cool. It is installed into a tool holder like a regular cutting tool would be and at the end of the program you can call the it up and run a little table-cleaning program to make your work a lot cleaner!

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Every month we are getting a good amount of feedback and suggestions.

Everything is getting prioritized and eventually implemented. Urgent stuff is getting done fast. And other "nice to haves" are getting pushed down according to their usefulness / difficulty (yes, everyone secretly wishes my program could also edit and create HSM g-code :)).

It is amazing, but almost half of HSMAdvisor's features were originally suggested by our loyal users!

The latest update HSMAdvisor 1.213 addresses some of the feedback I have received last couple of months.

So the New features are:

1. Smart Depth and Width of Cut (DOC/WOC) suggestion (user suggested)
2. Compressing of Shared Tool DataBases
3. Display of Stock status on Tool DataBase tables (user suggested)
4. Various little improvements like new Heli-Coil reference, better DOC/WOC calculation better multitasking, etc. (mostly based on user feedback)

Let's go over the most important ones here:

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Did you know there are three ways you can touch off your tools?

Because of how Machine Offsets add up, there are several ways CNC machinists can set their Tool and Work Offsets.

This is especially true for Tool Length Offsets.

Tool Offsets can be either Positive or Negative.
Depending on your Machine Shop equipment you should use one or the other.

Regardless of how you set your tool length offset, you apply it the same way.
Right after the tool change and after turning on your spindle and moving to your X Y position above the part.
The very first absolute Z movement should be the line where you apply the tool length offset.

Positive Tool Offsets (gage line tool length offsets)

In the case of Positive Tool Offsets, the offset represents the Length of the tool measured as a distance from the Gauge Line of the spindle (typically spindle nose) to the tip of the tool. The longer the tool, the larger your Tool Length offset will be.

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Before we run any G-Code program, we need to tell the machine where our part zero is.
A Part Zero is simply a bunch of numbers that offset the axis to give the machine a new coordinate point to work from.

Work Offsets is one of the most basic pieces of knowledge any machinist must-have.

Let us account for all the basic coordinate systems and definitions, available in a generic CNC machine

• Machine Home and (Absolute) Machine Coordinates
• Work Offset Coordinates
• Tool Length Offsets

Machine Home and Machine Coordinates: G53

Machine Coordinates (or Absolute Coordinates) is the absolute and constant representation of the machine axis position.
These coordinates never change between Machine Restarts and must remain such. In fact, there is often no way for an operator to adjust the Absolute Machine Axis Home position.

Machine Home is simply that magical place where all Machine Coordinates should become Zero.

To Home the Machine is to start a machine operation, that will move all Axis to their soft limit position where X, Y, and Z-axis reading will be set to zero.

Homing must be done every time you restart your machine. Without it machine does not know where is the position of its table or spindle.

When homed your machine coordinates will read X=0 Y=0 and Z=0 and it is going to look like this:

The point where Machine X and Y intersect is called Table Home Position and the one where the Machine Z-axis starts from is called Spindle Home.

Now, there is no agreement between machine tool manufacturers on where the machine home should be.

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Canned cycles are used every time we need to drill, ream or tap holes on our CNC machine

Standard Fanuc G-Code language supports more than a dozen canned cycles.

The most common cycles that will cover 99.9% of your g-Code CNC programming work are:

Subsequent holes

You can drill additional holes After your canned cycle has been initiated.
Any line with X Y position will be treated as another hole position.

Each position can have its own Retract value, feed rate and retract height modifier.

G80 - Canned Cycle Cancel Code

After all the holes of the canned cycle have been drilled, it is required to call G80 code in order to cancel the current cycle.

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