Author Topic: Rebirth of a Denford MIRAC CNC Lathe (Read 55506 times)

awemawson · « **on:** February 05, 2018, 02:46:12 PM »

Today my friend Derek and I left Sedlescombe in East Sussex at 06:00 in quite heavy flurries of snow heading off to Somerset to collect my newly acquired pile of scrap that once had been a Denford MIRAC CNC Lathe. Due to the snow, morning rush hour on the M25 and hold ups on the M3 we eventually arrived at Stoke St Michael 170 miles and four hours later catching the vendor still in bed

Now I hadn't been confident in the measurements he'd given me for either the lathe or it's stand despite his assurances, and sure enough either his tape had shrunk or the machine had grown - it was extremely tight getting it in the van. And again despite his assurance that the stand would fit over the machine there was absolutely no way it would

So having shoehorned the lathe into the van I got Mr Stay In Bed to take an angle grinder to the stand and put it in in pieces reasoning that I could make good the damage with the welder

Journey back was a breeze by comparison, and even stopping for a light lunch we were back ready to unload by 15:00

A quick cup of coffee, feed the pigs then unloaded by forklift (once the propane gasifier had unfrozen

)

So a quick examination found that it was a model of MIRAC that I've not seen before, with a Viglen Genie PC slotted into the drive box apparently as original equipment, with a bespoke inverter drive for the spindle complete with brake unit, a small Mitsubishi inverter for the tool turret that looks like a replacement for (perhaps) another bespoke one, and custom power supply and two axis drive board.

Tomorrow I will start a clean up, remove all the swarf and oil from the base and try and get it up onto a pump up trolley for better access and investigation.

Probably I'll try and get the original PC drive working but I very much doubt I will keep it. Currently I have my eye on the Centroid Acorn offering:

http://www.centroidcnc.com/centroid_diy/acorn_cnc_controller.html

Cheap it ain't once landed in the UK with Shipping, VAT and customs charges, but it seems a very capable controller that ticks most of the boxes.

DICKEYBIRD · « **Reply #1 on:** February 05, 2018, 06:17:50 PM »

Very nice Andrew, it even came pre-swarfed! That's going to be a great machine when you finish with it. I like my little ORAC but being based on the Compact 8 design is only 8" swing. The Mirac's bigger I'm sure. About 10" I think. Have you looked at what size stock it'll take "up the snout?" The ORAC's only 20mm. Sure wish it would do about 25.

Can't wait to watch you do you thing!

tom osselton · « **Reply #2 on:** February 06, 2018, 01:42:22 AM »

Should be another interesting project! I'll pop some corn!

Meldonmech · « **Reply #3 on:** February 06, 2018, 04:33:35 AM »

Hi Andrew

Looking good, new it would'nt be long before you embarked on another big project to keep you amused.

Good Luck
Cheers David

Will_D · « **Reply #4 on:** February 06, 2018, 06:24:04 AM »

You are an inspiration Andrew.

Following your projects is what gives me the Kick-up-the_ar*e I need to keep plodding on.

Looking forward to this.

I also looked at the Acorn controller for my little Sieg X2P CNCconversion.

Cheers

Will

awemawson · « **Reply #5 on:** February 06, 2018, 07:48:29 AM »

Thanks chaps

This mornings job was to glue the trolley base back together having had to cut it apart to fit in the van.

Turns out not only were three of the castors missing their tyres, but they were welded on. So - cut off old castors - do a bit of weld preparation - weld the frame back together overcoming the inevitable springing out of alignment with some innovative clamping - then drill and tap for replacement castors.

.... what could be simpler

DICKEYBIRD · « **Reply #6 on:** February 06, 2018, 09:30:58 AM »

Might I suggest to the master titivator the addition of a couple or 3 geodesic braces to the base?

PekkaNF · « **Reply #7 on:** February 06, 2018, 09:45:50 AM »

Loosely...396,49 € tax incl.

http://makersupplies.dk/motion-controllers/312-acorn-4-axis-motion-control-w-free-pc-software.html

Don't know that shop, I was looking for a stepper motor with 8 mm shaft and remembered this thread. Would this be cheaper from EU?

Pekka

awemawson · « **Reply #8 on:** February 06, 2018, 12:52:39 PM »

So the afternoons task - put it back on the trolley and start the clean up. Just a rough first pass to get the bigger clods out !

krv3000 · « **Reply #9 on:** February 06, 2018, 04:19:55 PM »

a job well dun I need a stand making for me mill

David Jupp · « **Reply #10 on:** February 07, 2018, 08:31:13 AM »

Andrew - I presume you've already found the information on the Mirac on the Denford forum.

awemawson · « **Reply #11 on:** February 07, 2018, 09:29:57 AM »

David I have and I haven't - I cannot identify the exact machine nor can I find a suitable circuit diagram - there seems to be a myriad of Mirac models

This one has an LCB3 control board but seems to differ from ones on Denfords site - they share one invertor for the spindle drive and the tool turret motor for example whereas this one has one dedicated to the spindle and another for the turret. Also I've not yet found one where the PC is slotted into the side of the machine.

A bit of progress today. I decided to see if I could get the original controller to work, so blew a century of muck out of the keyboard and monitor and plugged it all together. After checking for no stray wires I plugged it in and was AMAZED to find it booted up after what must have been a decade of sleeping

The various Mirac screens can be brought up but at the moment I can't move any axis or spin any motors other than the coolant pump as I cannot get it out of eStop. I need to 'knife and fork' my way through the eStop chain - I've done a bit but I need to go and prepare supper as we have guests this evening.

Pete. · « **Reply #12 on:** February 07, 2018, 01:54:37 PM »

That's a surprise. I would expect to be getting all sorts of BIOS errors. Very encouraging Andrew.

awemawson · « **Reply #13 on:** February 07, 2018, 06:49:06 PM »

Yes I was rather taken aback

The PC must have been changed at some time as there are socket converters in line with the keyboard from PS2 to DIN and 25 way to 9 way on the serial port. it looks like the PC sends commands to the Denford LCB3 card over the serial port as the parallel port on the PC is unused.

I suspect that if I can overcome this eStop issue the controller might actually work. I'm tempted as a diagnostic aid to hard wire the eStop relay permanently 'on' for testing purposes. Then if the controller drives the axis and spindle it's worth spending time to bottom the issue.

Pete. · « **Reply #14 on:** February 08, 2018, 02:08:23 AM »

If you need to replace any door/safety/limit switches I have a box full of nice Telemechanique limit switches I salvaged off a machine. Fully IP resistant and with one NC/one NO contact in each.

awemawson · « **Reply #15 on:** February 08, 2018, 09:35:31 AM »

So I took my courage in both hands and 'wired out' the Emergency Stop circuit, feeding 24v directly to the ES Relay and lo and behold everything sprang into life

We now have power to the axis drives and spindle motors and can home and jog etc

Had to do a dummy trial using one of the programs resident on the original PC hard drive but first I had to work out how work and tool offset are stored - turns out they are in a common file on the HDD:

Having proved it now works it was a case of slogging through the Stop chain to find the fault, which turned out to be a voltage sensing relay that looks at a thermistor buried in the tool post turret motor. Although it's input was OK it's contacts were permanently open circuit. I've linked it out of the chain for the moment.

philf · « **Reply #16 on:** February 08, 2018, 09:43:14 AM »

Andrew,

Looking good

although the tool changer sounds as though it needs some grease. (Unless they always sound like that.)

I hope you're going to backup the hard drive before you do anything else!

Phil.

mattinker · « **Reply #17 on:** February 08, 2018, 10:38:55 AM »

I'm glad to see it works, bit too easy though!!

Regards, Matthew

awemawson · « **Reply #18 on:** February 08, 2018, 10:51:22 AM »

Thanks chaps - yes the gears or motor on the turret sound horrid - probably never been greased !

So the voltage sensitive relay - what to do ?

I could leave it wired out, and ignore the turret thermistor . . . .but that graunching sound . . .

I could buy another one, except that RS part 346-154 is now obsolete, and new equivalents are not only very expensive but also not an 11 pin base so physically different.

So nothing to loose I pulled the old one apart and having put my electronics head on started poking about for a look see. 110v AC comes in to a transformer followed by a four diode bridge with a filter capacitor across the input and a 100 mFd 40v electrolytic as a reservoir - pretty standard. Start testing the diodes and they all read 700 ohms BOTH WAYS - something wrong here, they should be that one polarity only ! Quck test of the capacitor in circuit - dead short

Whip the capacitor out, test the diodes, all is well this time. Pop a replacement 100 mFd capacitor in (35v working but it'll be fine) and do a quick test in circuit before replacing the cover. Well how about that - it works

Pop the cover on, take out the link I'd put across it's contacts and it all seems to work - the tweaker gives a reasonable range and at one extreme the Emergency Stop Relay drops out just as it should. Well that saved a bob or two !

DICKEYBIRD · « **Reply #19 on:** February 08, 2018, 11:37:46 AM »

Feels great getting making an old soldier healthy again doesn't it?

I have a Denford MicroMill and those chaps up in sunny Brighouse make a very solid machine . Mine's a training machine & has a puny little Sherline mill but the control is robust. I was going to use the original software as well but the lack of the magic dongle made that effort futile. I snatched off Denfords proprietary serial board & hacked straight into the SmartStep board with step/dir signals from Mach & a parallel port.

In searches on their site I found that they offer the old DOS software for free download, or used to anyway. There's nothing wrong with DOS & it probably works reliably without the influence of Windoze. As long as it will recognize the encoder, threading should be fine. I wonder if it came with any conversational programs or any CAM functions?

Gotta luv your

projects!

tom osselton · « **Reply #20 on:** February 08, 2018, 03:00:05 PM »

That was way too easy! But you deserve a break after that last one you did well done!

awemawson · « **Reply #21 on:** February 08, 2018, 04:12:17 PM »

Quote from: philf on February 08, 2018, 09:43:14 AM

Andrew,

Looking good although the tool changer sounds as though it needs some grease. (Unless they always sound like that.)

I hope you're going to backup the hard drive before you do anything else!

Phil.

Phil, Just finished a full disk back up. Thirteen 1.44 floppies under MSBACKUP under DOS 6.22 - no easy other way to do it. I may try and fit a CD drive now I have a backup but it's a bit of a rigmarole loading the extra drivers as I don't think DOS 6.22 had CD support

philf · « **Reply #22 on:** February 08, 2018, 04:58:04 PM »

Andrew,

I was thinking rather of lifting the drive out and cloning it. I did that for my Mach3 PC after the length of time it took me to configure the PC and Mach3 - I didn't want to start from scratch again.

I'm surprised anyone still has floppies!

Anyway, better safe than sorry.

Phil.

awemawson · « **Reply #23 on:** February 08, 2018, 05:20:59 PM »

My approach was to get the data off before poking about and the PC possibly dying

As I was hunting for floppies I discovered that I had a set of DOS 6.22 original install disks tucked away !

DICKEYBIRD · « **Reply #24 on:** February 08, 2018, 06:27:56 PM »

Andrew, one of the fellows on another forum reported success with a floppy/USB adapter with DOS. He was saying that it's somewhat popular with old CNC machine users to get away from the hazards of floppy usage. I'm sure we've all lost important data using those %$^%& things!

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Author Topic: Rebirth of a Denford MIRAC CNC Lathe (Read 55506 times)