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Fobco star chuck question

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Ed Muddeman23/12/2018 12:40:39
6 forum posts
5 photos

Hi all,

i recently picked up a fobco star drill and need some advice on removing the chuck i want to replace. I fell like my drill is missing the knurled ring that winds down to push the chuck off the taper, can anyone confirm this from my photo?

if so, what is the best way to remove the chuck? wedges?

and does anybody know what size JT my drill is?

thanks in advance20181222_111319.jpg


Clive Brown 123/12/2018 13:39:26
229 forum posts
6 photos

My Fobco has a JT6 taper, which is perhaps the most common type. It doesn't have the threaded section as in your photo. I suspect that's unusual. Your chuck is unlikely to be original IMHO.

Wedges are probably best for chuck removal, though in the past I've found that using the machine for end milling is also effective.smiley

Just read on the Lathesuk website that JT33, which is slightly smaller, was sometimes used

Edited By Clive Brown 1 on 23/12/2018 13:42:01

Vic23/12/2018 15:47:52
2040 forum posts
10 photos

Yes agreed about the chuck, that doesn’t look anything like original equipment for a Fobco. When they have Knurling like that it’s often a threaded chuck.

Ed Muddeman23/12/2018 16:58:25
6 forum posts
5 photos
Just had another go and I had no luck removing it by unthreading, if it is threaded that is. Is it possible my drill has a different spindle then? Or does it look like the original spindle but missing the knurled ring, I'm assuming that is what threads on above my chuck.
Ed Muddeman23/12/2018 22:51:49
6 forum posts
5 photos
So it turns out the chuck has a female 1/2" x 20 thread in it. Can anyone confirm if drill chucks have a standard thread or a left hand thread?
Chris Trice23/12/2018 23:03:27
1360 forum posts
9 photos

Standard right hand threads or the action of drilling would undo them.

Michael Gilligan23/12/2018 23:46:47
13057 forum posts
570 photos
Posted by Ed Muddeman on 23/12/2018 22:51:49:
So it turns out the chuck has a female 1/2" x 20 thread in it. Can anyone confirm if drill chucks have a standard thread or a left hand thread?


Presumably 'turns out' means you have found a documentary reference.

As Chris says, right hand thread is standard ...

But, if you are having difficulty removing it: Have a look up the spout ... There could be a lock-screw inside, and that would have a left hand thread. [common on portable tools]


Chris Trice24/12/2018 00:09:45
1360 forum posts
9 photos

That chuck looks to me very much like a Bosch hand held power drill chuck (cheap replacement) and definitely NOT what would've been on there originally.

Ed Muddeman30/12/2018 14:55:40
6 forum posts
5 photos


Bit of an update, my spindle was threaded, which i found odd as i cannot find any other examples of fobcos with 1/2" x 20 threaded spindles on the internet. But anyway I successfully removed the chuck.

Whilst on the subject of the fobco star drill, can somebody with one please post a photo of the depth gauge dial that covers the quill return spring disassembled?

I am not sure if mine is missing something behind the dial. With the nut all the way on the dial has about 3mm of play between the nut and the quill spring, therefor there is obviously no friction. What creates the friction to turn the dial?

Vic30/12/2018 16:12:08
2040 forum posts
10 photos

Looking at this **LINK** Fobco never made a drill with a 1/2” x 20 Spindle nose.

I’m guessing your machine has a morse taper arbor in it with a threaded nose. If that’s the case you should be able to eject it and fit an arbor of your choice?


Howard Lewis30/12/2018 16:53:54
1917 forum posts
2 photos

All the 1/2 x 20 threaded chucks that i have come across have had a c ountersunk head L H thread scdrew inside, to prevent unscrewing when revers rotated. Also, this thread is a relatively recent useage, (A F A I K) and suspect that the Fobco possibly predates it, so there may be a MT adaptor in the quill. Can you access the top of the quill, to try drifting it out?


Ed Muddeman30/12/2018 18:19:40
6 forum posts
5 photos

There is no hole to drift out an arbor on the quill. I have removed the pinion but still cannot remove the quill by pulling it downwards. It is stopping against something on its furthest projection.

Here is a photo of the depth gauge dial i mentioned, as you can see it has movement with the nut all the way in, can anyone confirm if there is meant to be something behind the dial that provides the friction?



Clive Brown 130/12/2018 18:44:25
229 forum posts
6 photos

Under the dial is the main spring, a plain washer 1.25" x 0.5" x 0.65" thick and a spring washer of  0.75" bore which locates on the OD of the dome nut. This washer provides the friction to set the dial, it's 0.023" thick and is curved only in the one plane if that makes sense.

I wonder if someone has made and fitted a non-standard quill to your machine.

Edited By Clive Brown 1 on 30/12/2018 18:55:01

Edited By Clive Brown 1 on 30/12/2018 18:57:29

Clive Foster30/12/2018 20:06:26
1702 forum posts
46 photos

Something very odd going on there. At first glance that short piece of larger thread looks about the right size to be the 1.25" x 12 tpi nose thread used on the Type D spindle to hold Myford style MT2 collets with a Myford end cap to close them.

Picture of a type D spindle complete with arbor removal slot close to the bottom of the the page linked to by Vic.

I have encountered an MT arbor with a 1/2 x 20 thread on the end. Well made. Whether all factory or shop made from a blank end arbor I know not.


Edited By Clive Foster on 30/12/2018 20:09:30

JohnF30/12/2018 20:24:59
807 forum posts
88 photos

My Thoughts --- From what I can see on the photo's I don't think the larger thread is 12tpi it looks little different to the 1/2" 20 tpi in pitch, maybe its for a missing extraction nut assuming the spindle does have a Morse taper ? Never having or used a machine of this make I may be wrong but it seems illogical not put a drift slot in the spindle unless of course it has insufficient travel to expose said slot then a threaded extraction on the end of the taper would be used ?

The thread is almost certain to be 1/2" x 20 UNF this seems to be the standard thread on power tools.

Vic30/12/2018 20:26:34
2040 forum posts
10 photos

I’ve got a small Rohm chuck that’s threaded. I had no trouble getting a morse taper arbor for it. No idea of the thread though.

Ian P30/12/2018 21:59:02
2088 forum posts
89 photos

I does look like someone has fitted a non Fobco spindle but have you checked that the quill barrel has a Morse taper removal slot.

If you fully extend the quill there should be a slot where you will see the spindle, which should also have a slot to accept the wedge drift.

Ian P

Mike Poole30/12/2018 23:38:11
1922 forum posts
46 photos

I would hazard a guess that someone has remachined the spindle nose from the original Jacobs taper to the chuck thread you now have. If the screw on chuck is satisfactorily true running then it may be easiest to stick with it. To return the machine to standard is going to require a new spindle or build the old one up and remachine or even make a new spindle from scratch. If you want a really nice chuck Albrecht make ones with the 1/2x20 fitting as do Jacobs and Röhm so plenty of choice if the nose register is accurate.


Edited By Mike Poole on 30/12/2018 23:46:38

Ed Muddeman04/01/2019 23:06:48
6 forum posts
5 photos
Thanks all for your advice. For ease I stuck with the existing spindle and bought a Jacobs 33BA chuck for the 1/2 x 20 mount.

I am struggling to source a 3/4" ID disc spring washer that goes with my depth gauge. I have also tried Tony at lathes UK with no luck. Does anyone have a spare lying about I can purchase?

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