Its far easier to feel what’s going on when adjusting gibs if you can remove or disengage the screw letting you test by sliding back and forth by hand. Gives a much better feel for WTHIGO, especially if there is a sticky bit.
Especially with an unknown history component I’d advise doing the strip, clean, careful inspection and make sure it all fits right without binding thing before trying to adjust gibs. In particular remember that the old, gone off oil, dust, stuff, swarf and gremlin poo mixture which builds up everywhere that isn’t positively swept out can take a deal of removing. Keep your thinking cap jammed on tight and visualise where the nasty stuff gets swept to during the operation of the slides. On small lathes I’ve often found that alleged “lots of play ‘cos its worn out” is actually due to only part of the travel being covered by back’n forth movement allowing thous of “stuff” to build up in the rarely traversed areas. Darned hard too. Vices suffer in the same way although its harder to feel. Usual symptom is holds nicely over part of the travel but pants where you normally use it. I like to undercut the dovetail sharp corners a fraction with a couple or three strokes of a saw blade or three square file and remove the sharp edges from gibs.
Check the gib to see if its straight and flat and inspect the pressure point dimples where the screws act for smoothness and clean shape. Similarly inspect the ends of the screws. Bent and battered screw ends working in manky dimples destroy any chances of good adjustment. If you find such damage it is perfectly acceptable to comprehensively curse the perpetuators. Seems to be a Gib Screw Over-tightening Fellowship out there. Also inspect the alignment of the gib where it rides on the adjustment screws. Its not uncommon to find one or more screws a touch out of line or a slight skew on the gib so it drags on the top of slot.
Don’t be afraid to re-make a damaged gib, not difficult as the material isn’t critical. Flat with a decently hard surface are the main criteria steel, brass, bronze are all fine, but it does need to be as thick as possible. Ideally all but filling the gap so it is stiff to slide in. Best way is to get ball ended adjusting screws and use the common slocombe centre drill operating through the screw holes to make precisely aligned conical recesses for them to work in. Carefully shape the top edges of the nascent gib and push it tight up into the top of the slot when drilling. Good idea, if you feel up to it, to add a dowel to stop any tendency of the gib to float back and forth on the screws. The dowel works fine with the usual pointed gib screws but their condition and alignment must be beyond reproach. A carefully re-made, fitted and doweled gib with ball ended screws can run at rather tighter clearances than the usual variety.
Clive
Edited By Clive Foster on 18/11/2010 23:46:15