Sieg KX3 Rigidity

[cowcowlee]

Hello

Anybody own the sieg KX3 here?? I have found my one the head stock got a lot of flex (0.1mm) even push and pull with my hands side by side (I'm not a Muscle guy), I suspect it cause by the weak vertical column, it caused a lot of chatter when I tried use the 10mm endmill cutting with 6061 even only 3mm depth.

Kral

[scudzuki]

Are the gibs properly adjusted?

Joe

[Crevice Reamer]

I'm pretty sure that's the same column as my SX3. Properly braced, the X3 column is VERY rigid.

CR.

[ihavenofish]

yes, make sure the gibs are tightened and the ball screw bearings also tight. there will always be some degree of flex on every machine, but i think this one should be a bit better than .004" with just light hand force (30-40lbs).

for the gibs, youll have to pull up on the head somehow. an easy way is by resting the spindle nose on a block of wood. then youll find you can tighten them significantly better than if the spindle is just hanging normally.

[cowcowlee]

I'm sure the gib is well adjusted, also I read some elder post talked about this issue, the back side of the head stock near the vertical column just got about 0.01mm when I push it, however it comes 0.1mm near the spindle (caused by the lever effect), it makes the cutter bounce a lot even with the shallow cut. Just not sure it caused by the gap from dovetail or flex of the column, will take more measurement tomorrow.

Kral

[ihavenofish]

Originally Posted by cowcowlee I'm sure the gib is well adjusted, also I read some elder post talked about this issue, the back side of the head stock near the vertical column just got about 0.01mm when I push it, however it comes 0.1mm near the spindle (caused by the lever effect), it makes the cutter brounce a lot even with the shallow cut. Just not sure it caused by the gap from dovetail or flex of the column, will take more measurement tomorrow. Kral

that sounds alot like a loose gib. it could be flex, but its alot easier to rule everything "simple" out first.

[Teyber12]

Originally Posted by Crevice Reamer I'm pretty sure that's the same column as my SX3. Properly braced, the X3 column is VERY rigid. CR.

holy sh!t, your a master fabricator!

[ataxy]

id like to see more picture of the brace if possible

[Crevice Reamer]

Originally Posted by ataxy id like to see more picture of the brace if possible

My goal with this was to have a lightweight yet very rigid CNC industrial-duty milling station. The braces are part of the flood cooling enclosure framework. The mill is easily accessable from all sides--including underneath the base.

CR.

[Eson]

Try and lower the head till it rest on a piece of stock and then tighten the gibs.
The weight of the head can jam the gibs.

[cowcowlee]

ok....I did some more measurement on the vertical column yesterday, it's really flex, especially much more easy to lean forword/backward then the left/right, that's why the much more chatter when milling in Y direction rather then the X direction I have experienced before, however still don't know the root cause, most of the possibility is the column's base plate since it's only locked down by 4 bolts, it may twist or life up on the edge while the force applied on the column.

[ihavenofish]

Originally Posted by cowcowlee ok....I did some more measurement on the vertical column yesterday, it's really flex, especially much more easy to lean forword/backward then the left/right, that's why the much more chatter when milling in Y direction rather then the X direction I have experienced before, however still don't know the root cause, most of the possibility is the column's base plate since it's only locked down by 4 bolts, it may twist or life up on the edge while the force applied on the column.

have you tightened the Z gib yet? thats really where you need to start. without checking that 100% youll never be able to track down the issue.

the column will have a little flex for sure. so will the head. so will the tool, etc. there might be a little play in the Z ball screw breaing mounts.

you need to go systematically through each one to find out which is the biggest cause of flex, fixing them along the way if possible.


my little kx1 had loose z gibs, and play in the ball screw mount on both the z and y. when i tightened it all up, there was virtually no meaningful flex left without exerting more pressure than the machine sees while running.