Hello Guest it is March 28, 2024, 07:00:40 PM

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - jimpinder

441
You have no need to run the machine to find out whether your switches are active or not.

If you look on the diagnostics page there is a full read out of the switches, in real time.

If you connect your switches and look on the diagnostics page, then they should NOT be lit until you activate them. Activate them manually and see if they show up. If they do, you know they are working correctly and can take your hand off the reset.


442
If you  have the cutter offsets "ON" then Mach creats a "barrier" round the tool, equivelent to the diameter of the tool. If you are cutting a circle, this is apparent, becasue the tool is on the inside, (or the outside) of the circle, so the path the tool decribes is not the diameter you asked for, but is the radius minus (or plus on the outside) the tool diameter.

However, it is clear, on a circle, that this barrier must ne all the way round the tool, since at some time or another, all the tool comes into contact with the work.

When the circle is complete - say you have asked it to go all round from X0 to X0, then it does, buts stops short of X0 by the tool diameter when it arrives.

You can either describe the circle by putting the radius described by the tool centre (and doing away with the tool diameter offset), or adding a further line to make the tool go over the X0 line by adding in an amount equal to just over the tool diameter.

443
General Mach Discussion / Re: homing swithes
« on: July 07, 2008, 01:20:15 PM »
You must try and understand how the LPT1 port works. All the input lines are pulled high +5v by internal pull up resistors. If you have the limit switches activated (but no limit switches attached) then the inputs are at +5 volts - and as far as Mach 3 is concerned this is the active state - so the led's light up.

To cancel the leds, then you must go into Config/Ports and Pins/Input pins and tick the  limit switches as "active low". This means that Mach3 will only recognise the switches as "on" when there is a 0volt signal on the pin.

When he connects the limit switches - what does he do - in other words, when the switch is NOT activated, what signal is connected to the pin - a 0v or a 5 volt. If nothing is connected, then the pin will assume a 5 volt signal with it's own pull up.

When the switch is activated, what does it do - does it connect thepin to 5 volts or 0v. If 5 volts, then in Post and Pins/Input signals, that needs to be shown as "active HIGH" in other words the "active low box is unticked. If 0 volts then the "Active low" box needs ticking.

You should be able to connect your switches, and see on the diagnostic page, the switch switching when you activate it manually.

444
General Mach Discussion / Re: Progressive Move Error with X and Y
« on: July 07, 2008, 04:03:37 AM »
We are getting bogged down here.

I will return to the point I made in my first (and only) post - which has been , to a certain extent, picked up by Brett.

I have not seen yet where you have calculated your steps per inch movement for your axis. I know you say you have done thousands of tests til you are sure it is accurate, but any measurement is suspect.

I have said it before many times, and I will say this again - not because I am stubborn (which I am) - but becasue it is a mathmatical fact - steps per unit should be calculated not measured..

Can you please tell me what result you arrived at when you calculated your steps per inch.

I do not know how many steps per inch you arrived at - but if this is out, it will not show up on moving a table up and back. Your measurement could be in handspans - but as long as you went up three handspans, and then back, you would arrive at where you started.

If you have a relatively small number of steps per unit, your error, if you have made one, will be greater, although if these are clock parts I would have thought you would have a large steps per inch for accuracy.

When moving two axis together, the axis moving furthest takes the lead, and moves at what speed is set. The second axis has to move as per the tangent of the first, not often a precise number, at whatever speed is set, and the figures for the steps the computer puts out are necessarily truncated. Again, if you have made mistakes, then the calculation of tangent is being made on a mistake, which again, must produce a larger mistake.

I do not really want to get involved in this post, becasue I have laboured these points often in the past, but I would like to see some calculations for your steps per inch (for both axis, if not identical) and then perhaps we can pursue Bretts worry about your backlash.

In the post you quoted an error of 0.00035 - am I correct - are we talking about 1/3 of a thousanth of an inch. I do not have kit that can measure that accurately, and I do not think my hands and eyes could use it if I had.

They only problem  - going back to your steps per unit - if you are looking at errors that small, you are looking at a small number of steps
My steps per unit is 60,000 per inch, actually 6,000 if you ignore the Gecko microsteps - i.e. 6 per thousand - so 1/3 of a thousanth is two steps. If you have fewer steps per than that, one step could be 1/2 a thou.

Have you tried, on your motor driver lines, ticking "low active" for steps and direction (or vica versa if they are already on active low) . For your breakout board, it may be that the first step is missed if your output lines are artificially held in one state or another.




445
General Mach Discussion / Re: Spindle speed
« on: July 06, 2008, 03:49:42 AM »
The spindle speed will not affecr Mach 3. I do not think the difference between 200 and 350 will matter. The thing that matters is the top speed - i.e. 3500.

How is you spindle motor controlled now. Does it need an input voltage to control it from the computer?? You may need a Digispeed PWM to Voltage converter.

446
Thanks Chip

KTM -
1. Are the sizes of the sheet metal standard - e.g. 8 feet by 4 feet etc
2. Are you wanting to be able to specify different sizes of piece on each
3. Having specified the size of work do you want to calculate best fit  and how many you can get out of each.
4. I take it the bed of the machine is fixed, so any different angles of cut would have to be software induced.

447
General Mach Discussion / Re: Setting up a 4th axis?
« on: July 06, 2008, 03:11:58 AM »
I can't understand all this.

Can you get a 36 to 1 gearbox - then all your theory is solved and all the sums cancel out. There are 360 degree in a circle - why bother with 30 unless you are forced down that road. Failing that, put a 5 to 6 step down between your motor and gearbox, using toothed pulleys - say using 10 to 12 teelth pulleys - this will also cancel out your 30 ratio gearbox and give you a simple figure of 36 on which to calculate steps per degree - and enough has been said about that in the past.

Hood - in my experience there is no backlash in modern toothed belts - look at car timing belts. The only error is that particulary tooth having a little bit of play with the corresponding gap in the belt, but since there are many teeth in contact with the belt, the resultant movement is non-existant

448
I have tried to have a look on the web for a diagram for Galil boards - but without success.

You do not say what board you are using.  The part of interest, however, is only the breakout board, since the drivers are sorted anyway.

If, on the Galil board, your inputs are identified for you, then test each one with a voltmeter. They will be held high +5volts, or low 0volts. If you are using normally closed switches, then your switch should be connected to the pin and the opposite voltage line.
i.e. if the pin is normally high, then the switch is closed and connects the pin to 0volts. When the switch opens and disconnects the pin from 0volts, the input is pulled hign and gives a signal to the computer. (or vica versa for 0 volts)

If your computer is connected, you should see the switching on the diagnostics screen. You must then configure the input on Config/Ports and Pins/Input Signals.

You can either connect each pin individually or all the pins in series - but come back to that when you get the first bit sorted.

449
Sorry - I'm having a great deal of difficulty downloading the file - can you post it again.

450
General Mach Discussion / Re: classes on g code and mach 3
« on: July 05, 2008, 09:27:02 AM »
I must agree that most of my code is now a step up from writing lines of code longhand, because most of my regularly used programs are GCode macros in Vis Basic. I fill in various parameters and the Vis Basic generates the GCode directly to the machine, I never even see it.

All in all then, get to know your way round GCode, but don't spend too much time on it, there is lot's more fun to be had with good CAD and CAM programs.