Messages

791

General Mach Discussion / Re: Steppers stalling occasionally

« on: March 23, 2008, 07:01:51 AM »

Also try adjusting the acceleration as well - acceleration needs POWER - and if this is too high, to get to your 700 - the motors might just baulk at it.

I notice you have the step pulse at 9 - I thought the limit was 5 - but I'm not sure if it makes any difference.

You have probably just tightened the gibbs up a touch more than they were and this is causing the extra drag, particularly at the ends of travel, where there is less wear.

792

General Mach Discussion / Re: Shut down Windows services, which ones?

« on: March 23, 2008, 06:55:39 AM »

I dont know anything about the list, but yes.

In theory, Windows can (and does) run many programs simultaneously. Many of these run in the background and you are unaware of them. They do, however, take up processor time, since the processor can only process one instruction at once (discount dual procesors at the moment).

These processes can be seen (as you probably know) by pressing Alt,Ctrl and Delete. Selecting processes will show what is actively loaded on your system. Many of these - especially those marked "User" - can be shut down, and, in theory, will leave more processor time free to run Mach 3.

I must admit I would like to get hold of an "essential list" - in other words those programs Windows needs to function - and then I could shut the rest - particularly on my workshop computer.

793

General Mach Discussion / Re: Home switches

« on: March 23, 2008, 06:37:11 AM »

Think about it !!!!

The diagnostics page shows whether the COMPUTER thinks the switches are ACTIVE or not.

You would appear to be quite correct with the setting for the limits and homes - all should show port 1 pin 12, and all should have the "active low" box with a red cross - in other words the switches are active on a high voltage. Your switches are showing on, because pin 12 is not detecting a 0v signal.

The fact they are all showing "active" when they should be off means that (as in the safety case I mentioned earlier ) one of your switches could be faulty, or one of your wires could be loose, or one of the switches is connected the wrong way round, or the 0v return pin you have selected may not be connected internally in the computer, or to your break-out board if you have one.

As a "quicky" go into config and change one of the active high to an active low - and see if the corresponding LED on the dianostics page changes.

Make sure none of the switches are activated by the carriage.

Then connect a longish wire to a 0v terminal on your board - and, with the diagnostics page open, starting at pin 12, touch the wire onto pin 12 and see if the diagnostic page changes (a multi meter probe with a sharp point would be a good idea ). If it changes, then work from pin 12 backwards through the switches, checking with the 0v probe as each connection.

The  LEDs should change as you "inject" the 0v - until you come to the faulty switch/wire/connection whatever.

On your system - all the LEDs will be lit or out simultaneously. Once you get them out, you are in business.

The three switches will work as limit switches in normal use - have a look at the instructional video about them - and how to configure the system so you can "back off" the switches if hit. If you ask the carriage to "home" the same switches are in use, but their method of working is changed by the computer, until the carriage is homed, and then they revert to limit switches.

794

General Mach Discussion / Re: mach 3 keeps setting itself to incremental in the distance mode

« on: March 23, 2008, 05:38:39 AM »

We have just had this on another post under a different guise.

The problem, I think, is to do with tool width compensation.

If you think about it, on tool width compensation the tool has a "shield" all around it - equal to the tool width radius. It has to be all way round, because unless the tool knows exactly which part of the tool is in contact with the work, it does not know in which direction to apply the compensation.

If you start at the centre of a circle (0,0) say of 1 inch diameter with a 0.25 bit, then the bit will travel out to (0.875,0) to start. There will be no compensation on the Y movement - because there is no movement on that axis.

If you then describe the circle, both axis are moving, therefore both will be compensated.

When you get right round and are approaching position (1,0) again the cutter will actually stop at (0.875,0125) - short of (0,0) on both axis (actually slightly less than 0.875 on the X) but you get the idea.

Depending on how the code is written, either the cutter will pull out and go back to centre, then repeat - with the same effect, or the cutter will take another pass, and overcut the part it had missed, but somewhere you will be able to see it.

How do you get round it - it depends - if there is no material in front of the cutter, you can move the cutter the extra 1/8" or whatever. I have not tried turning off the cutter compensation - and moving to (1,0) so whilst this would correct the Y axis shortfall, I am not sure of the effect on the X axis.

The complete answer is to program the G2 or G3, without cutter compensation on.

That is the theory from observations I made when cutting some (largish) windows with rounded corners with a large routing tool - it would never get right round. I had to compensate by starting halfway down a straight side and over-running on completion.

795

General Mach Discussion / Re: six phase stepper reprogram?

« on: March 22, 2008, 09:37:34 AM »

A bit late in the day to come on this  one, but I hate to see a 0 on replies.What is is exactly you are thinking of.

Something to do with a six wire motor. I have just been wiring up a new drive, which is four wire, and the diagram shows a six wire motor wired to four wires, by ignoring the centre wire of each set. - so you can use what is now I think a standard four wire stepper driver. My 8 wire motors are wired in series to a four wire driver.

Now I read your post again, and have my brain switched on, I think this might be something to do with trying to drive an inverter for your spindle drive.

I cannot see where the small pic boards for hobbyists fit in, although I have done a fair bit with PIC chips

796

General Mach Discussion / Re: mach 3 keeps setting itself to incremental in the distance mode

« on: March 22, 2008, 04:48:12 AM »

When you say an arc - is either of the axis reversing direction - if so have you got backlash configured. If there is backlash, and you have not got it on, the arc will not be machined correctly.

Is there any tool compensation inserted - G41 or G42.

I can't think of anything else - but some of the G Code experts might help.

797

General Mach Discussion / Re: Mach is turning the wrong motors, outputing on wrong pins!

« on: March 22, 2008, 04:39:01 AM »

I use the demo version without any problems.

You say the jogging is off - but what about code. does a G0 on the x axis produce x axis movement, similarly with the others.

The only thing I can think of is check you jog configurations on the Config/Hotkeys page.

798

General Mach Discussion / Re: Home switches

« on: March 22, 2008, 04:32:35 AM »

Get the home switches done and configured.

What are you wanting to do with the spindle - do you mean an index counter to check the RPM - if so that can use any input wire and be configured the same way as the home switches.

799

General Mach Discussion / Re: Laser Gunsight

« on: March 22, 2008, 04:25:37 AM »

Yes - I,ve read Brunsons site - not sure I understood all of it. The problem is without the kit you can't do anything.

Your idea of relecting the laser bean say onto the ceiling or even back behind the laser - to give it a longer travel, then adjusting it to zero movement might work - I'll give it a try.

If I home the beam at the chuck, then insert the mirror, then move the carriage to the other end, I should see even quite a small movement.

800

General Mach Discussion / Re: Laser Gunsight

« on: March 21, 2008, 04:55:42 PM »

Thanks Rich - I think I understand the principle, we studied something similar in physics at school, but that was 50 years ago. I'll have a look on the net.

I think I have decided to always home near the chuck (although it does negate some of the design principles of the laser sight). I only use the far end of the lathe if I am finishing wheels on axles for the railway, although I must admit there will probably be other applications I can think of.

I still have not got used to, nor do I trust, my lathe repeating time after time to the same accuracy, so to be able to zero to the lathe centre at any point on the lathe bed would be an advantage.