1022V Concentric Circles when Facing? Loose gib?

[C-Bag]

My lathe did that and in my case it was way stiction. The combo of too smooth and no way lube retention. Did some light scraping and for me it went away. I also use way oil, not motor or hydraulic oil. YYMV.

 

[ToolOrDie]

starting and stopping the feed will cause those lines.
Have you let it feed on it's own without interruption?
Are you feeding into the center or away?
That tool is designed to cut from the center to the edge, not the other way around.
I prefer cutting into the center, and sometimes, I clean up exiting the center.

starting and stopping the feed will cause those lines.
Yes but I was stopping and starting in-between those concentric ring intervals. No change to the frequency or spacing of the rings.

Have you let it feed on it's own without interruption?
The first post images are without interruption of the automatic feed.

Are you feeding into the center or away?
I was feeding from the center to the outside. Here are photos using a different tool outside to inside. Same spacing

I would suggest trying to test it with an indicator while just feeding the cross slide (not cutting, spindle not running). Bent cross feed lead screw or other problems in that mechanism would be my suspicion as well.

I'm assuming you mean indicate it like this. There is a fair a bit of needle bouncing towards the middle of the cross slide but not as much as I was expecting to see.

Have you tried facing using the compound ?

No concentric rings facing with the compound and same tooling.

 

[ToolOrDie]

Looks like harmonic nodes to me, like a phonograph. Since speed doesn't' affect it (speed drops as you move inward in diameter), then maybe a different tool bit or a different presentation angle? Also make sure the chuck, backing plate, and spindle interface are tight. May need to re-do the preload on your spindle bearings.

I was thinking that but I've used about 15 different tool profiles with about a half dozen materials ranging from 17-4, 303, 304, 6061, 7075, brass, bronze. I've even got so desperate to use threading tools, boring bars, and no matter what profile use; I see those artifacts. Cutting inward, outwards....
Always right at 2.5mm apart no matter what variable.

It happens with my 3 jaw, 4 jaw and everything is tight. I'll look into the spindle preload. Would I see issues in the OD of parts if the preload needed adjusting?

I ran an indicator across my cross slide as another poster suggested. The gibs could use some adjusting, I just think they are exacerbating the issue rather than being the cause.

 

[pontiac428]

Set the cross slide gibs tighter than usual, just to see if it eliminates the problem. See if you have any end play on the spindle with the indicator on a face that is coupled to the spindle (chuck, work, spindle nose, whatever) and check your free end play before touching the spindle preload. You shouldn't see much. The SB9 will show some small amount of flex under hand pressure on the spindle, but you're looking for a thrust measurement, so it shouldn't be much. Low end of the single digits to zero is what I would expect. Also try radial play at this point. If it's tight, move on to the cross slide. Then try again with the dial indicator on the slide. Look for rocking nose to heel and up/down.

I enjoy looking at and pondering tool vibration patterns, but what you've got is a profound amount of movement that can keep you from finding precision in your work. Inspect and control every degree of freedom until you find it. It may turn out to be a bellmouthed chuck or an out of square tool holder in the end, but go through the obvious in a systematic way and work outward from the spindle until you find the bug and squash it.

 

[Jim F]

Looks like you need to tear into the cross slide.
If facing with the compound gives a good finish, that is where to look.
Inspect the screw, nut , gib and dovetails.

 

[ttabbal]

It wouldn't hurt to make sure your gib is snug and the cross slide is oiled properly. I'm not sure that the test with the indicator says much, as that might not be a precision surface. That it improves when using the compound makes me think it's something moving on the cross slide.

I know it's a fair bit of work, but I would suggest disassembling the cross slide. Thoroughly clean and inspect the ways and screw. Make sure the surfaces are clean and look undamaged. If you have a surface plate, you could inspect the straightness of the gib as well. You could probably get close enough inspecting the gib against the ways. Also check the screw. The precise interval sure seems like it could relate to the screw. If the gib is tightened, does the screw bind up only on one part of the rotation? That would make me think it might be bent and the loose gib is allowing sideways movement on the cross slide.

 

[pontiac428]

It wouldn't hurt to make sure your gib is snug and the cross slide is oiled properly. I'm not sure that the test with the indicator says much, as that might not be a precision surface.

Roger that, looking for movement not gauging a surface. Different operation.

 

[woodchucker]

Looks like you need to tear into the cross slide.
If facing with the compound gives a good finish, that is where to look.
Inspect the screw, nut , gib and dovetails.

since the compound is not causing it, I wonder if you are getting a slip stick on the carriage.
it should be a nice smooth motion, not one that's smooth, sticks, and smooths out again.

tearing in should tell.. I am curious if you are too tight on the gib vs too loose.

 

[pontiac428]

Another possibility is a chewed up V belt. That could potentially cause an alternating rumble/smooth loop track. Lots of little things to check. Chips under the tool post? Loose tool post mounting bolt? Keep at it!

 

[Jim F]

Another possibility is a chewed up V belt. That could potentially cause an alternating rumble/smooth loop track. Lots of little things to check. Chips under the tool post? Loose tool post mounting bolt? Keep at it!

All of that was pretty much eliminated when the compound does fine.