Drive centre stuck in headstock - help please

[Dancie]

Hello all, I am an enthusiastic amateur,

I have a Jet 3520B lathe,

The 4 prong drive centre is stuck in the headstock,

I've tried hitting the knock out bar with a mallet but this hasn't shifted it,

Three questions if I may:

First any ideas on what to do next please?,

Second by hitting the knock out bar hard and several times am I doing any damage to the headstock i.e. the bearings?

Third how can I make sure this doesn't happen again?

This happened once before about a year ago with a different drive centre ( I think ) that one cleared after a few heavy wacks but this time its much more suborn, it looks like it might be there to stay,

Any help or advice please - many thanks - Dancie

[Wood spinner]

You say mallet ? a wooden one ?

Try a 5lb club hammer

When yo used the 4 prong drive did you hammer it into the wood before putting it in the lathe ? or did you wind the tailstock up until the 4 prong drive embedded itself into the wood , I suspect the latter

Re getting stuck again all I can suggest is some fine valve grinding paste and lap the 2 surfaces and hope it doesent get stuck again , Once the 4 prong drove is hammered in manually it only needs enough tension on the tail stock to hold it in place

good luck 

[Paul Hannaby]

Try some penetrating oil, give it 24 hours to soak in then give the knockout bar a good clout! Don't hold back, one good clout will do far less damage than several half hearted blows because once the centre separates, the force on it isn't acting on the spindle.

[Dancie]

Hello both,

Yes I did hammer the drive into the wood before I presented it to the headstock,

I was turning the outside of a green hollow form and to make sure, every now and then, I re-tightened and pushed in the tailstock as it is a large lump of cherry and no way did I want it to come off,

That has probably pushed it in too far, if thats possible,

I've googled, looking for suggestions, but wasn't sure which way to go, most say smack it hard but I wasn't sure if I would do damage to the headstock in some way i.e. the bearings,

One suggestion was to grip the drive with an adjustable wrench and pull it that way,

The last time it happened (10 months ago ish) I did finger inspect and all felt ok,

I've had the lathe for 3 years and its been, sort of, trouble free,

If, or should I say when, I get the blooming thing off I will certainly consider grinding paste a Morse tapper reamer has also been suggested to me,

Many thanks,

Dancie.

[Bryan Milham]

I'll add one thing. Most lathes come with a Knock-out bar not worth the effort. ¼" light steel, with a useless plastic knob on one end.

Get a length of 3/8” (10mm) Silver Steel, I've never had an issue moving anything from a 2MT, even one drive centre that was rusted in.

[seventhdevil]

bryan, the 3520b knockout bar is a proper tool.

dance i have the same lathe and have on occasion had the same problem usually when i've been using the MT in the lathe for a couple of weeks and it gets stuck in there.

get a sledge and whack it mate. i had to do that once and the bearings are fine on mine.


can i suggest that instead of the MT drive you use a chuck mounted drive like a stebcentre. i've been using that for years and i think it's better overall.

[Hartwood]

Try warming up the Spindle with heat gun or Hair Dryer.

[Dancie]

Hello all,

Many thanks for all your advice, its very much appreciated,

So, its now free,

I took Hartwood's advice and heated the headstock spindle with a hairdryer,

I then took Wood Spinner and seventhdevil's advice and hit the knock out bar with a heavy metal hammer, almost like being at a fairground, it took 2 blows and then it was free,

I'd used a nylon headed mallet previously, not wanting to damage the headstock in anyway,

My next step is to work out what to do next, there is scuffing inside the headstock spindle that I now need to address,

All the best,

Dancie.

[burywoodturners]

You have had some good advice on this, but note that seventhdevil left his in for two weeks, with centre drives and chucks, dont leave them on for any legth of time or you will get  the same again.
Plumbers have a wire brush shaped like a bottle brush, available from a DIY Shed near you. This is ideal for cleaning out the junk you get in the headstock.
Ron

[Dancie]

Hello Bury,

Many thanks for your input,

Personally I've never left a chuck or drive centre on the head stock, I always remove them at the end of the day or session,

I think the problem here is that there is slight damage inside the headstock spindle, how I correct this is my next problem,

All the best,

Dancie

[Derwent Woodturning club]

Hi Dancie,

I recommend all my students make a 'taper cleaner' to clean out any sawdust from the morse taper before inserting any drive centre. It is simply a long dowel that will pass through the full length of the spindle, with a longitudinal saw cut at one end that will take a twist of wire wool. Just push this through and you will be surprised at the amount of 'muck' that comes out.
Unfortunately this won't address any serious damage to the taper that is already there but, once you get that sorted, it might prevent a recurrence of the problem.

[The Bowler Hatted Turner]

Dancie your safest bet is to look at the RDG tools website, for about £15 you can get a morse taper reamer, this will clean the taper on your lathe and cut any lumps and bumps that have formed in it. The amount of metal you will remove will be minimal but it will allow your drive centre taper to seat itself properly in the future.

[Dancie]

Many thanks Derwent and Bowler and not forgetting dragonfly,

All input gratefully received,

I'm taking everything on board and its all very much appreciated,

All the best,

Dancie.

[Redtails4]

Hi
 I would not ream it for two reasons (1) the spindle may be harder than the reamer in which case you can kiss your
Your reamer good bye.
(2) if the spindle is soft then you could scrap it reaming it oversize.
Leave well alone keep the taper clean  and a smear of oil on the female taper.
I think someone on this forum has already suggested that you drive the centre into the wood  rather than wind than wind the center using the tailstock handwheel it's surprising haw much force you exert using the handwheel.

[Redtails4]

Hi
If your knockout bar is on the light side you can take off the plastic knob and replace it with a piece of steel say two inch in diameter by say three inches long good luck.