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Messages - jimpinder

801
General Mach Discussion / Re: Home switches
« on: March 21, 2008, 04:44:17 PM »
You have the idea - but not quite right.

You do not need any 5v supply - this is provided internally by the computer on pin 12

A quick diagram is provided.

As Hood says - you can shield the cable if you require - you can use solid copper if you wish - there should not be any movement - fasten the switch to the frame of the  mill and let the carriage operate it.

Hood also says you can , when you configure the switches, have them act as limit switches as well. This would be a good idea, you dont want the carriage to go beyond the switches or they will be damaged.

802
G-Code, CAD, and CAM discussions / Re: Lathe Gcode
« on: March 21, 2008, 06:12:45 AM »
Start with the lists shown on Mach3 Mill.

803
General Mach Discussion / Re: Breakout Boards
« on: March 21, 2008, 06:00:43 AM »
I am using a breakout board - from Routout CNC (in the UK) - I don't think he makes them - just markets them. It is a "dead" board and just provides any easy way to connect to the computer - and a good strong terminal strip in my "box of tricks".

The connections to the stepper driver boards (also from Routout) are direct from the breakout board. Wirng is so short that no shielding is necessary. I find outputs, for spindle motor, and coolant are best done via relays. Mine are 5v driven direct from the breakout board via a Darlington array chip - all four relays from the one chip. The relays are then connected to the Omron spindle drive inverter, and to the fluid pump. If you need a bigger relay - then keep the small relay - and just get it to drive the bigger relay - don't mess about with different voltages etc.

All my limit and home switches (see "laser gun sight") are wired at 5v - and linked directly back to the breakout board.

So - do you need opto isolation - then only trouble is - if things won't work it is a devil of a job finding where the fault is if you are  trying to check voltages and everything through several "stages" - and the more complex you make it, the more likelyhood you have to make a wrong connection.

I have everything going into my control box on DIN plug connectors, or external connector strips. If anything goes wrong, I can unplug the affected bit and test it - in isolation to the control box. - then open the box and quickly test from the computer to the connector using the breakout board - which is easily accesible. I also have direct access to what the computer is putting out.

In my opinion - and I am aimed at the amateur/semi professional end of the scale - keep everything simple. Try and plan everything to use just one voltage at "ground" level - which avoids any likelyhood of feeding something nasty back to the computer. Isolate simple switching via relays - which guarantee a clean voltage seperation. I must admit that, with drives you are in the hands of the manufacturer, maybe so far I have been lucky. I use seperate boards for each axis, I am unlikely to blow all three at once - and replacing one board is a simple and relatively cheap job. I have just blown one on the Xaxis forcing the motor to push a tool against the workpiece - quite by accident, whilst I was testing something else - the replacement should arrive today.

As for Stepmaster boards - I used them, but found their marketing etc a bit convoluted and long winded- they seemed to work well enough though.
I blew them connecting the power supply the wrong way round one day ( a thing I  have now protected against by using a big diode bridge on the input). I use Routout bacause they offer good delivery times here in the UK.








804
General Mach Discussion / Re: Home switches
« on: March 21, 2008, 05:18:09 AM »
You can wire home and limit switches either way.

You do not need a 5 volt supply. Inputs to your computer are pulled to 5 volts by internal resistors in any case.
You may start at one of the ground pins - 18 - 25, go to the first switch, go to the second switch, then the third switch and then to the computer input which you seem to say will be pin 12. (why 12 - what have you got on the others ?? - you may use 10,11,12,13 or 15).

If you wire the switches normally closed, then this will put a 0v on the input - which will be pulled to 5v when a switch is opened by the carriage. This method is preferred by some, because it means that if any wires come loose, then a fault will occur before your carriage hits the end of travel - but to Mach3 it does not matter,it will work either way.

In you Config/Ports and Pins - show all the homes (if you are doing them all) as Port 1, Pin12.  Do NOT tick "active low"

There is very little current in the circuit, so any thin wire will do - I use wire taken out of a an old 25 wire printer cable. It does not need to be shielded - but do not run it NEXT to stepper motor wires etc that have a lot of changing current. 



805
General Mach Discussion / Laser Gunsight
« on: March 20, 2008, 06:30:43 PM »
Here is a picture of the laser homing device I have just fitted to the lathe/mill.

My Problem was I really needed two seperate homes on the X axis - one when the lathe was in use, and the other when the mill was in use.

I bought a cheap laser module from Maplin at £10. This is mounted on the cross-slide and shines parrallel to the length of the lathe to pickups mounted on the motor housing. The laser unit is mounted in a turned plastic holder and the beam is narrowed by shining it down a 1 1/2 mm x 1 inch long hole in the holder. The whole thing is mounted in a square steel tube bolted down to the table - with a screw adjustment for parralleling it to the lathe. It requires a 5 volt supply.

The detectors are Osram SFH 5840 Scmitt trigger infra red detector. These are three wire - +5v, 0v and output, in a 5 mm round can.
These are mounted in a strip of 1 inch square plastic strip - drilled 5 mm then narrowing down to 1 1/2mm for 1/2inch. The output from the detectors is TTL/cmos compatible and is Schmitt trigger - in other words it changes fast and needs no debounce.They use two seperate inputs to the computer (configured differently on lathe or mill) the outer on (on the right) also acts as a limit switch.

I have tested it all afternoon by repeatedly homing the axis, without the auto zero on, and it homes to between  0 and 0.0001 of an inch. This will do for me.

I have also tried homing with the crossslide at the opposite end of the lathe instead of near the chuck - and have managed homing between 0 and 2 thou (it will home to the same tolerance as the other end - but can be 2 thou out compared with the other end). The problem is ensuring the laser is exactly in line with the centreline of the lathe (hence the crude screw adjustment - but without a much finer thread I don't think I can get it better).



806
When you initiate a Tool Change, the number of the tool is displayed in the Tool Number display - but I think you know that - are you asking how you get additional information out of the tool table - so that you can , perhaps display it, and choose the correct tool, without having to write the information elsewhere - or do you want the name of the tool displayed on the screen so you can put the correct tool in.

I have my tools in a box in number order - all in quick change holders - so on a tool change M6 the machine stops, moves to a suitable location, and displays the new tool number. It waits until I change the tool, then carries on.

It would be possible to display more information, if the information from the discription box is easily recoverable from the Tool Table. Quite clearly all the offsets are - I don't know about the discription.


807
I would hate to have to reply in French - let me think about it for a bit. Yes a Macro should do it, but it is how to activate it whilst a G Code program is running. I would have thought it best to have the X axis go up (or down) a preset amount - maybe 0.5mm - I take it you are metric??? - so that you didn't have to do too much - just press the button, if that is not enough, press again.


808
General Mach Discussion / Re: Turn Newbie
« on: March 19, 2008, 03:27:04 PM »
Sorry - I missed something

809
General Mach Discussion / Re: Turn Newbie
« on: March 19, 2008, 03:24:39 PM »
I have several Macros in my machine that will do just that.  I have put extra DRO's on the front of Turn in which I can enter various parameters - Start dia, End dia, Length of Cut etc. I work in steel so only take off 20 thou at a time, but you could also include depth of cut.

I don't know how adept you are at changing the screens - and I can't work out how to get a screen shot onto the forum - but here is the Vis Basic.

M201 does what you want, M202 puts a rounded end on it.

The screen is on 1024.lset - page 4

810
I don't really want to get involved in this one, and I don't know how to do it (yet) until I think about it a bit, but as far as I understand what you want to do is watch the job, and if it is not cutting to the correct depth (because of variances in the material) adjust the cutting height up (or down) to suit - as the program proceeds ?

Is that right - as I say I don't know how to yet, but Mach3 is so versatile that there must be a way without invoking any special tools or whatever. I would have thought that you could augment the Z axis controls with a couple of buttons, (up and down) and just press them to achieve the result you want.  That is what I should be aiming at. A computer is there to do what you want, you should not have to bow to the computer.