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

[John Rudd]

   looks like you got your work cut out there Andrew..........Carry on!...

[vtsteam]

Lots of lateral thinking going on 

Plus lateral some shifting!

[awemawson]

Oh yes - some shifting. That's today's task.

Clear the way from the roller shutter (external access) to the lathe and prove that the electric roller shutter still works. I ended up earlier in the year with a massive wasp's nest in / on / and about the roller shutter and the pest controller fellow wasn't sure at the time how much debris had gone inside. I couldn't open it then as the 3D printer and it's gubbins had cables too close to risk moving it.

A late start as this morning I had an interesting talk on Concord(e) at the local U3A but after that cracked on before the next two sets of cottage guests arrive (due 15:00).

The Versatool cabinet with the communications receiver on top was massively heavy as full of tooling and the castors are too small a diameter, but using levers I moved it out of the way along with various other bits of clobber.

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Then moving the desk with the 3D printer on it let me shift the cables so I could try the roller shutter. Apart from getting tangled in the 'Chuck Crane' it amazingly worked fine (not been lifted in perhaps two years) shedding detritus all over the place.

Just need to find a temporary home for two pressure washers.

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Now at least the dog can see the rabbit and I can start rigging the fork lift. Approaching like this leaves full access to the bits that I need to unbolt to remove the heavy bits.

I suppose that I should load up the extended forks and see what droop I get over their considerable length with a heavy lump on the far end!

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So not huge progress but with a little bit each day I should get there. (How do you eat an elephant - one bit at a time!!)

[awemawson]

Today's task - remove the tool disk from the spindle. How hard can it be, I've previously several years ago been able to rotate the disk to align the tool pockets to the curvic coupling so I kow that the eight large cap screws lock them together but what actually fixes them. There is a row of ten smaller cap screws that I feel MUST be involved but are they?

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As eventually I will need to set the alignment of tool pockets to curvic coupling to cam features on the spindle I wanted to resolve this before yanking on the original disk in the lathe.

I dragged out my spare (but busted) tool turret to experiment with to have a look see. Plan was to sit it on it's rear flat casting face with the tool disk upwards and pull it apart. Absolutely no way I could get it in the attitude so I roped in a passing friend. We also failed what is this thing made of, solid uranium to judge by it's weight.

So out comes the engine hoist again and we managed to get it sitting as I wanted it.

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First I slackened the eight big bolts a long way out and did a tentative lift, no the whole turret came up. Then I did the same with the ten slightly smaller bolts with exactly the same null result. So glad that I'm working on the spare and not the one in the lathe!

OK last resort - what does the drawing say ? Well the only drawing that I have is from the Patent Application so may not be 'as built' but here it is:

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Now to me that is clear as mud. I can see the large bolts screwing into the outer half of the front curvic coupling allowing for a bit of rotational adjustment (as I have previously done). But the ten smaller bolts from the way that I'm reading the drawing don't seem to do anything.

I've retreated for more head scratching.

[awemawson]

OK the plot thickens!

Looking at the photo of the tool disk on the lathe there appears to be two location dowels 180 degrees apart threaded for a slide hammer, and an adjacent threaded hole possibly to screw in an extractor bolt.

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Looking at the spare disk it seems someone has been here before me. I suspect that they broke off an extractor bolt and tried to drill it out on one side, and there are extra holes drilled at a further offset from the axis. Was this an attempt in the past to make new threaded holes for an extractor.

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Not quite sure where to go from here !

[AdeV]

OK last resort - what does the drawing say ? Well the only drawing that I have is from the Patent Application so may not be 'as built' but here it is:

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Now to me that is clear as mud. I can see the large bolts screwing into the outer half of the front curvic coupling allowing for a bit of rotational adjustment (as I have previously done). But the ten smaller bolts from the way that I'm reading the drawing don't seem to do anything.

I've retreated for more head scratching.

As best I can tell, and I'm not much cop at interpreting those kind of drawings either...

The smaller bolts look exactly like the pattern that typically holds a car flywheel to the crankshaft. My best guess would be that if you undo and remove them all, you then screw bolts into the two holes top & bottom & use them to push the whole front piece off. Or maybe just the middle comes out, since the drawing shows all the bolts flush with the same surface, but neither physical unit matches that (the centre bolts being further in). Best guess, the big outer bolts are holding the coupling together (with,as you say, enough play to make minor radial adjustments), the inner bolts are what's holding it together. Probably gravity isn't strong enough to overcome the sticktion between the two parts, hence the push-it-out bolt holes in the centre portion.

Should be easy enough to test the theory - loosen the inner bolts, screw a bolt into one of the things you suggested might be for a slide hammer, and see if a) it bottoms out and b) if so, that it does indeed dislodge the coupling.

[pycoed]

Re the forks:- how about welding  loops to each C channel to fit over the forks? More secure than clamps - probably (have you SEEN my welding?)

[awemawson]

Thanks for your thoughts chaps.

I have a feeling that the tool disk currently on the lathe will be easier to dismantle than the broken spare one but I'd still like to get that apart first to see what's what. Latest plan is to lug out my rather heavy magnetic drill (it's old school not Temu!) and drill out the broken off bit and tap those outer holes for a strong 'push off bolt'.

Need to do some careful measurements to stop the drilling before breaking through into the main casting and either create a flat bottomed tap, or push off bolts with reduced ends to pass through the inevitably tapered end of the tapping.

Why does everything get so complicated !

[awemawson]

Curiously the larger of those holes in the rows of three is precisely 9.9 mm and shows no sign of ever having been threaded. It does as far as I can tell go all the way through to the flange - this is assuming that there is a slight locating recess in the back of the tool disk, which the drawing does seem to confirm.

So what thread has a tapping size of 9.9 mm ? Chat GPT tells me 7/16 UNF 20 tpi so if this is true I shall tap those holes and see what happens ! Obviously can't tap right to the bottom UNLESS i CAN PRODUCE A 7/16TH UNF tap with a 90 degree end which should be possible if I have enough standard taps to sacrifice one.

[smiffy]

No need to tap full depth ,go as deep as possible and insert a small piece of brass bar at the bottom of the hole and wind the bolt onto that .   Mike

[awemawson]

Yes Mike that also dawned on me a couple of hours ago prompted by the hole beings almost 3" deep!