Thread: Tail Stock: To Lock or Not to Lock

Originally Posted by oreos40

For speed and high production there is nothing that chucks up faster and more positively than a lever action over center tailstock. It cant vibrate loose! often peices can be changed without shutting the machine off.

Couldn't agree more.

Originally Posted by Jim Carroll

As with all things it is about safety.

There is generally some form of vibration on the lathe and it does not take much for the quill to back of slightly and the live centre looses drive then you get this peice spiraling to you.

It is more common with those that just use a cone centre as this is the least amount of grip.

The safer way is to use a cup centre or a pin and ring style or even safer is the steb centre as the spring loaded pin give a bit more drive when things come loose.

So lock the tailstock in position then adjust the quill and tighten, run for a moment and nip up as some timbers with the lateral load embed themselves a bit more in the spur drive and this them gives the tailstock less running pressure.


This brings us to the next question on how to use the spur drive properly.
We find that most people put the spur drive into the headstock and rely on tailstock pressure, this is not enough for a good purchase on the wood.

It is best to have a second spur drive that you use as a punch off the lathe.
You mark your centre then use your spare spur drive as a punch and hit the end of the spur drive into the end of the peice of wood with a good thump, this is why it is your spare drive as over time the taper will mishape slightly and be of no use the the headstock taper. This gives you deeper indents than just using tailstock pressure.
You then bring the peice of wood to the lathe and locate the wood into the marks left by the spur drive and then bring up the tailstock, this gives maximum insertion in the wood and you are not relying on the tailstock to push into the wood.

This is what safety is all about and anyone teaching should be puting safety first before you start turning.

I agree that tailstock pressure is insufficient for engagement. But I'm not too keen on using a spare spur drive, because of infinitesimal variations in shape. Even within the spur drive, spurs can vary because of manufacturing tolerance. So if remounting is at all potential, I mark its position on the wood - referring to a scratched mark on the drive, or the setscrew socket on replaceable points.

To avoid distortion of the taper, I use a leather-faced mallet to thump into position, and/or several thumps to assist alignment. Never touch it with a metal instrument.

Cheers,
Joe

Originally Posted by Jim Carroll

As with all things it is about safety.

There is generally some form of vibration on the lathe and it does not take much for the quill to back of slightly and the live centre looses drive then you get this peice spiraling to you.

It is more common with those that just use a cone centre as this is the least amount of grip.

The safer way is to use a cup centre or a pin and ring style or even safer is the steb centre as the spring loaded pin give a bit more drive when things come loose.

So lock the tailstock in position then adjust the quill and tighten, run for a moment and nip up as some timbers with the lateral load embed themselves a bit more in the spur drive and this them gives the tailstock less running pressure.


This brings us to the next question on how to use the spur drive properly.
We find that most people put the spur drive into the headstock and rely on tailstock pressure, this is not enough for a good purchase on the wood.

It is best to have a second spur drive that you use as a punch off the lathe.
You mark your centre then use your spare spur drive as a punch and hit the end of the spur drive into the end of the peice of wood with a good thump, this is why it is your spare drive as over time the taper will mishape slightly and be of no use the the headstock taper. This gives you deeper indents than just using tailstock pressure.
You then bring the peice of wood to the lathe and locate the wood into the marks left by the spur drive and then bring up the tailstock, this gives maximum insertion in the wood and you are not relying on the tailstock to push into the wood.

This is what safety is all about and anyone teaching should be puting safety first before you start turning.

For marking center, I thump the ends with a Vicmarc Drive Dog Punch. No need to worry about deforming the taper, just don't drop the blessed thing on you toes

Originally Posted by Jim Carroll

This brings us to the next question on how to use the spur drive properly.
We find that most people put the spur drive into the headstock and rely on tailstock pressure, this is not enough for a good purchase on the wood.

It is best to have a second spur drive that you use as a punch off the lathe.
You mark your centre then use your spare spur drive as a punch and hit the end of the spur drive into the end of the peice of wood with a good thump, this is why it is your spare drive as over time the taper will mishape slightly and be of no use the the headstock taper. This gives you deeper indents than just using tailstock pressure.
You then bring the peice of wood to the lathe and locate the wood into the marks left by the spur drive and then bring up the tailstock, this gives maximum insertion in the wood and you are not relying on the tailstock to push into the wood.

This is what safety is all about and anyone teaching should be puting safety first before you start turning.

Sometimes you don't want a big ding in your wood as you need to adjust it in teh lathe to make sure your pomel it square. Which may not be the same as being square with the end of the bit of wood.:S

Originally Posted by tea lady

Sometimes you don't want a big ding in your wood as you need to adjust it in teh lathe to make sure your pomel it square. Which may not be the same as being square with the end of the bit of wood.:S

If the timber is dressed properly this should not be a problem

I’m with Ann Marie on this one.

Just because the wood has been machined doesn't mean it will run true at the transition points (pommel).

There can be a number of reasons for this, poor machining, moisture content, incorrect storage or it just might be a twisty bit of wood that moved after machining.

Using a spring loaded centre punch or punching a drive centre into endgrain of Pinus Twistus is problematic if you hit the hard winter growth ring.

The hard winter growth ring can kick the point off to one side.

Drilling a shallow 3mm hole will help overcome this.

I have used the Vicmarc drive dog punch but it is really only a good fit for the Vicmarc drive centre.

I use this method for driving large diameter (150mm) hardwood posts.

For sizes around 75 or 100mm I like to use a 32mm Steb centre and a smaller steb live centre.

It's easy to adjust the centres if the work doesn’t run true.

Cheers

Tim

Originally Posted by Pat

For marking center, I thump the ends with a Vicmarc Drive Dog Punch. No need to worry about deforming the taper, just don't drop the blessed thing on you toes

I looked at getting one of those once and found the drive dogs are about $20 cheaper Far better off just buying two drive dogs and using one for a punch

The only time I lock my tail stock is when I'm turning cabriole legs, but don't when turning balustrades to save time! but I advise students to when teaching for safety until their confidence grows.

Originally Posted by Jim Carroll

If the timber is dressed properly this should not be a problem

amazing how bendy a verandah post can be and still LOOK straight.

Originally Posted by tea lady

amazing how bendy a verandah post can be and still LOOK straight.

Now you are talking real spindle turning