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

[awemawson]

I think that it would be wise to try and manually drive the Z axis to see how stuck or free it is. By dangling my iPhone into the works I've managed to get a picture of the servo motor name plate - if I'm reading it correctly it's developing 15 Newton Metres of torque at 2000 RPM and taking 25 amps at 150 volt to achieve that 

The actual ball screw is coupled via a toothed belt drive to the servo motor - I'l try and get time tomorrow to remove it's cover and probably have to fabricate something to engage one of the pulleys

[nrml]

I am surprised that you don't have an industrial grade bore-scope in your box of toys. It would make inspection of these tight spaces much easier and i-phone dangling unnecessary.

To be honest, I don't understand a lot of what you are doing but that doesn't diminish my interest in the slightest. This is truly a worthy sequel to the Traub epic.

[PK]

There is a series pass regulator comprising three 2N3055 power Transistors with load sharing resistors in the Emitter circuit, and this group of three is driven by a fourth 2N3055 making a 'super alpha pair' (well quad in this case!). The base of the fourth 2N3055 is driven by a UA723CN voltage regulator IC

What vintage is this machine Andrew?
I can remember building power supplies like that 30 years ago, and they were a little dated then.....

[awemawson]

Spot on PK, it's 29 years old !

[awemawson]

This morning, bright and early, I whipped the cover off the Z axis ball screw pulley and tentatively  tried turning it by hand. It turned remarkably easily, but before any significant travel  I needed to move a pile of tooling that came with the machine, and clear as much of the rust on the ways as I could.

Then grasping the pulley I moved the carriage to it's extreme travel towards the tail stock, revealing the expected rust under the moving element. Nothing major, and a bit of judicious scraping and stoning and it will be fine. No doubt when I move it back towards the head stock end more will be revealed.

I need to clean up the ball screw as it also has suffered - again nothing major but it needs cleaning,

. . . quite a pleasing start to the day - now off to do some fencing !

[awemawson]

I managed to grab a few more minutes and cleaned up the ball screw - it's not perfect but perfectly serviceable. Before actual powered use I'll have another go at it.

Meanwhile Angie the MyHermes courier turned up with  the transformer that Pete Rimmer has kindly found for me - goes in a treat. I need to make a mounting plate and then it can be wired up, possibly this afternoon 

Many thanks Pete

[awemawson]

As it happens where I first plonked the transformer is a very handy place. Those bars are tapped M6. So I made an adaptor plate, fixed the transformer and wired it all up.

No mechanical problems but oh boy what a pain wiring it up. This transformer is taking 415 volts single phase from two of the three phases driving the cooling fan for the spindle motor. It's DIN rail terminals are right at the bottom of the cabinet and not big enough to safely take the third 'bootlace ferrule' - three as there is the motor, a suppressor network, and this extra terminal where I'm pinching 415 volts . I ended up removing the boot lace ferrules and soldering the wires before putting them in the DIN terminals - took ages to sort out as immediately behind this bit of the cabinet is the Fanuc Wire Eroder so space is very limited.

All works so a big thank you to Pete for the transformer

[awemawson]

One thing leads to another . . . .

Yesterday while rolling on the floor having difficulty getting those wires into DIN terminals, I'd managed to kick the screw lid of my bottle of Hellermann Hellerine Sleeving Oil that you use to slip Hellermann sleeves onto wires. I heard it go, it went skidding across the floor, but no way could I find it 

So this morning, first task after pig mucking out, find that cap. Well opening the roller shutter door to get more light on the scene there it was, hiding under the spindle motor drive belt guard 

. . . . but, putting my head down there i noticed a horribly blocked and apparently inaccessible air input filter on the intake for the spindle motor cooling fan 'snail'. Well no not inaccessible, there's yet another unbolt-able panel allowing me to remove and replace the filter. I'd thought that the airflow was a bit sluggish !

The filter comprises  polyester fibre formed into an open felt, trapped between a pair of weld-mesh sheets and it just so happened that I had most of a roll of this stuff left over from when I rebuilt the Fanuc Tapecut Model M Wire EDM Machine (*)

Went in a treat and airflow is improved but frankly not fantastic




(* https://madmodder.net/index.php/topic,10085.0.html )

[awemawson]

The Postman (well actually woman - Steve is on holiday!) brought the electronic components for me to be able to continue the repair of the 24 volt Kayser power supply.

Turned out to be two 2N3055's that were leaky Collector > Emitter - would be a nice simple fix, if it were not that of the two I pulled from the batch of ten that I had bought, one was dead short Collector > Emitter  and it would have been EVEN simpler if I'd tested them BEFORE I soldered them in. No big deal but a bit confusing at the time.

Of course that meant that I had to go through the rest of the batch and test them before putting them in the 'stores' drawers.

I was rather surprised that Kayser only used a Mica insulator and no thermal paste between the 2N3055's and the case / heat sink. Being a linear PSU it does develop quite a bit of heat.

I'll leave it on soak test for the rest of the morning, but I will still go ahead and replace the pair of them with a switched mode one that is on order as it will run cooler (hopefully!)

[awemawson]

I am surprised that you don't have an industrial grade bore-scope in your box of toys. It would make inspection of these tight spaces much easier and i-phone dangling unnecessary.

To be honest, I don't understand a lot of what you are doing but that doesn't diminish my interest in the slightest. This is truly a worthy sequel to the Traub epic.

NRML,

I did at one time try to find a good one, but they all seemed very low resolution, but that was some years ago - I'm open to recommendations if anyone knows of a 'workable' one of reasonable resolution and price

[charadam]

Andrew,

I bought one of these a couple of years back. It feeds to a laptop, so although resolution is not exactly crisp, it has done eveything from tracing cable routes in the house to reading labels on my Chipmaster lathe motor. It also reassured me about the condition of the bore of my Brown Bess.

And, its only a few squid!

https://www.ebay.co.uk/itm/Waterproof-2M-USB-Endoscope-Borescope-Inspection-HD-Camera-for-Android-Phone/222599632400?epid=1677185312&hash=item33d3f8d610:g:A78AAOSwutFZgHI3

[awemawson]

Thanks for the suggestion. I do have one of those somewhere, but I was somewhat unimpressed - maybe they have improved but mine gives horrid 'fish eye' distortion and is rather low resolution.

[awemawson]

Bit busy with other things today, so I set myself a nice simple objective - remove the tail stock end panels so that I can clean up round there and inspect the ways for rust and debris.

Well I totally FAILED 

If you look at the first picture, the big panel "A" is flapping about unfixed at it's right hand (outer) edge, and is fixed to panel "B" and panel "C" with socket head cap screws into welded in nuts on the flange, screws having entered from the front of the lathe.

Panel "B" that looks as though it should just come out, has no fixings up or down, but is fixed to panel "A" as mentioned and to the cream main body of the machine similarly.

Panel "C" is L shaped with a return angle - again no up fixings only fixed to panel A and the cream body of the machine.

Now all these cap headed screw are totally inaccessible unless your arms are quadruple jointed and ten foot long - mine aren't !

I tried hand cranking the main carriage by turning the ball screw pulley as far as I dared (look how close that drill is to the wall of the enclosure  ) hoping something would be revealed - well it wasn't 

Taking the pictures and studying them is slowly drawing me to the conclusion that the only way to get at them, is to somehow release the way covers at the tail stock end - slide them to the left and then just perhaps it might be possible to reach through, though I suspect I'm going to have to find how to move the  tail stock itself out of the way - no idea how that happens - there's a crank handle, some locking cylinders and a big ram (but I think that the ram only moves the quill  )

Anyway the good thing to come out of this, is that the box ways and ballscrew on the far side of the carriage are in good shape  as are the swarf covers

[awemawson]

Well the tail stock movement question was easily resolved. I couldn't crank the handle because it has a locking detente - pull the handle out and crank away. But even moving the tail stock fully towards the headstock it is very much in the way for access to those screws behind the way covers   

[awemawson]

Determined to get at the bolts to remove those panels, I started investigating inside the tailstock hydraulic cabinet below the controller. There is a wiring duct with a bolt on cover that just might give access to one screw on panel "C". So off it came - sure enough I can see the rear of the hank bush that the bolt goes into, but no way can I undo the bolt itself. OK duct cover replaced, and a clean up inside the cabinet was in order.

[awemawson]

Having started a bit of a cleaning spree, I thought that I'd clean up behind the tailstock before I wound it back out of the way. Just as well I did - it revealed another panel that just might . . .well you get the idea 

OK panel off and guess what - hex headed button cap screws revealed - OK a long way away . . .if only I had a 30" long x 4 mm hex allen key. Well go make one my man 

A bit of 8 mm rod drilled 4.4 mm one end and a 4 mm stub of allen key silver soldered in, and a Tee handle formed on the other end - worked a treat and guess what - panels "A" and "B" are now OFF 

Panel "C" just has one cap screw left and is supported on wooden blocks - BUT looking again at the tailstock end of the lathe, that sloping panel unbolts and will I'm sure let me get Panel "C" off at last - but just now it's far too hot and sticky to continue !


I have a feeling that I'm going to re-design how these panels fix - maybe something along the lines of keyhole slots or maybe rare earth magnets 

[PekkaNF]

.....

I have a feeling that I'm going to re-design how these panels fix - maybe something along the lines of keyhole slots or maybe rare earth magnets 

Keyholes, slots or such locating features gets my vote every time. Too much slop or vibration? O-rings, NBR sealing strip or two sided foam tape (particulary god stuff, holds parts well, but comes appart with a little yank).

Magnets are good for a location where you need a repeatable force to actuate, but they are magnets really for any swarf etc. and really a nuisance magnetizing tools, instruments etc.

Pekka

[WeldingRod]

I suggest Dzus quarter turn fasteners.  They are spring loaded, easy to use, and vibration resistant.

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[awemawson]

Pekka, I agree about the swarf attracting properties of magnets !

Weldingrod - yes the Dzus fixing are good - not sure I'd be able to retrofit them but definitely one to bear in mind.

Well it was only another six cap heads to remove that sloping panel, so off it came revealing . . . . .  well not a lot! A bit of square ducting, where is the cap head? No way I could see it, but groping about I could feel it, and just about get an allen key to it, and eventually off it came releasing panel "C"

. . . .now why did I want these panels off 

[WeldingRod]

Because you NEED to know what's behind it ;-)

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[PekkaNF]

I suggest Dzus quarter turn fasteners.  They are spring loaded, easy to use, and vibration resistant.

Sent from my SAMSUNG-SM-G891A using Tapatalk

Those are good, if you have an easy access to them and you can plan them. Andrew here has some locations at the in accesible end of the panel.

Pekka

[AdeV]

I have a feeling that I'm going to re-design how these panels fix - maybe something along the lines of keyhole slots or maybe rare earth magnets 

Industrial Velcro. No... seriously... that stuff is insanely grippy. To the point where, usually, an attempt to disconnect two parts results in the glue giving up & the velcro still stuck together! It should be OK on a big flat metal sheet though, especially if you supplement the sticky back with some superglue or something similarly grippy. A couple of self tappers maybe...

[WeldingRod]

And. . It tightens with vibration too!
They make metal velcro too.  Some washing machines were assembled with it.  Limited number of uses, though.

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[russ57]

You clearly just needed special service tool part number X542984-45-92-VW

Available on special order, only £852.05
(plus tax)...



I recall an early high speed laser printer, special tools included a Philips screwdriver, only $50, plus a box of 12 toner plastic catch bottles only $120..(forget the printer model but the controller was type HP3000)


Russ

[awemawson]

So carrying on the 'Mrs Mop' cleaning theme I decided to attack the rusty swarf guards. I've wanted to do this for a while but realising that a wire brush on an electric drill was the only realistic way, and also realising that the brushes that I had were far too coarse, I had to wait for finer ones to arrive.

Firstly I needed to remove the tools from the Baruffaldi turret. Now I hadn't expected to be able to remove the ones round the back - normally you would rotate the tool to be removed to the forward position, and unscrew it's locking rack, but I can't yet rotate the turret. However, unlike the Sauter turret on the Traub lathe on this one there is actually just room to the rear to access the hex socket with an allen key - OK tools all removed.

Then extremely gentle and careful application of a wire brush, desperately trying to avoid the lips of the wipers, followed by 220 grit silicon carbide paper  with WD40 and lots of elbow grease gave quite a decent result. I'm not sure if the WD40 or my perspiration gave a better result 

I might just point out that most of this activity entailed me clambering inside the lathe  While in there I noticed that behind and above the tool turret was packed with PTFE swarf - a good half bucket full !

Then the chuck - well I certainly don't want to force any abrasives into it but it needed something doing. I used the same method as the guards but with even more caution. When the hydraulics are all commissioned I will be able to remove the chuck for a proper strip down and clean, but in the mean time at least the brown rust is no more.