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The Sequel - Oh Blimey I bought a CNC Lathe (Beaver TC 20)

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awemawson:
OK I've found the Crawford specifications for these collets and it seems that my 15 microns is within specification - seems rather a lot to me  :bugeye:

awemawson:
All enthusiastic I've recently re-measured and drawn up a pull stud for the tooling of the Beaver Mill, to be made on this Beaver TC-20 CNC lathe.

Going to the machine to review tooling, and powering it up there were odd and unfamiliar humming noises and the machine wouldn't go 'Ready'  :bang:

Now over the last few days we have had masses of rain and some very significant lightning - though not (I'd thought) very close.

So far I've spent a couple of days on the diagnosis trail and found a blown up memory card. Fortunately I had a spare, and now at least the controller is going ready.

At this point I've been able to load back ups of the PLC program and the other gubbins - in fact I've been through the process FIVE TIMES  :bang:

However, although I can 'reference' the machine, jog in X & Z, rotate the tool turret and select a tool, I cannot start the main spindle. You may recall this is driven by a vast Maudsley DC motor by a KTK DC drive and a propriety field current source. If I program a modest spindle speed (say 100 rpm but it doesn't seem to matter what) there is a slight increase in hum level but no rotation, and after a few seconds it errors with 'spindle speed too high' !

Putting a DC clamp meter on the field drive it's passing a reasonable 5.9 amps. Transferring it (On AC) to the feed to the KTK driver for the motor, it briefly is drawing about 40 amps (at 120 V 3 phase) before erroring.

The othere oddity is that one of the files that's been re-loaded (several times into RAM) maps PLC error and comment numbers to text, but despite this the controller is reporting the number and not the cross referenced scrap of text.

Now this controller has bits of ROM  and bits of RAM in several places and I've never satisfactorily managed to map what is supposed to be where - the manuals are as vague as a salesman's promise!

The spare could be faulty of course and explain both issues, but I seem to remember previously using it. There is another for sale on eBay at a reasonable price, but the postage and customs duties from the US are crippling :

https://www.ebay.co.uk/itm/130842358746?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

(This is one of the cards that were destroyed before I got the machine by oozing lithium battery juice, and indeed is the same as the card that was the source of he leak!)


. . . decisions . . . decisions  :scratch:

Sea.dog:
Parts are rare. Buy it!!  :D

tom osselton:
I’d buy it too it’s hard to say when another comes available.

awemawson:
You chaps are a bad influence !

Things have gone from bad to worse - I've ended up with a blank screen and no activity  :bang:

I had noticed an oddity. If I manually turned the spindle, even a degree, it immediately gave the spindle over speed error message. Now the spindle is monitored by a 'measuring card' that takes input from the optical disk - I had a spare so swapped it - no difference. Now this card talks to the CPU card - I had a spare (in fact the original that came with the machine - it's frame is slightly corroded but I'm sure that I've previously proved it OK. BUT swapping it into the machine - BLANK SCREEN. Putting back the one I took out but still BLANK SCREEN  :bang:

The video system is a pair of cards - a clever one and a bank of memory - no spares.  :( I reasoned that it was possible that the display itself may have died. Just putting in these two cards I got a random display, proving that at least the CRT was good (I'd tried to see the cathode filament glowing but couldn't)

The power supply is slightly suspect. it gives several rails none of which are accessible to monitor except the 5 volt rail which is good. I seem to remember having to inert pins into the backboard sockets to measure the +/- 12 volts but that entails the removaval of the entire controller and it's card compliment - not a job for today.

Meanwhile I have spares of the two video cards on order, and a memory card that has iirc 32 kByte of ram, and slots for three daughter boards that have the controller firmware on them. This card is minus the daughter boards but the chances are that mine are OK.

. . . .I didn't need this . . .  :med:

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