Autolock stuck drawbar won't screw in

Hi,

I am stuck at the first hurdle, the drawbar won't screw into the internal thread so im assuming its damaged and needs to be re-tapped. I have no idea what how the spindle/chuck/draw bar interface with one another.

There is currently an "s" Type autolock in the machine which i can't remove, but i don't know how it fits into the machine whether its by taper or screwed.

I've madfe an album but will try and attach some images when i can figure out how, if someone can assist it would be appreciated!

See below the images, which will hopefully help get some answers!

It's held in with a #2morse taper.

The thread is likely imperial

I have seen on other forums that that specific autolock is probably a 3/8" thread, however i have had no joy in getting a 3/8th threaded bar to screw in. Tried an M8 thread and that was too small, which led me to believe the thread was damaged.

I've seen other tips online about using a Jacobs Wedge to release the chuck however i was a bit uncertain as to what number wedge i should be using to release it, unless theres some other less conventional methods to releasing it?

If I remember correctly the drawbar thread is 3/8 whitworth, the large ring on the chuck should unscrew, it is supposedly a stiffening device but can also be used as an ejector by winding it up hard against the bottom of the spindle and giving it a good wallop.

If you can get a milling cutter into it then side mill a bit of scrap with no support under the tip for a few mm

The vibration will make it drop out (so only a few mm max clearance for safety)

The drawbar is to stop the chuck taper dropping out of the spindle under load which it will do if its not glued or welded in

I'd try a length of 10mm or 3/8" brass rod down the spindle, and a sharp tap with a hammer.

I would not be hitting the spindle of an FB2 (clone, by the look of it). Light duty parts & IIRC a "strange" bearing arrangement for the spindle and indeterminate parts situation - easy to damage something you may not be able to easily replace & when parts were available they were pricy.

If you got all the tools with the machine, there should be a thin sheet metal spanner to fit the flats on the end of the spindle nose - hold the spindle against rotation with the spanner & use a tommy bar in the support ring on the tool holder to jack the tool out of the spindle. It may well go with a bang, so have a piece of wood on the table to prevent damage when the tool is ejected. The drawbar should be axial restrained under the nut at the top of the spindle & this usually jacks the tools out. IIRC the original drawbar was M10 (actually an M10 socket head cap screw) - I can check when I get home if that helps.

Nigel B.

(who has a similar machine)

Hi, on my Emco FB2, the drawbar has an M10 thread on it.

But I agree with Nigel B's comments - not advised to resort to a hammer and drift.

I wonder if the MT chuck you have fitted has a 3/8th BSF or BSW thread - guess it depends on how old it is

Regards

Derek

The collar on top of the chuck is probably threaded with a fine pitch left hand thread. In use you are meant to snug it up against the face of the arbour to stiffen up the mt2 taper. You might be able to use it to jack the taper out,but try to get a proper Peg spanner rather than just a Tommy bar

You will be able to get a 12" (300mm) length of 3/8 Whitworth studding on ebay which is just under 10mm so the 8mm you tried wouldn't screw in. You might have been able to break the MT2 taper with the 8mm just by hitting the projecting end with a hammer. The thread on that collar with the tommybar hole in it is left hand.

Edited By old mart on 15/07/2021 18:43:10

Edited By old mart on 15/07/2021 18:44:24

I knew that I'd offend people's sensibilities with the suggestion of a drift and hammer. In my defence, the MT on my Raglan mill has suffered that treatment for the 60 or so years of it's life and it's still going strong.

British quality manufacture of course.

I generally use wedges (made on the mill), if more than a tap with a soft faced mallet is required, on my Raglan mill.

They can be very tight if pulled in by a gorilla or a cold cutter holder was fitted into a warm spindle. Worse, if both.🙁

Hi Michael,

It looks like your set up is an Emco mill. On mine to eject an S type Autolock I use a 5/16 rod 6 1/8 " long stepped at one end to 1/4" and inserted reduced end down then use fine threaded nut to eject.. To hold the Autolock , I have created an extension female- male, looks like 8mm female to 3/8"w/w male (but would check that) over al l7/8 male.so that I can use 8mm draw bar.

Will try to add photos later.

Nimble Neil

The clarkson i have is a 10mm thread. There was a thread on here not long ago with a guy who could not get one to come out. I think he ended up making 2 wedges slid in between the quill face & the clarkson. A wedge from each side. .Apparently it worked.

Steve.

Just want to say thank you for all your comments, going to have a go at a few things this weekend and see if I can get it loose. Would have saved me a whole lot of research time if I had just posted here in the first place instead of spending a few weeks trying to figure it out in my own!

Hi Michael,

Duncan has just reminded me of the method that I now use . I have a 32mm spanner machined down to 3mm thick which goes on the nose of the quill and using a "C" spanner in the dampening ring of the Clarkson (as Duncan mentions and from memory a left hand thread) you can eject the chuck easily. Use a cloth for the chuck to drop onto to avoid damage to the chuck. Best of luck.

Regards,

Nimble Neil

Giving the tool holder a twist, while under pressure, can facilitate ejection, too. Someone I know expounds twisting as the only means of removal, Not tried it myself since being told of his method - but he tightens and he loosens (so no gorilla involved).🙂

Michael, the Emco has a self ejecting mechanism for the MT2 tooling, it uses the draw bar and the small cap in photo 1. The draw bars are Allen screws and with the black cap in place you unscrew the draw bar until it comes to the black cap then continue to eject the taper.

I appreciate you say the thread is damaged so maybe you cannot use this method, however the type of Clarkson chuck you have has a stabilising collar that is threaded onto to body of the chuck, during use it should be snugged up to the spindle face. You MAY be able to use this feature to release your chuck by using a spanner [supplied with the machines] on the 2 flats on the spindle and a tommy bar in the Clarkson chuck collar it will hopefully eject the chuck --- put something under it to stop it dropping onto you mill table !!

Hope this helps John

PS PM me with you email if you want a copy of the instruction book page, look in my albums at Clarkson Autolock

Looking at the gap in the photo, and knowing that the ring can be screwed up and down, I would try a pair of motorcycle tyre levers. A block of wood placed underneath to limit the sudden movement to about 1/2" when the taper breaks would prevent any damage. The thread seems like being a choice of 10mm and 3/8 Whitworth. Tom Senior mills with MT2 definitely used 3/8W.