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C3 mini lathe bed and gibs

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28ten:
A big thank you to Bogs  :clap: :clap: and the banana has been straightened. The casting was nowhere near as bad as Darrens, but it is now within a thou along the bed. Next stop is the gibs!

bogstandard:
Glad to have been of help, but as I told you, don't forget the oil, that is a major factor in getting it run smooth and accurate.


John

Mike K:
2810,

One thing you might consider for the gibs is using shims.  Tapered gibs are nice, but a lot of effort.  And from what I've heard from the shim crowd it'll last quite a while before having to re-shim.  I think this is the route I'm headed.

One thing is for sure: the factory push-pull screw setup needs improvement.  Let us know what you wind up doing.

Mike

klank:
Hi 28Ten,
I noticed you mentioned "drilling for a saddle lock"?

Just in case you did not know - there are two tapped blind holes and socket head screws lurking inside (M6 I think) on the left hand side of the carriage saddle - next to the oiling points, which act as friction locks for the carriage.
If the screws in them are screwed down, their ends mark the bed surface.
To save fabricating/drilling for a carriage lock and avoid marking the bed - I made a 5mm dia. brass slug/pad insert to a tight fit in the end of an M6 socket head screw, so as to cover its steel tip, and screwed it into the front hole where it bears on the flat side of the bed.
The rear hole bolt will bear down on the "V" part of the bed, so I filed up a wedge ended 5mm dia. slug of brass and drilled/tapped the flat end M3 so it could be extracted later if necessary by a bit of threaded rod. This was dropped into the hole so the filed/angled end mated up with the V and followed it up with another M6 bolt to push on the flat (threaded) end of the slug.
Its a simple job to lock the carriage now by just doing up these two M6 bolts and push the brass pads against the bed a bit.

I do wish the lathe bedways had been induction hardened though - they seem to show marks all too easily.

I just dismantled all of the jibs/screws (the ones at the rear of the carriage were all gummed up with powder coat), replaced the chocolate jib adjusters with proper socket head screws, and csarefully lapped all of the dovetails and jib strips with grinding paste. Worth it but a lengthy job and tedious.

I hope this may help?

Peter

28ten:
I have re assembled it electrically and done a quick test with the old gibs and john's magic oil and it is already much better, so the effort to mill it has been worthwhile. I can't make tapered gibs until I have replaced the current flexi gibs, so I will indeed shim it in the first instance, if this proves satisfactory I won't be in any hurry to make tapered gibs.
Klank, Bogs gave me some very handy brass grubscrews for the carriage lock, so I can do something with them. I agree with you about the gib adjustment, the current ones will go, once all that is done I will turn my attention to the dovetails.
Bogs also milled out the carriage so I can get extra travel on the crossslide so I have that to sort as well, but at the moment I need to get it up and running so I can make the parts  :D life is tough when you only have the one machine available  :)

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