[iandh]

I've got a new Seig X3 from Grizzly, I purchased it second hand with packing oil still on it.

I've been trying to get everything tightened up and working right, and I can't seem to get decent accuracy out of the z-axis.

There's about 1-2 thou of flex in the column, which is to be expected, but the play is just nuts.

With the Z-axis gib loose enough to crank Z up and down without dislocating my shoulder, There is over .010" play (this is with a mag base attached to the top of the head indicating on the ground way, so this is actual head play, not column flex).

When I crank the gib screw down to where I think I am going to snap it, and I can barely crank the Z-axis up and down any more, there is still almost .005" play.

If I stick the mag base on the table, and indicate to the head, then do plunge cuts in aluminum, the weight of the head seems to be enough to keep the play in check, as it is only about half-thou, and that's only when reversing crank direction.




My worry here is that having .005" in play with the gib fully tightened means the gib isn't correctly ground, and isn't parallel to the dovetail on the column. If that's the case, this machine is total garbage to me as I don't have time to tear it down and get a new Gib ground. I'd just as soon sell it for cheap on craigslist and start over with a G0704.


I was hoping that some X3 owners could chime in and let me know what is "normal" slop for the Z-axis.

[H500]

How did you do the measurement? Can you post a pic?

[pete from TN]

I do not own an X3 mill... However I have owned quite a few chinese machines. Unfortunately this is the nature of the beast. I seriously doubt the Grizzly machine would be any better. The thing you gotta ask yourself is what are you planning to do with the machine. If you intend to cnc this machine then you will probably add a ballscrew and some sort of zero backlash nut so it really does not matter what the factory screw does. IF you intend to use it manually then it can be a problem. If you go with a DRO then you can accurately track the heads position regardless of what the screw does so it is again not a problem. There is no such thing as perfect with these small chinese mills but many of their shortcomings can be worked around and result in a good accurate machine within reason. Does this make sense? peace

[iandh]

How did you do the measurement? Can you post a pic?

As mentioned above, I indicated from the mill head to the column.

The mag base was attached to the mill head.

The indicator was indicating on the column.

When the mill head comes to rest on the table, the head tilts/wobbles up to .010" away from the column.

I do not own an X3 mill... However I have owned quite a few chinese machines. Unfortunately this is the nature of the beast. I seriously doubt the Grizzly machine would be any better. The thing you gotta ask yourself is what are you planning to do with the machine. If you intend to cnc this machine then you will probably add a ballscrew and some sort of zero backlash nut so it really does not matter what the factory screw does. IF you intend to use it manually then it can be a problem. If you go with a DRO then you can accurately track the heads position regardless of what the screw does so it is again not a problem. There is no such thing as perfect with these small chinese mills but many of their shortcomings can be worked around and result in a good accurate machine within reason. Does this make sense? peace

I think you misunderstood what I was saying... the screws are fine.

The z-axis way has .010" of slop in it, even when the Z-axis gib is fully tightened to the point where you can not move the axis at all. The head of the mill wobbles up and down in relation to the column.

That means that one end of the gib is tight against the column dovetail, while the other is loose... which means the gib taper is likely totally wrong, or the inside dovetail of the head is shaped like a sand dune.


To be honest, I can't see how a new machine from Grizzly could possibly be worse

We're talking .010" of play in one of the ways with a fully tightened gib. That is HORRID, even for a chinese machine.

[rwestbr]

If you do replace the gib I suggest going with BRASS, I replaced my X2 gibs with BRASS ones I made, it is probably the biggest improvement for the least amount of money that I've invested. They allow you run the GIB adjustment much tighter and do not appear to wear very badly or quickly (ran a 3 hour job and GIBS remained tight).
HUGE difference over the steel ones.Try it you will not be disappointed!!!

Hope this helps....

Robert

[pete from TN]

Obviously I misunderstood your post. What you are saying ( I think) is that your head is loose on the ways. Despite your gib adjustment you are still getting play. EVEN WHEN THE GIB IS BASICALLY LOCKED? How is that possible? You said that you measured .010 when the head is resting on the table and it tilts towards the column.... I do not get it....


If you suspect the gibs are bad or the ways are not machined right, I would be inclined to take the gib strip out and have a look at it. Lower your millhead onto a piece of plywood or something on the table and carefully remove the gib strip. This may not help but my Lathemaster mill I found needed a very small bit of the gib ground off the bottom so that I could more fully seat it into the slot. Basically when I had the screw tightened down on the adjustment the gib was still loose. When I tore this machine down for the cnc conversion I noticed it. I just trimmed a small bit off the bottom and now it gets snug and I can adjust it to where I want it. Put it on a good flat surface and make sure it is not bent and also look for damage from the gib locks as some people really crank them down. This could possible cause a wobble despite being tight. Do the ways look straight and undamaged? Is there any crap stuck inside the gib slot and is everything else on the head tight? that millhead does not tilt right so there is not a collar to millhead joint that may be moving either is there.... Just throwing out ideas here....

If the head is heavy enough to counteract the slight wobble as you said even on a plunge cut it may still work fine but that is something you would have to decide. I would be inclined to take it all apart and investigate it but that is up to you... peace

Pete

[Teyber12]

before you make any drastic changes i would email grizzly... they have great customer support.

cheers

[BobWarfield]

When you get the gib out to look at, you may see an obvious problem. Let us know if you do.

If not, it could be more subtle. Perhaps the taper angle is off.

Take a Sharpie to it and color it all in and then reinstall and tighten it. Run the head up and down a few inches and then pull the gib back out. You can see where the Sharpie ink rubbed off which parts fit and which don't. You've very likely going to find most of the ink is still there and there are some high spots.

Another possibility is that the gib needs shimming. It might have reached the end of its travel without engaging properly. There have been some posts you can search for on shimming your gib to take care of it. I'm guessing this isn't the issue since you can get it tighten so it is hard to move the head, but it is something to keep in mind if all else fails.

Cheers,

BW

[rwestbr]

Also the gib maybe dislodged at the top or bottom ie. the adjuster ends are not lining up with the dimples in the gib.If you have a mirror try to look up from the bottom of the Z dovetail....Hope this helps. I had this similar problem before.

Robert

[iandh]

Thanks for the help everyone, I went ahead and pulled the gib last night, and it turned out to be horribly misshapen.

It was pretty much beyond saving, but I was able to get the slop down to .005" with some creative sanding.

Basically, the taper on the gib strip was done wrong... the second half of it had a steeper taper than the first, so it allowed the head to rock. I understand it's a chinese machine and all, but this is sub-par, even for them. I mean, compared to the reasonable quality of the rest of the machine, I really have to wonder what this particular worker was smoking.



I'm going to start by ordering a new gib strip and adjustment screw (only about $10), and work from there. I wasn't expecting any better than .003" including column flex, but .005" is still a bit much for me and I know it could be better. The above suggestion to try brass was noted...



I did realize, at least it rocks up, so the head will always return to the same cutting height. I was going to work on it more today, but I was too busy mating a QCTP to the cross-slide on my 9x20.



Sorry for any attitude last night, I was nor very happy at that point in time.

[TXFred]

I wouldn't bother ordering a new gib. Order some brass stock instead and machine new gibs. You've repaired the mill enough that it will suffice for this job.

Fred

[Teyber12]

just to mention, im not sure ordering a new gib will help any. i had to order a new z gib for my x3 and it was just the stock they use to cut the gib from. I just through it in the spare parts pile and ground down the stock one i dinged. you will have to machine it yourself. i would just look into brass. if i can find my extra ill send it to you for whatever throwing it in a envolope costs if your interested.

cheers

[TangentAudio]

The original post resonated quite a bit.. I've been trying to figure out what the heck is wrong with my ProMiCA-CNC'd X3 and I think sloppy Z gibs are a major issue.

Is there a guide somewhere for what's "normal" on these machines, and a "best practice" adjustment guide? This would be helpful for all of the axes, actually. I understand the basic idea, but seeing or reading about it in more detail would be nice.

[TangentAudio]

With renewed interest in trying to solve this problem, I took a look at my mill again this morning. I tightened the single Z gib screw down as much as I could, but I still have considerable "nodding" in the head of my mill. I can easily pick up the front of the head from the front edge and feel it rock up and down. I didn't put my dial on it to see how much it's moving, but it's significant and easily visible to the naked eye.

I tried bringing the head down on a 2x4 to take the weight off (effectively tipping it back towards the column) and cranking down more on the gib adjust screw, but it's still got a lot of play. It may have improved things very slightly.

I removed the Z gib lock when I converted my machine, but I do recall it moving the head significantly when I locked it down.

Any advice at this point? I fear I was too inexperienced when I first got the machine and used it manually to note this, and now that it's converted to CNC (not to mention 10 months old), it may be challenging to get Grizzly to help me.

I've read of people lapping their existing gibs, getting replacement gib stock from Grizzly, and making replacement gibs out of brass - any guidance on any of these?

[TangentAudio]

So this may not be the absolute best test setup, but I wanted to capture a video to show what I'm seeing on my machine.

I attached the magnetic base to the head, on the left hand side near the front edge. I set up the dial indicator to indicate off of the surface of the table. I then apply upward force on the front edge of the head, causing it to "tip back."

I can feel the head wobble in the ways as I do this, and the dial indicator moves ~0.030" typically, though I've seen it jump as much as 0.040".

My Z gib adjustment screw is cranked all the way down as far as it will go.

Here is a video that I grabbed quickly this morning:
[ame="http://www.youtube.com/watch?v=a6_xZJGfPPI"]YouTube- Sieg X3 Z Slop[/ame]

[TXFred]

Deleted.

[Thorpydo]

I'm in a similar situation with an X3 and it's Z axis.

Is there any documantation on these brass z gibs?

[MotoGems]

Hello,

I wouldn't mind knowing where to get some "gib" material from here in australia and then making up a new one for my "Z" axis... i've got around .3mm slop in the "Z" axis... it would be good to be it tighter....

I'll try to keep an eye out on what evolves..

MotoGems.

[yantra3d]

I had a similar problem with my z axis gib strip on my grizzly x3 and after lapping the crap out of it to bring it in line it was then too thin to seat properly in the head. As a result it would hang down past the bottom of the head about 1.5" below it.

I attempted to make my own gib strip from some expensive ground flat stock only to warp the heck out of it trying to machine it into a gib strip. I then contacted Hoss about making one for me cause I knew he had a grinding setup on his x2 freak and he brought my attention to the LMS and their replacement gib strips.

I picked up a Y gib strip and (what was supposed to be) a Z gib strip from LMS only to have the Y axis be in worse shape than the stock Grizzly one (warped!) and the Z gib strip was not anything near a match to the grizzly x3! It was about 3 inches too long, thicker, and did not have the grooved slots for the tension screw.

However, I was able to measure up and cut off an inch or so from either end and then use a small 1/16" endmill to cut the grooves for the tension screw and then do some more lapping to the backside of the strip to make it work for me. The good side of the strip was actually very flat so I was able to make it work for me.

Would not mind making one from brass however in my limited experience in working with brass I don't see how it can be done. That brass seems to be the worst in terms of stress - I can't keep it from bowing with even the lightest of cuts. Not sure how you guys are pulling that off.

[TangentAudio]

Is this what you bought from LMS?
http://www.littlemachineshop.com/pro...ory=1716750115