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

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).
 
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.
 
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
 
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
 
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".
 
...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).
 
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
 
...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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