Help needed getting a Triac up and running

Hello, and Merry Christmas!

I have recently inherited a Triac ATC milling machine, but am having some real trouble getting it to work consistently. The machine was given to me due to a leak in the bank of pneumatic valves, as I'm working on a very tight budget I decided to decommission the pneumatic side of the machine and removed the valve bank entirely.

After some troubleshooting I was able to complete a very small spiral milling job to clean a piece of aluminium. Once completed I changed the tool and tried to route a pattern in billet, when I started the second program the machine juddered, the lights dipped and a puff of smoke (I think from the spindle) came out. Since that happened I can't power the machine up without the spindle starting by itself, a very helpful member of staff at Denford has suggested the Sprint 1200 board could be damaged, and it would cost £230 to replace.

I have couple of questions for you.

1. It was suggested that a lack of amps on start up could have damaged the spindle/board. The mill is in the garage which has a single line in which runs the lights and sockets, there was a heater running when it initially failed and the lights did dim. Could a lack of current cause damage?

2. It looks like a lot of people do a Mach 3 conversion on these machines. I'd like to keep the machine as low cost as possible, and keep the existing control system if I can. Is this advisable, or is it better to bite the bullet and convert the machine? As far as I can tell it has had very little use since it was sold to the school so should be in a sound state mechacnically.

Any advise much appreciated.

Thanks. Dan

Can't help with your main problem I'm afraid but in reply to item one.

Yes, falling voltage will cause an increase in amperage to compensate and that can/will damage compensation.

I don't think the Sprint controllers are smart enough to increase the current to compensate like that, a spurious correlation I think. Anyway, it sounds like the thyristors have failed short circuit. It would probably be possible to replace it if it's all that has failed. Similar controllers come from KB and also available on eBay for not a lot, but may not be so easy to interface to the pc if you want to control spindle speed.

I recommend you head over to the Denford forum **LINK** for help on Mach 3 conversion, also on the spindle problem. I have found it very helpful with my Novamill. I built new interface electronics for Mach 3 from bits purchased on eBay for around £200 if I remember right. I think people have managed to use the Denford stepper drivers with a new breakout board for the pc interface for Mach3, see the Denford forum.

Thank you for the help. I will remove the Sprint board for a closer inspection, fingers crossed it is a thryisitor that needs replacing. I will let you know how I get on.

I have had 3 Triac's and had a lot to do with sprint drives you can easily change that board out for the newer model the 340 or 680 is what I normally use but will not work with the old control system. Don't try and plug any other board in to the system as the control side is all mains voltage and not 12V like modern drives. The spindle motors are a week point and if they get stalled can burn out very easy. As there DC just plug a power tool battery in to the motor and see if it will run it does not matter what way round you hook the wires up it will not harm the motor the 2 smaller wires are just for temp sensing.

And good luck with the ATC its nice to have but give more problems that its worth.

Thanks for all the help earlier in the year.

I examined the Sprint board an found a tell tale scorch mark from the Thryistor bank (Thanks John Haine) I ordered a replacement and 5 months later (!) my part arrived. I replaced it, applied new thermal paste to the heatsink, and upgraded the supply to a 6mm single line from fusebox to machine. It worked for about 30 seconds! Now every time I power on the control box lights up like a Christmas tree, lots of relays start clicking and the spindle once again powers itself up automatically.

My question is this; should I continue trying to repair the existing control system, or would you advise buying new hardware and going for a Mach 3 conversion? Any thoughts or advice would be much appreciated.

Dan

Hi Dan,

There will probably be more help for you on the MYCNCUK forum, regarding a conversion e.g:- **LINK**

Even though I use Mach4 to run my Syil X5, if you do decide to convert, I would suggest looking at UCCNC **LINK**

rather than the no longer in development Mach3.

Nick.

Hi Nick

Thanks for the pointers, from what people have said here, and elsewhere it seems like running it with the existing hardware & Denford software isn't a viable option, so I'm going to pursue either a total or partial conversion of the existing electronics. I've not come across the MYCNCUK forum yet, so I'll have a good read through that before I start the conversion.

Not too sure which software I'll go with yet, there seems to be huge variance in the pricing. I've seen Mach 3 selling from £15 - £175! UCCNC seems much more reasonably priced at E55, I'll need to do my homework!

Thanks for the help.

Not used UCCNC software myself but I saw it in action by a satisfied user recently and it looked pretty capable. I've been using their DC servo drivers on my large CNC machine and been very happy with them, From my relatively limited experiences in this field, it looks like a sensible contender. Requires a Windows PC, monitor, keyboard, breakout board etc. Will also take a fair bit of wiring and setting up.

The other approach would be to fit one of the standalone controllers like the DDCSV1.1 which you can get for under £150. There is even an open source firmware replacement if you want to enhance the operation. You don't need a PC, operating system, CNC program, monitor etc to run these and they interface directly to the servo / stepper drives. I'd have thought they would be fine for Triac retrofit. John Stevenson and Steve Blackmore played with a 2 axis version of these on a lathe and seemed to be very happy with what they found.

Murray