[How do I?] Parting with backlash

Shortly after I got my new 1640 lathe I developed a parting problem, could not figure out the problem, it was square to ways, on center, sharp etc. CXA toolpost worked and locked fine. Finally I noticed the scratches on compound that I did not remember being there when lathe was first set up. Upon further inspection I found a couple of small chips under toolpost keeping the toolpost from sitting tightly on compound, got rid of the chips stoned out the scratches got everything back together and voila parting happiness. I have a lot of lathe work under my belt, I was embarrassed that it took me so long to spot this, sometimes its easy to miss the obvious. Hopefully it will be something this simple for you to find.
 
Faster feed is better up to a point. The chips became more continuous but the tip dug in and snapped.
 
ericc said:
The chips became more continuous but the tip dug in and snapped.
Click to expand...
Tip digging in may be showing lack of rigidity somewhere. Look at everything from the bed up that might let the tool be pushed downward. Also make sure you are truly on center height when you start cutting.
 
Hi Bob. That is pretty much correct. There is a lot of vibration during cutting. The slide is pretty tight, and the top of the compound where the toolpost sits is clean of chips. Everything seems tight, but there is still vibration. When I shake the assembly with the power off, only the backlash moves. Still, it seems that there must be something else. I am about to lock the cross slide and feed with the compound. That might show some indication of what the problem is. It will take me awhile to cobble something together.
 
If you have a magnetic base indicater try setting it up on the tail stock to take a reading at the highest point of the tool post both inline with the bed and accross the bed when cutting and see if there is any deflection
 
Hi Savarin. Thanks. Just to make it clear, I have attached a small diagram. The measurement across the bed would implicate backlash (or twisting of the carriage)?

measuc.png
 
sorry Ericc, not sure what you are saying here.
Heres what I meant
parting-2.jpg
If I lift up on the silver handle I get 6 thou deflection

parting-3.jpg
if I lift up on the black handle I get approx 3 thou deflection, backlash here is around the 40 thou mark.
If I set up this on the cross slide I could measure the deflection whilst cutting (but not backlash.)
 
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