Messages

1081

General Mach Discussion / Re: where is my calibration.....

« on: September 30, 2007, 04:49:38 AM »

To calibrate you machine -

Have a look at the setting for the motors as they are set - or set them at a reasoanble figure to start with.

Move the axis by one inch on the DRO , measure the ACTUAL movement of the axis.

The number of steps per inch is equal to the number of steps the machine is set to, divided by the distance the axis actually travelled.

Bear in mind stepper motors are usually 1.8 degress - i.e. 200 steps per rev,(multiplied by motor settings - e.g. 1/8 step or whatever)  multiplied by any step down you have to your axis, multiplied by the number of turns per inch - so it is usually a round figure - in my case 64,000 - so if your answer above comes out to 63,995 - give it the benefit of the doubt.

1082

General Mach Discussion / Re: Why won't the pins go low?

« on: September 30, 2007, 04:33:23 AM »

Why are you using the Axis enable  - they should be on anyway. On my drive cards each axis can be turned on or off by switching a switch on the card, or connecting an external signal to an input.

Switch the axis on at the card and leave it on - it has to be on anyway. I happen to have my external connections to switches on the control box so I can turn each axis on and off manually if I need to ( I have a lathe with a milling head - so I turn the milling axis off so power does not go through the stepper all the time).

You should find that when you attach Mach3, it will work. You are just making things complicated.
I cannot remember if Mach3 automatically puts out an enable signal  on the Enable pins or not. You would have to tell Mach 3 which pins you are using as enable pins anyway - on the Ports and Pins config if you wanted to use them.

1083

General Mach Discussion / Re: z after running file

« on: September 30, 2007, 04:16:39 AM »

I do not understand your problem.

Either your tool IS slipping - or you are not starting at the right place - it is as easy as that.

You do not say how you set up the machine before running. You cannot throw the work on the table, and set the machine off - you must somehow zero the machine to tell it where everything is. Neither do you say where your GCode program expects  X0 Y0 and particularly Z0 to be

Although most of my work is with the lathe, the same things apply using the mill. In my case my GCode starts with Xand Y position 0 on the bottom left hand corner of the work AND Z 0 is when the tool is just touching the work surface - I then zero the DRO for Z. My first move in the code is then to lift Z and move it to the start of the cut.

If you ARE doing that then you either have a serious problem with your Z axis missing steps, or your code does not actually finish where you think it does.

1. Run the program on Mach 3 without the machine connected - and see where the DRO's are when it is finished.
2. The only problem with my milling attachment was that it had a strong spring on to hold the weight of it. Using it manually you never noticed, but putting a stepper on it was difficult - in that the stepper had difficulty in driving the head DOWN against the spring. I had to unravel the spring to make the head more balanced.
3. I take it that you have adjusted and corrected backlash and all the other bits and pieces.
4. Go through your tool table, especially for the tool number you are using, and delete anything to do with tool length. Make sure in geneal config, etc anything to do with offsets is off.

It follows that your Z height should always follow the DRO (as should the other Axis) - insert some pauses in the Gcode and check the various positions at different places in the program.

Finally put your Gcode on the forum and see if anybody else has the same problem with it.

1084

General Mach Discussion / Re: Constant velocity

« on: September 27, 2007, 03:01:56 PM »

I have read through this post and I am getting a little confused as to what we are trying to achieve.
As far as I understand, CV is a system that comes into play when the motors cannot decelerate and accelerate quickly enough to achieve instantaneous speeds required, constantly. The computer therefore decelerates one axis as it accelerates the other so the speed of the tool is overall constant. I don't know if anybody has studied the resultant curve or not  - is it circular, parabolic or what. I dont suppose it matters.

You can turn this effect on or off - and the off position should result in a sharp angle of cut.
A question - IF THE COMPUTER CAN ACHIEVE A SHARP CUT, WILL IT DO IT REGARDLESS OF WHETHER CV IS ON OR OFF

I understand that you are able to alter CV Distance and CV Feedrate. I can only assume that these two parameters only come into play if CV is ON - if it is off the computer will decelerate to 0 and then accelerate up again. I cannot see that you need both parameters - the computer will compute its dec/acceleration from either the distance it is told to start from, or the feedrate it is told to maintain round the shape - I cannot see how it can do both.

As far as the angle is concerned - Stirling - keep it simple.
Try a right angle and run with CV mode on.
I assume the feed rate must be pushed fairly high or the motor will be able to start and stop quickly enough - and up it until you are clearly getting a rounded corner.
I would try the Stop CV on angles, and try ENTERING from 88 to 92 - it may be that at 90 - if it is programed to stop when angle >90, it doesnt catch it - and see where the change from round to sharp occurs (if it does).

I cant see this diatribe will help much, but I cleared it up a bit in my mind, anyway.

 

1085

General Mach Discussion / Re: zero doesnt equal zero?

« on: September 27, 2007, 06:00:55 AM »

Kent - glad you have it sorted. The tool length is not important - if you are using one tool - or if you touch the work with the tool tip and zero everything. The machine needs to know where it is in all respects.

It is the same with limits and homing. You can set soft limits which will stop your machine banging the physical extremeties of the machine, and, as you say, knocking everything out of kilter.

As for homing - I do not bother, since I much prefer to set each piece of work manually before I cut it. If you are in a high cost, low volume scenario, I think this is better - i.e I like to know I've checked evrything before setting the machine off - it saves ruining a piece of work that I might have spent some time on beforehand.

If it is low cost, high volume, then yes - get the machine to go to a home, throw in a workpice and press the button. If you spoil the odd piece it doesn't matter.

You will probably come up against another offset shortly - I assume you have set up backlash - that is tool width. If you are doing circles and other complex scrolls, you will have to take notice of tool width  and set the machine to compensate for it. - it is great fun to watch the machine cutting something you have designed.

Jim.

1086

General Mach Discussion / Re: lazycam pro

« on: September 26, 2007, 06:45:35 AM »

Les - I have Turbo Cad version 6. I have had it for a few years. I have not had much success with Lazy Cam either. particularly if I drew and posted a three dimensional drawing. There just seemed to be two much information for Lazy Cam to interpret. A two dimensional one worked - but it couldn't tell the inside from the outside.

You are not alone !!

1087

General Mach Discussion / Re: zero doesnt equal zero?

« on: September 26, 2007, 06:40:33 AM »

I'll go along with Stir;ling - having looked at the road runner file you posted, there is only two z positions, one is Z0.2 and the other is Z-0.1. This is the first time I have looked at this file, and I am suprised to see that there is an entry for X,Y and Z on each line.

It doesn't actually matter, though, because the tool should only move if it is different to the previous entry for that axis.

As Stirling says - and you can check this - the first movement is 0.2 and should be up, the only other movement is -0.1 which is 0.3 down from its upper position.

When you have jogged your axis, I assume you put the x and y at the start position, touching the work, and the Z axis is positioned with the tool just touching the surface of the work. DO NOT FORGET to ZERO the Z at this position.

The first move should be up - away from the work, and the second movement should be down. If it is the opposite way check your ports and pins and check the direction pin for the Z axis. If it is checked for active 0, uncheck it, and vica versa, and the direction will alter.

I read you first post again, and I think where you are going wrong is messing about with the Z axis at all. Clear all your offsets, particularly tool depths etc. To get going, merely touch the tool tip on top of the work and set Z DRO at 0. This will tell the machine where it is (in relation to the depth). As we said - from there it should go 0.2 up, move, then go down to position -0.1 which is 0.1 into the work (since you set the top of the work at 0).

1088

General Mach Discussion / Re: What is disabled in the unregistered version ?

« on: September 24, 2007, 07:47:12 AM »

Phil -

I am using the versi9on of Mach3 that is downloadable from the internet.

As far as I know, there is nothing disabled in the program itself, and it certainly all works fine on my set up (both lathe and mill)

The only thing I know that is limited is the number of lines of cade that can be used, and the downlaodable version is limited to 500 lines of code.

Lazy Cam and I suppose other add ons are limited

Jim

1089

General Mach Discussion / Re: lazycam with turn

« on: September 24, 2007, 07:42:42 AM »

I do not think you need lazy cam to work your lathe.

You have only two axis. Basically you set one axis to a diameter (or radius) and then cut with the other. It is very simple to write code to do this.

With CNC you can, of course, round the end of a bar, which is a G2 or G3 move.

The most difficult thing I have cut so far, is a handrail post, or stanchion, which is a bar with round end (for the top rail),  a round knob halfway, (for the middle handrail) and a half round base. I managed to program that with a CAD program, then wrote the GCode.

I would have a go at writing GCode first to get going.(There are tutorials on the Internet) I have tried lazy cam with the lathe without any success - and I think there is still a bit of development work to be done on it.

1090

General Mach Discussion / Re: Macros, Visual Basic and all that

« on: September 24, 2007, 07:24:06 AM »

Thanks Stirling - I was away yesterday, running the railway, and also thinking about it, and realised that I had not written the code correctly with while and wend, and if and end if and I wondered if that was where the fault lay. I telephoned my daughter who was also working on the same prog, and she sorted it - it works OK now.

Yes - Vis Basic is completely new - my last major brush with code was Pascal (some years ago) and recently some Microchip PIC chip programming for a signalling system.

The trouble is you are always playing catch-up. Still - Mach3 is first class, and has - and will - make a big difference to my engineering.

Jim