# 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


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## 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.


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## 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.


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## wrmiller

cazclocker said:


> 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.


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## 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 ?


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## 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?


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## 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


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## wrmiller

Northern az Internet connection was cut yesterday.


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## wrmiller

cazclocker said:


> 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.


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## David Kirtley

wrmiller19 said:


> 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.


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## randyc

David Kirtley said:


> 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?



Please note that I qualified my statement, limiting it to leaving experts _to make selection of materials_.  I don't think making gibs sacrificial is a sensible idea, and gibs are the topic, right ?  And regarding the decisions manufacturers make, you're agreeing with me 

I also stand by the premise that brass is not a good bearing material.  If it was, we'd see most gibs made from brass since it's way cheaper than cast iron nowadays and a LOT easier to work with (no abrasive particles getting into everything).


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## cazclocker

Hey guys, when I wrote about not being able to log in here, I was in Tucson (southern Arizona) and I was able to log into other stuff but not here! Weird... Anyway, I'm home again now and all is well - I read about the fiber cable being vandalized, but I guess they have it fixed now. Good grief...

wrmiller, thanks for the idea about making the gibs "fatter" to lessen their tendency to tilt as the screws are adjusted. Makes a ton of sense.

randyc, I took a look at your treatise on tube amp designing. Wow, almost 400 pages! I just skimmed through the table of contents and was mightily impressed. I also noticed your pic of you (I guess) playing either a Telecaster or a Tele-clone. I'm a bass player, so I had to comment.


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## Zoltan

The stock gibs are cast iron and work very well, provided you make some modifications. The big issue with them isn't the material, but the terrible way the set screws interface with the gib. On my mill I switched to cup point set screws and milled pockets in the gibs for them to seat into. It made a huge difference. In fact, I ended up modifying my lathe's gibs in the exact same manner (also a huge difference). Also, switch out the y axis gib for a mini mill z axis gib since it fits the space much better (though it will need to be cut to length).

Details:
http://benchtopmachineshop.blogspot.com/2013/06/mill-gibs.html


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## cazclocker

Zoltan, thanks for the tip! That's brilliant. And, thanks for the link. As always, a picture is worth a thousand words.
...Doug in Arizona


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## Zoltan

Couple notes:
- Using the cup point set screws I had to tighten my gibs a couple times as the cup points seated on the gib.
- I turned the last couple millimeters of the set screws down until they just fit in the gib pockets. This helps position the gib laterally.
- I got rid of the locking nut on the set screws and use green Loctite instead, which is specifically made for set screws. It makes gib adjustment 32784327843780237602 times easier.
- Don't adjust your gibs too tight or you'll introduce wear on the gibs, dovetails, and leadscrews. For reference, when I adjust my gibs I measure play in the table 6" from center, and shoot for 0.001" to 0.002".


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## cazclocker

Dang you're tricky!


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## randyc

cazclocker said:


> ...Randyc, I took a look at your treatise on tube amp designing. Wow, almost 400 pages! I just skimmed through the table of contents and was mightily impressed. I also noticed your pic of you (I guess) playing either a Telecaster or a Tele-clone. I'm a bass player, so I had to comment...



Thanks Doug.  That was written mostly when I was recovering from a lung removal.  I was in bed all day, bored stiff for months.  My wife bought me a laptop and suggested that I condense my various posts on jazz guitar forums and add enough information to make a book.  It was excellent therapy !

The guitar is an original Telecaster - the photo was mainly to show the little dog sticking her head out of the cutaway.  I have just over twenty guitars, most of them jazz archtops, but I've never owned a Telecaster before.  One showed up on Craig's list at a reasonable price recently ...  I'm surprised at how much I like it.

(I play a little bass too: Fender jazz bass that matches both the Telecaster and my white Stratocaster).


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## 2bob

Hi all I would knot use brass--bronze is the go better working properties, our go find an old fly wheel for the cast I.  The other thing is to use a shim on back face of  org gibs  work very well an used in the trade


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## randyc

2bob said:


> ...The other thing is to use a shim on back face of  org gibs  work very well an used in the trade...



Good advice Bob !  Epoxying a shim on the _back_ of the cast iron gib on my 1944 Sheldon lathe cross slide tightened it right up.


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## Zoltan

randyc said:


> Good advice Bob !  Epoxying a shim on the _back_ of the cast iron gib on my 1944 Sheldon lathe cross slide tightened it right up.


Does it use tapered gibs?


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## 2bob

Hi all if you shim gibs- wedges tapered or parallel make the shim longer an fold up at each end the width of gid-wedge so that the adjusting screw pushes on it,there is on need to use glue to hold in place but it's up to you ,I have used this method without any problems in the past even with multiple shims


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## Zoltan

I think you're talking about shimming tapered gibs. From what I understand, you can't really shim gibs which use setscrews, or at least, not easily.


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## randyc

Zoltan said:


> Does it use tapered gibs?



Yes, the side in contact with the cross-slide is tapered.


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## randyc

Zoltan said:


> I think you're talking about shimming tapered gibs. From what I understand, you can't really shim gibs which use setscrews, or at least, not easily.



I agree; it is certainly possible but would be a pain.  On the other hand, this type of gib shouldn't require shimming due to the adjustment screw configuration which is very different from tapered gibs (and not nearly as good).


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## randyc

deleted - dual post


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## cazclocker

randyc said:


> Good advice Bob !  Epoxying a shim on the _back_ of the cast iron gib on my 1944 Sheldon lathe cross slide tightened it right up.



Wouldn't there be worries about the gib & shim coming apart? I'm assuming that the job would require a certain epoxy. Thoughts..??
...Doug in Arizona


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## Zoltan

randyc said:


> I agree; it is certainly possible but would be a pain.  On the other hand, this type of gib shouldn't require shimming due to the adjustment screw configuration which is very different from tapered gibs (and not nearly as good).


That's what I was trying to slowly lead up to. The X2 doesn't use any tapered gibs, so shimming the gibs is of little to no value.


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## cazclocker

Zoltan said:


> That's what I was trying to slowly lead up to. The X2 doesn't use any tapered gibs, so shimming the gibs is of little to no value.



Thanks Zoltan. Yeah, I really wouldn't want to just shim my existing gibs anyway. I'd much rather go to the trouble to fabricate new ones.
...Doug


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## randyc

cazclocker said:


> Wouldn't there be worries about the gib & shim coming apart? I'm assuming that the job would require a certain epoxy. Thoughts..??
> ...Doug in Arizona



Doug, the shim must be placed on the stationary cross-slide side of the gib, not the movable side.  Not only would the shim wear and possibly come apart but the advantage of the cast iron on cast iron bearing surface would be lost.

You are right in being concerned, however, regarding the epoxy.   I soaked the gib in mineral spirits for several days, scrubbing it regularly followed by immersion in boiling water for about an hour.  Clearly the purpose of all this is to attempt to release the lubrication that was applied over the seventy years of the old Sheldon's life.

The gib and the shim were then wiped down with denatured alcohol and a thin layer of "J.B. Weld" applied to both surfaces.  The two pieces were joined and placed between two oily milling vise parallels.  About eight small woodworking clamps were used to sandwich the assembly together and 24 hours allowed for curing.

After curing, the excess epoxy was cut/sanded off and the restored gib re-installed in the cross slide.  I posted this entire process with photos on the Sheldon Lathe forum if anyone can figure out how to search their threads - I couldn't !


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