The Craftmans Shop > New from Old
The Sequel - Oh Blimey I bought a CNC Lathe (Beaver TC 20)
vtsteam:
Glad to see you back on this project, Andrew. :beer: From the looks of the discoloration around the bottom of that crack, I'm wondering if the turret was used in that condition for some time.
Andrew, are you considering brazing/repairing that casting?
awemawson:
No Steve I've no intentions of using that turret - I only got it with a load of spares I bought from a chap in Ireland. It has proved useful as a diagnostic aid though.
When I packed in a couple of weeks ago, the turret disk was stuck mid motion - now it has relaxed into the rearmost (locked) position (presumeable under pressure from that spring), and hydraulically I cannot drive it forward into the fully unlocked position (I'm referring to the front curvic / hirth coupling which is not the one in the pictures above) so I am more convinced that I have a valve issue. First approach is to uncouple the appropriate hydraulic hose but to say that they are hard to get at is an understatement. Somewhere I have a hydraulic piping schematic - hopefully that will let me relax pressure further down the line but it's a bit of a jungle of pipes at the manifold where the valve are.
awemawson:
So yesterday I managed to get at a pair of hydraulic fittings that would allow me to release any trapped pressure locking up the turret - the only problem being that they are 'bulkhead fittings' and trying to undo them they just rotate in the bulkhead and I can't get my arms round the intervening metal work (one side is in the lower part of the control cabinet and the other is in that lathe enclosure.
Then I had a brain wave (or so I thought) the control valve in question is a 'Ceetop' variety mounted in the same lower control cabinet on a manifold plate as they are. If I slacken the four mounting screws a bit with the power off so no pump running, the valve will no longer seal to the mount and any pressure will be released - have a picture of the valve in question:
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So I slackened the mounting screws and tried levering the turret spindle as per my experiment on the spare one on the floor. Absolutely solid - no movement what so ever - very odd. So I thought OK re-tighten the valve back to it's sealing mount and try driving the solenoids electically.
At this point there was a nasty squelching sound and oil pouring in vast quantities into the cabinet and on to the floor :bang:
I suppose that the valve is not seated properly - I'll investigate when I've cleared the mess up
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Quick power off and large numbers of workshop rags applied to the flood. Luckily I recently bought a bail of washed rags. I've left it to soak up for the moment.
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As you can see, the base of the cabinet is going to be fun clearing up!
vtsteam:
That's no fun.... :Doh:
awemawson:
So at long last the O rings have arrived to re-seal the mounting face of the two way valve to it's mounting face. Rather an odd size - 9.25mm x 1.78 in hard nitrile - they are apparently BS012 seals.
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Removing the four valve mounting screws (which previously I'd only slackened) I was surprised to find that it was mounted on an intermediate block. I suspect that it's an over pressure bypass but cannot find any diagrams. Sure enough two of the original seals were distorted but I probably (or maybe) did that when I'd slackened those mounting screws.
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Luckily I'd bough excess of the seals so was equipped to replace all eight involved with this valve.
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I'd previously pumped just short of a gallon of hydraulic oil from the base of the cabinet with an Amazon Oil Sucker (bargain at ?23 special offer)
All reassembled using a light smear of grease to hold the o-rings on the vertical surface as I tightened the bolts.
Moment of truth - I fired up the machine took it out of eStop to power up the hydraulic pump and held my breath - phew no spurts of high pressure flying about :ddb:
Now I've mopped the residual oil from the cabinet base as best I can, but it's still seeping out of nooks and crannies and probably will for a while as there is a 'false corner' bolted on to protect some wires which will have filled up. Rags stuffed everywhere to absorb what I can.
This means that I can resume fault finding on the turret (which is where this all started) - I have a feeling that I'm going to have to do an 'in frame rebuild' on the turret - it's jammed solid but far too heavy for me to lift out onto a bench.
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