Gib Material

After a lot of thinking, I'm about to embark on a major rebuild of my Sieg C3 lathe. The plan is to replace the spindle bearings with taper rollers, fit tapered saddle gibs, following John Bogs more or less definitive process, fit thrust bearings to the compound and cross slide leadscrews, and fit an outrigger bearing to the saddle handle. Nothing startling really and I'm sure that there are those who will be thinking thoughts involving pigs ears and silk purses. However my thought was that it's a pretty good machine to start with, and I'm just trying to make it a bit better.

After that preamble my question is about the gib material. To start with I was planning to use some gunmetal, similar to John Bogs, in fact I've bought some. Then I started thinking about it, and wondered about using steel, after all the original (barely adjustable) gibs are steel. So my questions are...

1/ What do "quality" machines use for gib material, running against cast iron? (i.e. Schaublin, Hardinge, DSG, Smart and Brown etc)

2/ What do others think?

cheers

Bill

The gibs in my lathe are steel, but I am considering changing them with bronze plate or brass or some thing that is used for bearing bushes. I haven't looked into it very much yet but it is on mt To do list.

I recently made a tool to dress the diameter of my bench grinder with a diamond. I set it up to use a similar arrangement as the cross slide on the lathe. True, it was mostly made from aluminium but I did use a piece of brass plate as the gib, and the diamond in its holder traverses across the wheel very smoothly.

I used brass on my sc3, they made a noticable difference.

.

Bill ... My understanding [which I am sure is incomplete] is that the better machines, such as Schaublin 70, use hard steel gib strips running on finely finished cast iron. The 'theory' being that the cast iron surface 'glazes' in use, and produces a very hard-wearing surface.

I know that many have had great success using Bronze/Brass/Gunmetal strips on the typical Chinese lathes: But I suspect that this is largely because they are better sized and finished than the original Mild Steel strips.

The surface quality of the cast iron may be a significant factor in your choice of material for the gib strips.

.... I shall be very interested to see how this thread proceeds.

MichaelG.

Edited By Michael Gilligan on 23/09/2015 08:16:19

I recently made a new one out of brass for my WM250V-F compound slide as the OEM version was a complete joke, pics in album...

George

The Pultra 1590 used some form of hardened steel, but tapered gibs were normally for industrial environments with up to 7 day working weeks. The machines were literally worked to death

I would say you can use a good ordinary steel on a hobby machine and you might have to make a new one in 40 years

Edited By Ady1 on 23/09/2015 09:39:32

I would expect steel for gib strips would be best for sliding on cast iron due to its stiffness between adjusting screws as used on most hobby machines but on tapered- gib machines there may be a case for bronze as a lower friction material although I've never seen it used for that purpose. Colin

I"m sure that there are those who will be thinking thoughts involving pigs ears and silk purses.

Nope, just sounds like basic re-fettle and up grade.

As far as, what material to use for gib strips, i would [and have] used bright m/s strip as big as you can get in there, machined to suit, i modded a Drummond top slide awhile back to fit on a Ml 7 top slide base, this involved making a second fixed jib first to bring the feed screw to alignment, and then making the usual adjustable jib, so steel gibs both sides of the top slide.......Made a real difference !!, Some time back mew ran a article on friction to do with slides and such, cant remember which number though, It was about ten years ago.

bodge.

My Chester 8" lathe has steel gibs. After a few weeks I took them out, they were a bit rough, so cleaned up with file and emery cloth. Much better, and now after a few years use they are pretty good, just need a bit of running in.

Purely as a 'Silk Purse' Benchmark

Here is the Schaublin 70 manual.

... We can but dream.

MichaelG.

Thanks to everyone for the responses. I especially liked the Schaublin 70 ops manual!! A friend of mine used to run a business making dental implants, he had 3 Schaublin 70s!! All bought new, the first one cost over AU$26,000, in the early 2000s. Making new gibs in about 40 years might be up to the next user Ady1!!

Anyway, the conclusion that I've come to is to use free machining steel, S12L14; up here in 'straya, probably very close to EN1a. I'm confident that I can get a good finish (i.e., smooth and flat) on them for the sliding faces, by draw filing and lapping. If I could, I would case harden them, but that's unlikely and there's always the risk of warping. The gunmetal option is very appealing, but I think I can probably get a better finish where required on the steel ones.

So thanks again chaps.

cheers

Bill