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Messages - jimpinder

631
General Mach Discussion / Re: Calibrating each axis?
« on: May 07, 2008, 09:51:15 AM »
Yes - you have calculated your steps per inch correctly - that does NOT now need fine tuning. What you need to do is TURN OFF backlash compensation. Move to the right.Stop. Set up your DTI on zero. Move 1 inch to the right on an MDI command (to ensure that Mach 3 puts out the correct number of pulses). Move BACK one inch on an MDI command.

In theory your DTI should read 0 - but I don't think it will. Whatever your DTI reads is the backlash you have in your system.

Enter this in the backlash and switch it back on.

Do not expect Mach3 to apply backlash so you don't notice it. It starts, stops, starts again, stops and then finally gets going. You are quite right, you can adjust the speed at which it does it, but I wouldn't put it up too fast - maybe 50% if your top speed is not too fast. It does not matter in the scheme of things - what you are after is accuracy - not a ballet. Backlash is accurate - mine is about 56 thou - (I,m working on it - maybe these super dooper ball screws are called for) - and in the end my system gets there. I did some ball shapes on a rod the other day (in brass) and you couldn't see the join.

632
General Mach Discussion / Re: input value in DRO
« on: May 07, 2008, 09:41:27 AM »
When I read your post again, you are saying that what you want to do is enter a diameter in the A axis - I don't understand this - what DRO are you trying to access. The A axis is linear or rotary - as selected in configuration. The A axis DRO shows either the number of degrees you are moving, or the number of inches. Diameter does not come into it

Similarly with the tool change - have you got anytools entered in the tool table - they must be entered before they will show (I have just tried mine but it will only enter up to 88)

633
General Mach Discussion / Re: input value in DRO
« on: May 07, 2008, 09:26:52 AM »
Pierre - Stop jumping up and down.

In Mach3, you can enter values in the DRO's. You do not need VB's and anything else exotic. If you cannot do it, then you have a fault.
Mine does it, Hood's does it, most other people's will do it.

Lets get back to basics. What is your set up. You have downloaded Mach 3. You are using a thinkpad X3 (is that an IBM machine) running Windows XP. What other bits and pieces have you got on the machine - what machine are you trying to run. Why have you got a joystick attached.

What you should be able to do is - on a DRO that is showing program co-ordinates (not machine co-ordinates) - click on the DRO to locate the cursor, Type in the relevant position, Press return - the DRO should have reverted to it's normal colour and your information should be displayed. If you do not press return but go straight to another DRO (or something else) the first DRO will revert to what it was showing before you started.

You seem to be saying that your computer is not doing this  - are you sure you have the correct procedure.

634
General Mach Discussion / Re: Calibrating each axis?
« on: May 07, 2008, 04:56:45 AM »
In your 10,000 "steps" are you including micro stepping by the driver - maybe 8 or 10 or even 16 microsteps. Stepper motors do not stop accurately on microsteps.

However to echo Chip - this is backlash.

Your problem is in your fine tuning. You have tuned this problem into the system.

Back lash is the non-movement of the axis - and from what you say appears to be about 7 thou on your system. That 7 thou is a constant on any change of direction - and should be taken up before the axis moves.

There should be no need to "fine tune" an axis drive - it is a mathematical formula - x number of steps per rev of motor - y number of revs per 1 inch of movement - answer x times y. (Mine is 60,000 - if you are using a metric screw for 1 inch of movement the result is not as neat - but is still calculable)

What you have done is fine tune out the backlash and shared it along 1 inch of movement, so you are actually moving maybe 0.1007 for every 0.1 of an inch. Move 10 times for the inch and this gets rid of your backlash. However - for the first tenth, there is still a full 7 thou of backlash -maybe nearer 8- and you have only compenstated for 0.7 of a thou. On the second tenth you have compensated a bit more, but you are still short - and so on one up to 1 inch where you are accurate.

What you must do is calculate your steps per inch - and put this in your motor tuning.
Check then to see if there is any backlash. Move the axis to the right, Stop, Setup your dial test indicators and Zero them. Move to the right a further inch using a G0 X1 command on the MDI line and then move back using a G0X0 command. Check your DTI and the result is the backlash - that distance the axis doesn't move as the gears etc, settle in to push the other way. (You dont have to actually move as far as an inch - backlash is not dependent on distance - half and inch or quarter would do - as long as the movement is equal.)

7 thou actually seems pretty good - I would hate to tell you what mine is - and you may be able to adjust it out mechanically - but despite what everybody says, there will still be some. If everything was so accurate - nothing would move - it might, however, be so small as not to be noticeable or measurable.

Enter this amount in the backlash table and turn the backlash on. You should then get accuracy all along the range, because the backlash is taken up first by Mach3.







635
General Mach Discussion / Re: input value in DRO
« on: May 07, 2008, 04:05:54 AM »
Make sure the reset button is not flashing when you are trying to make any changes.

They will not change if the machine needs resetting.

636
Better still - I f you have the "Auto Limit Override" selected, this will allow you to reset the Limit Switch and back off the switch automatically. It then resets it to the limit again.

637
What system is your computer running ???

638
General Mach Discussion / Re: Moving off Limit switch
« on: May 06, 2008, 01:23:56 PM »
If you select the Settings Page and tick Auto Limit Override - this will allow you to back off the switch.

Without being pedantic, you shouldn't make a habit of hitting them - you can set your soft limits to avoid it. The limits are there as a last resort.

Yes - you are right - if you turn off the limits - your switches get wiped out, which happened to me a time or two. My limit switches are now laser beams shining on detectors - which avoids the crunch.

639
General Mach Discussion / Re: Urgent Help needed with Screen4
« on: May 06, 2008, 12:54:11 PM »
Thanks Scott - I'll have a look at that

640
General Mach Discussion / Re: Urgent Help needed with Screen4
« on: May 06, 2008, 06:35:09 AM »
Thanks for all the replies lads, I got the screen done.

Still don't know how to do the overlay for the blue screen, unless it was done with some other artwork program - but the main thing is the buttons. The tutorial I saw obviously referred to one of the earlier programs.