That's how I drill on a lathe. Centre drill first, then use smaller drills first for big holes. But it takes a lot of force to push the drill, especially if not sharp, more force than is needed when turning between centres.

The tailstock on my lathe also slips back sometimes and has to be tightly locked down. Slippery lathe ways do not help but have to be oiled to prevent rust and wear.

You also need to learn to sharpen drills properly, look at a drill and know its going to be ok, feel a drill trying to work and know it's not ok, yet more skills only learnt with time and effort

Edited By Ady1 on 15/07/2022 10:26:24

Chris,

There's usually a plate that sits under the bed, with a threaded bar or bolt passing through it from the tailstock above. Locking the leaver (or tightening the bolt on some lathes) raises the plate to lock the tailstock in position.

There's usually a nut to tighten to adjust the locking force, It doesn't take much of a turn to set it correctly. You may have to slide the the tailstock off the bed (or at least partially) to get to the nut.

All lathes differ but the principle is basically the same.

Good luck!

Have you checked that the spindle and tailstock centres are in alignment?

Turn a 60 degree included point with the compound slide, stick a dead centre in the tailstock, and bring the points to near-touching. Lock the tailstock and its barrel. Examine the alignment with a jeweller's eyeglass. Adjust with the tailstock side screws – as with the locking levers, designs vary slightly.

You can get very close with this method and patience. If you've got a dial gauge plus a test bar that's known to be round, straight and parallel, you can get closer still – but that decision's on balance of time/cost/requirement.

I had to do the same as Rex described but found after a while it became loose again but a very small amount of thread lock has now sorted out the problem

Blunt drill and/or difficult metal can cause a properly adjusted tailstock to slip. It can be helped by the operator pushing as he turns the handle, but if the drill is sharp and material cooperative, it's time to look to adjusting the tailstock clamp. It may also require cleaning – a clamp soaked in oil and running on swarf is likely to slide.

Run a clean cloth along the underside of the bed where the clamp grips: if it comes out plastered in oil or dirt, consider removing the tailstock and so the clamp can also be cleaned.

If that doesn't fix it, check the adjustment.

Some tailstock clamps are just pulled tight by a nut on a stud; not much to go wrong. However, because having to spanner the tailstock is a time-waster, it's more usual for a lever on the tailstock to cam the clamp tight. Much faster but can come out of adjustment and be fiddly to reset because the mechanism is often on the crude side.

The nuts are adjusted until the cam-lever operates correctly. Loose enough for the tailstock to slide without binding when the lever is off, and tight enough to pull the clamp hard enough to brake the tailstock firmly when the lever is on.  Sounds simple but it may take a few attempts to get right especially at first. The cam may allow the stud to slop from side to side, so be prepared to experiment with the angle as well as how the nuts are positioned. With luck simply tightening the nut a little will be enough, but expect fun and games if the tailstock is removed or the adjustment is way off.

Opinion on the best way to drill larger holes varies. Everyone agrees always start with a good pilot hole, because they reduce wandering. (Twist drills love to wander).

My feeling is it's best to drill the hole full-size in one go because it shares the cutting load across the full edge and big diameter drills are less likely to wander than small ones. But the lathe may not be powerful or stiff enough for this, in which case stepping up is the answer. On the downside, stepping up concentrates wear on the outside of drill tips, and I think using a progression of small drills gives each a chance to decentralise the hole. Twist drills are bendy creatures.  There's always a risk the hole won't be straight, and I've had a few dreadful curves!

Boring is best when it's important for holes to be straight or diametrically accurate. A twist drill is used to make a hole big enough to take a boring bar, which then opens up the hole as required. Slower, but boring cuts on the rotating axis, doesn't wander, and will cut to any diameter. Tailstock not used!

Dave

Edited By SillyOldDuffer on 15/07/2022 14:23:45

The nut illustrated has to be carefully adjusted as the eccentric turned by the locking lever has a limited throw. It is easy to get it too tight or too slack, Smart & Brown is similar design.

There could be a number of nreasons for the Tailstock ,moving back when attempting to drill a hole.

1 Did you use a centre drill?

2 Did you use a pilot drill? (Trying to drill a large hole in one, requires a lot of pressure. )

3 Are you drills sharp? A blunt drill, or any other cutting tool won't cut, or will require a lot too much pressure.

At your stage, there is not much point in extolling the virtues of four facet drill grinding, because you really need a cutter grinder for that.

4 As already suggested, the clamp may need to be tightened. Self locking nut or no, they do need to be reset from time to time to maintain sufficient clamping pressure.

SUGGESTIONS

a Tightern the Clamp

b Use a centre drill

c Drill one or more pilot hole(s More than one if a large hole is the required end product ) The pilot hole allows the centre of the larger drill to be unloaded. (Since it runs at Zero cutting speed , it doesn't do much )

d Check that the drills are sharp. (Some drills are less than properly sharpened. even when new. Cheap drills are a waste of money for a variety of reasons )

DON'T try sharpening drills yourself. It takes skill to grind a drill so that it cuts properly and to size.

Some of the cheap drill grinding appliances are of dubius worth. It is easy to melt a plastic one. and some of the metal m,ones are better, but benefit from careful attention to detail.

If you take the advice to join a model engineering club, you will learn why and how.

e Don't expect a HSS drill to cut hardened steel.

Howard