Jacob's chuck drawbar question

[Rodpr]

I have had problems trying to use my MT2 mounted Jacob's chuck to hold small items for sanding on the lathe (with chuck mounted in drive). I have the Axminster 13mm MT2 B16 chuck and realised I could replace the arbour with a tapped one, to allow me to fit a drawbar (only £6.95 from rdgtools.co.uk).

But then I asked myself, might this just move the problem from the morse fit between lathe and arbour to the B16 fit between arbour and chuck? Or is the arbour/chuck fit less prone to shaking loose (I have never experienced this)?

Does anyone have experience of using a drawbar with a two-taper arbour (MT2 and B16)?

I have attached pictures of my current arbour and the rdg one (though I suspect their image may be of a MT3 B16).

 

[scooby]

It’ll be fine, I’ve used a jacobs chuck in my lathe for sanding and polishing a lot, probably more than actually drilling. Never had the Chuck work loose off the arbor. A while ago, i swapped the Chuck off my cheap pillar drill and it was quite difficult to remove it off the arbor.

By the way, I just a threaded rod with a knurled bolt and washer as a drawbar

 

[Phil Pascoe]

Mine does work loose I do use a drawbar, as said just a threaded rod, washer and wingnut. Mine's MT2 - JT6

 

[ChaiLatte]

You have to work very hard to separate a chuck from its arbor.

You can increase the grip if you are worried by making sure both parts are surgically clean and putting the arbor in the freezer and chuck in the airing cupboard before rapping them together with a rubber mallet.

Your drawbar will work a little better if it is centralised in the spindle at the opposite end to the chuck. A wooden or plastic oversized Polo mint is more than good enough to do this.

 

[Rodpr]

Many thanks everyone - great advice as always!

 

[Richard_C]

As above, mine has worked loose once in 4 years, nowhere near as dramatic as an un-drawbar one flying out, and I did the freezer thing when reassembling, no trouble since. The centering 'cup' is useful and makes it easier to access the securing nut, you have a lathe, you probably have wood offcuts, so you have a tapered insert in very few minutes. No offcuts? Take an inch off the rolling pin, nobody will notice. (I needed some spacers. 3 weeks later during Scone making "is this rolling pin shorter than it used to be?" "Dunno, can't imagine they shrink...")

 

[J-G]

Take an inch off the rolling pin, nobody will notice. (I needed some spacers. 3 weeks later during Scone making "is this rolling pin shorter than it used to be?" "Dunno, can't imagine they shrink...")

Then it's time you treated 'her' to a decent MARBLE rolling pin - there isn't a better one !!

 

[Phil Pascoe]

I have a wooden one, a glass one and a marble one. The wooden one's used, the other two aren't.

 

[Richard_C]

Wooden rolling pins have met our needs for nigh on 3000 years. Most people, even those of advanced years and with arthritic wrists can use one. We know this. I keep meaning to make a French style rolling pin.c 15 mm dia at the ends, 45 in the middle and nicely curved as a spindle turning exercise. Will probably start with an inexpensive ordinary one as I don't have any long beech spindles at the moment. This is of course way off the original topic so I will stop now.

 

[Phil Pascoe]

I make French pie pins and pins like this one for friends who have arthritic wrists (I use this one) -

 

[Rodpr]

Ordered tapped arbour from rdg tools on Friday and it arrived today!

 

[Rodpr]

And now I see why the old arbour was breaking free. Time for a thorough clean out!

 

[Chief Sawdust Maker]

Morse taper arbours shouldn't be used with a draw bar as they are drive tapers, they should be clean and any blemishes or dings addressed with a stone.

Draw bars should only be used of drive tapers for location purposes of the taper with the drive being provided by the dogs on the spindle aligning with the cut outs in the chuck as usually found on milling machines etc.

D

 

[ChaiLatte]

Draw bars should only be used on drive tapers for location purposes of the taper with the drive being provided by the dogs on the spindle aligning with the cut outs in the chuck as usually found on milling machines etc.

If you read his original post, he is using a Jacobs chuck to hold items for sanding. Hence, there is side force on the chuck and taper, exactly like in a milling machine and precisely why he needs the drawbar to stop the arbor coming loose.

 

[Chief Sawdust Maker]

I have read the original and stand by my original comment
The taper on a milling chuck is purely for location and not for drive
A Morse taper is not designed for for sideways force a safer way would be to mount a Jacobs chuck in the usual lathe chuck particularly as if small items are being worked then high spindle speeds are likely

D

 

[Phil Pascoe]

... a safer way would be to mount a Jacobs chuck in the usual lathe chuck ...


odd.

 

[niall Y]

I have to be naive and ask the obvious question. If Morse tapers are not meant to be used with a draw-bar, then why do some come with internal threads?
Surely, any Morse taper drive on a wood-lathe, is subject to sideways force, even during normal spindle turning operations. In the OP's case using a draw-bar will just be applying force to hold the taper in position, which would normally be supplied by the tailstock.

Or am I missing something here?

 

[J-G]

Or am I missing something here?

Not in my opinion

 

[Lefley]

I have a wooden one, a glass one and a marble one. The wooden one's used, the other two aren't.

I agree. Marble rolling pins are for the aesthetically aware And laminated dough enthusiasts. They are really only good as a show piece and making puff pastry, as you can cool the marble first. And they are really heavy, and if you drop on ceramic floor or marble countertop, they just got more expensive!

 

[chaoticbob]

Not in my opinion

Mine neither. Morse tapers have long been used in milling machines - the Centec 2B to give one example is a light industrial machine equipped with an MT2 female spindle bore.
Because Morse tapers are self-retaining they have to be removed from the spindle by force. Sometimes quite a lot - my metalworking lathe has an MT5 spindle and I need an 'anti-drawbar' to get fixtures out. Or a sledgehammer I suppose, but I don't want to knacker the bearings! Tapers such as Bridgeport's R8 aren't self-retaining so they just drop out (ideally!) when drawbar tension is released. That's obviously more efficient in an industrial setting when tooling needs to be changed quickly. The principle is the same though - the toolholder is registered by the mating cones and torque is transmitted by friction between the conical surfaces. The pin on R8 type spindles is there to prevent the fixture rotating while the drawbar is tightened, not to transmit torque.
Anyhow, of little use to the OP I know, but it's difficult to pass over stuff which seems clearly wrong without commenting.
Bob.