Denford Triac Spindle Issue

[GingerNinja54]

Having had some issues with connectivity, I’ve had some success… yay!

I can now connect to and drive the axis from the laptop.
This includes by home and jog functions.
I can operate coolant pump etc, so machine and laptop are talking.

I’m struggling with the spindle though…
When activated, I can hear a solenoid/switch flick inside the control box, but nothing happens at the machine…

Any thoughts on where to start investigations??

Thank you

(Also posted on the Denford forum)

[John11668]

What sort of spindle drive / controller do you have

[GingerNinja54]

Sprint 1200

[John11668]

Do you mean this one . isolated inputs??

https://www.sprint-electric.com/product/1220i/

[GingerNinja54]

This is an image of the drive…
Bearing in mind it’s 1995 machine… maybe today’s equivalent has the version you attached the link for?

https://www.sprint-electric.com/product/1200/

It may be that Sprint still support the old drives, if mine proves defective? Maybe worth asking the question.

[John11668]

I am sure sprint will be helpfull so worth asking them for info. Looks like you can download technical data on that link if you provide your details.

They are based in Arundel but last time I tried I had difficulty getting through but I did manage to get a number for their tech sales chap which I can maybe hunt out if you are stuck.

One thing that is apparent is that it is a non isolated board so your computer must be connected to it via an intervening board. Where do all those pale blue wires come from. Ideally post a pic.

[m_c]

What hasn't been mentioned, is the spindle drive fuse was blown (there's a concurrent thread over on the Denford forums).

I've just had a look at the wiring diagram, and the fuse should be 6.3A.

If the motor stutters/stalls briefly when running, it's could be either the SCRs on the drive are failing (they tend to fail short circuit under certain loads, which causes the stuttering/stalling), or the motor is either shorting out internally, or the brushes are not making good contact (which again gives the stuttering/stalling).

The issue with the spindle motor, is due to it having a tacho fitted, beyond removing the brushes, they are a nightmare to dismantle and clean.

I personally removed the DC motor and sprint drive from mine, and retrofitted it with a servo motor and drive.

[GingerNinja54]

Thanks for replies guys
(I’ve also got the thread running on the Denford forum… my thought was to cast the net wise to try and capture as much input as possible)

I had found fuse #F1 (spindle) to have blown…
I changed for a new 10A (as per wiring diagram I found for this year machine?)

Upon firing up the machine, the spindle ramps up to full revs and back down, to approx. 60-100revs, and stays there.
Once I reference the axis, I can stop and restart the spindle in manual mode, but can’t change the rpm??
I rebooted the machine and the same occurred…
I get 200mV across wires #54 & #55 at all revs.

Could defective brushes cause this?
Or more likely to be a drive issue or other?

@M_C… what was the cost of your drive and spindle, and where did you source this from?

[m_c]

I've not got much time just now to give too much of an in depth reply, but the revving up then settling down isn't normal.

As has been mentioned on the Denford forum, it could be a tacho fault.
The 60-100revs does sound correct for 200mV, given it's a 0-10V signal, so 200mV should give around 2% of max spindle speed.

If changing the jumper to ignore the tacho input doesn't work, I'd measure the voltage across the 54/55 wires when you power the machine up. IIRC the spindle drive shouldn't even be powered until the controller is fully booted, and the spindle go relay is activated.

I seem to remember there being some machine settings within VR Milling. Is there any relating to the spindle?
If the analogue output isn't working, then it somewhat restricts your options for controlling the spindle from the software.


I fitted a Kinco servo motor and drive at the time, which cost quite a bit. If I was doing it now, I'd look at Lichuan servos, but it involves making a complete new motor mount. I do have a thread on here about my Triac retrofit, and I think it includes some details for fitting the servo.

[John11668]

With the later drives I seem to remember mine running wild on tach feedback, but on my motor the tach wires had long been cut off . Maybe it just was not reliable ,
If you can select Avf feedback it should respond to the the analogue input.