[binfordw]

Does anyone have info, a how-to, or tips on making a replacement Z gib for an X3?

I've read a bit here and there, My X3 has come a long way since I bought it, but I still think I can get it alot better/less chatter by replacing the Z gib- just not quite sure how to go about it.

Thanks

[Chilli]

Wouldn't it be more efficient to buy a replacement from Little Machine Shop? Failing that, you could shim the back of the gib. The Z gib on my SX3 ran out of adjustment range and adding a brass shim worked wonders!

[binfordw]

I wasnt aware LMS sold replacements, Ill look into that.

I removed mine, and it looked absolutely horrible- like it was ground with a hand grinder. I tried to clean it up a bit, and put it back. I havent had alot of time to mess with it yet, but it did seem to help from what Ive seen. The one job I cut after cleaning it up, it plunged much cleaner, with less chatter. I never thought about shimming it, mine is basically out of adjustment as is.

Thanks for the info,

Ben W

[Chilli]

LOL, welcome to the Sieg club! I think there is a rule that at least one part on every mill HAS to be badly hand scraped. Mine also had a very rough Z gib and after some light smoothing, it was well past it's adjustment range. It was cheaper & quicker for me to shim it, plus I didn't want to get a spare that might be just as bad.

You might want to check the other gibs; on my mill they were also quite rough and one was bent like a banana to make it appear to be tight.

[binfordw]

Well, I attempted to add a .030" brass shim, but I apparently goofed up the taper on the gib in the process of trying to make it fit.

Not sure what to do now really. I ordered a replacement, but it wont be here till next monday.

I guess I will have to try to make a new gib with the mill, I can use the damaged gib and just lock the Z axis to cut a taper in a piece of stock-

Does anyone know what amount of taper I need? I think my original had about .070" of taper from end to end


EDIT- I managed to fix it with some creative shimming, and while it might not be 100%, wow what a difference. My x3 struggled with plunge cuts with the crappy Z gib, and with a quick test I I was able to plunge at 10+ipm with a .250" endmill without any problems.

[binfordw]

Still struggling with this. Im suprised that with so many people having issues with low quality gibs on these mills, I cant seem to find much info on a solution to the problem.

I ordered a gib from LMS, but I also saw that these gibs would need machining to fit, so they arent a direct replacement. It should be here early next week, I hope it solves my problem.

I began trying to cut a new gib on the mill from steel stock, but without any real dimensions, its not going to work out the best I doubt.

[knudsen]

similar: http://www.cnczone.com/forums/showthread.php?t=109675

[binfordw]

Thanks, I had seen that, didnt seem like there was any details though.

I finished a new Z gib, and spent HOURS carefully filing and testing the fit. I am still puzzled, I tried painting the gib and checking the contact areas, I need to get the top and bottom of the gib contacting the dovetail. My Z axis has been loose from day one, and I believe is the main cause of all my troubles.

I finally filed the new gib to where I had minimal rocking of the headstock, but when I put a dial on the table up to the spindle, I still have .034" of backlash. I fiddled with the backlash setting in Mach3 and now the Z axis travels correctly, I.E, jogging from 0 to .050" and back matches with the dial indicator, but I haven't tried any cuts with it yet to check the chatter.


I checked the X and Y gibs, and suprisingly they were in very nice shape. I just want this mill to work correctly!! I've wasted ALOT of nice endmills and its mostly due to chatter problems.


Does anyone else have backlash or rocking problems in the Z axis? What is to be expected of an X3?

[Thorpydo]

My z gibb was out of whack from the factory- I think most of them are. One side was ground nice and flat but the other... Like a banana. I took the z saddle off and measured the taper with some gauge pins and a caliper. If memory serves correctly, the taper was .5*. I used the surface grinder on campus, angling the magnetic base with a gauge pin of the calculated diameter. The taper matched but I had to take a good chunk of material off. I used a shim on the non sliding side. After reassembling.... I found that the z adjustment screw would shift slightly with each change of direction and that was inducing some backlash. I drilled and taped a small hole to one side of the z adjustment screw. A bolt in this hole locks the adjustment screw in place. Later on, the thrust bearings on my z gave out so I bored the z leadscrew block out for a/c bearings. I still have a thou of backlash but am satisfied with the results for a hobby machine.

[knudsen]

I just measured the angles, machined it to match, and lapped it on rough emory cloth on a flat stone. Rough is good, lets oil flow through. Original was fine, but I wanted smooth brass rather than CI, and ability to oil it. It's tapered, but that was not intended. Taper won't hurt with brass, too much might not be good with CI. It sure is a lot easier to adjust and a lot smoother. No effect on backlash.

My next gibs will be to long for me to use the RT so I'll have to come up with another way to cut the angles.

[Tonyr]

Following this thread with interest.

Rebuilding my SX3 and have exactly the same issues bent Z gib, nicely ground on the unimportant side & like ploughed field on the one that contacts the dovetail.

Hoping to get access to a surface ginder to make a new one. I'll be just running mine manually but want to get everything moving a sweetly as possible.

Tony

[knudsen]

Tony, could you just grind smooth the damage from the adjusting screws on the "good" side and flip it over? If you use a soft metal, you should be able to make a new one on the mill.