Topics

331

General Mach Discussion / Another Tangential Knife problem.

« on: September 07, 2012, 06:20:31 AM »

When cutting a rectangle, the knife is rotated to the direction of the first cut (A Axis), lowered into the work (Z Axis) and at the end of the line the knife is retracted from the work, rotated to the direction of the next cut, lowered into the work and so on. Nothing wrong here and everything works just as it should.

When cutting many circles it is an entirely different situation. After completing the first circle the knife rotates to the start direction of the next circle as a blended move with the Z Axis retracting the knife (the knife rotates within the work whilst being withdrawn).

I can overcome this problem by creating a tool path where each circle starts and finishes in exactly the same direction (and not optimizing the tool path for shortest route) but is there an easier solution please ??

Tweakie.

332

Tangent Corner / F1gur471v3ly 5p34k1ng?

« on: August 28, 2012, 03:58:11 AM »

7H15 M3554G3
53RV35 7O PR0V3
H0W 0UR M1ND5 C4N
D0 4M4Z1NG 7H1NG5!
1MPR3551V3 7H1NG5!
1N 7H3 B3G1NN1NG
17 WA5 H4RD BU7
N0W, 0N 7H15 LIN3
Y0UR M1ND 1S
R34D1NG 17
4U70M471C4LLY
W17H 0U7 3V3N
7H1NK1NG 4B0U7 17,
B3 PROUD! 0NLY
C3R741N P30PL3 C4N
R3AD 7H15.

Weird. 

Tweakie.

333

General Mach Discussion / Decimal precision.

« on: August 21, 2012, 07:38:47 AM »

Does anyone have any ideas on how I can convert an existing GCode file which has 4 places of decimal precision to a similar file with just 3 places of precision please ??

It doesn't have to do anything fancy such as rounding, I would be happy to just loose the 4th decimal place.

Don't ask why 

Tweakie.

334

Show"N"Tell ( What you have made with your CNC machine.) / Tangential Knife blade holder.

« on: July 13, 2012, 02:10:16 AM »

I needed a new blade holder for a tangential knife which would enable relatively quick and easy blade change and positional setups.

With just a couple of hours to spare, whilst another CNC job was running, this was the result (the only CNC operation was milling the flat).

Tweakie.

335

Tangent Corner / A Silly Idea ??

« on: June 02, 2012, 05:08:21 AM »

This is a really stupid project for a very, very rainy day.

Many of the old mobile phones, like this ancient Nokia, will dial the first number stored in their directory with just 3 presses of one button so program in your best mobile phone number as name AAAA.

Making a holder for the old phone and mounting an RC servo and a bit of electronics (pic processor) it is then connected to a spare Mach output.

When the currently running GCode program finishes, it switches off the output and the old phone dials your best mobile phone to alert you that the machine has finished. The pic processor is also programmed to wait a pre-determined time then hang-up.

With this little gizmo you can be just about anywhere in the world and know exactly when your CNC machine has finished it’s job.

Seriously though, this was the prototype for a number of units, I built some years back, to alert of site problems in a remote location without phone lines. I came across it last week, whilst tidying up, and took a picture for posterity.

Tweakie.

336

General Mach Discussion / We all make mistakes.

« on: May 30, 2012, 04:20:32 AM »

I don't normally post pictures of the trash but this may be of help to others.

I recently replaced the flexible coupling on my Y Axis and everything was fine until I cut this piece (which was profiled in two passes with a 30 degree engraving point).
The new coupling was bored 1/4" and the motor shaft is 6mm - what I thought was tight obviously wasn't (but it is now  ).

Tweakie.

337

Show"N"Tell ( What you have made with your CNC machine.) / Tweakie's De-Mag.

« on: May 27, 2012, 06:32:48 AM »

Another little project for a rainy day.

After trying one of Art’s ideas of wooden clock gearing using small magnets instead of teeth I encountered a problem. First, one of my small screwdrivers became magnetic then it spread, like a virus, to most of my other small bench tools and having used some steel wool (on a previous occasion) almost all my tools were picking up minute, unwanted steel whiskers.
Having seen a de-magnetizer project on eHow I set about making one and this is how I did it.

Taking an old, unwanted, mains power unit (from a long gone printer) I removed the transformer. The Mu laminations were carefully removed, the ‘I’ sections discarded (well some have been kept as lathe tool packing pieces) and the ‘E’ sections replaced, all in the same direction. The first ‘E’ is the hardest to remove but don’t worry if it is damaged or bent because on replacement they all fit back, except one, so the damaged one can be discarded.
It is only the mains, primary, winding that is used so the secondary windings are just left open circuit.
I fitted a small piece of iron onto the centre pole using epoxy then cut an appropriate sized hole in a project box and glued in the transformer again using epoxy.

When the transformer laminations layout is altered in this way, the whole flux pattern is changed and as a result it is necessary to limit the current flowing through the winding. This is best achieved by using a mains rated capacitor, connected in series (the larger the capacitance value the larger the current and visa versa). The original mains lead was re-used and the de-magnetizer was tested - it works just beautifully and removed all the residual magnetism from my small bench tools in just seconds.

The capacitor I used was a 2uF 400Volts starter capacitor and this is connected in series with the coil. Incidentally if the capacitor used does not already contain a shunt resistor then a 1 Megohm 5W resistor should be fitted across the capacitor to discharge it once power is disconnected.

Tweakie.

338

Tangent Corner / If Only.

« on: May 21, 2012, 08:12:39 AM »

If only I had the CNC files for the Olympic Torch - have you seen the price these are currently fetching on eBay ??

Tweakie.

339

Tangent Corner / Extremely clever electronics.

« on: May 17, 2012, 12:20:37 PM »

For anyone interested in electronics this video is well worth watching.

It is not a ‘fake’ video, it does exactly what it is shown to do – the ‘trick’ is in the fact that there are a lot more electronics, comprising the circuit, than are visible to the eye.

http://acidcow.com/video/32323-unbelievable_6_leds_chain.html

Tweakie.

340

General Mach Discussion / G31 command.

« on: May 14, 2012, 03:48:10 AM »

Hi Guys,

I would be most interested to hear of others experiences using the G31 command.

I have been using it for some years now and with the exception of having to liberally add the ‘While isMoving() / Wend’ statements to the scripts (following a Mach revision some time ago) it has worked perfectly and without any other issues.

Does it sometimes go cranky and what is the suspected reason??

Your comments would be much appreciated.

Tweakie.