[Newbie] Very Basic Cross Slide Vs Compound Slide

RegisG

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I've read & seen use of both cross and compound slide for cutting and it seems that for many cuts you could use either. When is the right time to use cross slide and when is the right time to use compound slide? And, I guess when doesn't it matter which one you use?

Trying to do all this right!

Thanks,
Regis
 
In a quick thinking back. I am recalling to just use the compound for producing an angle cut. Then use the cross for everything else, even for threading!...Dave.
 
About 98% of the cutting forces encountered on the lathe are tangential forces and this force vector is essentially straight down when turning. When using the compound this force is borne by a cantilevered component so rigidity is compromised to a degree. This may not matter as much for the smaller cuts you take when cutting threads or angles but for general turning, when cutting loads can be very high, the cross slide is much more rigid.

Bottom line: use the cross slide for general turning and boring and use the compound for threading and angle cutting. Lock the compound when not used for those operations.
 
Another use for the compound.

With the gap removed getting the tool across it to the part may often proove difficult, I turn the compound parallel to the spindle and advance it as far as possible as seen here.
ringindicate_zpsvzlzf2uq.jpg
On these parts I turned the toolpost 90 Deg. then used a boring bar upsidedown and ran the spindle in reverse.
ringodturnlive_zpsqk3jni7x.jpg

ringindicate_zpsvzlzf2uq.jpg

ringodturnlive_zpsqk3jni7x.jpg

ringindicate_zpsvzlzf2uq.jpg

ringodturnlive_zpsqk3jni7x.jpg
 
I use the compound for angle cuts and threading. However, for non DRO machines (or other means to measure z axis movement), the compound proves useful for precision z axis movement. Align the compound parallel to the spindle axis. You can now lock the carriage and move precisely in the z direction.

Another use is for cutting to a shoulder. I would set my carriage stop so the cutting tool just touches the face of the part and zero the compound. I then back the carriage off and dial in the compound for the depth of the cut. I can then cut to my shoulder using the carriage knowing that I will not overcut my shoulder. Kind of like setting a stop on a drill press.

One more use is for making sub-thousandths turning moves on the lathe. The compound it set at an angle of 5.74º to the z axis so a movement of .001" of the compound causes a movement of .0001" of the tool in the direction perpendicular to the spindle axis. It isn't perfect as there is a significant movement in the z axis direction as well but if you are turning a press fit, for example, it increases your control of the diameter dimension. This can be carried further by setting the compound angle to .57º and get a 100fold increase in resolution.
 
I appreciate the replies and wish that I understood all of them. I'll have to get in front of my lathe and re-read and try to figure these out.

Thanks all,
Regis
 
I use the compound for angle cuts and threading. However, for non DRO machines (or other means to measure z axis movement), the compound proves useful for precision z axis movement. Align the compound parallel to the spindle axis. You can now lock the carriage and move precisely in the z direction.

Another use is for cutting to a shoulder. I would set my carriage stop so the cutting tool just touches the face of the part and zero the compound. I then back the carriage off and dial in the compound for the depth of the cut. I can then cut to my shoulder using the carriage knowing that I will not overcut my shoulder. Kind of like setting a stop on a drill press.

One more use is for making sub-thousandths turning moves on the lathe. The compound it set at an angle of 5.74º to the z axis so a movement of .001" of the compound causes a movement of .0001" of the tool in the direction perpendicular to the spindle axis. It isn't perfect as there is a significant movement in the z axis direction as well but if you are turning a press fit, for example, it increases your control of the diameter dimension. This can be carried further by setting the compound angle to .57º and get a 100fold increase in resolution.

I use RJ's method with the compound set at a 30 deg. angle when facing. I don't have a DRO on any of my 3 lathes, so if I want to take 0.020" off the face I turn the compound in 0.040" which gives 0.020" on the Z-axis.

Bruce
 
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