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Cross slide lock...

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lordedmond:
John

I understand now the gib is the thin line on the left
The bit that I thought was the gib was I fact the cross slide body

Sorry but it was unclear as Andrew says pointed grub screw would work but normal hard balls would do after all ball races are OK

Stuart

philf:
John,

Just an observation.

I assume the ball on the right hand side is retained by a grub screw. When you tighten the grub screw on the top, to press the ball between the two others, the right hand ball can't go anywhere and thus the top ball will try to embed itself in the left hand side of the vertical hole.

You need to make the vertical hole a good clearance on the ball so it's got somewhere to move.

Alternatively, instead of a ball on top you could make a hardened plug with a (e.g.) 45 degree angle machined on just one side.

 :beer:

Phil.

John Hill:
Thanks, your comments have shown up a few challenges which I will have to think on some more! :doh:

vtsteam:
I like the look of it. But it will only work well if the degree of movement is small for reasons PhilF mentioned. How small is probably important. Clearance in the hole is probably important, too.

Breakout (if any) would be at the bottom corner of the hole. All depends on the magnitude of the vector force when locked and the slide material properties (CI, I assume). Might be fine, might not.

Also, depending on the hole clearance to the ball,  it isn't just movement to the left wall of the hole by the upper ball that might be a problem as the lower ball moves, it is also movement fore and aft (in this profile view) if clearance allows it. These are balls so they slide in two degrees of freedom with pressure from above. Any movement that will allow the top ball to seat lower will occur, so that may not be just movement to the left. Depends on clearance, movement, etc.

But mental experiments take second place to real ones. I'm a great fan of reality! It wouldn't be too hard to mock this up in scrap to intended dimensions and see what happens with this kind of lock.  :dremel:

vtsteam:
ps. just remembered reading something way back about bathroom silicone rubber caulk used for a "hydraulic" lock.

Basically the brass pin bearing against the gib would be retained, but the balls would be replaced by silicone rubber caulking compound. Pressure from the screw transmits via "hydraulic" pressure to the pin.

I've never tried it -- just one of those memory things tucked away. Seems removable if it doesn't work. Once again a mockup would prove it out before risking the real thing.

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