Progress 1S Pillar Drill Jacobs 34 Chuck

Our club workshop pillar drill really needs a new chuck. Weve got a keyless jobby in mind but need to get the existing chuck off the spindle.
The Progress 1S spindle has a neat slot, right through the spindle, and just above the chuck. Below that is a round knurled nut that can be screwed down, presumably to help with chuck removal. We just cant understand what the slot is for. Its about wide and high, and theres what looks like a block of steel full-width across the bottom. Can anybody clarify please? Im anticipating that the mount is probably going to be JT6. Its evident that considerable BF&BI is going to be needed to free the taper. Id guess that its been on there for 50+ years. From the state of the round nut its evident that others have been there before us! The existing chuck simply says its a Jacobs 34. Current-day Jacobs numbers have a suffix which identifies the mounting taper e.g. 34-06 for JT6. Weve got a pair of wedges but initial trials indicated that a force greater than we could apply from a big toolmakers clamp would be needed. Any thoughts? Geoff Johnson
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Andrew Mawson wrote:

It might sound like it Andrew, but it ain't! The slot's only an inch or so above the chuck. This model definitely doesn't have the modern, technological advancement of a MT drill hole. G
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Geoffrey Johnson wrote:

I think we need a picture. All the progress drills I've seen have an ejector slot. The advent of a JT extension on the end of the spindle is (to me) a modern embuggerance seen on cheap chaiwanese drills. Intruiging though! Bob
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On Sun, 17 Aug 2008 17:48:23 +0100, Bob Minchin

Funnily enough I've just been through the same exercise, more or less - trying to make a better drill from a goer and a less worn non-goer. The older one did indeed have a slot and it was/is for MT ejection. The somewhat later one (1960's ish) doesn't have a slot and after considerable head scratching the chuck was eventually removed and does have a JT6 nose to the solid quill and a knurled collar with a tommy-bar hole to remove the chuck. I'd guess the slot on the one in question is for stopping the quill rotating while walloping the collar tommy bar with a beating stick.
Where I went wrong was thinking that the collar would remove a MT from the quil so I was screwing it the wrong way Doh! obvious once it's all apart, but not so when you've got one that _is_ like that on the bench and this one refuses to budge.
The initial intention was simply to swap the quills since the old one is presumably slightly bent as it orbits a little - useable, but irritating. Not possible, although externally the two drills look near identical, the quills are different dias. and different chuck fitings. OK so swap the whole head, got to swap a 1ph for a 3ph motor, but not the end of the world. NO.... Another twist is that the old one has a 2.750" pillar the later one has some cock-eyed size approx 69.6mm (about 015" below the older one) so swapping the whole head wasn't possible. Ah OK thunk I, swap head and pillar, but then the table doesn't fit and the pillar is loose in the base.
In the end and by a staggering coincidence I had a bit of 2.750 bar recovered just a month ago from a horizontal mill I scrapped and near enough the right length. So I turned the top 8 1/2" down by 015" so the 'new' head fits at the top and the original table and base are all OK below. What a palava for what looks like a hours tinkering before lunch......
Richard
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To solve this problem on my old pillar drill which did not have a Morse Taper and ejection slot, I dismantled the spindle from the quill, set the spindle up in the lathe using a 3 jaw steady and drilled a hole through the back of the chuck and tapped it for some suitable size (M6) and used a suitable capscrew to push the chuck off. I now predrill keyed chucks before fitting them on arbors. This works well for keyed chucks but not for the albrecht pattern keyless models.
Alan
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The Jacobs 34 chuck comes in at least two forms of mount, the JT taper mount and a threaded mount. The threaded mount is a female 5/8 X 16thread. The chuck body may also have a locking screw through the centre of the body.
To find out if your chuck is of the threaded type look for the model number, if it is 34B and stamped under the opening sizes is 5/8 16, it is a threaded mount.
If either threaded or JT mount, the slot in the spindle may be for a bar to be used to hold the spindle while the chuck is removed.
These mounts can be a real sod to undo, both screw and JT mounts. A JT mount number 34 chuck which wouldn't come apart with kindness so I pressed the chuck apart leaving the body on the mount,drilled a hole through the centre, made a ram, put the chuck in a manual press, heated the body with a blowtorch until it came apart - with a loud bang!!
Good luck!
John
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Alan Bain wrote:

Thank you both Alan, John and the earlier responders. The chuck, as I orignally said is simply marked `Jacobs 34'. Nothing else other than its Hartford Connecticut place of birth and the size 0-1/2". The cross-slot in the spindle is almost filled up with a recangular block that will slide just a bit from side to side. There is no longitudinal hole above the slot and it's all way too close to the chuck to be MT related. Four knowledgable club members looked at it on Monday evening but none could shed light on the assembly. We decided it's almost certainly a Jacobs taper and definitely a wedges job. Just need to work out how to apply the appropriate force without damaging the important bit. I've taken pics but got nowhere to post them. If you're interested in a butcher's, mail me on geoff(at)johnsonlb(dot)plus(dot)com and I'll gladly send them. Geoff
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Having looked at a Jacobs 34 chuck in my workshop, I think M10 looks like a more suitable size to tap the hole. It was a Jacobs 32 which I tapped M6 for removal.
The main thing to watch if you go the drilling & tapping route is not to damage the centre in the spindle in case you need to put the spindle between centres e.g. to clean up the taper. Clearly there should be a gap between the back of the chuck and the end of the spindle, but care is still needed.
Alan
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Alan Bain wrote:

Thank you both Alan, John and the earlier responders. The chuck, as I orignally said is simply marked `Jacobs 34'. Nothing else other than its Hartford Connecticut place of birth and the size 0-1/2". The cross-slot in the spindle is almost filled up with a recangular block that will slide just a bit from side to side. There is no longitudinal hole above the slot and it's all way too close to the chuck to be MT related. Four knowledgable club members looked at it on Monday evening but none could shed light on the assembly. We decided it's almost certainly a Jacobs taper and definitely a wedges job. Just need to work out how to apply the appropriate force without damaging the important bit. I've taken pics but got nowhere to post them. If you're interested in a butcher's, mail me on geoff(at)johnsonlb(dot)plus(dot)com and I'll gladly send them. Geoff
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