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Messages - matttargett4

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21
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

22
General Mach Discussion / Re: Setting steps per unit and pin assignments
« on: January 18, 2011, 08:49:23 AM »
Hood,

Sorry for showing my ignorance, what do you mean by manx nc and max cl??

Matt

23
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

24
I have also not given up!

Summers are very busy for me, im a farmer! Add in that just after i last posted i got offered an old esab magic eye machine for cheap, which i bought and then sold my home made contraption and you understand my absence, its a weak excuse i know! The stuff still goes round in my head buut i just dont get to note it down.

Heres where i am with it.

Im trying to build a new machine to improve cut quality, speed, accuracy etc etc, i have bought a larger transformer type plasma and everything i read tells me my results will only be as good as my thc. As you may have read ive always been of the opinion that using your pc for the processing seems obvious to me, the trouble is you have to get the signal there and get it back again, im sure its quite possible and could be very fast and accurate but we have to be able to integrate it with mach and make it quick and easy and cheap. Invarialy if you want to get it into mach you appear to have to use modbus, this gets accused of being slow which personally i dont buy but for me i think where it falls down is the modbus devices availabe with analogue inputs lack flexibility, fo instance we ended up on much debate about if the voltage signal from the plasma needed to be inverted, if you were able to use a different device with more flexible analogue inputs then maybe it wouldnt. The other thing that worries me with any mach based system is that the only ability we have to adjust the z on the go is simple up or down with no adjustable speed, thats ok but for best results surely a servo responce is required?? My new z axis also has a straihtforward dc window wiper motor on it as it was only ever meant for gas cutting, but this is what the big boys use, so im thinking that in order to make the system as cheap and simple and effective as i can im going to have to sell my soul a little, im thinking i will use a pic or plc connected to the dc motor with a motor controller, much like a servo drive and with an encoder so speed will be infinately variable using a pwn about from the processor allowinf a servo response,. this will integrate with mach as if there were no z in mach, mach has the x and y co ordinates correct and wishes to start the cut it will send a signal tot he plc and the plc will control the z axis move down to the metal, touch off, fire the torch and when the plasma gives the ok to move signal it wil move, the plc then monitors voltage and thc.

It may sound complex but i think it might work and be easier and cheaper!

matt

25
General Mach Discussion / Re: Slaved axis steps per unit
« on: November 08, 2010, 08:35:18 AM »
Thanks hood, so that wont work then? CAn you think of any other solution apart from changing the mechanical gearing between the motor and the axis??

matt

26
General Mach Discussion / Slaved axis steps per unit
« on: November 08, 2010, 02:17:13 AM »
Hi,

Im just wondering if i can tune the steps per unit 4 2 axes separately and then slave them with mach allowing me to have a different gearing from the motor to the axis on either side of my x axis but still slave them together??

Its a servo system if that makes any difference.

Thanks

Matt

27
I think im in the same camp as stirling there, there is no avoiding it is negative with respect to true earth and so has to be inverted

28
General Mach Discussion / Mach and multiple screens
« on: April 12, 2010, 02:09:05 AM »
Hi all,

I was just wondering if i was to get a second monitor for my pc would it be possible to display the program run screen on one and the toolpath on the other so i can have a large toolpath display and still have control of the machine?? Im thinking touchscreen for the one that would do the controlling and just a monitor for the other one?? Any thoughts?

Matt

29
Im interested to know what you find when you do it stirling?

Matt

30
The bit that is causing confusion i think is that the plasma clamp which everyone calls the earth clamp is actually the positive side of the circuit and the torch is the negative, meaning that if you connect one side of the meter to true ground (a ground pin into the ground) and the other side to the clamp on the plasma (positive side of the plasma) you will read a few volts positive or negative, maybe 2 or 3, if you move the meter to the torch and true ground you will measure - 300vdc when firing into open air and -80 to -120 volts ish when cutting.

Hope ive confused you some more!!

Matt

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