Topics

1

General Mach Discussion / Reading a pwm signal into Mach 3

« on: August 31, 2015, 04:26:32 PM »

Hi,

I have an application where a want to control 4 servo motors using Mach and make their speed relative to another control system which puts out a Pwm signal, is it possible to read this into Mach? I think I can handle a script to make it adjust feedrate if I can get it into a variable.

Any ideas?.

Thanks

Matt

2

General Mach Discussion / Plasma accel values, position accuracy and cut speed, servo tuning

« on: January 31, 2013, 04:42:39 PM »

Hi,

Im looking to get the views of plasma users on my set up/ tuning.

I have an old boc falcon which i have fitted up for cnc with mach, i have two 250w dc servos on the x and one on the y, whale drives from cncdrives.com driven with rack and pinion.

For anyone who is no familiar with the machinery it looks a bit like this

http://fplreflib.findlay.co.uk/articles/22842%5CESAB_refurbished_cutting_machine_main.jpg

My plasma is a hypertherm max 100

I have been asked to do a job in 3mm steel with loads of 3mm holes and slots and i told the guy im not sure but i wanted to try so i found at 1000-1500mm/min i could operate reasonably well at the proper cut speed 2000mm/min or higher the cut was hopeless, most lines look like saw teeth.

Really what im after knowing is do i have a problem i need to find or am i tryin to achieve something thats impossible? After trying some parts in steel i tried some on paper with a pen, with my aceel valu at around 15-20milli gee's the paths were pretty straight but at the 40-50milligees that people say you need for plasma the machine just resonates back and forth whilst cutting these small parts, but at the 15-20 value when trying to achieve 4m/min the machine never gets up to full speed when cutting the perimeter of a 50mm square, but the corners are perfectly square, is that a problem? When running these parts if i get the error viewer up for the x and y axis i never see more than what equates to 0.3mm error even under the highest acceloration so i was kind of thinking my motion looked good in terms of position error and the trouble was caused by mechanical resonance in the frame.

Where would a proffesional go in trying to improve this?

Matt

3

General Mach Discussion / Simple code for simple shapes

« on: December 20, 2012, 02:49:26 PM »

Hi,

Im a mach user of several years and i love it, i had a friend call me today and ask if i could help him, he has a gas profile burner which copies a part and woul like to convert it to cnc. He makes really simple geometirc shapes, circles from 2 inch plate to turn into bearing housings squares rectangles etc and its really important that i can get him the ability to generate code for tese simple shapes easily, i mean really easy, hes not fussed by work offsets, he knows his nozzle has a set kerf and is happy to add it to the size of shape, he needs no z axis at all, no gas on and off, he literally needs something that will run along a path when he presses the cycle start button, what is the best way to do this? I looked at wizards, very close but most of them seem to be aimed at milling operations, is it something i could develop easily myself?

Thanks alot

matt

4

General Mach Discussion / Acceloration, cv settings and cut speed

« on: April 29, 2011, 09:11:18 AM »

Hi,

Ive recently built my second plasma table using servos, my first was using steppers. I have been having trouble reaching the recomended cut speeds in the book for the plasma but have found that when i decrease the acceloration value i can achieve much higher speeds, using the servo configuartor sofware i have i have tuned the servo drives so that the following error is pretty small so i think that is ok but if i reduce the acceloration enough to get the correct cut speeds my accuracy is hopeless, i never encountered this problem with the steppers, is it likely a cv problem or a servo problem, im sure the first response will be asking for more detail about the machine but i thought i should ask a general question and hope for some advice.

Thanks alot

Matt
 

5

General Mach Discussion / Spindle speed

« on: March 25, 2011, 02:32:25 PM »

Hi,

Im looking to try to use the pid loop available for spindle speed to do other things, im feeding in a pulse on the spindle index pin which is being recognised, is there a dro number for where the resulting spindle speed is displayed that i can pick up in a brain? Is it possible to pick up the outputs of the pid loop in a brain aswell?? I want to use the pid loop to control the z axis position, if i were to select the step/dir control in the spindle setup and then configure it to my z axis outputs which are also used byt he g code im sure it would cause problems wouldnt it??

Sorry if i m being a bit vague!

Matt

6

VB and the development of wizards / Frequency input from pp to vb

« on: March 10, 2011, 04:53:42 PM »

Hi,

Im looking to read a frequency input from the parrallel or serial port into a macro, is this possible?? Forgive me if im being thick but im not too up together on macros.


Matt

7

Brains Development / Average stuff

« on: March 09, 2011, 02:11:30 AM »

Hi,

Im looking to take an average of an analogue input over a period of time, maybe also a couple of inputs averaged into one oem dro, im struggling to see how to do it with timers and things, any ides?

I need to do something like continuosly sample the inputs(s) and give an avergaed out put every 0.5s from the previous 0.5s.

Thanks

Matt

8

General Mach Discussion / Analogue Inputs

« on: February 25, 2011, 08:47:15 AM »

Hi,

I was wondering about analogue inputs, what is the fastest and most effective ways to get an analogue figure into mach?  I have a pokeys 55, but i read that the information is relatively slow to update, i have also tried a gecko g100, is ethernet faster or better than usb? Is there and easier way? i was interested in getting it into the serial port but there is no serial in.

The alternative is turning it into frequency, would that be more effective??

Thanks

Matt

9

General Mach Discussion / Pierce delay for plasma

« on: February 10, 2011, 07:17:21 AM »

Afternoon,

I have just changed my plasma cutter to one which has a arc ok signal on it, it seems to activate this signal as soon as the arc has transferred not once the plate has been penetrated, this means that when i have the thc mode set on in mach as soon as the arc transfers the machine starts to move but the arc hasnt penetrated the plate, i need to get some kind of a pause in there so i modified my sheetcam post processor to have a pause at the right time but mach seems to ignore it and as soon as it sees the arc ok signal it goes to the next line which has a machine move in it, any ideas why this happens? or if not any ideas on how i can get round it??

Help would be greatly appreciated

Matt

10

General Mach Discussion / Setting steps per unit and pin assignments

« on: January 18, 2011, 02:52:26 AM »

Hi,

This morning ive finally got my servos working with mach, trouble is they arent! My firat problem is with pin assignments for step and direction, i have the x working as the y and the y working as the z, if i change the pin asignmnets it makes no difference, i remember this from a previous installation, i simply swapped the wires around then, should i do that now??

The next one i also remember from before but i dont remember how i got over is the steps per unit, if i use the set steps per unit macro the axis will move 35mm no matter how far i ask it to move and when i put in the new number of steps per unit the axis still moves 35mm??? Any ideas, i know i had the problem before but i dont remember what i did, i was initially worried about native units but that is correct so im not sure??

Any help would be appreciated

Matt