Facets in my 16 TPI Threads - Need some help!

[TX COWDOC]

Left Hand Thread. DTI @ WaysNew HSS bit. 0.002" with the Cross slide.

 

[TX COWDOC]

Surface finish after a few passes on LH threads. Very rough. Didn't thread any further.

 

[TX COWDOC]

RH 200 RPM DTI Tool holder & Compound

 

[TX COWDOC]

RH Thread 200 RPM DTI Tool holder. Ranged from 0.0005" to 0.0008"

 

[savarin]

It looks like the metal is tearing out rather than being cut with a sharp tool.
It actually looks like one of those close up micro photos of a lathe tool in action that shows the metal crumbling.
Do both sides of the cut look the same?
Is the tool bit honed to very sharp?
The last video appears to show a downward flex of the tool holder as it starts to cut, that may be the culprit.
If it flexes downwards at the start it must bounce a little although it didnt seem to.
Why does it drop that much just as the cut starts.

 

[TX COWDOC]

Here are the control surfaces I would instrument with a 0.0001" or 0.0005" indicator (tenths):

1. Carriage to bedways
2. Carriage to compound
3. Carriage to top or side of QCTP
4. Carriage to top of the A.R. Warner threading toolholder.

Do one at a time and observe the fluctuation in the indicator during the cutting operation. This should tell you if you have rigidity issues.

View attachment 351796

David,
I took the measurements and posted some videos. What amount of movement on the DTI is acceptable? I did get movement at the tool holder DTI @ 200 RPM as well as the Compound @ 65 RPM. All cuts were 0.002" with the cross slide from 0.000 to 0.028 then 0.001 + spring passes until 0.0375.

 

[TX COWDOC]

65 RPM DTI @ Compound. What amount of movement is acceptable?

 

[xr650rRider]

That looks like a lot of material for a .002" cut off the diameter. You sure your not doing a .020" cut? Each tick mark on the dial is .002" off the diameter, so you saying your splitting the tick marks for .001" off of diameter and it's still doing it? That would usually result in barely a sliver.

 

[TX COWDOC]

That looks like a lot of material for a .002" cut off the diameter. You sure your not doing a .020" cut? Each tick mark on the dial is .002" off the diameter, so you saying your splitting the tick marks for .001" off of diameter and it's still doing it? That would usually result in barely a sliver.

0.002 on the DRO which is 0.004 total removed off diameter........ not taking a 20 thou cut.

 

[xr650rRider]

OK, you showed your dial, so thought you were using it. I keep my DRO in diameter mode and I usually take .020 for 1st cut, then .010" for a cut or 2, then .005" up until close to final cut and maybe .002" and then spring pass or 2.