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Messages - jimpinder

311
General Mach Discussion / Re: lpt problems
« on: September 16, 2008, 11:40:26 PM »
There is no connection between the port and the printing software when used for Mach3. A completely different set of drivers are installed to run the port, so it is not a throw back to it's printer days.

What you seem to be saying it that you have a detector on your spindle. You have applied this to pin 13 of the LPT1 socket. I assume you have set this up on Config/Ports and Pins/Input signals as the index input. I assume you have tested the iput - i.e. it gives a good signal when not connected, and when connected, the input shows up on the diagnostics.

Does it work ?? Do you see the rev counter count when you fire up your spindle.

Are you using a BOB board, if so which one. Does this reverse the inputs. The input pins on the LPT1 are normally held high by internal resistors (so this is their normal OFF position) your input should be active low, (to the LPT1 - not necessarily to the BOB)  i.e. your detector should go to 0v to give an index signal.

I cannot see that holding the index signal high (it's normal OFF state) can give a signal OUT on other pins - these are to your stepper motors, I presume. Are these through a BOb as well.



312
General Mach Discussion / Re: Bad printer test results
« on: September 16, 2008, 11:20:49 PM »
Jeff - I was going to say that as well - Windows needs nearly all the 256 mbyte for itself, leaving precious little for Mach. When Windows needs some, it just grabs it (it gives it back when it is finished). Get a 500 Mbyte memory card, either on its own, or with your 256 Mbyte already and you will be a lot better.

I say 500 Mbyte, becasue they seem to be quite cheap at the moment. 1 Gig would be even better.

313
This is probably your BOB board - if you have one. Many BOBs have opto isolation and voltage switching circuits in them which alter the timings of the signals from the computer.

Try running your Geckos directly from your computer ports, i.e. by pass your BOB for the step and direction signals and see if this cures the fault.

Geckos are opto isolated, and if your BOB is opto isolated as well this could be slowing things down.

I run Gecko 201's through a non-powered BOB and they work perfectly.

314
General Mach Discussion / Re: Bad printer test results
« on: September 15, 2008, 03:44:02 AM »
You are saying a lot, but not saying anything.

Have you downloaded Mach 3 - Yes/No.
Can you see Mach 3 on the screen  Yes/No

What computer are you using ( + RAM memory size). Which version of Windows are you using.

You do not need any board fastening to the computer to make Mach 3 work. The computer I am using now is in the office, and is not connected to my machine. I have Mach 3 on here to write GCode programs on, and do design work. It works perfectly. I have it running at a much faster speed than my machine will run to save time when checking programs.

Do you have a 25 pin printer port on the computer - if not you might need Smooth Stepper which plugs into the USB, and also does not use the computer to generate timing signals for the drives.





315
General Mach Discussion / Re: backlash for both direction on same axis
« on: September 15, 2008, 03:32:32 AM »
Backlash is a mechanical "shortcoming" made up of all the little spaces between gears and other things in your drive train. If you are down to 0.0001 (1/10 thou) in one direction, it doesn't sound like you have any and 3 thou in the other is perhaps a little high, I like to be + - 2 thou, but whatever - it must by definition be equal in both directions.

I would first check you steps per unit and make sure that is accurate. This should be calculated althoug if you are saying someone else made the machine you might not have all the detail necessary. Check the steps per unit by moving the axis one way and checking the dial indicator and zeroing the DROs, then moving the axis the same way by typing in the MDI line G0 X1 or X-1 as the case maybe. It is essential you move in the same direction, to take up any backlash. Check the distance moved. It should be exactly one inch.

I am assuming you checked the backlash by moving one direction, zeroing, then moving (with the MDI ) in the same direction one inch, and coming back (with the MDI) and checking if you are at zero. (You should be but will not be, there must be some backlash, although whether you can measure it or not is another matter.) This should be done with backlash compensation OFF.
You can, of course check backlash in bother directions. Enter your backlash in the table, and switch on.

If movement is consistantly short in one direction, this coud be missing steps, as your BOB board (if you have one), changes direction, since many BOBs have voltage and signal changing electronics which upset the timings of the signal from your computer. I do not know how many steps per unit your are using, but missing a few could make this difference. I am on 6000 steps per inch (ignoring microsteps, so I woud need to lose 18 steps for a 3 thou error - on your system it may be less)

I do not know what drivers you are using, but most driver boards will drive directly from the 25pin output from the computer. (Mine are Geckos and drive through a non-powered BOB board) Try making a direct connection and see if this alters things at all. You can leave all the rest of the wiring intact, just use a direct link from your computer to your driver for the step and direction pins. Probably the simplest way is to unscrew the output wires to your driver board and fasten these onto your input wires from the computer.

To go back to the opening, however, if you are down to 3 thou and zero the other way, you are doing well, you should see mine (although backlash compensation takes care of it)






316
General Mach Discussion / Re: Machine loosing position when estop
« on: September 13, 2008, 04:46:59 AM »
I'm afraid Mach is NOT guaranteed NOT to loose position when you hit E Stop. That's the whole point - stop the axis moving as quick as they can.

Are you saying the axis stops moving, but the DRO's keep moving, or do the DRO's stop and then the axis slides gracefully to a halt

317
General Mach Discussion / Re: Auto run soft limits when Mach starts ?
« on: September 13, 2008, 04:40:15 AM »
Jeff - As far as I know - and I have just tried this on my "office" computer with Mach (but no machine attached) - if you set up your soft limits in the table, provided the soft limit button is lit when you close Mach down, it will be lit when you restart Mach the next time.

318
General Mach Discussion / Re: Jogging in 3 axis problems
« on: September 13, 2008, 04:26:50 AM »
If the move you are making is all written on one line - e.g. G0 X10 Y20 Z2, then the computer works out the relative speeds of the axis so they all arrive together - as though it were a cutting move, so therefore in the above, if you take the rapid as the axis with the  longest travel, Y, X will move at 1.2 Y speed and Z will move at 1/10 Y speed.

If you put the moves on separate lines, they will move at whatever the rapid speed is for that axis.

319
General Mach Discussion / Re: Home and/or limit switch
« on: September 12, 2008, 02:59:55 PM »
Thanks Blue -

Hood -

Yes - I haven't used the Home off feature before becasue of my laser type detectors for homing, and I have one which homes the lathe without any large movement away from the centre, which as you say, is x0.

Ah Well - there's always something on this bl**** program to swot up on - I'll have to look at that, now, I suppose.

Just spent the day fitting a dremel type unit on the mill spindle, to have a go at cutting copper clad circuit boards. It was a fine idea - a holder went up the mill spindle apeture with an arm on holding the dremel. I though it a great idea, until I fitted it and realised I had no way of locking the spindle, and it wagged about like a dogs tail. So I had to fit a stabaliser, which had to fasten on a post , which had .....

I used to get reports at school - ideas good, execution careless !! Now the ideas are getting careless as well.

See you later

Jim.


320
General Mach Discussion / Re: Home and/or limit switch
« on: September 12, 2008, 04:06:26 AM »
To Blue Pinnacle -

Try using a Darlington array chip. These are normally 18 pin packages 0v, supply voltage (which can be quite high to suit the load) and eight pair of input/output conveniently arranged across the chip from each other.

They can be driven directly from the computer output - and when sent high, the output side sinks to 0v. Each pin can sink 1/2 amp and you can double up input/outputs to drive what current you want.

Best of all the are cheap (less than £1 or 2$)