Messages

7471

General Mach Discussion / Re: Keen to learn mild steel with my CNC router!!

« on: May 31, 2016, 06:24:29 AM »

Hi there,
I have a 750W router spindle in a small homemade bedmill, cast iron beds
and a 3 inch by 3 inch solid steel column. Thought it would be rigid enuf for
steel and it is JUST.
The low torque of the spindle has made an effective limit of 3mm endmills.
You need to keep the federate up otherwise your tool does a lot of rubbing
but not much cutting and wont last 5 minutes. If you stall your spindle the
tool breaks almost instantly so federate/depth of cut are critical. Plunging
and slotting must also be carefully planned federate wise.
I had no real success until I adopted flood cooling, I wont be going back to
dry/mist/air anytime soon. I've made quite a few parts like this, slowly and
quite a few learning humps along the way....
The last few months I have been building a new spindle based on a 2.5kW
servo to get the torque required to mill steels. While servos are readily
available on Ebay pretty cheaply matching servo drives are not. Don't be fooled
by sensorless vector drives, I tried and was disappointed. I'm designing and building
my own servo drive, tourqe and speed loops only at this stage. This hobby has a way
of engaging you to learn lots of different things, in this instance programming 32 bit
microcontroller to enact 'field oriented control', what a mission! If success is measured
by what is learnt along the way I'm going great guns....

Craig

7472

General Mach Discussion / Re: Need help!! Mach 3 upgrade

« on: May 20, 2016, 06:12:56 AM »

Hi,
I'm not familiar with your BOB. I get mine from Homan Designs in Austrailia, near enuf to local for me.
These BOB's have LEDs on the outputs and make diagnosis ALOT easier. While I have not used other BOB's other
well respected forum members have reported that other well made BOB's have the same feature.

For instance my X axis is pin 1 for direction and pin 2 for step. when I command, either part program or MDI, a
clockwise rotation the no.1 LED lights up. Even when the move is finished it will remain light until I command a
counterclockwise move, ie the direction  is persistant.
My stepper drives move on a positive going step signal and consequently have set the step pin as active high. When a move
is commanded the LED blinks between off and on, very commonly so fast that it appears to be intermediate brightness. When the
move is complete in returns to idle ie. LED off. Should your setup require active low then the step LED will light when idle.

Multimeters are a poor choice for this, they reflect an average and can be quite slow to respond. Of course you can only observe
one pin at a time whereas LED's offer observation of all pins at once. Additionally one slip of the probe and its very possible even
likely that one or more of the outputs is toast.

I would recommend such a BOB. there are some very good ones out there, any forum search should catch a few recommendations.
The very cheap ones are an excerise in frustration.

Craig

7473

General Mach Discussion / Re: soldering iron info, please

« on: May 18, 2016, 05:47:54 AM »

Hi there,
have to support Dave my Weller Magnastat has been going for twenty plus years, one new element, one new mag switch, several barrels
and plenty of tips...
Temperature controlled is the only way to go, any iron with enuf power to do a heavy job is when sitting idle going to overheat and the first
touch of such a hot iron on any semiconductor/circuit board/other heat sensitive gismo and you wreck it.
The Magnastat tips have a little magnet on the end of them and when the tip reaches the Curie temperature the magnetic field collapses and the
reed switch opens, when it cools the magnetic field re-establishes, the switch makes and the heater powers up. Really simple and reliable.
If you want a hotter iron just buy the tip with the next hotter range. I usually have one or two hotter tips where I need the thermal mass to
hook into something a bit larger. It has a 50W element and with a little patience can tackle quite large jobs and yet not overdo surface mount
components.
Simplicity means that they are reasonably cheap, I saw an ad for one at $290NZ, about $180 US. My experience says that great value.

Craig

7474

General Mach Discussion / Re: Multimeter info

« on: May 15, 2016, 06:58:07 AM »

Hi,
I work for a company that repair welders and I use a multimeter ALOT!! Tig welders produce HF and that is fatal for any miltimeter
Fluke or otherwise. I uses a Tenma (Chinese or Taiwanese I think) which cost about $60US, Cat III.
It will measure 20A but the shunt is unfused so be careful. I don't use Temp, Capacitance or Frequency very often. Volts,Ohms,Current and Diode
I use ALL the time.
Fluke is great but expensive and to my thinking provides little better than low to mid priced units epsecailly when one moments inattention
can allow HF into the meter and its a throwaway thereafter.

Craig

7475

General Mach Discussion / Re: mach 3 requirements...

« on: May 15, 2016, 06:46:01 AM »

Hi Arbo,
my old XP computer was getting very cranky so I replaced it with a miniITX board based on a dual core Atom processor
running Windows 7 Embedded. Works a treat.
The board I chose has one built in PP and a PCI slot to which I have fitted a second PP. The Atom has a built in video engine
and shares RAM with the CPU, I've had no issues with video with part programs of 200kB.
A miniITX board (less RAM and HD) of this type can be had for $80-100 US.

Craig

7476

General Mach Discussion / Re: Steps per inch

« on: March 11, 2016, 10:03:36 PM »

Hi,
that's great, its a lot of fun when it starts coming together but don't worry there is still plenty of time
for things to stuff up...lol

Craig

7477

General Mach Discussion / Re: Steps per inch

« on: March 11, 2016, 07:53:35 PM »

Hi Leversole,
obviously with a leadscrew on z axis settings will be different to your xy settings. Sounds like you are cutting thru the confusion.

Craig

7478

General Mach Discussion / Re: Steps per inch

« on: March 11, 2016, 07:05:53 PM »

Hi Leveresole,
sounds right to me. I take it your table/tool or whatever is attached direct to the belt? No leadscrews?

Craig

7479

General Mach Discussion / Re: Toolpath generated out of limits

« on: March 11, 2016, 07:00:41 PM »

Hi ,
I have not used 4 axis so I can't help. May I ask how you code A axis movement. The simplest method I've read about is where
you code A as a linear axis, so G1 A100 causes 100mm 'movement' of A stepper which with gearing etc may amount to 35 degrees
rotation say. A move G1 A1000 means a rotation of 350 degrees, easy. But what happens if your soft limits are set to 500mm. Would
then Mach3 warn you that your movement is out of bounds?
Clearly a rotational axis cannot go out of bounds in the same way you can drive a linear axis off its stops.

Craig

7480

General Mach Discussion / Re: New computer build

« on: March 11, 2016, 01:19:59 AM »

Hi Mogal,
I haven't tried the combination of hardware you listed but I think that combination would work.
I like you was none too keen on a recycled PC and wanted to buy new. I settled on a MiniITX
board from Unigens, a Tawainese manufacturer. The board is based on a dual core ATOM at 1.8GHz.
I fitted 4G RAM (overkill I decided later) and a 64G SSD. It has a built in PP and one PCI slot for a second
PP. I recycled my PSU and monitor and installed Windows 7 Embedded as OS.
Been stable and reliable from the get-go.
My experience is that new hardware can run Mach3 and PP which runs contrary to some other comments
made in the forum.
Have to say that the prices you are talking for brand name second hand platforms would be mighty appealing
to me. I do have a certain satisfaction about 'building' my own system tho...

Craig