How do you machine gibs for an 8x12 or 8x14 lathe?

KenS

KenS

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I have an 8x12 HF lathe-- same as the Lathemaster 8x14-- and have had a compound milled to accept an AXA QCTP. The compound I purchased for the new tool post came without a gib. I have decided to make a gib out of brass in hopes of having a tight, smooth sliding action. I am looking for ideas concerning how to machine the brass rectangle into a suitable parallelogram-shaped gib. I know that many users on this list have fabricated their own gibs, but I have found very little information about how to do this here or on the web. Any and all suggestions-- especially with photos and blueprints-- are welcomed. In addition to my lathe, I have an HF mini-mill.
 
I strongly advise you to NOT use brass. It will not wear as well as steel,or better yet, cast iron. If you can get a piece of Dura Bar(continuous cast iron.) it would wear the best.

I'd machine the top and bottom of the gib to the parallelogram shape on its top and bottom surfaces. Then,I'd clean all oil off spotlessly,and super glue the gib-to-be in the tapered side of the slide. Then,very carefully indicate the parallel side absolutely true. Carefully machine the glued on gib with a dovetail cutter. A little heat,and the gib will come loose. Clean it off with acetone.Mill in the groove for the adjustment screw carefully,so it fits the thickness of the head of the screw with as little play as possible,or the gib will slide a little when you try to back up the cross slide,and jam it.

Maybe someone else has a better way to hold the gib. I've found that super glue works well for holding pieces that are hard to clamp.
 
george wilson said:
I strongly advise you to NOT use brass. It will not wear as well as steel,or better yet, cast iron. If you can get a piece of Dura Bar(continuous cast iron.) it would wear the best.

I'd machine the top and bottom of the gib to the parallelogram shape on its top and bottom surfaces.
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Thanks for the response George. I guess my question is how do I jig the gib to mill (or possible grind) the parallelogram shape? I was looking at brass because I have to consider the limits of my mini-mill. Do you think key stock would work for the gib?
 
I'm not used to machining key stock. Can't you buy regular cold rolled steel ? Keyway stock may be tougher than regular cold rolled,and dovetail cutters aren't the strongest milling cutters. I suggest getting some reliable metal to machine lest you break a dovetail cutter.

If it is possible,use a woodruff key cutter to remove as much metal as possible,then use the dovetail cutter.

HOLD ON!! You have a HF lathe??? It likely does NOT have a tapered gib,but has the old fashioned type that just uses several set screws to hold it in place,and is parallel,not tapered. I have seen a number of gibs of that old style that were just made of a length of flat steel with both edges rounded over. they have a little dent milled into them where the gib screws touch them. this does not hold the gib on,but keeps the gib from moving sideways when the slide is operated. Is this what you have?
 
HOLD ON!! You have a HF lathe??? It likely does NOT have a tapered gib,but has the old fashioned type that just uses several set screws to hold it in place,and is parallel,not tapered. I have seen a number of gibs of that old style that were just made of a length of flat steel with both edges rounded over. they have a little dent milled into them where the gib screws touch them. this does not hold the gib on,but keeps the gib from moving sideways when the slide is operated. Is this what you have?
Click to expand...

I kept thinking this should be a flat gib from the start of the thread, having worked on several of the 9x20's which are very similar and has a flat gib - and the 9x20's gibs seem to be prone to arrive very crappy. I have made several flat gibs for the 9x20, and other lathes by just digging around in the scrap box. Ideally a nice piece of cast iron would be best, but few of us HSM'ers have that laying around. I do mill both sides of the material Im using to relieve any stress there might be - probably not necessary in that small a piece, but.. The last one I made up came with a gib about 3/32 thick needing to fill about 3/16 gap, some .100 difference! - made for a cross slide that would give chatter horribly.
 
In making gibs for the Atlas, which is a flat stock and tapered across the top and bottom with little divets for the adjustment screws. Does this match yours?

I simply draw filed the top and bottoms to match the old one and made the divets with a drill.
 
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