The Craftmans Shop > New from Old
The Sequel - Oh Blimey I bought a CNC Lathe (Beaver TC 20)
tom osselton:
Remember this?
https://youtube.com/watch?v=beVgHSO4Ewg
tom osselton:
Gremlins from the Kremlin 1944
vtsteam:
--- Quote from: awemawson on February 16, 2026, 06:02:38 PM ---It?s probably full of them Steve. At the moment I?ve walked away from it to preserve my sanity.
The turret is in an odd jammed state, not being able to move the tool disk forward or backwards. Something is mechanically stuck, but also my oil central heating boiler in the workshop has sprung a leak requiring total replacement. I?ve had the new one delivered (?3049 !) but not yet installed. I am required to employ a registered installer so that?ll be a few more ?100?s
--- End quote ---
Man if it's not one thing, it's another....
vtsteam:
Wow, Tom, no! Never saw that one. Usually it was just Bugs vs the Gremlin.
Why did they name a car that anyway? :scratch:
awemawson:
OK I've been away from this for a couple of weeks to let things soak in in my brain. Sumarising, the tool turret seems mechanically stuck in that the hydraulic cylinders cannot move the central shaft forwards or backwards. Now I call these hydraulic cylinders but actually they are machined cavities in the casting with the central shaft acting as the piston / rod. There is a powerful spring pushing the shaft rearwards aided by one half of the hydraulics with the other side of the double acting 'cylinder' pushing it forwards when a tool change is called for.
So is it a stuck valve maintaining locking pressure, or something internally physically miss-placed?
As an aid to seeing what is going on I dug out my 'spare' turret and rigged it so that I could try moving the shaft with a crowbar against that spring. The whole thing is plonked on the tool disk face with the central shaft pointing upwards and it's too darn heavy for me to shift it so in fact in this experiment the tool disk and central shaft are staying still and I'm raising the rest of the turret upwards by leverage - this direction corresponding to 'forwards' were it mounted in a lathe.
Rear Hirth coupling disengaged (this is the one that applies rotation to the tool disk) - ignore all the detritus on the coupling, this has been sitting open in the workshop for months:
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Rear Hirth coupling engaged by crowbar:
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So it is possible to mechanically move the shaft on the 'spare' turret with the hydraulics disconnected - I could hear the gurgling of the residual oil as I did it !
This gives me confidence to perform the same experiment on the actual turret in the lathe which is the next step I think.
While I was inside the 'spare' turret I think I've found out why the chap couldn't get good tool alignment with it - there's a massive crack in the casting !
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