Theory – Lathe Operations

What is one thing to be aware of when using the crossfeed dial?
Backlash. To avoid issues because of backlash if you overshoot your correct setting turn your dial back one full turn to take out the backlash then approach the correct setting again.
What are the 5 steps you should take before parallel turning?
Step 1: Align the Tailstock to Centre
Step 2: Taking a Trial Cut and set the crossfeed to zero
Step 3: Use the crossfeed dial to set your depth of cut
Step 4: Taking Roughing Cuts
Step 5: Taking your finish cut(s)
On a direct reading(Corrected) dial what does each graduation on the crossfeed dial represent?
Each graduation on a direct reading (Corrected) dial represents 0.001″ on the DIAMETER of the workpiece. (When you turn the dial 1 graduation the diameter will be reduced by 0.001″)
On an indirect (Uncorrected) dial what does each graduation on the crossfeed dial represent?
Each graduation on a indirect reading (Uncorrected) dial represents 0.001″ on the RADIUS of the workpiece. (When you turn the dial 1 graduation the diameter will be reduced by 0.002″(2x the radius))
What are boring bars used for? What sized bar should you pick? How should they be held on your toolpost?
Boring bars are used to cut internal holes of any size accurately. You should always pick the biggest boring bar possible. They should always be held with the smallest overhang possible. (Short and fat is where it’s at)
When facing where should you set your tool in relation to the centre of the workpiece?
You should set your tool on centre.
What should you be doing when centre drilling?
You should be peck drilling and using lots of oil to prevent breaking your tool bit. Drill about 2/3 of the way up the tapered portion of the drill.
What are the 4 steps of reaming to produce an accurate hole with a good surface finish?
The 4 steps are
1) Centre Drill
2) Drill
3) Bore (Make Hole True)
4) Ream
For reamed holes smaller than 1/2″(13mm) use a drill that is __”(__mm)undersized. For reamed holes 1/2″(13mm) and bigger use a drill that is __”())mm) undersize.
For reamed holes smaller than 1/2″(13mm) use a drill that is 1/64″(0.5mm)undersized. For reamed holes 1/2″(13mm) and bigger use a drill that is 1/32″(1mm) undersize.
When reaming what should your spindle speed be set to?
Half the speed you would normally use for a drill of the same size.
What are 3 ways to use a lathe to cut a taper?
3 ways to use the lathe to cut a taper are:
Using the compound rest
Using the Tailstock Offset Method
Using a Taper attachment
What is the centreline angle?
Half of the included angle
When parting set the spindle speed to _____ of the speed you’d want to use for turning. Do not ever part ____ ____.
When parting set the spindle speed to half of the speed you’d want to use for turning. Do not ever part between centres.
What speeds and feeds should you use for knurling?
Your speed should be approx. 100rpm. For fine knurls use about 0.015″ feed rate. For medium knurls use about 0.020″ feed rate. Finally for coarse knurls use 0.030″ feed rate.
When cutting a 60 degree thread with slant depth what angle should you set your compound rest to?
You should set your compound rest to approx. 29.5 degrees.
What is the purpose of a steady rest? Where do you attach it?
The purpose of a steady rest is to support long pieces of work either at the end or in the middle. You attach it to the ways.
What is the purpose of a Follower rest? Where do you attach it?
A follow rest keeps the workpiece from deflecting away from the cutting tool but supporting the workpiece directly where the cut is taking place. It attaches to the saddle of the lathe.
What is the taper of a solid mandrel?
The taper is 0.006″ to 0.008″ taper per foot.
When you are filing what hand should you hold the file in? What should your file always have before using it on a lathe?
You should ALWAYS hold in in your left hand. The file should always have a handle.
When using emery cloth on a lathe what should you do?
Always be alert that the strip of emery cloth can wrap around the workpiece and pull your hands in. Keep your hands away and lean away from the lathe.
If you take a trial cut at each end of a workpiece held between centres and find that the cut at the tailstock end is 0.010 inch smaller than the cut at the headstock end, you must adjust the tailstock:
a) 0.010 inch away from you
b) 0.010 inch towards you
c) 0.005 inch away from you
d) 0.005 inch towards you
c) If you take a trial cut at each end of a workpiece held between centres and find that the cut at the tailstock end is 0.010 inch smaller than the cut at the headstock end, you must adjust the tailstock 0.005 inch away from you.

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