Messages

451

General Mach Discussion / Re: Spindle speed

« on: July 05, 2008, 03:10:56 AM »

Yes - the minimum duty cycle will only go down to 10%.

How important is the low speed - bacause at 10% duty cycle your torque will be very small - on my lathe anything below 50% is in danger of stalling - even with a 2HP motor in place of the 1HP motor.

I cannot think - and I am sure someone will tell me - where the difference between 200 and 350 would spoil a job.

To properly run a spindle over such a wide range of speeds, and have a reasonable even torque over the whole range, you really need to introduce some pulleys in the system, unless your motor system is well regulated.

452

General Mach Discussion / Re: classes on g code and mach 3

« on: July 05, 2008, 02:56:41 AM »

Yes - I didn't mean for you to try and become a GCode expert - but as Gerry says - knowing the GCode helps to troubleshoot.

Ron - I think your approach might not be universal - I have a friend who has some BIG CNC machines - your have to winch the workpiece into place. He is maching parts for oil pipelines out of solids - and he writes all his own code. I am an engineer and the parts I make tend to be simple, axles and things and I write my code, because Solidworks takes too long.

Those who have written to the forum recently about jerky movement in CV and Adsolute Stop need at least to be able to look at the code and have a reasonable undertsanding of it, to be able to determine if their CAM system is writing arcs or lots of straight lines.

I want to do some nameplates next (not engraving) where the letters stick up from the backgorund - now I might need a CAM program for that !!!

453

General Mach Discussion / Re: size of screew

« on: July 04, 2008, 03:29:09 AM »

and why do you want to change.

454

General Mach Discussion / Re: classes on g code and mach 3

« on: July 03, 2008, 02:41:50 PM »

you could try this .

Even this, to me, is a bit fussy at first, but does contain some decent explanation of the syntax of GCode in the later paragrahs.

Print it out and stand it by the computer.

There are Books on the market, but I wouldn't know which to recommend.

www.linuxcnc.org/handbook/gcode/g-code.html

455

General Mach Discussion / Re: CNC Boring machine

« on: July 03, 2008, 02:33:05 PM »

I am at a loss to understand how you can change a boring machine into a MIG welder.

Do you mean  this has a table with an overhead drilling platform that can move about the table and drill holes where you want.
You want to replace the drill with a MIG or Tig welding torch and use it to automatically weld to a pattern

The electronics look very old. Does it all work, or have you just got all the parts that you want to assemble.

This forum is for Mach 3, and is not a general engineering forum (although we have a lot of good engineers) so to advise you on that machine would be impossible, unless someone has experience with it.

Mach 3 is a computer program which runs on a P.C. It can provide outputs for up to 6 axis motors, to move them in accordance with a GCode program. The problem is the interface with the machine - your machine.

Mach 3 provides computer level signals (0 - +5V) to drive your axis motors, relays etc. It provides step signals and direction signals to tell the motors what to do. If your servo motors and amplifier system does not accept step and direction signals then Mach 3 cannot run it - and you would have to replace all your servo motors and drivers with ones that would.

I am sorry to be so gloomy, perhaps someone else to give an opinion

456

General Mach Discussion / Re: Power supply in parallel

« on: July 03, 2008, 02:05:59 PM »

I might argue a little bit with Dave about the current required wiring these in parrllel, but - yes - in the scheme of things your power supply is not adequate even to supply two of these motors when running at full chat.

I would get Gecko 201 drives. These are rated at up to 7 amps, but are fully adjustable up to that - e.g. mine are set at 4 amps, but they are also capable of running up to 70 volts (or so). You will find that your motors as they are will run better on the power supply you have, but when you can afford to uprate the power supply to say 36 volts at 20 - 24 amps, they are sturdy enough to cope with that as well._

As a stop gap limit the Geckos to match the pwoer suppy you have to avoid any problems.

457

General Mach Discussion / Re: Relay Board

« on: July 03, 2008, 01:51:20 PM »

Your description of what you are trying to do is a bit vague. Are you trying to activate the spindle motor??

The probotix relay board is a simple driver to power three relays from your breakout board signals - these can be anything you have configured on Mach 3.

The three inputs require +5 volts signal to activate the relay. You do not require a connection to the A axis header.

If it is the spindle motor you are trying to activate, then the M3 command is the correct signal to use. This must be turned on  - see Config/Ports and Pins/Spindle set up - top left hand conrner and allocate M3 and M4 (reverse) to Output pins. These can be anything, but use 1 and 2 if you have not used any before. Then on Config?ports and Pins/Output signals, apply Output#1 to whatever pin you wish to use. If you need Reverse, apply Output#2 as well.

On your breakout board then run the connection from that pin to a relay input on your relay board.

If you test it by typing M3 on the MDI line, then your breakout board pin should alter.  If Probotix have their voltages right, this should produce a +5 on the output.This, applied to the relay board, should fire the relay. You then need to connect the relay to whatever fires up your spindle motor.

Typing M5 turns it off.

458

General Mach Discussion / Re: classes on g code and mach 3

« on: July 03, 2008, 01:25:57 PM »

There is no better way to learn GCode (and Mach 3) than by sitting down and doing it.

Basic GCode is very simple. The X and Y axis have co-ordinates, and a line of code tells your machine to move from where it is (it knows where it is) to a new location. That is it.

If you mention one axis in the line, than one axos moves, if your mention two axis, then both move simultaneously in time with each other, and if you mention 3 axis at one time you are better than me - but the same rule applies - all axis move simultaneously.

The move can be at hgh speed - i.e. what your motors are set at for top speed by using G0, or you can use G1 where you can specify the speed the axis(es) travel at - using F (Feed) in units per minute.

The codes G2 and G3 are for cutting an arc. This is a circular arc, as opposed to a hyperbola or other type. Here, as before the finish points are required, together with a radius (R parameter) or a centre paramter (I or J or K).

These codes are all that is required to make your machine do meaningful work. The other codes listed are all to do with offsets, or specialist drilling moves, or metric and imperial, etc, to make the first four codes do the job at the correct place - and, quite frankly are ignored by a lot of the Cam programs, which simply write what they want to do in the first 2 codes, G0 and G1.

Get stuck in and sit down and write some GCode program for yourself. Get some graph paper, which gives you a co-ordinate system, and draw out on that, where you want your tool to go, and then write the GCode to match it. You will be amazed that you can achieve so much with so little.

As you progress, you will investigate if there is a more efficient way of writing the Code, and there might be, but as I said before, many of the CAM programs are not efficient, they stick to writing things in lots of little lines.

The most important thing about all this is to make sure that you write your program, from a point 0.0.0. This is a point that you can set on your machine and know that when you start your program, the machine knows where it is.

One a lathe, X0 is normally the centreline of the lathe bed at rotation height, and Z0 is normally the right hand edge of the workpeice, both things you can easily find.
On a mill, X0Y0 is normally the bottom left hand corner of the workpeice, with Z0 being with the tool resting on the top of the workpiece, again a place that you can easily find - and more important in both cases - you can set your machine to.

These places are known as Work Co-ordinates. The machine itself always runs in Machine Co-ordinates - and the Mach DRO's display either. As you get more proficient, you will learn (or should I say - come to understand) how you can have the machine set itself to home co-ordinates, then apply offsets to bring it to the correct place to begin work. That, however, is a fair way in the future, and something you do not need to know at the present time.

Keep it simple at first, have a go writing your GCode and you will learn very quickly.

459

General Mach Discussion / Re: Power supply in parallel

« on: July 02, 2008, 12:08:52 PM »

Yes - we understand - BUT - what is the rating of your motors - mine for instance are - forget the name, because it doesn't matter - 220Ncm, rated at 2.5 amps at 7.5 volts - this is the important bit - and it enables you to work out what power you are likely to need as per da21's post

460

General Mach Discussion / Re: Power supply in parallel

« on: July 01, 2008, 01:04:33 PM »

Yes - well, just fasten them in parrallel - pos to pos and neg to neg.

I would, however, include a fuse in line wtih each supply.