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!

I regularly follow practicalmachinist.com forums.
Especially the cnc machining section of it.

I notice when CNC Speeds and Feeds questions come up people often suggest my HSMAdvisor Machinist calculator.
A referral by a satisfied customer is the best referral in my opinion. Thank you to everyone doing this great favor to me and my prospective users!

Other times users of HSMAdvisor question speeds and feeds it generates and instead of going to me, they ask on forums.
Which is always fine, because extremely often "wrong" results mean something wrong in users expectations or the data he feeds the calculator

In the process of discussion it usually turns out that the calculation results were correct, but because user decided to use a depth of cut or tool length, larger than he should have, HSMAdvisor compensates and gives a very conservative feed rate.

Just like in this forum post over here: Engraving with a 1/32 ball mill machinist wanted

Using Peck Cycle is often needed when drilling deep holes.
When using proper feed and speed no peck is required at depths of up to 3xDia for regular or 5xDia for High-Performance Parabolic drills.
At depths up to 10x, up to 5 pecks are required for regular  drills and up to 3 for Parabolic.
Anything over 10x Dia requires constant pecking of 0.5-1x Dia for regular drills and 1.5-2 Dia for Parabolic.

Since for programming you need a peck amount. Here are the numbers:

Of course our HSMAdvisor Speed and Feed Calculator suggests not only the Speeds and Feeds but also the proper peck depth for various drill types and depths of the hole.
It in fact was the first machinist calculator to do so. This feature was much later borrowed by our competition.

And here is a pretty image showing Peck VS Hole Depth for regular twist drill:

This not only means that peck amount should be different for different styles of drills and depths of holes.
But also that peck distance should be different for different stages of drilling the same hole.
Ideally we should start the hole with large pecks, that continually reduce as the hole gets deeper and deeper.

Let's find out how we can apply this knowledge when programming our toolpaths.
This is format for normal Pecking:

Recenty ordered a 3Flute High Performance End Mill From NIAGARA.
Was very glad and slightly surprised that when punched in all of the endmill's data into my Calculator nothing broke down.I had a rason: At 5000RPM and 3/8" Deep slot cut. The feed came to around 92.0IPM. Chips were making this nice ringing noise that sounds like money.

Setup:
HAAS VM-3
Hudrolic Tribos Holder
3/4" 45DegHelix 3Flute 1.625FluteLen, 2.375"Overhang TICN HP End mill

S:5000RPM
F:92.0IPM
DOC: 0.375" Slotting
Coolant:FLOOD

The calculation was pretty much dead on.

Renishaw OTS tool probe cycle for HAAS can set both length and diameter offsets.

Too bad there is no choice: it only puts absolute measured diameter of the tool into D- diameter offset and makes wear offset=0

But if your programming is done with the center of the cutter, then you actually only need the difference between actual and programmed diameters of the tool.

I.E.: When probing 5/8Dia end mill, we get D=0.6248. You would normally have to subtract 5/8 from it and leave the -0.0002 difference.

But there is an easier way

Problem: Work offset G54 Z0 shows some "weird number" which is very hard to relate to.

Can we make top of fixture show Z0=0.000 ?

Solution: