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Offline Monty

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Re: My new project
« Reply #10 on: December 19, 2008, 08:42:14 PM »
Brett,

There are four wires. two to each of the sensors. I imagine one is power and the other is signal. I am using the combo board from Bob Campbell. There are two sensors, one for the index pulse (one per rev) and the other (lots per rev) They are separate. If it is 5V I can just use the 1/rev signal. I was just hoping there was a way to use the finer resolution as well.  I don't have a pin out or any documentation other than what I posted. The documentation with my lathe shows an entirely different setup. :(

Monty

Offline Monty

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Re: My new project
« Reply #11 on: December 19, 2008, 09:01:46 PM »
After taking the board off the encoder, it appears to use a couple of photo detectors of some sort. Both pulse streams use exactly the same detector, one is just spaced up a bit to read the elongated one per rev slot.
If it is just five volts no problem, but do I need the finer resolution or will the one per rev pulse be enough?


Monty

Offline Hood

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Re: My new project
« Reply #12 on: December 20, 2008, 07:33:01 PM »
One pulse per rev is exactly what you need but afraid I think that will be too short a pulse if you are using the parallel port, if you have a SmoothStepper then it will be fine. You can lengthen the signal with some electronics but the easiest thing to do would be as Brett said and get an OPB 917B opto switch and a 220 Ohm resistor, in the UK that would cost about £6 (under $10). You could then fit a single slotted disc (around 10mm width slot) and threading will be no problem at all :) I use that on both my mill and lathe and the lathe threads perfectly, see below, in the first pic two were done with parallel port and the other 2 were with SmoothStepper. Have also attached a pic of the sensor on my Bridgeport.
Hood

Offline Monty

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Re: My new project
« Reply #13 on: December 21, 2008, 01:38:32 PM »
Moran taing Hood.

I ran the math on the slot width per the user guide and I got .0631" for the slot width, about twice the width of the current slot. I am using the parallel port. Do you think If I were to widen the slot to around .12" the pulse will be long enough?

I am going to try to get the existing sensor to work. If I can't I'll try the OPB 917B. It can't hurt and I have it here in my hot little hands.

Monty

Offline Hood

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Re: My new project
« Reply #14 on: December 22, 2008, 09:56:25 AM »
seems a bit low on width but I have never calc'd it myself so could be right. It will probably work ok as long as the rest of the slots aren't picked up as well, if they are then you will need to use the timing and then I am not sure if it will work as they will be so quick they will be intermittent over the PP so no way to tell Mach how many to look for. No harm in trying though :) If just the index is picked up then you use the Index input.
Hood
Re: My new project
« Reply #15 on: December 26, 2008, 04:19:32 AM »

The ones Emco use is functionally the same as OPB 917. Use the existing PCB as it has the parts you will need anyway.

Don't modify the code disc, make a new one with a wider slot. The existing one will come to use in the future when this PP is obsolete and new (faster) hardware will be in common use. Then I'm sure Mach will use a finer resolution than one reading per revolution, and your Emco coding disc will come in handy again.

There are also easy solutions to widen the pulse from the index slot on your disc. Look for 74LS121. If you're handy with a breadboard that may be easier for you than making a new disc. Then just leave the other sensor there for the future.

Offline Chip

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Re: My new project
« Reply #16 on: December 27, 2008, 03:03:57 PM »
Hi, Monty

Making a new disk is the way to go as suggested above.

On my Emco Comp. 5 lathe, I used the existing OPTO sensor/pickup, Only needed to add a current limiting resistor to power the OPTO sensor properly.

Original Disk was about 5 inch in dia., With the single slot width being about a 1/4 inch, Increased it to 7/8 inch and It's good to 4000 rpm.

Mach3 just need's additional time/width to see the change of State of the OPTO sensor at your max spindle speed.

Nice looking Lathe, You haft'a do what you haft'a do to u-load these machine's.

Hope this Helps, Chip

Offline Monty

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Re: My new project
« Reply #17 on: January 03, 2009, 11:01:08 PM »
Alas the dremel is faster than the internet. I have irreversibly altered the disk. It's OK. I can always make another one with my mill if need be.

Mach 3 is installed on the machine and it is talking to the breakout board. I have calibrated the spindle speed output and configured the spindle run and direction relays. The index input is working using the existing EMCO sensor. I just supplied it with 5V, ground and used the index pulse. The timing pulse and sensor is unused. I Just have to hook up the E-stop circuit and deal with a few little wiring snafus that arise when converting from EU to US power.

Thanks for the feedback.  :)

Monty

Offline Chaoticone

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Re: My new project
« Reply #18 on: January 04, 2009, 09:59:33 AM »
 :) You'll get there Monty.............. Your on your way.

Brett
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!

Offline Monty

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Re: My new project
« Reply #19 on: January 06, 2009, 04:15:57 PM »
After fighting with some noise issues and a bad connection in the crimp type parallel port connector, the axis drives are finally working  8). Unfortunately the best I can get for rapids is about 180 in/min. The 5 phase steppers are quiet and smooth, but 24 volts just doesn't pack that much punch. I will probably update to newer steppers and gecko drives so I can get the voltage up. I still haven't gotten the bugs worked out of the main spindle drive. I just don't have the voltage available to get the RPM high enough. The motor is rated 2500-6500 rpm :o. So far I have gotten the spindle up to about 1700 rpm. The motor is turning about 3200 rpm or so. Not much more I can do there. The spindle is also not very linear in response, so tuning is a bit tough. I'm going to keep fiddling with it for a while, but I have a feeling that there is a new AC spindle motor in my future, or perhaps I will try a DC motor set up for our voltage. Most DC motors have too low an RPM rating to be useful.

Monty