In this tutorial we are going to explore different options and techniques when programming cutter movement.

Lets begin with a simple part shown in a drawing below.

Basically it is a rectangular piece 4.00x2.00
For the purpose of simplicity lets make the depth of our profile (z- dimention) 0.75"

We are going to use a 0.5" dia endmill, again because it is a very common size and is easy to do basic math with.

I took a liberty of puting locations for our part/toolpath, so it is easy to extract numbers from the drawing just by looking at it.

Notice the green rectangle. This rectangle represents the path that the center of the tool will have to take to produce the part with required dimentions.
The thing is: because endmills have certain diameter, the center of the tool must be always offset by its radius.

There are two ways of doing that.Read More 

At my day job I am starting to do more and more manual programming.

Which i do not realy like, but since am at it anyway i have decided to keep piling little articles about G-Code programming into this new category.
This way when i forget things again i will be able to quicly refresh my memory.

Program Start

O0001 (COMMENT OR PROGRAM NAME)

Starting safety blocks

(G20 IMPERIAL UNITS, G21-METRIC)
(G17 XY ARC PLANE, G18-XZ, G19-YZ)
(G40 CANCEL TOOL RADIUS COMPENSATION)
(G49 CANCEL TOOL LENGTH OFFSET)
(G80 CANCEL CANNED CyCLE)
(G90 ABSOLUTE POSITIONING MODE)

G20 G17 G40 G49 G80 G90

Tool Change Routine

(T14 - call 2.5" Face mill)
(M6 - Perform tool change)
(G0 - rapid feedrate)
(G55-G59 - Choose Work Offset)
(X, Y - Command a Position to move to)
(S - choose spindle speed)
(M03 - Turn spindle on Clockwise, M04 - Counter-clock wise)

T14 M6
G0 G54 G90 X{X} Y{Y} S{SPEED} M03;

Apply Tool length offset at retract height, Turn on Coolant

(G43 H14 Z2.0 - All codes must be in the same line Apply cutter length offset from record #14 to cuttent tool, move to 2.0 above work at the same time )
(M8 - Turn on Coolant)

G0 G43 H14 Z2.0 M8

Rapid tool to plunge height

G0 Z{Z_PLUNGE}

Plunge to cutting depth at plunge feedrate

G01 Z{Z_DEPTH} F{F_PLUNGE}

Make a straight cut in xy direction at cutting feedrate

G1 X{X_POS} Y{Y_POS} F{F_FEED}

Retract to plunge height at either rapid or retract feedrate

G1 Z{Z_PLUNGE}

Retract to rapid height, turn off colant

(M09 - Turn OFF coolant)

G0 Z{Z_RETRACT} M09

Retract to tool change height, turn off spindle

(G28 G91 Z0 - all coes must be in the same line, move Z axis to HOME POSITION through a reference point)
(G91 Z0 - Causes reference point to be the current location, thus sending axis straight up )
(M05 - Turn off spindle)

G0 G28 G91 Z0 M05

Perform Next tool change or end program

M30(end program)

In this update i fixed some of the annoying things that were present in my app before.

Firstly i have totally changed the way app renders. Instead of using gradient backgrounds i am now using background images everywhere. This prevents glitches that some users reported before.

Then main menu now takes the whole screen. Small but descriptive icons were added to ease the navigation. Also scrolling problems for all of the devices were fixed there.

Phone Back button now exits the main menu or the virtual keyboard.

To shut down the app you have to tap Back key twice. This prevents acidental exits.

Phone Menu button opens main menu now. So the workflow is a lot like in the rest of android apps.

As a test i gave it to my wife to try out. She was pleased and managed to run through the whole app within a couple of minutes and never got lost. She especially liked menu icons, said they looked cool.

Email me or post on forums if you have any feedback.

main menu updated keyboard

This is another video from his Productivity Series.

In there we get a quick demonstration of HSM techniques Eric is using to produce his beatiful vise.

Also my own HSMAdvisor is featured there!

Thank you Eric!

Orange Vise are produced in the USA.

Check out this website for more info http://orangevise.com

Lately there have been a lot of really interesting HSM topics on PracticalMachinist forums.

In one of them a guy who owns his own resharpening business posted a video of his endmill milling a block of D2 hardened to over 60 RC.
The forum topic is located here First try on D2 62Rc(video)

Here is his post so you know what we are talking about:

In the ensuing discussion i posted my own take on how and why HSM works

HSM works in many ways.

1) Reduced cutting time per edge per revolution allows it to cool down more.
2) Chip thinning allows to increase chipload (advancement per tooth per revolution)
3) Increased depth of cut combined with shallow radial positively affects deflection. Tool bends less as it is more rigid towards the tool holder.
4) Higher cutting speed actually reduces cutting forces as heat generated in the cutting zone makes it easier to shear off a layer of metal. Yet because the time of contact is so small, most of the heat is carried away with the chip.
5) Higher RPM also allows to get rid of hot chips faster thus further reducing heat transferred to the tool.
6) Higher feedrate actually reduces relative cutting speed.
7) At high axial engagements more than one flute is in contact with the workpiece at different points along the axis of the tool. This too helps combat vibrations and chatter.
8) You are using more of the tool than just its tip, so technically you can do more work with one tool before it gets dull.
9) lastly it looks cool as hell and is very impressive. Whenever we know visitors or bosses are coming we try to make sure some HSM is going on even if application does not merit that
I am not sure if the air that is moved by the endmill is doing much, but i suspect he didn't mean exactly that.

Shrink fit holders and extensions often come with a big through hole.

Its primary use is to allow the shank be knoked out from he back should the tool ever snap off. It is also used to supply coolant for CTS machines.

Unfortunately said hole affects rigidity of the holder making it more likely to chatter leaving bad surface finish and badly affecting tool life.

There is however an old trick to prevent or minimize the chatter.

All you have to do is pack that hole with some thick grease.

Don't forget to cap off the oppening so that grease does not escape when the tool is spinning.

Here are several photos of surface finish before and after grease application. All cutting parameters were exactly the same in both cases.

before. deep chatter marks after. surface finish is ideal tool in extension holder showing capped hole

HSM or High Speed Machining is becoming more and more popular each day.
Many of us have seen those youtube videos where endmlls remove large amounts of material at high speeds/feeds.

While definitions of HSM may vary between tool manufacturers and even individual shops, the physics behind it remain the same.

In this article i would like to explore flat endmills.

HSM is not about ramping up your speed/feed overrides to 200% and puling out your smartphone to record another youtube-worth video.

What is HSM?

HSM is a complex of programming, machining and tooling techniques aimed at radical increase of productivity.

Programming

The cornerstone of HSM is low radial and high axial engagement of an endmill with the workpiece.

There are many CAD/CAM systems that allow you to create HSM tool-paths. Mastercam's Dynamic milling and SurfCAM's Truemill are some of them.

When radial cutter engagement with the material is smaller than the radius of the tool an interesting thing happens.
Chip load- the distance the tool advances per cutter revolution per tooth- does not equal the actual chip thickness anymore.
Chip thinning mainly happens at radial engagements below 30% of the diameter.

In order to get compensated chipload you need to multiply recommended by manufacturer chipload by the chip thinning factor.

Usual Radial Engagement for HSM toolpaths however is between 5 and 15%.

Axial depth of cut varies depending on geometry, but Read More 

Radial Chip Thinning HSMAdvisor Screenshot

Sevaral weeks ago i saw a post on CNCZone.

A HSMadvisor user Peter Neil used it to calculate cutting conditions for cutting a block of pre-hardened stainless steel.
His machine was Tormach.

Here is an exact copy-paste from that forum post:
_____________________________________________________________________________________

Did a test cut on the Tormach today using feeds & speeds from the latest version of the excellent HSM advisor.
To make it interesting, I did the cut using some 1.2085 pre-hard Stainless Steel as I have plenty of stock of it and have a job in mind for this, and wanted to see how it cut on the Tormach.
The material is like a stainless P20, at 16% Chrome/1% Nickel & 0.5% Sulphur (which makes it slightly free-er machining) and is hardened to around 33-35 Rockwell C, so I used the HSM advisor guidelines for machining P20 rather than Stainless. Cutter was a 10mm 4-flute Carbide TiAlN coated EM.

So...... ticking the HSM/Chip thinning option I got a speed of 5120 and feed of 2214mm/minute( 87 IPM). I used a DOC of 10mm and WOC of 0.5mm/0.020" - and turned off the flood cooling to machine it completely dry. The finish pass on the 1st level was 15mm DOC and 0.5mm WOC and slightly lower speeds/feeds.

Loaded up a 40mm x 63mm block , pressed the start button, and it went from this....





...to this!

Read More 

Tool:0.281 dia 0 helix TIN coated carbide drill

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.