Orac Spindle Sensor

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Trispectiv
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Orac Spindle Sensor

Post by Trispectiv » Sun 07 Feb , 2016 10:38 am

Hello,
Has anybody managed to use the original spindle sensor(s) on the Orac for a Mach3 conversion? I would need to know what voltage they need to be powered at and if that PCB next to the spindle will output 5V signals for my BOB.
Thanks

triac
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Re: Orac Spindle Sensor

Post by triac » Mon 08 Feb , 2016 23:11 pm

How's the refurb getting along ? did you decide to use the original steppers and PSU, how about the spindle drive motor, was that working OK ?
Emgee

Trispectiv
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Re: Orac Spindle Sensor

Post by Trispectiv » Tue 09 Feb , 2016 7:58 am

I still have the original drivers and they were working in the original setup. However, as I read on some other thread in here, they don't take 5V signals for step/dir. At this moment the Orac is running using some TB6600 based drivers. These don't provide the expected amps and only go up to 40V as I remember (I couldn't use the original PSU), so the motors are underpowered. I probably should craft a BOB that throws the slightly higher voltage signals required by the original drivers.

The spindle is working just fine using the original inverter - the parametrics.. paragen.. paramount? I forgot its name, it's the original one used back in 1983. It works without a glitch using spindle relay on the BOB and PWM 0-10V from the BOB.

The only problem I couldn't figure out was the spindle sensor(s). The PCB in the back of the headstock has 4 wires, I am assuming two of them are power and two are signal from the two sensors. I cannot find any specs/diagram/etc in the electrical docs.
So, I can turn but I cannot thread yet.

triac
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Re: Orac Spindle Sensor

Post by triac » Tue 09 Feb , 2016 23:41 pm

Hi
Thanks for the update, it is interesting to know you have a 0-10v facility on the BOB to control spindle speed, what make BOB are you using ?
There was a circuit on the forum showing a method to use the 5v or 12v signal to send 24v to the steppers, I have a copy somewhere, will look it up if it helps.

Emgee

Trispectiv
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Re: Orac Spindle Sensor

Post by Trispectiv » Wed 10 Feb , 2016 6:56 am

Hi,

I am using probably the cheapest BOB you can buy. It looks just like this one:
https://www.ebay.com/itm/CNC-5-Axis-Inte ... 3a9c296626
A poorly written manual can be found here, if you need an overview:
https://www.machsupport.com/forum/index ... tach=40507
Of course, you need to supply it with an extra 12V-24V power for it to output that 0-10V. It also includes the relay I needed to start/stop that para-something VFD.

About the spindle sensor, in my particular Orac, I have the reflective sensors. My disc has reflective foil on it, unlike the slotted type. One of my sensors (one pulse per rev) outputs 5V when triggered and the other one (many pulses per rev) outputs 12V.
My BOB needs a switch, a circuit closing/opening action, not a 0V/5V wire, so it was not a plug and play solution. More specific: the inputs on the BOB are optoisolated; the switch you add closes the circuit on one side of the optocoupler, hence putting the actual parallel port pin to ground. In other words, you are actuating the input pin of your parallel port, instead of operating it directly which might sometimes fry your port.
I tried to pass the Orac sensor output through a switching transistor or a optocoupler, but it didn't work. The current put out by the sensor was too thin to trigger my optocoupler. Getting tired of it I ended up using one of my 3D printer optical sensors which was easy to integrate and since I also build a lot of 3D printers, it was also already available to me.

It would be very helpful if there was a simple method to up the step/dir signals from 5V to 12V or more. The way I would do it is by using a hex inverter, something like a 74ACT14 but rated for 12V or 24V, this one being ok for 5V only. There is only one downside, the old drivers have a high tone hissing sound when operating. It is quite disturbing. Not sure if that is normal, it almost sounds like those unfiltered TB6560 drivers.

Trispectiv
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Joined: Thu 28 Jan , 2016 8:31 am
Hardware/Software: Denford Orac

Re: Orac Spindle Sensor

Post by Trispectiv » Wed 10 Feb , 2016 14:42 pm

How exactly does the Orac spindle get to 2000RPM if the motor is only 1400RPM? Not to mention the pulley reduction.
IMG_3595_resize.JPG
IMG_3595_resize.JPG (311.65 KiB) Viewed 18377 times

Martin
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Re: Orac Spindle Sensor

Post by Martin » Wed 10 Feb , 2016 17:17 pm

It's wound to hit top speed at 87Hz.

triac
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Re: Orac Spindle Sensor

Post by triac » Wed 10 Feb , 2016 22:21 pm

Thanks for the info, I will look up and post that cct to provide the interface you mention.

I think Martin was in a hurry, he didn't give his normally comprehensive answer !!!

The spindle drive unit is a VFD, variable frequency drive, increase the frequency of the 3 phase AC motor supply and the motor speed increases, decreasing the frequency of course reduces the speed.

I have one unit that has been adjusted to provide spindle rpm of 2250 but the std unit is spot on the 2k.

Emgee

Trispectiv
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Joined: Thu 28 Jan , 2016 8:31 am
Hardware/Software: Denford Orac

Re: Orac Spindle Sensor

Post by Trispectiv » Wed 10 Feb , 2016 22:47 pm

Well, I haven't measured the pulley reduction, but if the VFD goes up to 87Hz, the motor should spin at (87 / 60) * 1400 = 2030RPM. The spindle pulley being larger then the motor pulley, it would still not hit 2000RPM at the chuck. Unless I am missing something.

triac
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Re: Orac Spindle Sensor

Post by triac » Thu 11 Feb , 2016 11:23 am

You used 60 for the Hz in your formula, plated motor speed is stated as 1400rpm at 50 Hz,
so (87/50)*1400 = 2436 motor rpm with VFD set @ 87Hz

I am not sure of the ratio between drive and driven pulleys but if Martin's 87 Hz for 2k at the spindle is correct then
the ratio can be calculated.

Emgee

Trispectiv
Posts: 7
Joined: Thu 28 Jan , 2016 8:31 am
Hardware/Software: Denford Orac

Re: Orac Spindle Sensor

Post by Trispectiv » Thu 11 Feb , 2016 13:34 pm

Well.. like I said: "unless I am missing something" :)
Thanks for pointing my error out, it makes sense now.

A couple of other questions if I may:

-I see some photos where the chuck has some protective cover right behind it. Some short round tubing painted in Denford green and black stripes. My Orac doesn't have it. Was it added after my manufacturing date (march 1983)?
https://s166.photobucket.com/user/allanj ... 8.jpg.html

-Neither of the 4 ballscrew nuts have protective wipers at their ends. Is that normal or my Orac is missing them. By wiper I mean a minimal plastic cover to protect against the larger chips, like the blue plastic in this photo:
https://www.thomsonlinear.com/pim_images ... t_300w.jpg

halftonner
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Re: Orac Spindle Sensor

Post by halftonner » Wed 25 Jan , 2017 19:01 pm

Hi have my spindle speed sensors running correctly, so that's fine ... but I sort of follow on with the query about the motor and getting to 2k chuck speed ...

I have a VFD (Siemens sinamics G110) to drive my motor, which all works fine and dandy (even the 'emergency stop is wired up to bring the motor to an almost complete stop in a fraction of a second) :) and when I got the lathe it was set to a max frequency of 50Hz.

I've read, re-read and re-re-read the VFD manual and changed the VFD to allow a max of 100Hz ... So, I go into Mach3 and say calibrate spindle and to go up to a max of 2000rpm .... and what happens is very odd! The motor does as it should, start slow and the Mach3 program records the speed, then steps up the frequency by a small amount to run the motor a little faster, and records that speed ... so far so good - it builds a nice calibration graph. But what I found at higher frequency's (can't remember exactly what the frequency range was - but beyond 65Hz+) there was a sudden noticeable drop in motor speed and a strange un-happy noise comes from the motor, almost as if it can't keep up with the frequency in the windings.

I've decided (for the moment) to set the max limit on the VFD to 60Hz which gives a spindle speed max of around 1000-1100rpm ... Ideally I would love to be able to get this (what seems to me mythical) 2000rpm at the chuck. Does anyone have any hints as to what is going in in my motor, or have I overlooked something obvious? You mention in the posts that the VFD max frequency ought to be 87Hz - have I interpreted that correctly?

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