Has anyone experienced vertical runout on 833 quill?

[Christianstark]

Sorry for the potentially dumb question, but my 833tv is doing something a bit unexpected.

At first I realized this when moving the quil down with the drill arms. I was plunging with an end mill, and noticed that when the end mill contacted the milling surface, I could continue down with the drill handle roughly another half inch or so till the gear matched the quill itself.

Put this another way, when the quill is fully up, and retracted, I can push up on the spindle assembly, and there is about 1/8th of an inch play upwards once I overcome the weight of the quill assembly. I can also reproduce this when using the fine downfeed. Is this normal, or do I have some tweaking to do somewhere? Is there some kind of eccentric adjuster I am missing?

 

[COMachinist]

That is called backlash between the quill and the drive gear and yes all mills have it to some degree.
CH

 

[Christianstark]

Is there an adjustment on these bench style mills, or just work around it?

 

[COMachinist]

I don’t have a PM833, but my PM932m PDF does not have a way to tighten up the quill back lash. I have a DRO on my quill so I just work around it. It is not a problem once you get used to it. Where it really shows up is when you use the fine adjustment wheel on the front of my machine. It does a good job for a hobby machine. If your bothered by it, or you are in business, pony up a lot more money and get a Bridgeport class of machine.
Good Luck.
CH

 

[7milesup]

Well....you maybe could machine new gears to take all backlash out.

I have an 833T and it is the same way.

 

[Christianstark]

If that’s just the way it is, then no problem. Just wanted to make sure. It was more a curiosity thing than anything. I have been locking the quill during cuts. It just felt funny doing plunge cuts with the drill handles.

 

[Christianstark]

Measured it today at 40 thou.

 

[Firebrick43]

I am baffled by this. All quills have back lash in the mechanism. That is why you don't use them to plunge end mills. You lock the head and raise the knee or lower the head depending on the mill. Or you lower it to where you want it, lower the quill, and move onto the piece. You really shouldn't ever straight plunge with an endmill, even if center cutting. In CNC you can ramp in or spiral down. On a manual mill drill a hole first almost to final depth.

 

[Christianstark]

Don’t be baffled. 1 - I’m learning. 2 - it does it with drills also.

 

[Firebrick43]

With drilling you drill to a depth - the back lash and then let it dwell, although "typically" drilling is not as sensitive to depth. Ie if you want a hole to be 1" deep you drill to .960 and let it dwell. In harder/gummy materials such as stainless you may need to raise the knee that .040"