Odd issue with Grizzly G0678 mill quill lock

[Maplehead]

Hi All
So I've been using my new knee mill for a bit now and I have one issue with it. I often use the fine feed on the quill and when I do I like to lock the quill so that it does not move and give me an extra/unwanted cut. However, locking the quill has been doing just that. Often when I unlock the quill to advance say another 10 thou the quill drops to more like 20 or 25 thou on its own. Why is this hapening? When I use the fine feed without locking it, so far I have not detected any extra movement and it does not drop any further than what I advance it to.
Any and all help is greatly appreciated.

 

[derfatdutchman]

Use the knee to make your depth of cut adjustments. Back in the dark ages when I we learned the vertical mill, using the knee is how our instructors showed us to set your depth of cut. 90% of the reason I sold my round column mill was due to the problems of using the fine feed on the quill for setting the depth of cut.

 

[Maplehead]

Use the knee to make your depth of cut adjustments. Back in the dark ages when I we learned the vertical mill, using the knee is how our instructors showed us to set your depth of cut. 90% of the reason I sold my round column mill was due to the problems of using the fine feed on the quill for setting the depth of cut.

Would never think to use the knee since it's so hard to dial in a thousand'th or so.

 

[Skierdude]

I have exactly the same issue with by Chinese mill drill. I’ve found the problem is that once the quill is locked in position the vibration from milling action causes the fine feed adjustment to move a few thou. Since the quill is locked it ‘free wheels’ a little bit. Say I’ve locked the quill at 2.15mm on the dial. During milling the dial might move to 2.17mm. If the quill is then unlocked it will drop down until it fully engages with the adjustment gear. Really annoying. I need to either increase the friction in the adjustment drive or use add a quill scale to the DRO.

 

[Mitch Alsup]

Would never think to use the knee since it's so hard to dial in a thousand'th or so.

Looks like a G0730.....like mine

If the knee thread and gearing is well greased, and the ways properly oiled and not screwed down, a gentle tap with your hand on the handle can move the knee in small amounts quite easily. You can, instead, mount a dial indicator on the locked spindle, and tap the knee up in increments more precise than you can read on the knee dials.