Messages

91

General Mach Discussion / Re: Wiring of 2 wire proximity switch

« on: June 01, 2010, 03:52:23 AM »

That's also my last resort Vandal968 
I cut mine out a while ago and kept it just in case I couldn't figure out how to do it any other way. If the new board works i'll post a reply on here along with the final draft of the circuit. If not i'll probably be asking you a few more questions!

Thanks ...Sweep

92

General Mach Discussion / Re: Wiring of 2 wire proximity switch

« on: May 30, 2010, 07:53:23 PM »

No, it only blows the resistor on the simulation, I haven't built the prototype yet. I'll see how accurate the sim is tomorrow when I put it together 

...Sweep

93

General Mach Discussion / Re: Wiring of 2 wire proximity switch

« on: May 30, 2010, 02:01:38 PM »

It's just when the program first runs, and only when the switch is closed prior to running. I tried slowing the timing down so 1sec real time = 1us circuit time but it still blows R1(82R) quicker than I can see it. All I see is that the flow of current peaks instantly, as signified by the wires of the circuit lowing brighter, and then pop!
Running with the switch open then closing the switch, it all works fine. I have done the circuit mods as suggested and I get the following readings.
When the switch is open I see 9.1volts after R1(82R) with 27.34mA flowing to the Zenner.
When I close the switch I can see 9.06volts after R1(82R) with 12.62mA flowing to the Zenner and 15.16mA flowing to the switch, 717.44mV and 11.14mA after R2(750R).
Tomorrow I will build it as a prototype and see how it goes.

...Sweep

94

General Mach Discussion / Re: Wiring of 2 wire proximity switch

« on: May 30, 2010, 08:29:16 AM »

Hi All, and thanks for your support on this matter.
Whilst I could take a safe 12v from the PC I am trying to have as few leads as possible running from the PC to my enclosure, basically to make the whole set up look prettier! So far I only have the two 25pin parallel port cables. This approach has caused me problems, however, before as my high parallel pin voltage is around 3.8V which isn't enough to run my MPG which needs the full 5V (tried it but didn't work). I was going to run a USB but I thought it wouldn't look as nice so have decided to use a small DC/DC power converter inside my panel.

As such I would prefer to work with the transformer 12V from the old Denford machine and pick up off that. This, however, I think would require some optoisolation like Mr Bluepinacle suggests.
I would appreciate eveyones comments on the attached circuit which is based around the original Denford circuit posted earlier but with an opto front end. It seems to work fine on my circuit simulator but I have had to replace the proximity switch with a simple toggle switch (SW1) as no standard proxies were available in the program.
A couple of other points:
1) I would like to use the 4N25 6pin opto as i have quite a few of these on stock, and also because I like building all my stuff with seperate 6 pin DIL sockets so in case I mess up they are easier to change or upspec etc. As such if anyone suggests an alternative please try for 6pin.
2) When I run the simulation with the switch already closed I immediately blow the 82R resistor on the 12v side unless I increase the rating to >2W, but when I start the simulation with the switch open then close the switch I can get away with 1/2W with no problem. Why is this???

I've mentioned this before on some of my earlier posts, but I don't have great deal of electronics experience so please be gentle with me and explain things in very simple terms.

Thanks again ...Sweep

95

General Mach Discussion / Wiring of 2 wire proximity switch

« on: May 29, 2010, 04:47:09 AM »

I wonder if anyone could offer some suggestions as to the correct wiring of my existing 2 wire proximity switches into Mach3.
My old Denford Triac has three of these switches fitted for the X, Y, and Z homes, and the spindle speed. They are made by Balluff and the model is BES 516-324-E2-N-03. Please see below for data sheet which includes a very simple wiring diagram.
I want to keep the existing proximity switches as they work and to replace them would be quite difficult due to how the X and Y are buried inside the machine, and also because of the needless expense if I replace them.
Speaking to Balluff, however, they say I need to buy there very expensive amplifiers which, at £100+ each, is not going to happen.
Also, the original Denford wiring diagram didn't use seperate amplifiers but just had a section on the motherboard which dealt with this operation.
As far as circuit wiring is concerned I am quite happy to attempt any circuit, however complex, as I am using a PCB printing program and Press 'n' Peel paper.
I have also attached the original Denford wiring diagram which shows these sensors where 'Plug M' connects to them on the machine.

Thanks ...Sweep

96

General Mach Discussion / Re: Pins 2 to 9 as inputs

« on: May 27, 2010, 03:30:20 PM »

Me correct? Well after my last thread on 'lost steps' that makes a pleasant change 
At least it is good news this time; 18 inputs yippee !

...Sweep

97

General Mach Discussion / Pins 2 to 9 as inputs

« on: May 27, 2010, 01:43:19 PM »

As standard, I believe, the pins on the parallel port which are inputs are 10, 11, 12, 13, & 15.
If on my 2nd parallel I define "pins 2-9 as inputs" does this change pins 10, 11, 12, 13, & 15 to outputs as the manual says that I should have 13 inputs, yet I count a total of 18 ?

...Sweep

98

General Mach Discussion / Re: Another lost steps post...

« on: May 26, 2010, 02:57:52 PM »

ah, looks like I wasn't paying attention at school during maths.
1 / 5mm/rev = 0.2rev/mm of ballscrew shaft
0.2rev/mm x 2.5 belt ratio = 0.5rev/mm of motor spindle
0.5rev/mm x 400step/rev = 200steps/mm of motor spindle
therefore 1 step = 1 / 200 = 0.005mm/step or 0.00019"

I would, therefore, agree that 20 steps would need to get forgotton about to realise such an error. I'll have to have a closer look at mechanical backlash as I would agree that this now seems like the obvious problem.

thanks for the lesson Sterling

...Sweep

99

General Mach Discussion / Re: Another lost steps post...

« on: May 26, 2010, 03:37:26 AM »

Sorry,to fully answer your last post, i'll try move the axis by my smallest resolvable increment (200steps/mm) of 0.05mm and see what movement of the axis is measured on the DTI

100

General Mach Discussion / Re: Another lost steps post...

« on: May 26, 2010, 03:33:41 AM »

I am pretty sure that there is no mechanical backlash as have already pulled the table too and fro (well applied pressure in both directions) and the DTI needle never flinched. I think an experiment on the Z axis would prove or dispell your toughts as the weight of the whole spindle assembly will naturally remove any mechanical backlash. If there is 'electronic' backlash the error will still appear.