Chuck and taper nomenclature

[Roger Davies 4Participant @rogerdavies4]

I have a Record Power drill press, inherited. One of the jaws in the chuck is damaged so I need to order a replacement chuck. The arbor is a morse taper with a marking 2J6. The chuck itself is marked 2.5 x16 PURTA 3/32 – 5/8 J6 S3 I’m assuming the arbor is permanently attached to the chuck. I don’t understand chuck or morse taper nomenclature. What do I order as a replacement and where is best to get it?

[Roger Davies 4Participant @rogerdavies4]

Understanding nomenclature to order a replacement chuck

[old martParticipant @oldmart]

Starting with the chuck, it would seem to have a J6 taper inside the body. This is like a very short Morse taper. The chuck is a common size, 16mm /5/8" the maximum drill size it can hold. The 2.5 (mm) and 3/32" is the size of the smallest drill it can hold. The long taper will be likely MT2 or MT3. the chart will give you an idea of the exact size.

**LINK**

[SillyOldDufferModerator @sillyoldduffer]

It's unlikely the chuck is permanently fixed to the arbour, but it might be jambed and as it's is likely to be worn or damaged I'd junk the whole lot.

What's "best" depends on how deep your pockets are! Most of us start by demanding top-end professional gear and run away when we see the price! I favour mid-range gear from the likes of ArcEuroTrade.

What you need is an arbour, about £7, probably with a Morse MT 2 taper on one end, and a taper to suit the chuck on the other. Chucks come with various tapers, JT6 being typical for the 16mm size.

I prefer keyless chucks and ArcEuro sell a 16mm J6 heavy duty keyless chuck (part 040-011-00016) for £30, but it's currently out of stock. They also sell a range of arbours, including MT2 to JT6. Other vendors available

JT, 'Jacobs Taper' are designed to grip firmly, and have to be released with wedges. MT are an early quick-change tool system and the taper is designed to eject from the machine without fuss. The variety is to keep us amused. BT do the same job as JT, but the angles are different. It doesn't matter provided the chuck fits the arbour and the arbour's other end fits the machine. The marking 2J6 strongly suggests MT2 and J6, but use Old Mart's table to confirm MT.

[Swarf, Mostly!Participant @swarfmostly]

Good afternoon, Roger,

If the chuck is a genuine Jacobs item, you ought to be able to buy a repair kit. That will contain a new set of jaws. Using a repair kit, provided you ensure that it is for the actual model of chuck, gets around the business of identifying the taper because you'll be putting the same body back on the drill-press arbor.

The prospect of fitting such a kit may seem a bit daunting but there are several 'how-to' videos on the net. Your search engine ought to be able to find one or two before you commit yourself.

I fiited a repair set once, to a Jacobs ½" chuck. You do have to 'hold your mouth right' but it wasn't too difficult.

Best regards,

Swarf, Mostly!

[Clive FosterParticipant @clivefoster55965]

Roger

An arbor marked 2J6 would normally be assumed to be a J6 on the end that goes into the chuck and MT 2 on the other. Readily obtained for £ not too silly from all the usual suspects.

However

Taper mounted chucks can be removed from the arbor fairly easily. Proper tool is a brace of extractor wedges but drilling a hole in the back of the chuck from the inside so you can get a parallel punch in to knock it off works just fine. Hole size is whatever will take your punch, within reason. I use a 5/16 hole 'cos when I first did it the most suitable pin punch in my (then) small collection was 1/4" and I've stuck with what works ever since.

My habit has been to so drill new chucks before fitting so I can shift them easily if need be. I also believe that having a hole at the end lets the air out as the taper goes home giving a more secure hold.

I fit chucks by initially carefully cleaning both arbor and chuck then sliding them gently together so that theya re aligned. To get the proper fit I hold the arbor vertically, chuck uppermost, and sharply rap the tang end of the arbor on something solid a couple of times. The momentum of the chuck drives it on firmly. Done right it won't fall off. Actually it will be a total PIA to shift, last new pair I did needed my 12+ ton hydraulic press to separate when I wished to change the arbor from MT2 to MT3.

Everything self aligns with no risk of pushing it together skew-wiff as can happen if using a press or vice. Pressing in a vice as some may suggest is just to dangerous in my eyes as its almost impossible to get dead nuts aligment and bench vices are designed with considerable float in the jaws so they can adapt to thngs that are less than parallel.

My rapping block is a piece of steel about 2 inches thick by areound 5 inches nearly square. There is a U shape cut out about 1 inch diameter by perhaps 1 1/4 inches long halfway down one side. Nothing magic about the numbers but its very handy to have something with decent mass and the inherent inetrial solidity for rapping things on or punching things apart.

Clive

Edited By Clive Foster on 26/11/2022 16:05:53

[Roger Davies 4Participant @rogerdavies4]

Thanks all, so it appears it is an MT2… I appreciate all the advice, and I have more choices than I realised, namely by a repair kit and fixing the jaws, buying a chuck and fixing it to the arbour I already have, after removing it, or buying a chuck and arbour together. Thanks all for your time and effort.

[old martParticipant @oldmart]

With a standard keyed chuck, I back off the jaws and drill through the thin wall between the body and the end of the arbor. Then a drift can knock the arbor out of the chuck, much easier than wedges. The arbor can be used again with a new chuck if the main Morse taper if not damaged, most 16mm chucks will say J6 or JT6. In your first post, the code on the arbor, 2J6, looks like 2 Morse taper and 6 the size of the chuck end.

[Tom SheppardParticipant @tomsheppard60052]

It is not too difficult to strip the chuck down and you may be able to stone the damage out if it is not too badly damaged. Tightness of fist (or thrift, to give it its proper name) is a key qualification for model engineering.

[Roger Davies 4Participant @rogerdavies4]

Thanks, all. One of the jaws was fractured, not worn. I’ve decided to splash for a new chuck and arbour, to get me going again. In due course, I’ll remove the old arbour from the old chuck in case it might be of use at some point. Who knows, I may try jaw replacement in the future. I appreciate all yiu answers, thank you. As a beginner in this game its remarkable helpful forum members are.

[HopperParticipant @hopper]

Posted by Roger Davies 4 on 26/11/2022 15:14:29:

…The chuck itself is marked 2.5 x16 PURTA 3/32 – 5/8 J6 S3…

I don't think you will find parts for a Purta brand chuck these days so you might as well toss it.

Plenty of new chucks available already assembled with a Morse 2 (MT2) taper in place.

[Clive FosterParticipant @clivefoster55965]

Roger

With a fractured jaw repairing the chuck is almost certainly not worth the effort. That said I'd probably take it apart when I had a few spare minutes out of sheer interest and as a practice run l should I ever need to do one for real.

Absolutely do remove the arbor tho' ready to mount a second chuck.

A 3/32 to 5/8 chuck is rather bulky and a second, smaller chuck is often more convenient to use. Lots to be said for having a 0 to 3/8 or 0 to 10 mm as your main chuck and only slotting the 3/32 to 5/8 one in for larger holes. Although 1/2" is usual on pillar and bench drills there have been many times when I've ben glad to have the extra capacity that 5/8 brings.

If I were forced to thin down to two drill chucks that is the pair I'd keep even though I have more 1/2" chucks than any other size. Partly for historical reasons and partly because 1/2 is the standard size I have for my lathes. The drill and mill also came with 1/2" ones and I expanded to other sizes one at a time as needed or when opportunity knocked. I think there are 10, maybe 12, drill chucks in total about the shop!

Clive

[old martParticipant @oldmart]

I agree with Clive about having more than one chuck. A replacement 16mm chuck will not be able to hold drills under 2.5mm and would not really be happy with drills under 6mm. The ability of a smaller chuck to hold, say 10mm down to the smallest you have is helped by the chuck body being much smaller, it won't get in the way so much. A 10mm size would need an arbor to fit, the joint between the chuck and arbors is not meant to be disturbed during the life of the chuck.

[Roger Davies 4Participant @rogerdavies4]

thanks for the continuing advice.

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