Programmed and machined a T-800 head from thingiverse:

Here is a finished scull video from all sides: https://youtube.com/shorts/mdclf5LvdyM?feature=share

In the 1st op I milled the base with a 1/4-20 tapped hole right where my Z0Y0Z0 will be.

Then I mounted the base on a square fixture using the tapped hole. This way as I index the square fixture in the vise, my part Z0Y0Z0 remain in the same spot.

2nd op was the back of the scull

3rd op was the face, and the 4th and 5th were the sides

Here is a YouTube video of some of the 3rd op machining. Warning Loud Noise!

Did some testing for HSMAdvisor in A36

Tool: 3/16" 4 FL 0.25" LOC 0.7 Stickout

RPM: 5000 Feed: 32.0ipm

Original engagement DOC:  0.25, WOC: 0.083

Was successful and sounded nice, but the TTS holder started to pull out. Had to half both DOC and WOC for the video:

Finally got my proLIGHT CNC Mill running with UCCNC control software.

Chose that over mach3/4 because uccnc software seemed better made. Unfortunately, it too has bugs.

Most importantly, executing gcode.
Instead of running all codes in a block simultaneously, it does them in the incorrect order.

For example, code like

Instead of going to X0 Y0 defined in offset #54, it will go to coordinates of offset #55!
Only after executing that line, the offset will change to G55.
Similar issue with

Don't need to tell you this may lead to crashes.
So I changed the MasterCAM's post processor to output some of the codes in different lines.

Hopefully, devs will fix this issue soon.

In other news, I have just finished the first 2-tool piece.

It was a miniature skull figure made out of aluminum:

I got 150 bucks for machining that for a guy I met in a Facebook group. Nice!

The smallest endmill was 1mm ball nose, and it held up perfectly at max RPM of 5000 and feed rate of about 25ipm.

The DOC and stepover were about 0.004"

Now I wish it had a 20k spindle. If I could run at 100ipm, it would make a quick work of that little piece.
This way, it took 1 hour, which is not too bad either.

Cheers! 

In my days machining blow molds there were lots of parts where I had to make a completely through hole. Sometimes those were up to 4 inches deep and I had to go from both sides!

The trick to machining cores like that is to leave about 0.05" on skin all around AND pick milling direction and start point such that when the last bit is milled through, the core gently pushed away from the cutter instead of jumping out.

Often times CNC programming tutorials only teach you how to create the tool-paths and not enough attention is paid on showing how to properly hold parts being machined.

At the same time efficient workholding is an art in it self and mastering it could drastically improve shop productivity and accuracy.

Without further ado let's jump into the workflow.

Step 1. Analyze the Drawing and the Model

We would have to look at the drawing, tolerances and the CAD model to develop the machining strategy.

This particular part has tight (+/- 0.001) tolerances between the features located on the top and the bottom sides. In addition to that it has a 2.5 degree draft angle on external walls.

Thus I decided to not use the soft jaws approach and machine it in a fixture. Soft jaws are generally OK for tolerances down to +/-0.001" but because of the draft angle the part would always want to pop out of the jaws.

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On the heels of the previous post.

YouTuber Breaking Taps has just published another of his interesting videos:

In it he is testing various High-Speed Machining techniques on his benchtop CNC router.

Also it is mentioned that HSMAdvisor does not seem to like those small high-feed cutters: at some point some calculated values become negative.

This is a legitimate criticism and it actually happens because default cutting depth of 0.024" becomes too large for the 0.24" Lakeshore high feed and mill and an actual Flute length of 0.015" must be entered in order to get proper values:

With actual 0.015" flute length entered the recommended speed and feed values are now in the safe end of the ballpark suggested by the manufacturer.

Task added to the issue tracker!

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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Ever since we stopped offering free educational licenses, there has been steady demand for either free or discounted license options for colleges and schools.

We could not give out free licenses any longer because they still cost money in hosting and support. 

So today after a lot of consideration we decided  to start offering special Educational HSMAdvisor License Package 

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We have many helpful articles over at HSMAdvisor Help portal. But beacuse of that very reason not many website visitors actually read any of them.
It is a pitty that most advanced users will never actually visit the help section, because they already know how to operate HSMAdvisor.

And this particular one, I believe, is too useful (I just updated it to include more info) for my customers and other machinists to keep it burried in some help section that few ever read.

So here you go:

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