Anyone Ever Make New Gibs For Lms 3900-series Mini-mill?

[cazclocker]

Has anyone here gone to the trouble of machining your own new gibs for the Little Machine Shop 3900 solid-column mill? If so, what material did you start with? Do they need to be heat-treated afterward?

I would like to make a full set - for the X, Y, and Z axis.

Thanks,
...Doug in Arizona

 

[randyc]

Not familiar with that machine but American machine tools universally use cast iron gibs, no heat treating is necessary. Cast iron ingots are available for projects like this - do an online search. The material is not cheap, however.

 

[David Kirtley]

What are you going to do special for them? The replacements are only like $3. I got the brass gibs for my lathe cross slide and compound but haven't put the one in the cross slide yet. The jury is still out as to the improvement.

 

[wrmiller]

Has anyone here gone to the trouble of machining your own new gibs for the Little Machine Shop 3900 solid-column mill? If so, what material did you start with? Do they need to be heat-treated afterward?

I would like to make a full set - for the X, Y, and Z axis.

Thanks,
...Doug in Arizona

Hey Doug,

I made mine out of brass for my LMS mill. I made mine thicker than the factory ones to take up some of the gap so they would register a little better/have less slop. Was it worth it? Don't know, but it was fun making them.

 

[randyc]

If you must use a copper/tin alloy, then bronze is the best one, not brass. Bronze is not cheap, nor is cast iron as previously noted, but functionally, much better than brass.

It's always been my opinion that inventiveness is one of the qualities that define a good toolmaker/machinist. But arbitrarily selecting materials for a specific function isn't necessarily an indication of inventiveness.

Material used in a critical area of a machine tool shouldn't be based on what is in the scrap box but best left to metallurgists or those with lots of experience. I'm no metallurgist, just a garage hack with lots of old tools that are still working well.

The proper materials for machine tool applications was long ago determined by machine tool manufacturers (for 150 years) and cast iron is the choice for gib material

But, as the band Fleetwood Mac sang several decades ago: "You Can Go Your Own Way". And your application probably is not that critical, right ?

 

[David Kirtley]

Brass has a long history with precision machinery as well. It is not as long lasting but there is something to be said for having parts be sacrificial. Some of the plastics are used as well in many machines. The decisions that manufacturers make are based on more than just the "best" material. They also consider cost, longevity, production requirements, supply availability and more.

As far as always leaving things to the "experts", well we wouldn't have many hobbyists if we did that, would we?

 

[cazclocker]

Thanks guys. Actually my mill is working well as it is now, or at least as well as can be expected with the factory gibs adjusted snug-but-not-tight. I was asking mainly because I had read somewhere that the factory gibs are not that well made and installing new ones has the potential to be a worthwhile improvement. Jury's still out whether I go ahead and do it, though...lately shoptime has been a rare & precious commodity.
Hey guys, was it just me? I couldn't log in here all day yesterday!
...Doug in Arizona

 

[wrmiller]

Northern az Internet connection was cut yesterday.

 

[wrmiller]

Thanks guys. Actually my mill is working well as it is now, or at least as well as can be expected with the factory gibs adjusted snug-but-not-tight. I was asking mainly because I had read somewhere that the factory gibs are not that well made and installing new ones has the potential to be a worthwhile improvement.
...Doug in Arizona

The biggest improvement for me wasn't the material used (heck, they are making super precision lathes out of composites now) but rather the stability gains from making the gibbs 'just' small enough to fit in their respective slots. By making them over size they don't have much of a chance to tilt as pressure is applied via the screws, thereby maintaining more surface area contact. Movement was smoother, less chatter, and better surface finishes.

 

[David Kirtley]

The biggest improvement for me wasn't the material used (heck, they are making super precision lathes out of composites now) but rather the stability gains from making the gibbs 'just' small enough to fit in their respective slots. By making them over size they don't have much of a chance to tilt as pressure is applied via the screws, thereby maintaining more surface area contact. Movement was smoother, less chatter, and better surface finishes.

That was my motivation for putting the new gibs in my lathe. The original had a bunch of slop and was hard to adjust and able to move around under pressure. I have been occupied by other things and have not really done much with my lathe to see how much of a difference it made yet. I have not even gotten around to putting the new one in the cross-slide.